Date: Thu, 2 Jan 1997 15:32:09 -0500 From: INFINITY Aerospace <72124.347@compuserve.com> Subject: COZY: Cooley Hat and 4-Way Trim Switch Hi Steve, >Steve Wright here---I need the "cooley hat" switch you put on your stick grips. Where can I buy one .......can you sell me one. How does it work?< I take it you are going the purist route (building your own grip - send me pics when you are done for my scrap book). The switch I use is a 4-way switch, momentary in all directions, and springs back to the center, just like the $100 to $200 dollar mil-spec switch does, except my switch is good for 500,000 activations. The mil-spec switch is good for 100,000 activations. Also, this type of switch movement cannot get stuck under a surface causing run-away trim emergency situations like other trim switches on other attempts at making stick grips have. It takes 40 ounces of force to move the mil-spec switch in any direction, a little too hard for our small airplanes - Burt thought so too (you'll probably move the stick when all you wanted to do was trim the plane). My switch is only 11 ounces of force in any direction, a nice lite touch. The cooley hat itself is the same size as used on the mil-spec grips, but the steps making the hat are "V's" on my cooley hat, not just steps. So my cooley hat bites into your thumb a little better, instead of your thumb possibly slipping off the cooley hat when trimming. I can send you a switch and cooley hat for $10 total, plus shipping and handling - about $3, plus tax (if applicable). HTH. Infinity's Forever, EAA Member EAA Technical Counselor JD EAA Flight Advisor AOPA Member Test Pilot James D. Newman, President LCDR F-14 USNR INFINITY Aerospace Mailing Address: P. O. Box 12275 El Cajon, CA 92022 Shipping Address: 1750 Joe Crosson Drive, D-2 El Cajon, CA 92020 (619) 448-5103 PH & FAX 72124.347@compuserve.com OR INFINITY_Aerospace@compuserve.com Home Page http://ourworld.compuserve.com/homepages/INFINITY_Aerospace Date: Fri, 10 Jan 1997 14:48:02 -0500 (EST) From: AlWick@aol.com Subject: COZY: el cheapo strobe Been looking for alternatives to some of the expensive items for my plane. Found portable strobe at a marine supply store. It's intended to attach to your life vest, powered by three AA batteries (which last 24hrs reportedly). I tried it at store, still seeing spots in front of my eyes. $60 I would consider adapting it to aircraft power supply, or could keep it stock and power remotely with batteries in cockpit. I would make it readily accessable in case of replacement need. Would appreciate any comments. -al Date: Wed, 25 Jun 1997 07:34:38 -0400 From: David Domeier Subject: COZY: Master Relay Temperature I=92ve noticed, in the process of wiring my MKIV, that the master solenoid (Wicks part number 70-111226-5) gets very warm after about 5 minutes when closed. In fact, I will go so far as to say it gets hot to touch. If some of you all don=92t mind, how =91bout checking your master relay = for temperature. I=92ve talked to shop mechanics and no one seems to know ho= w warm a master relay should be. I have a second relay on hand and in bench checking it with a battery charger, it gets just as hot as the one in the airplane. Thanks. dd ps As far as I know there's only one way to hook up a master relay, battery to the battery pole and ground switch to the small lug. Date: Wed, 25 Jun 1997 18:25:22 -0400 From: Jim Hocut Subject: Re: COZY: Master Relay Temperature While I've never laid my hands on an aircraft master relay after it's been energized for a while, I am a EE and have used a relay or two in my work. It's just the nature of the beast, they get warm (sometimes quite warm) after being energized for a while. The coil has some small resistance, so you're producing several watts of heat while it's on. -- Jim Hocut jhocut@mindspring.com Date: Tue, 1 Jul 1997 10:44:09 -0400 (EDT) From: CozyBldr@aol.com Subject: COZY: Canopy & Wayne's Breaker Panel I'm presently building the canopy and I've noticed that there is not much room forward of the instrument panel under the plexi itself. I'm planning on using Wayne Lanza'a breaker panel but I saw one a few years ago and I seem to recall it being larger than the space I have under the canopy. Has anyone else installed the panel and did any problems arise from not enough space? Thanks. Paul Stowitts Cozy Mark IV #200 Date: 01 Jul 97 22:58:14 EDT From: "Edmond A. Richards" <103235.1336@compuserve.com> Subject: Re: COZY: Canopy & Wayne's Breaker Panel Paul, I have Wayne's breaker panel installed and it fits perfect under the canopy. I had the same concern while building the canopy so I wrapped the breaker panel in plastic and installed it in the instrument panel during the building. There is very little space but it all fits. I also left the unit in place while I made the small cover that must fit over top of the instrument panel and provide the space to house it. Ed Richards Cozy Mark IV #088 Date: Sat, 05 Jul 1997 10:04:10 -0400 From: David Domeier Subject: Re: COZY: Canopy & Wayne's Breaker Panel Paul, I just completed installing mine and it has about an inch of clearance to canopy. dd MKIV #155 From: Marc J. Zeitlin Subject: COZY: canopy, nose gear, throttle switch circuit Date: Wed, 20 Aug 97 17:03:06 EDT People; Well, we're going to buy a house with a 2-car garage so that I can get the dang plane out of the basement and assemble it. However, it won't be finished (the house, that is) until March at the earliest, so I'm spending the next six months installing random little stuff, like the electrical system and the instrument panel :-). At any rate, while studying chapter 22 for installation of the warning buzzer/light circuit for the canopy/gear/throttle, I've become confused (not being an E.E.). I can understand the logic of the three microswitches, and the function of the wiring for the warning buzzer and light, and I understand how the momentary push button turns off the buzzer while leaving the light on _WHILE THE BUTTON IS DEPRESSED_. What I don't understand is how the circuit latches so as to keep the warning buzzer off, while leaving the light on. Does the relay have an internal latching circuit? Am I missing something in the wiring diagram? Why wasn't this implemented with cams and gears - then I'd understand it :-). Is this some special type of relay that's used (heck if I can find "Colectro" relays anywhere) - does someone have a source for these things - Digikey, Mouser, Radio Shack?. Thanks in advance for the electrical tutorial. Also, I've purchased Bob Nuckolls' $35 book on aircraft electrical systems (discussion ongoing in the canard-aviators mailing list, and web page at http://www.aeroelectric.com) and it has a wealth of incredibly useful information regarding electrical systems. Bob also sells many useful items from his web page - check it out. P.S. - I've got my instrument panel laid out in my CAD system. I can make a DXF file, if anyone's interested - I've got the standard 3-1/8" and 2-1/4" instruments at true size, and the radio stack at the correct width (height is dependent on vendor). I've got the air vents that Nat recommends in place as well. I'm assuming all non-electronic instruments at this point (no $3K Vision Microsystems stuff), and it's amazing what you can pack into one of these panels with a little judicious shuffling, and with assuming that the fuse block and/or breakers go behind the panel, rather than in it. If there's enough response, I'll put it on the web pages and make it available for email download, but it's a work in progress at this point - it changes every few days. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Wed, 20 Aug 1997 19:34:25 -0700 From: Michael Antares Subject: COZY: canopy, nose gear, throttle switch circuit Marc, I'll attempt to answer your question about the circuit: Simply put, the relay is held latched by a rather convoluted path which starts at the ground connection located to the right of the push button (this is symbolized by the three decreasing length horizontal short lines--this is the return path of the 12V battery). This ground path goes to the "c" (common) connection of the throttle micro switch which will connect to the "nc" (normally closed) contact when the throttle is advanced and then to the "nc" contact of the canopy switch and to the "c" contact of the switch when the canopy is not locked. From this "c" contact it goes to the "c" contact of the relay and then to the "no" (normally open) contact (the relay has been energized by the push button). The relay "no" contact goes to the lower side of the relay coil and this will keep it energized since the top lead is going direct to 12V. The relay will be released by locking the canopy or closing the throttle. You can follow a similar path in regards to the gear microswitch. I hope this helps... Michael 6077 Old Redwood Highway Penngrove, CA 94951 707.792.7971 Systems engineering hardware/software Date: Wed, 20 Aug 1997 19:37:22 -0700 From: Michael Antares Subject: COZY: canopy, nose gear, throttle switch circuit A short PS: No, this is not a special relay. Almost any 12V DC relay will work as the contacts only need to carry the horn current (check the horn operating current and choose a relay that has a contact rating equal to or greater than the horn current (I would guess less than 1 amp). Michael From: SMilesCozy@aol.com Date: Wed, 20 Aug 1997 23:17:20 -0400 (EDT) Subject: Re: COZY: canopy, nose gear, throttle switch circuit In a message dated 97-08-20 17:05:38 EDT, you write: > What I don't understand is how the circuit latches so as to keep the > warning buzzer off, while leaving the light on. Does the relay have an > internal latching circuit? Am I missing something in the wiring diagram? > Why wasn't this implemented with cams and gears - then I'd understand it > :-). Marc, When relay-D1-974's coil is energized, it breaks the circuit for the horn...while "making" the circuit that energizes the coil. The NO contacts, (now closed) complete this circuit, keeping the contacts closed after the momentary contact switch is released, thereby "latching" it electrically. As soon as any of the micro switches are "opened" the coil in relay-D1-974 de-energizes and enables the horn again. Hope this helps, Steve Miles Cozy MkIV 272 Date: Thu, 21 Aug 1997 09:16:37 +0200 From: morten@scandisoft.no (morten scandisoft.) Organization: ScandiSoft AS Subject: Re: COZY: canopy, nose gear, throttle switch circuit Marc J. Zeitlin wrote: > At any rate, while studying chapter 22 for installation of the warning > buzzer/light circuit for the canopy/gear/throttle, I've become confused > (not being an E.E.). I can understand the logic of the three > microswitches, and the function of the wiring for the warning buzzer and > light, and I understand how the momentary push button turns off the > buzzer while leaving the light on _WHILE THE BUTTON IS DEPRESSED_. > > What I don't understand is how the circuit latches so as to keep the > warning buzzer off, while leaving the light on. Does the relay have an > internal latching circuit? Am I missing something in the wiring diagram? > Why wasn't this implemented with cams and gears - then I'd understand it Mark ! I've just redone my electrical warning system on my Cozy MKIII LN-USA. A lot of Long-Eze/Cozy builders say that they even forget to lower the nose gear because the original system provides a button to silence the warning buzzer. The fail-safe cheap solution I did: install the 3 micro-swiches as per drawing. Connect as per drawing and coupole a USD 2 buzzer and 5 mm dia LED with resistance (radioshack will know the capacity) in PARALELL. I had the electronic gadget with delay timer and push button. Have it still but do not intend to use it anymore. Now the system works and if the buzzer and warning light comes on, something is wrong, and should be corrected immediately. No reset-swich for me and I won't miss it. The total cost for 3 micro-swiches and a LED+resistance was around USD 10. From: lschuler@cellular.uscc.com Date: Thu, 21 Aug 97 12:08:15 -0600 Subject: COZY: canopy, nose gear, throttle switch circuit --simple boundary Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Marc wrote: >snip >Thanks in advance for the electrical tutorial. >snip You are welcome in advance of the below. Hope the following isn't too confusing (I understand it.... :-) ). 1. The circuit will work as shown and as described in the plans (if you can find the parts) and manage to identify the switch and relay contacts correctly when wiring it up. Radio Shlock has some nifty little pre-wired aligator clips that may be handy for testing stuff like this before commiting to solder. 2. In the following, remember that with the 5-Amp circuit braker closed, there is "always" +12 Volts applied to one side of the horn, the light, and the relay coil. The ground (or negative[-]) is what is switched or changed around in order to turn stuff on/off in the circuit. The +12 Volts comes in at the circuit breaker shown at the top, left of the wiring diagram. In order for anything to "work", you must have a plus on one side (12 Volts in this case) and a minus on the other. [Ground is shown in this drawing; but not really accurate for something not tied to or even sitting on the earth, but thats another issue]. Think of it as the "negative" (-) side of the battery and you will be ok. 3. The drawing shown on page 22-4 shows the canopy closed, the gear is up and the throttle is at or near idle. As such, there is a complete ground path through all the micro switches to the horn and lamp. The ground path starts at the symbol shown roughly as: | ----- --- - 4. The three micro switches are wired in the form of a logic "AND" gate if you understand the term. All contacts must be closed (as shown) in order to turn on the horn and lamp. If any one of them opens, the lamp and horn will be turned off. Simply means that if I am slowing down (throttle is at idle) and the gear is still up, I could open the canopy, put the gear down, "OR" increase RPM from idle to turn the lamp and horn off. 5. The ground (-) which triggers the horn is routed through the normally closed (NC) contacts of the relay. The "NC" contacts of 'any' relay are closed when the coil is de-energized (no juice flowing through the coil). In a like sense, the normally open (NO) contacts are Open when there is no juice through the coil. The point on the relay marked "C" is 'C'ommon to both the NO and NC points; this is what essentially moves when the relay coil is energized or de-energized. 6. The relay coil will be energized if the momentary (spring loaded) kill switch is temporarily closed. This, in effect, moves the "C" (Common) lead from the 'NC' point to the 'NO' point. The 'NC' point "WAS" supplying the needed ground (-) to one side of the horn, but this is removed, so the horn stops. Instead, the ground (comming via the "C" on the relay) will go back to the same side of the relay that the swich is connected to; this is make the relay "Hold" or stay energized when you take your thumb off the kill button. 7. Nat says that if you cycle the throttle you will reset the horn circuit. This is true; it will open the ground (-) path going through the throttle switch (remeber, it is shown in the "idle" position). The same thing would happen if you lower the gear "OR" open the canopy. 8. Key to remember that ALL THREE switches must be "Closed" in order to turn on the light bulb and start the alarm. Without any (single) one of the switches in the "open" condition, the lamp goes out and the buzzer stops. I looked in my last copy of the Digi Key catalog (# 965 last fall) and found quite a few relays that would work. Nat doesn't provide any mounting information (go figure), so I can't tell you which would work best. Depends mostly how you want to mount the darn thing. Here is the important elecrical stuff to look for: Coil must be rated at 12 Volts or have an operating range that covers our aircraft electrical system (most are 14 volts or so). Try to find one that has at lease 500 Ohms coil resistance (750 or 1,000 is better) if that is listed; if not, look for the 'smallest' coil current rating (usually in mili-amps (mA). The contacts should have a Minimum rating that will handle the current they will be expected to carry. Without the lamp specs, the horn specs and the relay coil specs, I can't give accurate guidance; but here is a SWAG: the circuit breaker is shown as 5 Amps; I would 'guess' that the max current will be less than that, say 2 or 3 Amps at the "most". This is 'probably' adequate for the contact rating. Look for one that is marked "SPDT" (Single Pole, Double Throw). One marked as "DPDT" (Double Pole, Double Throw) will work just as well, but you will have a couple extra wiring pins you won't need. DO NOT get one that is marked "SPST" (Single Pole, Single Throw); that type ONLY has an NO 'or' an NC set of contact, but not both; you need both with a Common between. If you have the same catalog, try to identify one or two that you think will work and let me know. I'll let you know if it will work or not. Larry Schuler, #500 Ch 8/9 (Still) lschuler@cellular.uscc.com --simple boundary Content-Type: text/plain; charset=US-ASCII; name="RFC822.TXT" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="RFC822.TXT" Received: from gatekeep.uscc.com by cellular.uscc.com (ccMail Link to SMTP R8.00.01) ; Wed, 20 Aug 97 16:07:52 -0600 Return-Path: Received: from www.uscc.com (ns.uscc.com [204.179.101.2]) by gatekeep.uscc.com with ESMTP id RAA10152 for ; Wed, 20 Aug 1997 17:04:44 -0400 (EDT) Received: from palrel1.hp.com (palrel1.hp.com [156.153.255.235]) by www.uscc.com with ESMTP id QAA21778 for ; Wed, 20 Aug 1997 16:04:12 -0500 (CDT) Received: from hpwarhw.an.hp.com (hpwarhw.an.hp.com [15.57.193.122]) by palrel1.hp.com (8.8.6/8.8.5) with SMTP id OAA15244 for ; Wed, 20 Aug 1997 14:06:05 -0700 (PDT) Received: by hpwarhw.an.hp.com (1.37.109.8/15.5+IOS 3.22) id AA16928; Wed, 20 Aug 1997 17:03:08 -0400 Received: by hpwarhw.an.hp.com (1.37.109.8/15.5+IOS 3.22) id AA16920; Wed, 20 Aug 1997 17:03:06 -0400 From: "Marc J. Zeitlin" Message-Id: <9708202103.AA16920@hpwarhw.an.hp.com> Subject: COZY: canopy, nose gear, throttle switch circuit To: cozy_builders@hpwarhw.an.hp.com (Cozy MK-IV Builders) Date: Wed, 20 Aug 97 17:03:06 EDT Mailer: Elm [revision: 70.85] Sender: owner-cozy_builders@hpwarhw.an.hp.com Precedence: bulk Reply-To: "Marc J. Zeitlin" --simple boundary-- by x9.boston.juno.com (queuemail) id QmG23621; Fri, 22 Aug 1997 16:39:24 EDT Date: Thu, 21 Aug 1997 18:35:21 -0400 Subject: COZY: Gear Alarm From: unick@juno.com (Nick Ugolini) I installed a simple redundent alarm for my gear after joining the "gear up" club. I purchased a LOUD alarm from radio shack ($12). I installed a micro switch on my belly board that closes when the belly board is extended. I ran a wire from my power bus through the micro switch on my gear (NC when gear is up) to the micro switch on the board (NO when the board is retracted) to the alarm and to ground. pwr----------gear (NC gear up) -----------board (NO board retracted) -------horn-----ground This is a INDEPENDENT system which alarms if I extend the board with the gear up. No matter what is going on around you during landing (talking a buddy through the landing as in my case), when you extend the board (which you ALWAYS do when on final to slow down) it will let you know if your gear is up... Total cost $15, time to install 2 hrs. Remember the quote of someone famous.... There are two kind of retractable gear flyer... Pilots who have landed with their gear up, and those who will.." From: "Frank" Subject: COZY: BREAKER PANELS Date: Sat, 23 Aug 1997 00:25:39 -0400 HI Mark Got your reply and have been thinking it over. There have been several times when the breaker panels have helped make a flight safe and helped the trip to be completed that would otherwise have a major problem. Or not ended well at all! I dont know how much time your frind has and may be he has been very lucky and not had major emergencys. But if you fly alot with diferent planes you can not always control the maintance the way you would like and the odds do catch up with you. I realy do hope that every one can fly with a good gardian angle and may your friend continue to be so lucky, however we should all be as prepared as we can. Last week a pilot friend of mine who flys for a comuter air line,and has military time in many craft ( I have a good deal of time in the seat beside him and would not hesitate to have my family fly with him ) was bringing a piper lance home from n.y. to Maine.45 min. into the trip the panel lights went dark as the main bus breaker poped ( over the mountain of new hampshire at night ).A remote breaker would have made this imposible to solve, a fuse is hard to change in the dark a local breaker is easy to reset. He turned off all the radios and lights and all electrical systems not critacal to flight and reset the breaker, it held ! He then turned on the systems one by one watching the amp meter for load . Each item by it self was ok except for the pito heat wich was greater than normal well as he said dam*** high. But by it self would not trip the breaker it was on, or the main. But with every thing else on it was enough to take the main out. The trip was completed with the pito heat and one radio bank off to keep system load in limits.Landing lights were not used. The battery was found to be the cause of the problem. The pito breaker was replaced because it did not trip and made him nervous so as he said for pease of mind it went. ( as voltage drops amperage rises ). Several years ago I was flying a twin seabee when I went to lower the gear the breaker would pop, after three atempts I lowered it with the hand pump. The motor had to be changed. But in this case the breaker was a good visual indicatur of the problem. Hidden away I would have only known that the gear would not go down but not why.Knowing the problem apeared to be electrical in nature I used the hand pump and left the geared down untill we landed and it could be checked and fixed. Breakers should be used, not fuses and should not be hinden or tucked away out of reach, or out of site. You your family and passengers depend on your choises now and in the future. Please give them every chance you can. I hope you dont over work your gardian angle! What is that old saying? A WORD TO THE WIZE! IF ANYTHIN CAN BE DONE TO MAKE OUR DREAMS SAFE LETS DO IT SO WE CAN DREAM ON FOR MEANY YEARS TO COME! Best wishes always Frank Johanson From: "Frank" Subject: COZY: breaker panels frank to mel Date: Sat, 23 Aug 1997 17:45:49 -0400 Hi mel You missed the mark by a long shot. I was trying to point out the benifit of a breakers over fuses and not having them hidden out of reach. Not to get into a battle over science. I will however answer your question and hope that at this point we can look at what the objective was to start with, to give real life reasons for a good handy breaker panel. The reason that your formula is wrong is that you did not allow for twin alternaters and a voltage regulator trying to make up for the shorted batteries low voltage. There is more info not mentioned here because it takes us further away from the original topic. Truce ok. Best Wishes Frank Johanson From: "Steve Campbell" Subject: RE: COZY: Electrical Date: Wed, 10 Sep 1997 13:06:01 On Wed, 10 Sep 1997 12:31:17 -0500, EpplinJohnA@JDCORP.deere.com wrote... >... What if the >vacumn line was used as the ground buss? I havn't really done any >research concerning the resistence of 5052 al. tubing but I think it >would probably suffice for several amps. Anybody have any reasons why >this may be a bad idea? > The tubing certainly could carry the current. Not saying that it's not a good idea, but the first problem that comes to my mind is ensuring a reliable contact to the tube. You no doubt remeber Al wiring in houses. The contact get warm from joule heating, it oxidizes, the resistance increases, it oxidizes more, etc. I believe that it is possible, but not easy, to make reliable electrical contacts to Al. Steve ************************************************ Stephen A. Campbell, Associate Professor, ECE University of Minnesota 200 Union Street Minneapolis 55455 (612) 625-5876 phone / (612) 625-4583 fax Campbell@ee.umn.edu ************************************************* From: Epplin John A Subject: COZY: Electrical Date: Wed, 10 Sep 1997 12:31:17 -0500 I have a crazy thought concerning ground wiring. The battery and alternator etc are located near the firewall and have rather short connections, however a good part of the load is distributed at the forward section, near the instrument panel. This means a rather substantial ground conductor must be run the length of the a/c, some bit of weight. Most of the Cozys I have seen have vacumn gyros installed which means a vacumn line running the length of the a/c. What if the vacumn line was used as the ground buss? I havn't really done any research concerning the resistence of 5052 al. tubing but I think it would probably suffice for several amps. Anybody have any reasons why this may be a bad idea? John Epplin Mk4 #467 From: Marc J. Zeitlin Subject: COZY: Electrical (fwd) Date: Wed, 10 Sep 97 13:56:58 EDT John Epplin wrote: >..... What if the >vacumn line was used as the ground buss? I havn't really done any >research concerning the resistence of 5052 al. tubing but I think it >would probably suffice for several amps. Anybody have any reasons why >this may be a bad idea? Yeah, aluminum's not as great a conductor as copper. However, you do have a good idea here, which has been thought of and used before in a slightly different incarnation. One of the suggestions in Bob Nuckolls' book is to use copper plumbing tubing, crimped at both ends and with big honking tabs soldered to them as the ground run in composite aircraft. Copper is a much better conductor than aluminum. You could combine these two ideas, use 1/2" copper tubing for your vacuum line (with appropriate fittings on each end), solder tabs to the outside, and also use it as your ground line. The copper tubing is also easier to bend to the right shape, although that's not a really big deal. On the other hand, if all you're powering is the panel and strobes (the battery is in the back), the 5052 might be OK. If the battery is in the nose, then you really need something with a lot of current carrying capacity, which would argue for the large diameter copper. -- Marc J. Zeitlin Email: marcz@an.hp.com Subject: Re: COZY: Electrical Date: Wed, 10 Sep 1997 14:00:47 -0400 (EDT) From: "Randy Smith" > which means a vacumn line running the length of the a/c. What if the > vacumn line was used as the ground buss? I havn't really done any > research concerning the resistence of 5052 al. tubing but I think it > would probably suffice for several amps. Anybody have any reasons why > this may be a bad idea? Well, it may be hard to pull a vacuum with all that wire clogging up the vacuum line. :-) I'm sorry, I couldn't resist. (Oooo, another pun!) > > John Epplin Mk4 #467 > Seriously, I think this would be a neat idea. Just make sure the connectors on each end are high quality and that they wouldn't crush the vacuum line. -Randy Smith From: Kelly Russell Subject: RE COZY: Electrical Date: Wed, 10 Sep 1997 11:04:16 -0700 >........What if the >vacumn line was used as the ground buss? I havn't really done any >research concerning the resistence of 5052 al. tubing but I think it >would probably suffice for several amps. Anybody have any reasons why >this may be a bad idea? Yes, ground loops (i.e. NOISE). Read Bob Nuckolls 'Aero Electric Connection' for a good explanation and a suggested electrical system layout. Basically Bob suggests that you use copper tubing as the ground and run your wires etc. inside it to get from the back to the front. Jim Hocut jhocut@mindspring.com (via borrowed e-mail account at work) From: Epplin John A Subject: RE: COZY: Electrical (fwd) Date: Wed, 10 Sep 1997 13:07:51 -0500 > You could combine these > two ideas, use 1/2" copper tubing for your vacuum line (with > appropriate > fittings on each end), solder tabs to the outside, and also use it as > your ground line. > -- > Marc J. Zeitlin Email: marcz@an.hp.com [Epplin John A] Thanks for the thoughts. This though had crossed my mind also. One could use steel bulkhead fittings, sleeves and nuts, at each end and flare the copper tube. This would carry the vacuum through to aluminum or hose fittings without a al to cu junction. Tabs could be soldered to the copper for the electrical connections. Think I just might do that. John Epplin Mk4 #467 Date: Wed, 10 Sep 1997 14:37:07 -0700 From: Jim Cullen Subject: COZY: Use of Copper Tubing for a Ground Bus Regarding the discussion on running wires inside a copper tube that acts as a ground bus... I read this recommendation by Bob Nickols several years ago and there was something that always bothered me about it. If any of the wires inside the tube are hot (energized) and if, by rubbing against whatever they would happen to abrade their insulation, you'd have a good opportunity for a short on your hands inside the confines of the tube. I've always wondered if it might not be better to run hot lines down one side of the aircraft and the ground bus down the other. Just a thought... by x9.boston.juno.com (queuemail) id SEH04464; Thu, 11 Sep 1997 18:29:09 EDT Date: Wed, 10 Sep 1997 18:33:50 -0400 Subject: Re: COZY: Electrical From: unick@juno.com (Nick Ugolini) In Bob Nuckells book (my personal wiring bible), he does have a drawing with the copper tubing as the ground bus with the positive wire running through the center to reduce electrical noise. Tabs are just soldered to the sides and your connectors are attached to them. In lu of this type of setup he suggests running your power wires along one side of the plane (twist the wires two turns per foot), and all your data wires (the ones carrying information EGT/CHT etc) along the other side of the plane. I thought about your idea and the possiblity of using the tubing with a power wire (sealed at both ends) along with the vacuum running with the wire.... But on second thought use the tubing for the shelding potential, with your power wires through the center and plastic tubing for your vacuum. It only took me 2 min to run my vac tubing at about $5.00 in materials. Can't beat it. Personally I used twisted power wires on my long, shielded wires for EVERYTHING else, and I have NO electrical noise at all. From: "Rob Cherney" Date: Wed, 10 Sep 1997 21:13:20 -0400 Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Jim Cullen wrote: >I've always wondered > if it might not be better to run hot lines down one side of the aircraft > and the ground bus down the other. Just a thought... This is not such a good idea for the following reason: If you separate the conductors such that the current is traveling in a loop by routing the wires as you suggest, the current will causes a magnetic field. This current could be substantial when you are charging your battery and would be huge when you are starting your engine. During a typical flight the magnetic field will be changing depending upon varying load conditions. Now, you and, more importantly, your wet compass are within the loop area. You will likely notice that your compass will swing around when you start up your electrical system. This ain't so good. Bob Nuckols advocates using *coaxial* conductors -- that is, a wire conductor surrounded by a copper tube for the ground return. This arrangement will make the loop area exceedingly small, since the center of the current paths are through the same geometric line (Is this clear as mud?). With this arrangement, the magnetic field of the wire will be exactly cancelled by the return currents in the tube. There are alternate approaches, such as separating the ground paths for each source/load and twisting a pair of wires together. Rob- +--------------------------------------------------------+ |Robert Cherney Home Phone: (410)465-5598 | |Ellicott City, Maryland e-mail: cherney@clark.net | +--------------------------------------------------------+ From: cdenk@ix.netcom.com Date: Wed, 10 Sep 1997 20:50:52 -0500 (CDT) Subject: Re: COZY: Electrical (fwd) On 09/10/97 13:56:58 you wrote: > >John Epplin wrote: > >>..... What if the >>vacumn line was used as the ground buss? I havn't really done any >>research concerning the resistence of 5052 al. tubing but I think it >>would probably suffice for several amps. Anybody have any reasons why >>this may be a bad idea? > >Yeah, aluminum's not as great a conductor as copper. However, you do >have a good idea here, which has been thought of and used before in a >slightly different incarnation. One of the suggestions in Bob Nuckolls' >book is to use copper plumbing tubing, crimped at both ends and with big >honking tabs soldered to them as the ground run in composite aircraft. >Copper is a much better conductor than aluminum. You could combine these >two ideas, use 1/2" copper tubing for your vacuum line (with appropriate >fittings on each end), solder tabs to the outside, and also use it as >your ground line. The copper tubing is also easier to bend to the right >shape, although that's not a really big deal. > >On the other hand, if all you're powering is the panel and strobes (the >battery is in the back), the 5052 might be OK. If the battery is in the >nose, then you really need something with a lot of current carrying >capacity, which would argue for the large diameter copper. > >-- >Marc J. Zeitlin Email: marcz@an.hp.com > > All electrical connections must be mechanical first, usually solder will cause a connection to weaken fatique wise, since it is stiffer. With the battery in the back, most of the load comes forward anyways, and the cable is still large. You want your main breaker where you can reach it - forward. From: TRCsmith@aol.com Date: Wed, 10 Sep 1997 22:14:45 -0400 (EDT) Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Rob You worry to much. not all aircraft wires are sheiled and the mag field you speek of will be to low to cause harm. That why all aircraft have a compass card in them..TURN ALL POWER ON, SWING AIRCRAFT!!! Tom From: "Rob Cherney" Date: Wed, 10 Sep 1997 23:01:07 -0400 Subject: Re: COZY: Use of Copper Tubing for a Ground Bus TRCsmith@aol.com wrote: > Rob > You worry to much. not all aircraft wires are sheiled and the mag field you > speek of will be to low to cause harm. That why all aircraft have a compass > card in them..TURN ALL POWER ON, SWING AIRCRAFT!!! Tom: Perhaps you are correct. You see, I have not had the opportunity to do it "wrong" and assess whether is good enough. Rob- +--------------------------------------------------------+ |Robert Cherney Home Phone: (410)465-5598 | |Ellicott City, Maryland e-mail: cherney@clark.net | +--------------------------------------------------------+ Date: Thu, 11 Sep 1997 08:12:00 +0200 From: Rego Burger Subject: RE: COZY: Electrical -R We have many conducting parts on our aeroplanes, I think they've just been ignored. e.g. 1.) Control tubes (under the arm rests ) 2.) The Engine mount. 3.) The Firewall. 4.) Fuel lines. Some advocate that these should be electrically bonded!? The problem comes in with them often having different materials.ie. Alu. and steel, we may accelerate corrosion by passing an electrical current through these, however where a continuous "line" of the same material is involved this would not be a problem. I just feel that copper should be used instead of aluminium, it's a better conductor. I have been toying with the idea of running copper "tape" along the longerons on each side. 1.) For ground and 2.) for the Positive. I get 1/2" x 1/16" "tape" or bar in rolls here and it should work fine for all the normal electrical needs. It might just be too light for a starter motor current. By having these two conducting "rails" along the entire span of the fuselage one will enable easy access to current. The only concern is the magnetic field may effect the compass a little. It will be important to paint the one red for easy recognition to avoid incorrect connections. The other place one can feed say a conduit/conductor is inside the heat duct, its hollow! Either of these routes I feel, is better than having spaghetti all over the show. The less connections the less chance of a malfunction. I wish to keep the wiring under my panel to a min. Thanks Steve Cambell for your Ideas. Rego Burger CZ4#139 RSA Date: Thu, 11 Sep 1997 08:51:07 +0200 From: Rego Burger Subject: COZY: Electrical Current and the Compass Just a short TRUE story! ( inspired by the conductor topics ) I noticed one during a run-up in a hired aeroplane that my compass moved up to ten degrees from idle to the run-up RPM! It would seem that a compass is sensitive and the extra power from a charging alternator or generator increases the magnetic variation. When mentioning this in the flying club Bar after a flight I was shot down as talking rubbish ( those were not the word used ) An instructor friend of mine was interested in my discovery and asked if I would demo it for him. I did and when he does a compass swing now it's with radio's on and at 2000 RPM. Remember most of our navigation work is done at cruise speeds with RPM's above 2000 RPM. The amount of change may be different for aircraft equipped with alternators vs. generators so each will have to investigate his own aeroplane and system. Food for thought. Rego Burger RSA From: TRCsmith@aol.com Date: Thu, 11 Sep 1997 07:23:34 -0400 (EDT) Subject: Re: COZY: Electrical (fwd) I use a 3/4 copper line in my Long, I run all wires that go to the engine compartment through it and it also serves as the ground from the batt. to starter. Tom From: SWrightFLY@aol.com Date: Thu, 11 Sep 1997 08:22:47 -0400 (EDT) Subject: Re: Re: COZY: Use of Copper Tubing for a Ground Bus In a message dated 9/11/97 7:53:05 AM, you wrote: << a wire conductor surrounded by a copper tube for the ground return. This arrangement will make the loop area exceedingly small, >> What wall thickness and diameter copper tube should be used? Steve Wright From: "mel" Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Date: Thu, 11 Sep 1997 08:44:09 -0400 wires dont short out in building conduits, but they dont vibrate as much as our planes do. breakers and fuses are there to protect our lives and projects, but why start out with a problem just waiting to happen? pipes carrying power are never a good solution, they make mag fields, and the corrosion rates are not predictable, not to mention what can happen to the devices they are delivering their fluid to weather the fluid be air, oil, water, gas, etc. the pipe now becomes an electroplating device of some type. weather material is to be deposited on your pipe or transferred from your pipe to another object is a matter of its polarity, current flow, pipe material, and medium being transferred in the pipe. now dont tell me its only AIR or VACUUM. remember their is moisture in that and after all we have acid rain dont we? these products WILL make their presence known. after all Murphy's law says "if it can happen it will" and always remember Murphy was an OPTIMIST!! norm (jafo) & monda (pilot) cozy IV #202 ---------- > From: MISTER@neesnet.com > To: cozy_builders@hpwarhw.an.hp.com; Jim Cullen > Subject: Re: COZY: Use of Copper Tubing for a Ground Bus > Date: Thursday, September 11, 1997 8:48 AM > > > Jim Cullen writes:"If any of the wires inside the tube are hot > (energized) and if, by rubbing against whatever they would happen to > abrade their insulation, you'd have a good opportunity for a short on > your hands inside the confines of the tube." > > That is what we have protective devices like fuses and breakers for. > Also, If there is a short circuit, I think I'd prefer to have it > confined in the copper tube rather than next to exposed structure, > > Bob Misterka N342RM > From: MISTER@neesnet.com Date: Thu, 11 Sep 97 07:48:10 EST Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Jim Cullen writes:"If any of the wires inside the tube are hot (energized) and if, by rubbing against whatever they would happen to abrade their insulation, you'd have a good opportunity for a short on your hands inside the confines of the tube." That is what we have protective devices like fuses and breakers for. Also, If there is a short circuit, I think I'd prefer to have it confined in the copper tube rather than next to exposed structure, Bob Misterka N342RM From: Kelly Russell Subject: RE: COZY: Use of Copper Tubing for a Ground Bus Date: Thu, 11 Sep 1997 06:20:11 -0700 > pipes carrying power are never a good solution, they make mag fields, That's the beauty of having the hot wires inside the conductive ground conductor, the magnetic fields EXACTLY cancel each other. Therefore you greatly reduce the potential of any kind of interference or noise. > the corrosion rates are not predictable, not to mention what can happen to > the devices they are delivering their fluid to weather the fluid be air, > oil, water, gas, etc. > the pipe now becomes an electroplating device of some type. weather > material is to be deposited on your pipe or transferred from your pipe to > another object is a matter of its polarity, current flow, pipe material, > and medium being transferred in the pipe. > We're not talking about having any fluid etc. flowing in the conduit, only electrons. I'm a EE and do industrial instrumentation for a living, and thus have to live with this sort of stuff in noisy (electrically speaking) plant environments. Bob Nuckolls is right on target with his ideas put forth in the 'Aero Electric Connecton' (otherwise I doubt Burt would have let him do the electrical system on Voyager). There are many many details to a good electrical installation, way too many to cover here. Get Bob's book, it's well worth the investment. (See www.aeroelectric.com) Jim Hocut jhocut@mindspring.com (via borrowed e-mail account at work) From: MISTER@neesnet.com Date: Thu, 11 Sep 97 08:35:31 EST Subject: Re[2]: COZY: Use of Copper Tubing for a Ground Bus T SMith wries: " You worry to much. not all aircraft wires are sheiled and the mag field you > speek of will be to low to cause harm. That why all aircraft have a compass > card in them..TURN ALL POWER ON, SWING AIRCRAFT!!!" I must disagree! Compass correction cards are monuments to poor design and/or poor installation practice! Also, when your flying who needs another calculation to do or another thing to slip from an already overtaxed memory? I used Bob Nuckolls approach on my 3 place and I'm very pleased with the results. The noise performance is excellent. Also, my compass correction card has all zeroes on it. Bob Misterka N342RM From: Howard Calk Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Date: Thu, 11 Sep 1997 09:46:34 -0400 The main draw back of using copper tubing is the cost. The problem is you do not want to carry around more copper than you need. Its just extra weight. For a 1" diameter conduit (which is a practical size), it turns out this is a very thin walled copper tube. Here is how to calculate the wall thickness of the copper tubing you need for a 1" conduit: Obtain the diameter of number 2 AWG wire. Compute the area of this (pi times the radius squared). Compute the wall thickness by computing the area of the outside diameter (.7854 for 1") and the area of the inside diameter. Subtract the two and this will give you the cross sectional area of the tube wall. Pick a inside diameter which yields a result that is close to the cross sectional area of the #2 wire. Bob Nuchols will admit that this is an expensive way to go and says that a twisted pair (hot and ground) will give almost the same performance for a lot less money. I looked into this and did all of the calculations (sorry I don't know what I did with them). I found that: a) I had a hard time locating a source of thin wall copper tubing and; b) the thin walled tubing I did find _was_ very expensive. Howard Calk Long EZ builder -----Original Message----- From: SWrightFLY@aol.com [SMTP:SWrightFLY@aol.com] Sent: Thursday, September 11, 1997 8:23 AM To: cozy_builders@hpwarhw.an.hp.com; owner-cozy_builders@hpwarhw.an.hp.com Subject: Re: Re: COZY: Use of Copper Tubing for a Ground Bus In a message dated 9/11/97 7:53:05 AM, you wrote: << a wire conductor surrounded by a copper tube for the ground return. This arrangement will make the loop area exceedingly small, >> What wall thickness and diameter copper tube should be used? Steve Wright From: MISTER@neesnet.com Date: Thu, 11 Sep 97 08:47:08 EST Subject: Re[3]: COZY: Use of Copper Tubing for a Ground Bus Steve: I went to Home Depot and bought a coil of the 3/4" soft copper tubing they sell in the plumbing department. Get whatever diameter you need to hold the wires you'll put in it. Don't remember the wall thickness. Bob Misterka N342RM From: MISTER@neesnet.com Date: Thu, 11 Sep 97 08:59:47 EST Subject: Re[2]: COZY: Use of Copper Tubing for a Ground Bus Norm Doty writes: "breakers and fuses are there to protect our lives and projects, but why start out with a problem just waiting to happen?" I didn't and don't advocate using the copper tube for anything but a conduit for the wiring. I also don't agree that doing so is making a "problem just waiting to happen". By the way, wires do short out in building conduits and circuit breakers do keep the occurances from becoming a problem. Based on Bob Nuckoll's long experience in the industry, I'm more than willing to take my chances with his ideas. Bob Misterka N342RM From: Marc J. Zeitlin Subject: Re: COZY: Use of Copper Tubing for a Ground Bus (fwd) Date: Thu, 11 Sep 97 10:25:39 EDT Howard Calk wrote: >I found that: > > a) I had a hard time locating a source of thin wall copper tubing and; Not sure what you were looking for - any plumbing supply house or hardware store will carry copper tubing for house plumbing. > b) the thin walled tubing I did find _was_ very expensive. Also not sure why - It's only a couple of bucks for a 10 ft. section of 3/4" copper tubing. Howard gave some equations for calculating the area needed. I've got the Nuckolls book here in front of me, as well as the "Marks Handbook for M.E.'s". The area of 2 AWG wire is listed as 0.0521 in^2. To achieve this area in a 0.75" tube means that the wall thickness must be 0.025" or more. I believe than ALL copper tubing will be thicker than this, so the resistance in the tubing will be less than in the 2 AWG wire (which is already a small part of the overall resistance). Nuckolls does state "I recommend that wired grounds be considered in all cases except where the advantages of installing and maintaining wires in conduit justify the added labor". Chapter 5 of his book has a full explanation of why you might want to do one or the other, and how to go about it. -- Marc J. Zeitlin Email: marcz@an.hp.com From: "Craig R. Bowers" Subject: RE: COZY: Use of Copper Tubing for a Ground Bus Date: Thu, 11 Sep 1997 08:34:29 -0700 Hi all; Bob has a good point, but... It all depends on where the circuit breaker or fuse is in the circuit relative to the point of the short. If the short occurs on the ground side of the protective device then, no problem. If the short occurs on the hot side of the protective device then, you have a real problem. Just a thought. :-) Craig R. Bowers I.T. Dept. Cerro Coso Community College cbowers@cc.cc.ca.us 760.384.6267 At home cbowers@truelink.net -----Original Message----- From: MISTER@neesnet.com [SMTP:MISTER@neesnet.com] Sent: Thursday, September 11, 1997 5:48 AM To: cozy_builders@hpwarhw.an.hp.com; Jim Cullen Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Jim Cullen writes:"If any of the wires inside the tube are hot (energized) and if, by rubbing against whatever they would happen to abrade their insulation, you'd have a good opportunity for a short on your hands inside the confines of the tube." That is what we have protective devices like fuses and breakers for. Also, If there is a short circuit, I think I'd prefer to have it confined in the copper tube rather than next to exposed structure, Bob Misterka N342RM From: Howard Calk Subject: RE: COZY: Use of Copper Tubing for a Ground Bus (fwd) Date: Thu, 11 Sep 1997 11:50:55 -0400 >Not sure what you were looking for - any plumbing supply house or >hardware store will carry copper tubing for house plumbing. >> b) the thin walled tubing I did find _was_ very expensive. >Also not sure why - It's only a couple of bucks for a 10 ft. section of >3/4" copper tubing. >Howard gave some equations for calculating the area needed. I've got the >Nuckolls book here in front of me, as well as the "Marks Handbook for >M.E.'s". The area of 2 AWG wire is listed as 0.0521 in^2. To achieve >this area in a 0.75" tube means that the wall thickness must be 0.025" or >more. I believe than ALL copper tubing will be thicker than this, so >the resistance in the tubing will be less than in the 2 AWG wire (which >is already a small part of the overall resistance). Yes, all copper tubing from the local building supply is much thicker than needed. That is my point, while there is no problem handling the electrical loads you will be carrying around a lot of unnecessary weight. How much does 10 to 12 ft. of 1" copper pipe weigh? Why carry extra weight when you can get close to the same performance from other methods? Also, I don't think that .75" copper pipe is big enough for a conduit. If you can't run all the wires you need down the conduit why not just use the twisted wire method? I spent a good bit of time talking to Bob Nuckolls and he recommends another alternative in his book as being more cost effective. Howard From: "Johnson, Phillip" Subject: COZY: Electrical Date: Thu, 11 Sep 1997 15:58:50 -0400 John Epplin wrote: >..... What if the >vacuum line was used as the ground buss? I haven't really done any >research concerning the resistance of 5052 al. tubing but I think it >would probably suffice for several amps. Anybody have any reasons why >this may be a bad idea? Marc Z beat me to the copper solution. 5052 may have problems long term. It is very difficult to achieve a good connection. In time corrosion will set in and grounding problems will almost certainly occur. Phillip Johnson Date: Thu, 11 Sep 1997 13:40:48 -0700 From: "LCDR James D. Newman" Organization: INFINITY Aerospace Subject: COZY: RE: Use of Copper Tubing for a Ground Bus Hi All, >Yes, all copper tubing from the local building supply is much thicker than needed. That is my point, while there is no problem handling the electrical loads you will be carrying around a lot of unnecessary weight. How much does 10 to 12 ft. of 1" copper pipe weigh? Why carry extra weight when you can get close to the same performance from other methods?< It seems the discussions have lost partial sight of the 'special purpose' of why to use 2 - 1" OD thin wall copper tubes from the nose to the tail in the fuselage floor (see subject line) - the copper tubes not only can provide a conduit to house the wires (among the other benefits noted), it replaces the need to, also, run the heavy #2 cables from the battery in the nose pos & neg to the engine, therefore saving weight. But, if the battery will stay in the back, obviously there is no need to run heavy cooper tubing to the nose when a plastic tube can be used as a conduit and the other methods mentioned of handling the wires is all you need. HTH. Infinity's Forever, JD From: Marc J. Zeitlin Subject: COZY: RE: Use of Copper Tubing for a Ground Bus (fwd) Date: Thu, 11 Sep 97 17:05:23 EDT Jim Newman wrote: >........ - the copper tubes not >only can provide a conduit to house the wires (among the other benefits >noted), it replaces the need to, also, run the heavy #2 cables from the >battery in the nose pos & neg to the engine, therefore saving weight. Not quite. Howard's point was that the copper tube will weigh MORE than the #2 AWG ground wire would have and he's right (because you can't get real thin wall copper tubing cheaply, although the plumbing stuff is cheap as dirt), by about a pound or so. The question then boils down to whether the electromagnetic, routing, and possible other advantages of the copper tube outway the extra weight and work. That's a personal choice, obviously. If, going back to John Epplin's original question, you used a copper tube as the vacuum line AND as the ground line, then you're probably even on the weight, since copper weighs more than the aluminum would have but you've eliminated the #2 AWG ground wire. In this case, you could wrap the #2 AWG positive wire around the ground/vac tube for Mag field elimination. Is this horse dead yet? :-). -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Thu, 11 Sep 1997 22:08:31 -0400 From: "Carl R. Denk" Subject: Re: COZY: Use of Copper Tubing for a Ground Bus MISTER@neesnet.com wrote: > > T SMith wries: " You worry to much. not all aircraft wires are sheiled > and the mag field you > speek of will be to low to cause harm. That > why all aircraft have a compass > card in them..TURN ALL POWER ON, > SWING AIRCRAFT!!!" > > > I must disagree! Compass correction cards are monuments to poor > design and/or poor installation practice! Also, when your flying > who needs another calculation to do or another thing to slip from an > already overtaxed memory? > > I used Bob Nuckolls approach on my 3 place and I'm very pleased with > the results. The noise performance is excellent. Also, my compass > correction card has all zeroes on it. > > > Bob Misterka N342RM > Mount the compass overhead on a 1/2" alum. tube with all non-magmetic hardware, and a small rubber bumper against plexiglass bubble. Frees up panel space, and not affected by electrical fields. From: "mel" Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Date: Thu, 11 Sep 1997 22:44:48 -0400 all thats been said is true but the only wires that usually short out in conduit in industry usually started out with a problem to begin with ie. vibration, sliced during pulling, not proper radius in boxes or devices, wire not correctly sized, not proper type of insulation for job or environment, fused or breakered incorrectly, conduit not properly prepared (rough edges after cutting), incorrect or no bushings on threads of fittings. and a whole bunch of other things that i cant remember at this time. this type of wiring is useable in an airplane and if done CORRECTLY can and would be a very good wiring system. i just dont think it suits our home built philosophy of the K.I.S.S. principle, standard wiring (mil spec type) and good common sense will give you a very good wiring system that should be trouble free for a very long time norm & monda cozy IV #202 ---------- > From: Carl R. Denk > To: MISTER@neesnet.com > Cc: cozy_builders@hpwarhw.an.hp.com; jimculle@vegasnet.net; norm.doty@worldnet.att.net > Subject: Re: COZY: Use of Copper Tubing for a Ground Bus > Date: Thursday, September 11, 1997 10:10 PM > > MISTER@neesnet.com wrote: > > > > Norm Doty writes: "breakers and fuses are there to protect our lives > > and projects, but why start out with a problem just waiting to > > happen?" > > > > I didn't and don't advocate using the copper tube for anything but a > > conduit for the wiring. I also don't agree that doing so is making a > > "problem just waiting to happen". By the way, wires do short out in > > building conduits and circuit breakers do keep the occurances from > > becoming a problem. Based on Bob Nuckoll's long experience in the > > industry, I'm more than willing to take my chances with his ideas. > > > > Bob Misterka N342RM > I agree, copper tube is heavy, probably twice the weight of alum. Stick > with the tried and true. Date: Fri, 12 Sep 1997 07:30:20 -0700 From: Jim Cullen Subject: COZY: Re: Use of Copper Tubing for a Ground Bus In a private conversation on the subject, J.D. from Infinity Aerospace mentioned something that I had forgotten. While a lot of the copper tubing on the market is manufactured by an extrusion process (so-called seamless tubing) other forms of tubing are manufactured by rolling flat stock around a mandrel and then welding a seam along the length of the tube. Seamed tubing has, as an inherent result of its manufacturing process, a rough joint on the inside of the tube. Combine that with the vibration of the aircraft and I can't help but wonder just how good an idea this Copper Tubing/Ground Bus idea is. Now I have a history in this group for gettiing spammed for pointing out non-existant problems -- sigh -- so you decide for yourself if this is a problem or not. I'll just plant the idea in your brain. You decide if it has any merit. Jim P.S. to Carl Denk: You have no idea as to how long I been have trying to figure out where to mount my damn magnetic compass. My panel is already full and I never liked the idea of putting it dead center on the panel cover. Your idea about mounting it on an aluminum tube -- overhead -- against the top of the canopy -- is a wonderful solution to my problem. Are there any vibration problems (compass bouncing against the canopy -- even with a rubber bumper) in doing this? Have you ever seen such an installation in a flying aircraft? If so, I'd love to talk to the builder, to see whether or not he likes the installation... Jim by InfoAve.Net (PMDF V5.1-8 #23426) with SMTP id <01INKBF8V2SA91NRK8@InfoAve.Net> for cozy_builders@hpwarhw.an.hp.com; Fri, 12 Sep 1997 17:57:18 EDT Date: Fri, 12 Sep 1997 17:55:27 -0400 From: Jeff S Russell Subject: COZY: Re: compass mount Organization: AEROCAD INC. Jim Cullen wrote: > Your idea about mounting it on an aluminum tube -- overhead -- > against the top of the canopy -- is a wonderful solution to my problem. > Are there any vibration problems (compass bouncing against the canopy -- > even with a rubber bumper) in doing this? Have you ever seen such an > installation in a flying aircraft? If so, I'd love to talk to the builder, > to see whether or not he likes the installation... Jim, I have ours mounted overhead in the top of the canopy cover because we do not have glass totaly overhead in our canopy. Looks like a rap-a-round windshield but we still used a full bubble canopy like the MKIV shape. Unless you look up for it you do not know that it's there. Works great and no electricial problems. You want them to (shake) with a rubber bumper or the compass won't turn and as long as it won't touch the glass it won't shake to much. hope that helps -- Jeff Russell/AeroCad Inc. E-mail: Jeff@aerocad.com Phone/ fax (call first): 910-961-2238 AeroCad: http://www.aerocad.com Composite workshop info: http://www.Sportair.com From: cdenk@ix.netcom.com Date: Fri, 12 Sep 1997 18:48:17 -0500 (CDT) Subject: COZY: Re: High mounted compass On my Cosy Classic, I have a high mounted compass. I have my GPS (bar of soap style) mounted on the top of the turtleback, 4" aft of the plexiglass (including the hidden part). I take advantage of this reinforced plus access to the top for screw heads. Under I have a say 3" x 3" x .043" aluminum welded to a piece of 1/2" aluminum tubing. THe tubing comes forward about 18", and then another piece of .035" alum. bent 90 degrees down, and avex riveted to the tube. THe vertical becomes a flange cut to fit the top of the compass. The compass is the style with rounded forward face, no bottom mounting ears, and illuminated. The wire goes thru the tube. The forward plate has a 1/2" o.d. rubber bumper foot (the type that squeezes thru a ~ 1/4" hole. THe tube is bent to follow the curvature of the plexiglass plus some spring to hold the bumper against the plexiglass. I have a fiberglass housing to cover the bottom of the antenna and aft end of tube connections. The housing has a tight fitting slot forward for the tube that gives upward force to the tube. It does not viberate, but you must be accurate with mounting the compass face at right angles to the airframe centerline. From: SMilesCozy@aol.com Date: Fri, 12 Sep 1997 22:51:20 -0400 (EDT) Subject: Re: COZY: Electrical In a message dated 97-09-10 14:16:57 EDT, you write: > I believe that it is possible, but not > easy, to make reliable electrical contacts to Al. > Steve > > ************************************************ > Stephen A. Campbell, Associate Professor, ECE > University of Minnesota Most modern electrical distribution equipment (panelboards, lighting panels), have aluminum busses. They make a comercially available paste (available at your local electrical supply house), that comes under several names, ( "no-alox," & "contax," are a couple off the top of my head), that inhibit oxidization / corrosion of the connections. To take this discussion on a tangent, why not embed properly sized aluminum busses under the glass, from front by the panel to the rear by the firewall, much, much, lighter than equivelant (for the amps) copper. And if you needed power anywhere along the length of the bus, you would just have to drill into the buss, tap the hole, and install a screw. Wire this to an appropriately sized breaker, and vola' instant electic, where you need it. Steve Miles From: SMilesCozy@aol.com Date: Fri, 12 Sep 1997 23:37:25 -0400 (EDT) Subject: Re: COZY: Electrical -R In a message dated 97-09-11 02:34:20 EDT, you write: > I have been toying with the idea of running copper "tape" along the > longerons on each side. 1.) For ground and 2.) for the Positive. > I get 1/2" x 1/16" "tape" or bar in rolls here and it should work fine > for all the normal electrical needs. It might just be too light for a > starter motor current. > > Rego Rego, standard procedure, is to calculate the total of all loads expected, and multiply by 1.25 as a safety factor. ie: total load expected at instrument panel = 40 amps, 40 X 1.25 = 50 amps. For a known, possibly continuous load of 40 amps, the bus or wiring should be capable of carrying 50 amps. As far as the size of the "tape" or bar stock needed, there are many references available that have tables for properly sizing wire, or busses ("tape") based on cross sectional area. 50 amps would require a 6awg copper conductor, on a 4 awg AL conductor, I don't know if 1/2" X 1/16" would be adequate or not, for that matter, I'm not sure if the tubing would have the required cross sectional area required either, maybe skin effect would take care of it in the case of the tubing. In the US the National Electric Code contains all of this and is a rather inexpensive reference if you do any wiring around the home. Sincerely, Steve Miles From: "Rob Cherney" Date: Sat, 13 Sep 1997 15:41:43 -0400 Subject: Re: COZY: Electrical -R SMilesCozy@aol.com wrote: >....... maybe skin effect would > take care of it in the case of the tubing. Skin effect reduces the effective cross-sectional area as signal frequency increases. It is not a factor for our electrical systems. Rob- +--------------------------------------------------------+ |Robert Cherney Home Phone: (410)465-5598 | |Ellicott City, Maryland e-mail: cherney@clark.net | +--------------------------------------------------------+ From: SMilesCozy@aol.com Date: Sun, 14 Sep 1997 01:37:27 -0400 (EDT) Subject: Re: COZY: Electrical (aluminum causes fires?) In a message dated 97-09-13 20:04:30 EDT, you write: > If you want to find the real practical facts on trying to connect to > Aluminum, I suggest talking to your local electrical building inspector, and > fire department, I think they will have some horror stories. Post what they > say. If you look inside the electric service of "almost" any new home with a 200 amp electric service, you will find that the entrance cable is 4-O 3 conductor ALUMINUM Service Entrance cable, that passes through a meter base that houses 3 ALUMINUM pairs of clips to hold the meter, to an inside panelboard with an ALUMINUM busbar, with a #4 ALUMINUM grounding conductor to the water pipe and a solid #6 copper grounding conductor to the outside 8' ground rod. (if required) ("solid" and "copper" due to direct contact with the moist soil and the corrosion potential) EVERY ALUMINUM connection in this arrangment MUST be coated with an oxide inhibiting compound or paste. Most branch circuit conductors used residentially that are over 100 amps (#2 AL) are also ALUMINUM cable, the reason for this is pure economics. Copper conductors usually don't show up until #6 or smaller. Why? Because with smaller sizes the price difference diminishes and the number of splices and connections (possible points of arcing, thermal expansion, and failure) go up. Making copper the best alternative for smaller branch circuits. > And most of the connections that went bad were in the nice dry inside > of a building with no vibration. MOST of the failures that I am aware of were related to the "wiring devices" (switches, recepticles, circuit breakers, etc.) failing. The original "aluminum rated" wiring devices, (AL-CU), were found to have a potentially heat generating, fire causing, compatability problem with aluminum wiring. Modern, properly "rated" wiring devices, (CO-ALR), work just fine on AL wiring. (at least no failures to date as far as I know) My personal home was built in the early 70's. The entire home is in ALUMINUM wiring. Since I am an electician, I replaced all the devices in the home with CO-ALR rated devices. I have absolutely no problem with my family sleeping here. > Incidently I don't append my name with the P.E. (Professional Engineer), because > I don't feel I have sufficient expertice to be an expert witness in court. I AM a licenced electrical contractor, and put my butt on the line every day. IMHO, like many other things, when PROPER procedures are used, AL is an economical alternative to CU, both in $ and #, for some higher amperage electrical applications. > The prudent thing to do is stick with the proven way! As far as "the proven way" with wiring procedures is concerned, any electricians handbook, or the National Electric Code handbook, would be a good place to start. > Be careful > what people on the net post, most of my time with email I end up cautioning > people on questionable at best practices. I agree with this completely. By defending aluminum as a conductor, I don't want anyone to think that I would recomend wiring your entire aircraft in AL wiring, besides you probably can't find it in smaller sizes. All I was saying is that it "could", FWIW, make a light, well insulated, built in, easily accessible, main bus, to get power from the back to the front or versa-vise. All of my branch circuits will be in aircraft grade, twisted pair, stranded copper, of the appropriate gauge, with properly sized overcurrent protection. But my main bus? hmmmmmmmm. Sincerely, Steve Miles Date: Mon, 15 Sep 1997 13:01:37 -0700 (PDT) From: Jerry Kennel Subject: COZY: Cozy: Suction Hose What is the best hose to use for the vacuum system on the Cozy? Where can I get this hose and fittings? Thanks for the help!! Jerry Kennel Date: Mon, 06 Oct 1997 09:49:53 From: "Robert L. Nuckolls, III" Subject: COZY: "A Switch is a Switch or is it?" I've submitted this article to Sport Aviation and would like to give them first North American rights for print publication. I've had some requests for permission to reprint in various newsletters, etc. As soon as the article appears in Sport Aviation, newsletter editors may feel free to reprint as they see fit. The topic came up on a list-server thread and I like to give my net-linked compadres a look at it, just hold off on reprinting for a little while. ============================================================ Switch Ratings - What Does it all Mean? Just catching up on piles of snail-mail and e-mail that tends to build up while were flitting from fly-in to seminar. Picked up a copy of the Oct 97 issue of Van's Air Force and read an article on switch selection that makes some good points but arrives at the wrong conclusion. The author was privileged to observe some work done at UL Laboratories on switches and expressed some concern for builder naivety with respect to AC versus DC ratings. He correctly cites an increased difficulty for BREAKING a DC circuit versus an AC circuit . . . particularly when inductive loads are involved. Quoting from the article: "Typical of this is the roller and bar micro switches made by MICRO(switch) Corporation. Rated at 10 amps for 125/250 volt AC, the same switch can only carry 0.15 amps at 250 volts DC! The voltage stayed the same!" The statement is true but not relevant to our task. We're not building 250-volt airplanes, we build 14 and a few 28-volt airplanes. Check out this data table plagiarized from the same Microswitch catalog . . . Elec. 28 VDC 115 VDC 250 VDC 115 VAC 230 VAC Code ------------ ------- ------- -------------- ------- Rating Ind Res Lamp Res Res Ind Res Lamp Res 1 15 20 5 .75 .5 10 15 3 6 2 10 15 4 .75 .5 7 15 2 6 3 15 20 7 .75 .5 15 15 4 6 4 10 18 5 .75 .5 8 11 2 6 5 12 20 5 .75 .5 15 15 4 6 6 10 18 4 .75 .5 8 11 2 6 As one picks from the various switch products in the catalog, an "electrical code rating" is quoted for each device . . . the chart above states the ratings for each code. When one buys a toggle switch from Microswitch . . . the choices above are all inclusive. The charge cites a variety of conditions for applying switches. Various combinations of AC or DC voltage along with loads can have a profound effect on switch life. Inductive load do call for some derating but look at the column for lamp loads . . . it calls for the greatest derating . . on the order of 75%! I'll call your attention to the 250 VDC column for ALL switches. Note that none are rated at more than 0.5 amps in spite of the fact that the same switches are good for 6 amps at 250 VAC and MANY more amps at lower voltages. Quoting again from the article: "Those of you who can still remember the old Kettering coil ignition systems will recall that when the condenser in the distributor went bad, the points generally turned blue and melted down in a few minutes. . . . " The cited capacitor was to slow the rate-of-rise for voltage across relatively slow moving, cam driven switch contacts. If an arc were allowed to form between the opening points, energy intended to spark combustible mixtures in a cylinder would be used up at the points instead . . . the most notable result of bad "condenser" was the car ran very badly if at all . . . the points were indeed subject to more electrical stress but seldom for very long . . . this situation demanded timely repairs. Switches of choice for airplane panels are not cam driven. Toggles use spring loaded, over-center mechanisms that provide higher contact spreading velocities. Going on with the article . . . "Cockpit switches don't have benefit of the condensers to absorb the electrical inertia present in a DC circuit and as a result, the gap temperatures get hot enough to weld contacts. That includes AC rated switches, even those made with exotic high temperature alloys." The Kettering ignition example is an excellent way to illustrate "inductive" circuits. However, there are few such circuits in an airplane. Most notable of these are battery and starter contactor coils. We don't put "condensers" on these systems but we do install "catch diodes" or MOVs (metal oxide varistor) to protect switch contacts. This has been standard practice in airplanes for 30+ years (just worked on my kid's '72 Chevy truck today and saw a 1N4001 diode crimped into the connector for the air-conditioning compressor clutch). The article also overlooks the differences in physics between burning contacts and welding them. Most damage to switches is done during the BREAKING of a circuit where an arc forms in the widening gap. Depending on contact spreading velocity -AND- thermal mass of the contacts, this can be the most stressful task for switching. However, this is when the contacts are getting FARTHER apart . . hardly the scenario for welding. The physics for CLOSING a circuit are different. Here, potentially high inrush currents are impressed across contacts that may have small hills and valleys erroded in them from previous switch openings. These little hills become potential welding material when the large inrush current is forced to flow through a small cross section of material. This can happen to ANY switch with either DC or AC. By-in-large, switched circuits in airplanes are resistive but let's look again at the purloined data from Microswitch. In nearly all cases (except Code 5) DC ratings at 28 VDC for the switches cited are BETTER than the ratings for 115 VAC! (????) As a general rule of thumb, I've told builders that the 115 VAC rating is directly translatable to 14 VDC applications. I'll offer the chart above in support of this advice. The article continues . . . "What often happened during UL testing was that the points welded shut, making it impossible to open the circuit." Sure, let me pick the test parameters and I can probably weld about any switch shut. Keep in mind that UL has to test for EVERY possible safety contingency in product design and utilization. We design and build failure tolerant designs and select electrical devices that perform in narrowly defined settings. In years of fiddling with airplanes, I've never seen a manual switch weld shut. I've seen them corrode open, I've seen over-center springs rust out, I've see wires break off the back, etc. But never a welding. Now, contactors weld . . . with some frequency . . . but that's another topic. Stresses necessary weld switch contats in the lab simply don't exist in airplanes. The heaviest currents handled by panel switches are landing/ taxi lights (which have their own special inrush values - see "lamp" ratings in table above), and pitot heat. For most 14 volt airplanes this is about 8 amps. Everything else drops rapidly from there. I can also tell you that switching an 8-amp landing light with a 4-amp "lamp" rated switch is not an automatic formula for welding. The overload will indeed reduce the life of the switch. However, let us suppose the switch was originally rated for 10,000 cycles (a low estimate) and the reduction was to 10% of rated life (also very low) . . . How long will it take you to put 1000 cycles on your landing light switch? Further, like the addition of MOVs or catch diodes for breaking inductive circuits, there are simple devices (inrush limiters) that may be used in high current lamp circuits to relive sresses on the switch to the extend that stresses are no greater than purely resistive loading. In a nutshell, 125 VAC ratings equate favorably and conservatively to 14 VDC ratings - as long as the switch has a healthy "snap" action . . . all toggle switches and most rocker switches do. Just because the numbers stamped on the side of the switch don't MENTION a DC capability doesn't mean that the switch doesn't have one. Manufacturers are unable to put ALL of the information from the chart onto the side of every product, the lettering would be too small to read! The article also alluded to a 3X increase in the price of switches to get "DC rated" devices and postulated that delta-dollars for 10 switches would be $35. Hmmmmmm . . . this means that the ORIGINAL switches being compared cost about $1.75 each! I can't think of any $1.75 switch I would consider for use on an airplane and it has nothing to do with AC/DC ratings! The switches we stock sell for $5.00 in a single-pole device and carry no markings for DC ratings. They are rated at 7 amps or better at 115 AC and will work just fine in virtually every slot on an airplane panel. No matter where you choose to purchase switches, know that concerns raised by the original article are unsupported either by experience or failure mode physics. Happy switching. Bob Nuckolls AeroElectric Connection www.aeroelectric.com Date: Tue, 07 Oct 1997 08:58:31 From: "Robert L. Nuckolls, III" Subject: COZY: Battery installation >The corrosive resitant paint you were discussing, is called "Black Bituminous >Paint" and is impregnated with black bituminous coal powder. Special paints of several formulations have been around for years and used in one form or another on airplanes to protect surrounding materials from the effects of lead-acid battery fumes and leaks. . . > >Batteries being what they are, an electrical storage device, as well as an >electrical "accumulator" of sorts, all have some sort of electro chemical >substance in them, that makes them work. The new "gelcell" batteries, >regardless of their claims, still have corrosive chemicals in them, and if >they should crack, and or leak, I think they might cause some problems. >(Ergo, they bear watching through close and reasonably frequent inspection.) > Actually, true "gel cells" are getting hard to find. There are some deep cycle versions popular with electric wheelchair manufacturers but the new sealed batteries for airplanes are liquid water-acid technologies. For some background please check out "The Batteries are Comming, the Batteries are Comming" in Sport Aviation, August 1993, and a short piece at which I am going to expand by tacking this thread on the end of it. >These "sealed" and "maintenance free" batteries, as a by product of the >chemical reactions taking place inside, probably still have to create some >form of hydrogen gassing. I have always wondered what they do with that >hydrogen gas. It has to go somewhere. Where does it go? Correct . . . but true to their name "recombinant gas" they contain and recombine evolved gases back into water. This can happen because all the liquid is TOTALLY contained in thin, fiberglas mats that are about 80% saturated . . drive a nail into one of these batteries and you get NOTHING out . . . the battery will continue to function until it dries out. The cells have pressure relief valves that will vent if the battery is abused. But even when horribly pressed, the battery simply goes "pffffsssst" and it's all over. Their liquid filled ancestors were wont to spew steaming jets of acid and water all over everything before going down for the count. > >At the risk of sounding crass, an excellent source for information that might >foster understanding of such things, are the books used by prospective >aircraft mechanics (technicians) who are going through A&P school. They are >divided up into pretty clear (though relatively general) subject areas, which >might lend to clearer understanding. I wish this were true . . . of the schools I've visited and books I've looked at, most a/p mechnics ciriculums have more to do with passing FAA multiple guess exams than on how to fix airplanes. If anyone finds a good book out there, please send me the particulars. I'd like to buy one to look at. > >The new Gel Cell batteries may not be mentioned in the books, but they still >have a lot of useful information concerning lead acids, and ni-cads. > These days, I wouldn't put a liquid lead acid -OR- a ni-cad in a small airplane . . . they need battery boxes and have too many other hazards associated with them. The RG battery didn't become a popular consumer item until computers in offices began to demand clean, fume free, totally benign sources of stored energy for un-interruptable power supplies . . . You think you have a problem with getting proper paint for your battery box, wait until you spill acid on the carpet of some lawyer's office!!!! The RG battery doesn't need a box . . in fact, is safer just simply strapped down to an open tray. Make sure the attach mechanisms are good for 10g's and use rubber booties over the exposed terminals. Simple, light, clean. NOW . . . if you'd truly wish for the battery to be the most reliable source of power in the airplane, either (1) do capacity checks every 6 months and discard when down to 50% or less or (2) simply replace the battery every two years. Regards, Bob . . . AeroElectric Connection //// (o o) ==========oOOo=(_)=oOOo========== | | | Go ahead, make my day . . . | | Show me where I'm wrong. | ================================= http://www.aeroelectric.com From: Gunrider@aol.com Date: Wed, 8 Oct 1997 10:51:54 -0400 (EDT) Subject: COZY: RIGHT SIDE CONDUIT? Being that I weigh much more than my wife (even when pregnant). I have been thinking of moving what I can to her side. Can the conduit be easily moved to the right side? I' m probably going to use the thin-walled copper tubing. Hugh Farrior puttin' in the control system From: Marc J. Zeitlin Subject: Re: COZY: RIGHT SIDE CONDUIT? Date: Wed, 8 Oct 97 11:10:05 EDT Hugh Farrior wrote; >Being that I weigh much more than my wife (even when pregnant).... I'd think that when you were pregnant, Hugh, you'd weigh LOADS more than your wife :-). > Can the conduit be easily moved to the right side? I' m probably going to >use the thin-walled copper tubing. What conduit are we referring to here? Vacuum, electrical? I don't think that there's any specification on which side either one have to go on; there's an electrical chase on both sides of the plane. Putting the battery way over on one side of the main spar would have a lot more affect, I think. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Thu, 09 Oct 1997 09:43:27 From: "Robert L. Nuckolls, III" Subject: COZY: The great breaker debate . . . I'll invite subscribers to this list to check out a new piece I've posted Regards, Bob . . . AeroElectric Connection //// (o o) ==========oOOo=(_)=oOOo========== | | | Go ahead, make my day . . . | | Show me where I'm wrong. | ================================= http://www.aeroelectric.com Date: Thu, 09 Oct 1997 22:35:51 From: "Robert L. Nuckolls, III" Subject: COZY: Re: Ready to saddle up . . . > >One suggestion for the postings relating to your web site -- if the three >samples you included in this posting are an example of your plan, they are a >bit cryptic for me although I can figure out what they might be about. If >you could add a short paragraph, or sentence, better describing the nature of >the content of posting, it might give a better idea as to whether it is >worthwhile visiting or not. Excellent point! Here's an annotated repost . . . > > > An annotated "wing and a prayer" story . . . "It was a dark and stormy night and all of a sudden, the main breaker blew leaving me in the dark." I wish it were really humerous and in this case the story does have a happy ending . . . BUT . . . it should not have happened in the first place. > > > Illustrated instructions on modifying the "Piper style" ground power jack sold by Aircraft Spruce for use on your airplane. Schematics and step by step instructions. > > > "The switch says '7A @ 125 VAC', can I use it on my airplane? Where do I buy DC rated switches?" Regards, Bob . . . AeroElectric Connection //// (o o) ==========oOOo=(_)=oOOo========== | | | Go ahead, make my day . . . | | Show me where I'm wrong. | ================================= Date: Thu, 09 Oct 1997 23:17:03 From: "Robert L. Nuckolls, III" Subject: COZY: RE: The great breaker debate . . .Yeahbut..... >Bob, > >Your web page on the use of fuses in place of breakers is right, I think. Maybe. > >With your wide experience you tell to use fuses but we amateurs, with the wisdom >gained from looking at existing panels say "yeah, Bob, but..." Here are a few >yabuts. > >"It isn't done this way, breakers are the standard way." > Who's "standard" . . . where is is written? FAR21, 25, 43 all speak to the use and maintenance of both fuses and breakers. How did breakers become a "standard". They certainly became a custom as people found out how BAD the little fuse holders are with the caps that drop on the floor and roll all the way back to the baggage compartment. Breakers became a convenience. No place in the FARs does it say that ANY fuses or breakers have to be located in reach of the pilot. They DO say that fuses in reach of any crew that powers "flight critical" circuits must be backed up with 50% spares. So tell me what systems on your proposed airplane are "flight critical" meaning that failure of the device presents an immediate hazard to flight? >"I can't risk the lives of my loved ones on something different." > Explain the risk. Paint the scenario where reseting a breaker in flight is going to bring some absolutely essential piece of equipment back on line. >"It is harder to replace a fuse in flight than to reset a breaker." > > You betcha . . . that's why I don't bother to put them anywhere I might even be tempted to fiddle with them in the air. Be a pilot in the air and save being a mechanic until on the ground. >"We should not use anything that is used on automobiles until it is proven on >airplanes" You got it backwards. The stuff on current airplanes was certified in 1940- 1970 with precious few changes since then. Take a walk through the Service Difficulty Reports on the net and see how often a "certified" piece of equipment fails. Of course it can be "overhauled" and yellow-tagged and put right back on an airplane . . . it's the same piece of 1960's technology that came off in the first place . . . you have any confidence in that? On the other hand, how often do you have problems with similar gizmos in your car? The environment under the hood of a modern automobile is just as punishing as under the cowl of an airplane. There's temperature cycles, splash, sand, dust, ozone, oil vapors . . . you name it. For myself, I've replaced one alternator on one of 7 cars owned over the past 12 years with a cumulative total of more than 4,000 hours operating time . . . As I write these words, B&C is doing a booming business in STANDBY alternators out of his booth at the American Bonanza Society show here in Wichita. He just told me on the phone about how often people have alternator troubles in their airplanes. If I owned a $40,000 automobile and had these kinds of troubles, I'd be all over the dealer. Yet people fly around in $250,000 airplanes and put up with the most rediculous problems because "fixing" the problem is too expensive . . . and besides, the current system is "certified." The majority of alternators, starters, fuel injection systems, ignition systems on cars go to the junk yard still working after 100,000+ miles of service. Airplane products and designs are "carved in stone" while automobiles continue to evolve and become better and better values every year. I'd put any modern automobile part on my airplane before I'd opt for a part out of a salvaged C-172 . . . even the new ones right off the assembly line. > >"What if I later want to sell my airplane - who'd buy it with fuses?" > Somebody who understands why you elected to use fuses instead of breakers and why they're out of reach just like on your car. Check the threads and articles out on our website for more info . . . > >"A few fuses aren't nearly as impressive as a panel full of switches." > Now there is an EXCELLENT reason for going to breakers. I had a client a few years ago hire me to do a wirebook for his proposed BD-10J project. It was a design goal to make this airplane "look as military as possible". We ended up with 65+ breakers in the airplane for a total of $1300.00. Personally, I'd rather use that money -AND- panel space for something really useful like a second GPS receiver or perhaps a CD player. Regards, Bob . . . AeroElectric Connection //// (o o) ==========oOOo=(_)=oOOo========== | | | Go ahead, make my day . . . | | Show me where I'm wrong. | ================================= Date: Fri, 10 Oct 1997 08:59:32 From: "Robert L. Nuckolls, III" Subject: COZY: Re: Ammeter Question At 01:56 AM 10/10/97 -0400, you wrote: >Bob: Have seen several of your articles, and have never failed to learn >quite a bit from each one. . . . Thank you. I'm pleased to be helpful. > . . . . . I have a T-6G, 28v system, generator with OLD >voltage reg. The ammeter is a generator-load meter, showing only positive >amps as the load increases, but not negative amps as the load increases on >the battery. The scale of the meter is wrong, in my opinion. Rarely draw >more than 30 amps, yet the meter goes to 150 amps. At normal draw of 5-10 >amps, the needle barely moves off of zero. Obviously, a poor selection of instrumentation. >I recently bought a combination voltmeter/ammeter.......the type that reads >amps until you push and hold a button in order to read volts. Max scale >is 30 amps. Both the installed meter and the new meter have an external >shunt. The existing shunt will carry up to 150 amps, with "X" millivolts >providing full-scale needle deflection. ( I forget what "X" is) >The new volt/ammeter came with a shunt that is rated at only 30 amps, with >the same "X" millivolts being full-scale (in this case 30 amps) deflection. This is good stuff . . and why I'm forwarding this letter to some list servers I subscribe to. A standard within the instrumentation world is to design remote shunt ammeters such that 50 millivolts on the instrument's terminals will cause it to read full scale. That scale could be 1 amp or 1,000 amps . . . it matters not. The remote shunt is simply a precision power resistor designed to drop 50 millivolts across its terminals as it passes design current levels. Hence, take about any remote shunt style ammeter and it will read FULL SCALE at whatever current the SHUNT is calibrated, irrespective of what the instrument's scaleplate sez. >My question is: How can I properly install an ammeter with a scale that >will let me read the meter, say 0-30 or 0-50 amps? Do I have to change the >Shunt? Yes . . . install your new shunt in place of the old one, wire in the new instrumenet across the shunt (use 5 amp in-line fuses in each lead coming from the shunt . . . the fuses mount as close to the shunt a practical). >If so, does the rating of the shunt have to approximate the rating >of the generator? Sure. The original situation you cited illustrated how impractical it was to monitor the output of a 30 amp machine with a 150 amp instrument. For alternator load meters, I don't calibrate them in AMPS, just percent of load. Then, I'll keep a selection of shunts around for the popular alternator sizes. The pilot's real interest is in how much of the alternator's capacity is being taxed. Hence, a meter that reads in percentage of some shunt value fills the bill. The the builder wants to but in a bigger alternator later, he just changes the shunt, the SAME instrument stays in place on the panel. Nifty huh???? >Does the shunt have to match the ammeter? Yes . . . the SCALE PLATE has to have the same full scale reading as the ampere rating on the shunt. >Thank you in advance for any advice you might have. And if time doesn't >permit you to answer these questions, I fully understand. You're most welcome and than you for the question. We'll make time. The institutionalized aviation community has held their "black art" very close to the chest. While ordinary citizens are building their own byte-thrashing computers from mail-order parts, citizens who own airplanes are not expected to know or even want to know how they work. It's time we stopped that and started sharing the knowledge. That's what these list-servers and our business is all about. >Peter C. Hunt > >"HUNTER" >Capt. USN, ret. Ex Fighter Pilot, A&P, T-6 Owner/Operator. > > > Regards, Bob . . . AeroElectric Connection //// (o o) ==========oOOo=(_)=oOOo========== | | | Go ahead, make my day . . . | | Show me where I'm wrong. | ================================= Date: Fri, 10 Oct 1997 10:38:23 From: "Robert L. Nuckolls, III" Subject: COZY: Re: The great breaker debate . . .Yeahbut..... <19971009.204841.4863.0.GASobek@juno.com> > I don't want to start another great debate over the fuse Vs Breaker >concept, but I have to take exception to your example. > > First of all, it would appear from your statements that you're talking >about UNMANNED spacecraft. I to beleive that fuses in this type of >installation is the correct approach. But there are times when an >intermittent short that opens a critical circuits breaker might result in >the pilots safe return with the ability to reset that breaker. I agree >that service work should not be performed in the cockpit while flying, >but I would rather have the ability to reset a breaker IF I NEED TO, and >it doesn't interferr with the control of the aircraft. Just my opinion. Let's try an ON-LINE FMEA (failure mode effects analysis). Over the next 24 hours, I'd like for people to post their response to the following questions: (1) Name one item of electrical equipment critical to safe completion of flight . . . or an item who's failure presents an immediate hazard to completion of flight. (2) List the ways in which this device or system might fail. (3) How will each of these failures become obvious to the pilot. Tomorrow, I'll carry the analysis of each response to the next step. This is just the kind of process we do in the "big" airplane business; it's a good exercise to know . . . Regards, Bob . . . AeroElectric Connection //// (o o) ==========oOOo=(_)=oOOo========== | | | Go ahead, make my day . . . | | Show me where I'm wrong. | ================================= Server 2.0b9); Fri, 10 Oct 1997 11:27:28 -0600 Date: Fri, 10 Oct 1997 11:13:40 -0500 From: Chris Anderson Subject: Re: COZY: The great breaker debate . . .Yeahbut..... <9710092240.AA03043@alliance.sybase.com> <19971009.204841.4863.0.GASobek@juno.com> At 10:38 AM 10/10/97, you wrote: > > (1) Name one item of electrical equipment critical to safe completion > of flight . . . or an item who's failure presents an immediate > hazard to completion of flight. The only eletric device that important in mine would be the electric pump to run the retracts. > > (2) List the ways in which this device or system might fail. Loss of fluid preasure. Power failure. Motor faulure. Pump failure. > > (3) How will each of these failures become obvious to the pilot. (respectivly) hyd. preasure idiot lamp in cockpit (green light for preasure over a set point red for under) meters when the gear don't come down, and the idiot lamp is red when the gear don't come down, and the idiot lamp is red From: lschuler@cellular.uscc.com Date: Fri, 10 Oct 97 12:05:53 -0600 Subject: COZY: Re: The great breaker debate . . .Yeahbut..... --simple boundary Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Bob Nuckolls wrote: >Let's try an ON-LINE FMEA (failure mode effects analysis). Over the >next 24 hours, I'd like for people to post their response to the following >questions: >(1) Name one item of electrical equipment critical to safe completion of flight . . . or an item who's failure presents an immediate hazard to completion of flight.< >(2) List the ways in which this device or system might fail.< >(3) How will each of these failures become obvious to the pilot.< >Tomorrow, I'll carry the analysis of each response to the next step. >This is just the kind of process we do in the "big" airplane business; >it's a good exercise to know . . . 1. Subaru SVX computer. 2. Short or open (just to keep it simple and keep away from the exotic single-sensor failure modes). Either of these may be either permanent or temporary depending on the actual source of the difficulty and any possible ability to clear it before "landing". Example maybe a short caused by a screw holding the circuit board in the chassis has come lose. 3. The engine quits in both cases. The affect is identical. Just thought I'd toss this out since you are keen on using stuff that wasn't designed in 1940 AND because I will be using a Subaru SVX with computer and (probably) full array of sensors. All of which were manufactured after 1992. Larry Schuler --simple boundary Content-Type: text/plain; charset=US-ASCII; name="RFC822.TXT" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="RFC822.TXT" Received: from gatekeep.uscc.com by cellular.uscc.com (ccMail Link to SMTP R8.00.01) ; Fri, 10 Oct 97 10:44:57 -0600 Return-Path: Received: from www.uscc.com (www.uscc.com [204.179.101.2]) by gatekeep.uscc.com with ESMTP id LAA20555 for ; Fri, 10 Oct 1997 11:41:39 -0400 (EDT) Received: from palrel1.hp.com (palrel1.hp.com [156.153.255.235]) by www.uscc.com with ESMTP id KAA16082 for ; Fri, 10 Oct 1997 10:42:26 -0500 (CDT) Received: from hpwarhw.an.hp.com (hpwarhw.an.hp.com [15.57.193.122]) by palrel1.hp.com (8.8.6/8.8.5tis) with SMTP id IAA14473 for ; Fri, 10 Oct 1997 08:44:31 -0700 (PDT) Received: by hpwarhw.an.hp.com (1.37.109.8/15.5+IOS 3.22) id AA19577; Fri, 10 Oct 1997 11:43:46 -0400 Received: from relay.hp.com by hpwarhw.an.hp.com with SMTP (1.37.109.8/15.5+IOS 3.22) id AA19572; Fri, 10 Oct 1997 11:43:44 -0400 Received: from dtc.net (dtc.net [206.242.217.15]) by relay.hp.com (8.8.6/8.8.5tis) with ESMTP id IAA15627 for ; Fri, 10 Oct 1997 08:41:30 -0700 (PDT) Received: from p3.ts1.dtc.net (p3.ts1.dtc.net [205.183.130.3]) by dtc.net (8.8.5/8.8.5) with SMTP id PAA09943; Fri, 10 Oct 1997 15:43:25 GMT Message-Id: <3.0.1.16.19971010103823.2807ce24@dtc.net> X-Sender: nuckolls@dtc.net X-Mailer: Windows Eudora Light Version 3.0.1 (16) Date: Fri, 10 Oct 1997 10:38:23 To: rv-list@matronics.com From: "Robert L. Nuckolls, III" Subject: COZY: Re: The great breaker debate . . .Yeahbut..... In-Reply-To: <19971010.081543.3350.6.wstucklen1@juno.com> References: <9710092240.AA03043@alliance.sybase.com> <19971009.204841.4863.0.GASobek@juno.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: owner-cozy_builders@hpwarhw.an.hp.com Precedence: bulk Reply-To: "Robert L. Nuckolls, III" --simple boundary-- by x9.boston.juno.com (queuemail) id V`D15527; Mon, 13 Oct 1997 21:01:04 EDT Date: Sun, 12 Oct 1997 10:53:43 -0400 Subject: COZY: Re: The great breaker debate . . .Yeahbut.....but... From: unick@juno.com (Nick Ugolini) When I wired my LongEZ, I followed Bob's advice (through personal discussions with him and his book). I used with FUSES. I loved the result. I have talked with aviation shops and found breakers to be highly unreliable in their protection ability. Conversely every one said a fuse pops exactly when it is supposed to. I have a bag full of "aviation brakers" I picked up for wiring my plane and they are still setting on the shelf. I elected to go with the B&C fuse block... a 10 and 20 for a total of 30 fuses and their ground strip (I think it has 40+, 1/4" spade push on connections. The fuse blocks are very small and are located in the nose of the plane well out of reach. I have ONE breaker for the alternater field which is "accessible to the pilot" as required by the FARS for a IFR plane. I have EVERY single circuit fused. Each selenoid, each radio, gear warn circuit, the little LEDs for the fuel level lighting, even the instrument pannel light circuit has its own fuse, and I still have spare fuse holders. If for some reason I lose a circuit I have got a REAL problem, and I only lost one circuit, not a bunch of things all hooked up to one breaker which is how you typically wire a plane. Think about it, when was the last time you blew a fuse in your car? From: Fritzx2@aol.com Date: Mon, 13 Oct 1997 22:45:25 -0400 (EDT) Subject: Re: COZY: Re: The great breaker debate . . .Yeahbut.....but... In a message from Nick Ugolin: << The fuse blocks are very small and are located in the nose of the plane well out of reach. >> How do you replace one in flight if it is "out of reach"? John Fritz fritzx2@aol.com Date: Tue, 14 Oct 1997 18:13:57 From: "Robert L. Nuckolls, III" Subject: COZY: Re: RV-List: Re: The great breaker debate >Date: Tue, 14 Oct 1997 18:12:24 >To: rv-list@matronics.com >From: "Robert L. Nuckolls, III" >Subject: Re: RV-List: Re: The great breaker debate >In-Reply-To: <199710140155.SAA02516@norway.it.earthlink.net> > >At 08:53 PM 10/13/97 +0000, you wrote: >>--> RV-List message posted by: "Tim Lewis" >> >> The "accessible breaker vs inaccessible fuse" debate is interesting >>to watch, and Bob Nuckoll's articles have had an impact on how I >>designed my electrical system (RV-6AQ, panel mostly done). I don't >>agree with everything Bob advocates, but he provides a lot of good >>food for thought. >> > > My reply to this is extensive . . rather than use up space here > I'll suggest those interested in reading it hop over to: > > > > Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= by x9.boston.juno.com (queuemail) id VQG18784; Tue, 14 Oct 1997 21:44:39 EDT Date: Tue, 14 Oct 1997 16:04:42 -0400 Subject: COZY: Re: The great breaker debate . . .Yeahbut.....but... From: unick@juno.com (Nick Ugolini) The fuses are mounted on a bracket in the nose next to the battery. Access is granted through the battery cover. The single breaker for my Alt. field is located next to my main non-vital bus switch. ' Total cost for 30 fuses and 1 breaker was $35 if I recall correctly. Date: Tue, 14 Oct 1997 19:42:42 -0400 From: Jim Hocut Subject: COZY: Re: The great breaker debate . . .Yeahbut.....but... It had slipped my mind, but there have been two occasions when I was glad I was flying a plane that had breakers instead of fuses. Once 'twas a Cessna-172RG, and the other time 'twer a Piper Arrow. The breaker for the gear's hydraulic pump tripped when the gear was in transit. Once reset it was fine. True I could have pumped the gear on the 172RG, and true the gear will free fall on the Arrow. And true there probably was some physical problem with the motor or pump that needed attention (these are rental planes after all), but it sure was nice to be able to reset the breaker and continue on. Jim Hocut jhocut@mindspring.com Date: Wed, 15 Oct 1997 00:43:59 +0000 From: Dean Arthur Subject: Re: Europa_Mail: Re: COZY: Re: The great breaker debate . . .Yeahbut.....but... cdenk@ix.netcom.com wrote: > > Nick Ugolin writes unreliable > > Murphey's Law will prevail, what can go wrong, will go wrong. One of the main failure modes > of fuses is vibration with the little wire breaking. I have replaced more than my share of > glass cylindrical fuses on autos, trucks, and farm equipment wher there was no electrical > fault. Just replaced the fuse, and worked for years. Also I usually have dropsy in flight > and in turbulence at night I would anyday go for the circuit breaker. I have replaced 1 in > 500 hours. > > Carl Denk: "cdenk@ix.netcom.com" > ______________________________________________________________________ > The Europa List is supported by Aviators Network UK - info@avnet.co.uk Capture a fuse block from newer American design cars using plastic fuse plug with "Z" shaped fuse link. NO CHANCE of those suffering vibration breakage. The amount of vibration required would most assuredly shake the plane to pieces first! From: cdenk@ix.netcom.com Date: Tue, 14 Oct 1997 21:13:21 -0500 (CDT) Subject: Re: COZY: Re: The great breaker debate . . .Yeahbut.....but... Nick Ugolin writes Murphey's Law will prevail, what can go wrong, will go wrong. One of the main failure modes of fuses is vibration with the little wire breaking. I have replaced more than my share of glass cylindrical fuses on autos, trucks, and farm equipment wher there was no electrical fault. Just replaced the fuse, and worked for years. Also I usually have dropsy in flight and in turbulence at night I would anyday go for the circuit breaker. I have replaced 1 in 500 hours. Carl Denk: "cdenk@ix.netcom.com" Date: Tue, 14 Oct 1997 21:26:16 -0500 (CDT) From: cdenk@ix.netcom.com Nick Ugolin writes Murphey's Law will prevail, what can go wrong, will go wrong. One of the main failure modes of fuses is vibration with the little wire breaking. I have replaced more than my share of glass cylindrical fuses on autos, trucks, and farm equipment wher there was no electrical fault. Just replaced the fuse, and worked for years. Also I usually have dropsy in flight and in turbulence at night I would anyday go for the circuit breaker. I have replaced 1 in 500 hours. Carl Denk: "cdenk@ix.netcom.com" Date: Wed, 15 Oct 1997 09:41:27 -0700 From: Paul Messinger Organization: MTF Industries Subject: Re: Europa_Mail: Re: COZY: Re: The great breaker debate . . .Yeahbut.....but... Dean Arthur wrote: > > cdenk@ix.netcom.com wrote: > > > > Nick Ugolin writes > unreliable > > > Murphey's Law will prevail, what can go wrong, will go wrong. One of the main failure modes > > of fuses is vibration with the little wire breaking. I have replaced more than my share of > > glass cylindrical fuses on autos, trucks, and farm equipment wher there was no electrical > > fault. Just replaced the fuse, and worked for years. Also I usually have dropsy in flight > > and in turbulence at night I would anyday go for the circuit breaker. I have replaced 1 in > > 500 hours. > > > > Carl Denk: "cdenk@ix.netcom.com" > > ______________________________________________________________________ > > The Europa List is supported by Aviators Network UK - info@avnet.co.uk > > Capture a fuse block from newer American design cars using plastic fuse > plug with "Z" shaped fuse link. NO CHANCE of those suffering vibration > breakage. The amount of vibration required would most assuredly shake > the plane to pieces first! I agree that it's not vibration here that is the primary cause. The typical failure mode in fuses is a result of the slight heating and cooling between power on/off cycles and the lead alloy just finally separates. Fuses work by the heat generated by the excess current melting the lead alloy. There is less heat but still some under normal conditions. This fuse failure mechanism is seldom addressed in fuse - circuit breaker comparisons. The "Z" fuses are better than the glass tube design in this respect. I personally would never use a fuse in an acft. Nor would I put a fuse or CB where I could not reset it in flight. If the related equipment was not important to some mode of flight then it does not belong on the acft in the first place! Resetting the CB has saved me and the acft from harm three times in my 40 years of flying experience. BTW FAR 23.1357 (d) requires cockpit resetable (replaceable) Fuses/CB for "critical to flight equipment". Paul Aeronautical and Electronic engineer EAA Technical Counselor Commercial, Inst., CFI From: Epplin John A Subject: COZY: Re: The great breaker debate Date: Wed, 15 Oct 1997 13:21:39 -0500 Paul writes: > I agree that it's not vibration here that is the primary cause. > > The typical failure mode in fuses is a result of the slight heating > and > cooling between power on/off cycles and the lead alloy just finally > separates. Fuses work by the heat generated by the excess current > melting the lead alloy. There is less heat but still some under normal > conditions. This fuse failure mechanism is seldom addressed in fuse - > circuit breaker comparisons. The "Z" fuses are better than the glass > tube design in this respect. > > [Epplin John A] Agreed. In the days of large rotary inverters, some fused as high as 300 amps, the maintenance procedures usually called for a periodic replacement of these large fuses. On the Grumman G1, these were in a junction box located in a closet. I had the cover off once when the inverter was started. The fuses have a transparent cover over the element which allowed the red glow to be visible. This explained why they were to be replaced periodically. I think that the rotary inverters would be about the worse case torture to fuses, however even incandescent lamps have a short term inrush current far higher than their steady state value. Now, does anybody know why we have fuses or breakers in the first place? The answer is to protect the wiring, not the device on the end of it. Circuit protection should be sized for the size wire, regardless of the device on the end of it. The connected device should have any protection that it needs on its own. Lamp bulbs are sort of self protecting, motors may have a overheat switch, most electronic equipment has some sort of current limiting devices inherent in their design...etc.. There are a few limited applications that should not be reset in flight, one that is common is combustion heaters. I hear the arguments of accessibility, but my personal feeling is these should be in flight resettle or replaceable, except in very few special applications. Also, except for very high current devices which are not likely to be found on the type of aircraft discussed here, I prefer a good quality circuit breaker that can be manually opened in flight. The above discussion is worth exactly what you are paying for it. John epplin Mk4 #467 Date: Wed, 15 Oct 1997 12:47:37 -0700 From: Paul Messinger Organization: MTF Industries Subject: COZY: Re: The great breaker debate Epplin John A wrote: > > Paul writes: > > > I agree that it's not vibration here that is the primary cause. > > > > The typical failure mode in fuses is a result of the slight heating > > and > > cooling between power on/off cycles and the lead alloy just finally > > separates. Fuses work by the heat generated by the excess current > > melting the lead alloy. There is less heat but still some under normal > > conditions. This fuse failure mechanism is seldom addressed in fuse - > > circuit breaker comparisons. The "Z" fuses are better than the glass > > tube design in this respect. > > > > > [Epplin John A] > Agreed. In the days of large rotary inverters, some fused as > high as 300 amps, the maintenance procedures usually called for a > periodic replacement of these large fuses. On the Grumman G1, these > were in a junction box located in a closet. I had the cover off once > when the inverter was started. The fuses have a transparent cover over > the element which allowed the red glow to be visible. This explained > why they were to be replaced periodically. I think that the rotary > inverters would be about the worse case torture to fuses, however even > incandescent lamps have a short term inrush current far higher than > their steady state value. > > Now, does anybody know why we have fuses or breakers in the > first place? The answer is to protect the wiring, not the device on the > end of it. Circuit protection should be sized for the size wire, > regardless of the device on the end of it. The connected device should > have any protection that it needs on its own. Lamp bulbs are sort of > self protecting, motors may have a overheat switch, most electronic > equipment has some sort of current limiting devices inherent in their > design...etc.. > > There are a few limited applications that should not be reset in > flight, one that is common is combustion heaters. I hear the arguments > of accessibility, but my personal feeling is these should be in flight > resettle or replaceable, except in very few special applications. Also, > except for very high current devices which are not likely to be found on > the type of aircraft discussed here, I prefer a good quality circuit > breaker that can be manually opened in flight. > > The above discussion is worth exactly what you are paying for > it. > > John epplin Mk4 #467 John I agree with you, in particular with the "real purpose" of the breaker and also the "manual open" type of breaker. It is the only kind that I use and recommend. In many cases use of this type of breaker can eliminate the usual switch and combine both into one device. Consider a circuit that is typically always on. Why have a switch when this manual open breaker can provide both functions? Just leave it on all the time and you still have the capability to open the circuit if needed. There are even breakers with a bat handle for frequent on/off action. I am well aware with Bob's positions' on various subjects and agree with some and disagree with others. I firmly believe there are many good solutions to an issue and think differing opinions should be accepted with out the usual heat and smoke sometimes found. I have yet to meet another A&P, FAA rep, or EAA Tech coun. that agrees with Bob on remotely located fuses. That doesn't make his opinion wrong, just different than my data base and personal position. When I was on active duty in the USAF, we saved an average of one mission a month by being able to reset the breaker and continue. A couple of times a year this ability saved the acft. As you can see, I am biased based on real experience (USAF and 3 personal cases in civil acf), and all the numbers games in the world will not change my mind. Sure breakers trip when they shouldn't, and they are "on paper" less reliable than fuses. But I never heard of one totally failing open when the downstream device was good. Paul Date: Wed, 15 Oct 1997 20:55:54 -0700 From: "LCDR James D. Newman" Organization: INFINITY Aerospace - http://www.flash.net/~infaero Subject: COZY: Re: The great breaker debate Hi Paul and All, >Paul wrote: >When I was on active duty in the USAF, we saved an average of one mission a month by being able to reset the breaker and continue. A couple of times a year this ability saved the aircraft.< Yes, in my 2000+ hours flying F-14's with 800+ circuit breakers, flying several of the other military hardware and familiar with the rest, NATOPS said we could not cycle the circuit breakers more than 3 times if one popped. NATOPS also said not to hold the circuit breaker in if it's trying to remain popped. I always got a laugh out of that one (someone obviously tried holding it in which I'm sure caused a lot of problems). Bob, any comments on this pushing it in 3 times policy [I think I know what you will say ;-)]? As Paul said, several a mission was saved because we could reach a circuit breaker and just push it in. With all the glitches that came up in these aircraft made by the cheapest bidder, we actually used circuit breakers as ON/OFF switches, and for many other trouble shooting situations so we didn't lose a mission. In 5000+ civilian flight hours, I've only had one incident where I'm very glad I could reach and pull the circuit breaker. The instrument panel light rheostat in a Turbo Cessna 210 I was flying one very dark night shorted over the water (which I found out later that this is somewhat common[!?!] in Cessna's with their panel light rheostats), melting the wires and catching fire under the instrument panel - the circuit breaker didn't pop. The globs of melting wires on fire dripped/dropped onto my legs and caught my Navy uniform pant legs on fire. Except for my legs on fire providing the only light in the cockpit, everything went very black. If we would of had ejection seats, my fellow Naval Aviator riding along with me would have punched out. For a few moments, I thought he was going to crawl into the back seat or even open the door and drop into the ocean. I got the fire out and my friend calmed down, and landed uneventful using a flashlight. A lot of the panel had to be rebuilt and rewired, and I had a sunburn and shorts that needed trimmed and cuffs. I'm sitting here laughing to myself about that night as I write, but it wasn't very funny at the time and was almost a really big problem. So, I will probably always fly my plane in my Nomex flight suit, and I will have a shroud under the instrument panel above my legs so melting things and things on fire can not drop on my legs or in my lap again. I also have a fire extinguishing system for behind the instrument panel and in the engine compartment. Bob has brought up many good issues though. I've never considered putting all the CB's out of reach in the air, or to use fuses. But, as Bob said, our Sport Aircraft hopefully are better thought out and wired accordingly than spam cans. There has been a lot of other good points brought up by the group, also. I've always liked lighted switch circuit breakers, too :-(. Alternator, landing gear, maybe a few others - I'll have to noodle on this one. Thanks Bob and All. Infinity's Forever, JD Date: Thu, 16 Oct 1997 12:03:44 From: "Robert L. Nuckolls, III" Subject: COZY: fuses At 08:56 AM 10/16/97 -0700, you wrote: >As a 65 year old EE, I would like to make one small comment about the >discussion that has taken place over the last few days (I previously put my >two cents in re: fuses vs breakers--I am on the side of breakers--so I won't >go into that again). I do want to say however that the purpose of fuses or >breakers can be and often is far more than just to protect the wiring. This has indeed been an Operational consideration in the design of some aircraft systems and I'm sure the military and transport category aircraft have many examples in their POH. Thing is, most of these aircraft are flown with two or more crew; or if single pilot, one that does this stuff for a living . . . highly trained and paid to accept the risks the job brings with it. > You >can make the argument that the unit that blew the protective device has >already failed so it is not necessary to protect it further but in many >situations the rapid removal of power to the failed unit will prevent >further damage to that unit (cascading failures). Which puts the pilot's head down in the cockpit. The argument isn't just breakers/fuses . . . it's system architecture and operating philosophy. At first sign of trouble, I have but two switches MAX that need to be operated. There are operational Plan B's in place before the flight launches. I like to go flying fully prepared to complete the flight with the whole electrical system SHUT DOWN. I make many flights with no electrical system at all. Ya gotta spend some time in J-3's and C-120's to appreciate what CAN be done with a very rudimentary compliment of equipment. I made a cross country round trip a few years ago in a rental airplane where the alternator died minutes after home base departure. The trip wasn't difficult not so much for the equipment I had but for the confidence in the airplane's abilty to perform a desired task WITHOUT all the electrons. >And certainly one major >reason for PDs is to prevent fire, not just from the wiring to the unit or >in the unit but from other components as well. These are certainly true words but do they apply in any way to the airplanes we should be buidling? Many seasoned and experienced people bring a wealth of knowlege to this discussion. Much of it comes from an air transport/military background working with designs and operational philosophies that were developed 30 years ago. I don't doubt the validity and usefulness of their training in the machines they were FORCED to live with. We're building the best airplane flying today. We're not FORCED to live with anything . . . Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= by post.larc.nasa.gov (8.8.6.1/pohub4.1) with SMTP id KAA14632 for ; Thu, 16 Oct 1997 10:31:07 -0400 (EDT) Date: Thu, 16 Oct 1997 10:26:02 -0400 From: Paul Krasa Subject: Re: COZY: Re: The great breaker debate . . .Yeahbut..... When the time comes to wire your airplane and you estimate the number of breakers you will need to cover all the systems and then compare it to the panel space available. You will probably come o the same conclusion I did. Only put breakers and switches on the panel that are absolutely nessecary. All the rest off the circuits get a fuse. I used a ten fuse block using the new type blade fuses that I got at Skycraft in Orlando, FL. When you are at Sun n Fun take an afternoon and go to Skycraft. Skycraft has surplus aircraft wire, bus bars, switches, and just about any other electircal thing you can think of. Paul Krasa Long EZ 214LP p.s. By the way the fuse block was less than $10 a piece. Date: Thu, 16 Oct 1997 08:56:54 -0700 From: Michael Antares Subject: COZY: COZY; fuses As a 65 year old EE, I would like to make one small comment about the discussion that has taken place over the last few days (I previously put my two cents in re: fuses vs breakers--I am on the side of breakers--so I won't go into that again). I do want to say however that the purpose of fuses or breakers can be and often is far more than just to protect the wiring. You can make the argument that the unit that blew the protective device has already failed so it is not necessary to protect it further but in many situations the rapid removal of power to the failed unit will prevent further damage to that unit (cascading failures). And certainly one major reason for PDs is to prevent fire, not just from the wiring to the unit or in the unit but from other components as well. My further two cents... By the way, I just had the pleasure, after waiting a year, to move into a hanger. The Cozy building cycle has been on hold for a few months as I made the transition to a new living location and in the process lost the ability to build in a garage. But now I have a brand new hanger (Petaluma Muni) and will happily continue building once again. Yeah! 11597 Summerhome Park Road Forestville, CA 95436 707.887.7260 Cozy#413 Finished through chap 14 except chap 13. Chaps 16 & 24 mostly finished. Now on chap 20. One wing/winglet finished, working on second--almost finished. From: Epplin John A Subject: COZY: Electrical sysstem Date: Thu, 16 Oct 1997 11:12:56 -0500 Getting around to trying to collect my thoughts on electrical requirements. I have made a list of devices that normally would need breakers/fuses and panel switches. * Boost Pump * Nav Lights * Strobe Lights * Landing Lights * Instr. Lights * Cockpit Flood * Pitot Heat * Auto Pilot Navcom 1 Navcom 2 Gps Xponder Intercom Alt. Field Turn & bank Eng. Inst. Landing Gear Speed Brake Trim Items marked * require a switch as well as circuit protection. Have I missed anything? Does anyone have any feel for how much and what size wire to order? I would think 2 sizes would cover most uses, 16 ga and maybe 22 ga for the light load things. Will need small amount of heavier for buss feeder and main ground etc. I plan on a copper strip located near the instrument panel for a common ground forward and a substantial stud through the firewall near the battery for the engine and any rear mounted equipment. This is my thoughts at the moment, subject to change at any time. Just looking for input so I can do it right the first time. John Epplin MK4 #467 Date: Thu, 16 Oct 1997 18:10:29 From: "Robert L. Nuckolls, III" Subject: COZY: It's not JUST breakers/fuses . . . >I have yet to meet another A&P, FAA rep, or EAA Tech coun. that agrees >with Bob on remotely located fuses. That doesn't make his opinion wrong, >just different than my data base and personal position. > I haven't met any either. Nor have I met one that goes through a dozen journals a month, participates in direct contact with over 100 active builders, sorts through up to 200 pieces of e-mail a day (10% of which has to do with electrical systems but many more deal with SYSTEM reliability) or writes 20+ articles a year thrown out in print or on the web for critical review. The grey-beards can and do offer a tremendous resource for supporting "how-it-used-to-be" airplanes. If amateur builders wanted that kind of airplane, they probably would have bought one. >When I was on active duty in the USAF, we saved an average of one >mission a month by being able to reset the breaker and continue. A >couple of times a year this ability saved the acft. As you can see, I am >biased based on real experience (USAF and 3 personal cases in civil >acf), and all the numbers games in the world will not change my mind. >Sure breakers trip when they shouldn't, and they are "on paper" less >reliable than fuses. But I never heard of one totally failing open when >the downstream device was good. Again, no argument for an airplane that was architectured in 1950s technologies with flight systems that were in themselves so hazardous to flight that pilot intervention was necessary and good. My goal is not to champion or bash any particular kind of hardware . . . rather to change the way we think about how airplanes are put together and what's expected of a pilot to operate the things; breaking free of the FAA/Military reverence for regulation and tradition in systems design. Some ideas are good, some don't matter, some will be discarded as non-productive but the last thing we should accept is the notion anything is protected from CHANGE . . we don't need anyone's blessing to evolve in positive ways. My personal definition of positive includes adjectives like, lower costs, equal or better performance, easier to maintain, easier to install, and FAILURE TOLERANT. Any failure that puts the pilot in a position of having to be systems analysis or mechanic in flight needs to be redesigned eliminate the problem. You couldn't tell that to your line-chief on the B52 or a Piper service manager on your Cherokee but you can sure do it on the airplane in your garage! Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= From: cdenk@ix.netcom.com Date: Thu, 16 Oct 1997 16:42:34 -0500 (CDT) Subject: Re: COZY: Electrical sysstem John Eplin writes <* require a switch as well as circuit protection. > I have about 20 circuit breakers and 4 fuses. I try to breaker everything, but the fuses are fractional amp for delicate equipment, and the strobe power supply is next to the rear battery, with its feed through a fuse and relay to reduce radio noise. The ADF wouldn't point right until I did this. It's nice to be able to disconnect something if you suspect radio noise, or another problem. THe breakers and fuses are mounted on a right side spacesaver panel. HAve had no negative comments from passengers. Carl Denk: "cdenk@ix.netcom.com" Date: Fri, 17 Oct 1997 00:20:50 From: "Robert L. Nuckolls, III" Subject: COZY: It's not just fuses vs. breakers >Bob, I have your Rev 7 of the Aeroelectric Connection. I agree with most >of it's content and it's a handy reference for electrical data. That >does not mean that my experience does not count or its wrong to have a >different opinion. Never said so . . never intended to imply it either. Paul, please understand that MOST of the people out here building airplanes are pretty bewildered by it all . . . I suspect that's a major contribution to the number of airplanes that are started but never finished. >The real issue is not to dictate ones opinion (or try to support >it with ones background) but present your position and let the readers >decide what is best for them. . . . >I have seen both sides of the discussion and think there is room for >both. Further I have found most people willing and able to decide for >themselves which way they want to go. I guess that's the variable that I don't know how to quantify. When it comes to "deciding for one's self" who is the most persuasive? The techno-wienie who speaks in some undecipherable language or the guy who sez, "I've been there and by golly, re-setting that breaker sure saved my buns!" Did you ever see the movie "Never Cry Wolf"? It's a fun piece but there's a scene in there wherein our hero has to "hold 'er steady" while the pilot climbs out the window to bang on a frozen fuel line with a wrench. I can laugh at the scene for its humor but the serious side is scenes like that drive public perception of aviation. Trading wing-and-a-prayer stories over a suds is fun too . . . but we're building airplanes here and lots of people are listening . . . while we're laughing over some guy's pucker-factor, someone else's wife is wondering if she really wants her husband to build his own "death trap." That's why I like people to learn data-speak. Just for grins, let us suppose there were an FAA rule tomorrow that sez all breakers shall be out of reach and left it at that. Do you suppose we could learn to live under that rule and design the airplane so it was not necessary to reach 'em. Sure we could. Well . . . if we can do it to accomodate the unwelcomed regulation, why not strive for that kind of reliability on our own? >The difference in reliability is insignificant in the real world and >builder comfort is more important. I am much more worried about the auto >engine conversion with only one battery than if he uses fuses or CB and >where they are located. Discomfort comes from lack of knowlege and skills. Most of our bretheren out there come from the padded cockpit environment where they were taught everything necessary to fly this here airplane, including the preflight check of breakers. I remember sitting there in the left seat waiting for my flight instructor to continue with some lessons on inflight systems diagnosis after he told me how useful it was to be able to push and pull on those things. But that was it . . perhaps two sentences. >As the FAR's (23.1357 (d)) do require crew replaceable/resettable >fuses/CB for "critical equipment" It seems to me the only one to make >the decision as what's critical is the builder/pilot based on his own >comfort factor and the type of flying being done. When I proposed the idea of remote fuses to my friends here at the FSDO, their eyebrows went up too . . . until I followed up with the statement that the system would be designed such that NO systems were critical to flight. Most of the folk on the lists are not designers . . . they ask questions and appreciate lucid answers. Most lack the skills to deduce criticality and are unable to make considered decisions as to what is or is not "critical." One contributor to this conversation made a statement to the effect that, "everything is critical . . . or it wouldn't have been installed in the airplane!" That's your and my responsability. As experienced pilots and knowledgable users of the hardware, we need to put our experience out there in the Plan A/Plan B format suitable for POH publication. That's where striving for system designs favorable to out-of-reach fuses is helpful . . . the instructions get real simple and the pilots get real confident. >Further what about all the existing factory and experimental acft that >were wired with CB? Should we worry these people by suggesting their >acft is less reliable? Worry them, no . . . I fly lots of those same airplanes. As the #2 item on my systems reliability list, I as a pilot couldn't care less if ANY of those breakers are open or closed at any given time in the way I use the airplane. My fondest wish would be to wave a magic wand and make all pilots as confident of thier ability to cope as I am . . . and yes, compared to what we are building, those spam cans ARE less reliable . . . that's why I refuse to depend on certain aspects of their equipment lists. >Both fuses and CB's fail and when they do the failure rate is >unimportant to the pilot. The ability to replace in flight is a personal >one and largely depends on the type of flying being done. What applies >IFR over an overcast in mountains is quite different from VFR in the >Midwest. But Paul, I'm not sure you understand the point. It's not a matter of breakers/fuses or the ability to fiddle with them in flight. If I'm IFR in the crud and a 10-cent resistor cracks, or a coax comes unhooked, or a knob suddenly fails to rotate the mechanism behind the panel, what comfort is there in being able to see that row of circuit protection? All of those goodies that depend on the power making it through the fuses can fail in so many ways. The frustrating thing for me is not the argument over hardware styles rather the importance we put on them. I.e. why spend $100 for a mil-spec switch to control a landing light when you KNOW the light bulb is going to fail? Extend that fact into every other system in the airplane and it makes this discussion on hardware look like a playground argument. That's why I fly with the assumption, mind set and backup equipment that ASSUMES that none of that stuff is going to be working when I land, and I DO intend to land on my own terms. My flight instructor hadn't the foggiest notion of that concept. It took me a long time to acquire it on my own but then the FAA would have a fit if we proposed this line be added to the approved flight sylabus, "Instruct student on use of aircraft in J-3 mode" How many new Bonanza owners would appreciate that kind of instruction? That's why we call some of those airplanes (doctor, lawyer, etc.) killers. Those folk paid a LOT of money for the things, the idea that they should KNOW how to get along without that panel full of goodies is UNTHINKABLE . . . so the training never happens. Can you see why I get wrapped around the axle of the "dark and stormy night" anecdotes? They have no educational value and serve only to make pilots more apprehensive because of what they DON'T know. There are reasons now to believe that John Denver was working a transponder problem with center or approach just before the accident. Wouldn't it be ironic if the man died with his head down, trying to get a band-aided, WW-II derelict working for the convenience of ATC and didn't see a bird coming? The answer seems quite clear to me . . . the fewer goodies to fiddle with the better. Deal with situations in a predetermined, simple, Plan A/Plan B procedure. I'd be very pleased to have you join me in helping to achieve this kind of cockpit environment. If we can reduce costs, weight and installation time too, that would be super. Interestingly enough, getting rid of excess baggage by the use of considered design tends to have those by-products. I'd love to look the administrator in the eye at OSH some year and seriously suggest, "certified aviation has fallen behind in some important safety issues and that some tutorials from the vast knowlege base that is (or should be) EAA are available for any interested FAA personnel." Kindest regards, Bob . . . Date: Fri, 17 Oct 1997 10:20:25 -0400 From: Ian Douglas Organization: WTC Subject: Re: COZY: It's not JUST breakers/fuses . . . Hey guys, How about you take the rest of this argument off line. I think that arguements for both sides have been stated and now it is up to the builders to decide. To recap: Breakers: Pros: Can be used as switches, easily reset in flight. Cons: Can be continually reset until a cascading failure or fire developes, more expensive. Fuses (Glass): Pros: When hidden from the pilot - flying main priority without distraction, cost less, no cascading failures, switch to "Cubby" flight mode. Cons: Take longer to change in flight - distracting pilot, not easily used as switchs (although a 1/4 turn seems easy), possible vibration damage. Fuses (Plastic): Pros: When hidden from the pilot - flying main priority without distraction, cost less, no cascading failures, switch to "Cubby" flight mode. Cons: Take longer to change in flight - distracting pilot, not easily used as switchs (although a "pull out" seems easy). Just as a note... Whenever I fly, I always bring a hand-held radio (I-COM with VOR) and GPS with their own power supplies esp. in IMC. All other essential primary flight systems are split between vacuum and electricity. -- Ian D.S. Douglas MK 0069 From: Jim Hocut Subject: RE: COZY: It's not JUST breakers/fuses . . . Date: Fri, 17 Oct 1997 08:03:19 -0700 >How about you take the rest of this argument off line. I think that >arguements for both sides have been stated and now it is up to the >builders to decide. I disagree. I'm getting educated from this. I'm a EE and harbor no illusion that I know it all. I appreciate the opportunity to have my horizons expanded. This little excercise of taking currently accepted "knowledge" and throwing it out the window reminds me a lot of sitting through one of Burt's forums and I find it very refreshing. I don't always agree with what's being said, but I learn from the experience. thanks. Jim Hocut jhocut@mindspring.com Date: Sat, 18 Oct 1997 10:22:50 From: "Robert L. Nuckolls, III" Subject: COZY: Alternator Field Switches >>There must be about 100,000,000 automobles out there running around without a >>switch on the alternator field. Why is a switch so common on our little >>airplanes. Or is it a case where I can't find mine on all my cars and >>motorcycles. Someone tell me the problem of not having the switch. > > Excellent question . . . and sure, the answer is simple. In airplanes, > the prudent way to architecture and operate an electrical system is to > assume that at some point, each and every electrical system component > is capable of failing in flight. After deducing ALL the ways an alternator > system can fail, one finds several conditions under which you need to have > separate and total control over the alternator field current. (1) the > alternator has become disconnected from the bus but is still drawing > maximum field current because the regulator thinks the alternator is > simply shirking . . . it applies full field current in hopes of > flogging the alternator to life. In flight, this is a LARGE and useless > drain on the battery that you'd like to conserve for running really useful > things. (2) You're on short final to an unplanned arrival with the earth > and you want a way to get all electrical sources shut down before > contact with the rocks, trees, whatever . . . (3) If for any reason, > one might turn the battery master off before stopping the engine, the > alternator may continue to run, self-excited but poorly regulated > and be a real bother to other electrical sytem parts that may object > to the poor quality power. There might be others but these are pretty > compelling. > P.S. Actually, most automotive alternators DO have a switch. It's the one your key is stuck into. There's often a control line running from the keyswitch to the alternator's built in regulator that kills the alternator when the key is turned off . . . and 99.9% of the time, it works. Problem that this line is not THE single supply source of field current . . . simply a control line to some itty-bitty transistors and stuff inside the regulator. If we're prudend in the design of our electrical system, we have to concede that those devices can fail to funtion . . . therefore, the stock control line into an automotive alternator cannot be depended upon for 100% authority over field current. This is the MAIN reason why B&C takes perfectly good, brand new Nipon-Dienso alternators apart to remove and bypass the built in regulators. When you open the alternator field switch for a B&C alternator (as most others flying around our there) the alternator is OFF. Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= Date: Sat, 18 Oct 1997 12:25:36 From: "Robert L. Nuckolls, III" Subject: COZY: PolySwitches At 09:41 AM 10/19/97 -0400, you wrote: >Cozy Builders: > >There is another way to protect electrical circuits without using >mechanical circuit breakers and wire fuses. About a year ago I received a >data sheet for RAYCHEM's PolySwitch Resettable Fuses. A PolySwitch will >trip when an overcurrent condition is present. The PolySwitch will reset >only after it has cooled and the fault condition has been corrected. >There's no need for manual resetting or replacement. These devices are >available with trip points as low as 0.120 amps and as high as 9 amps. > >Littelfuse, which makes auto fuses, has a similiar product called Positive >Temperature Coefficient(PTC) Resettable Devices. > >RAYCHEM and Littelfuse both appear to be using some type of conductive >polymer in their circuit protectors in lieu of wire links and moving parts. > There's at least on product on the market using these devices. I've posted both a design review and a usenet thread which intereseted parties may read at and . I and several dozen other folk at Lear and Beech have look at these devices several times over the last 15 years and still don't have a way to apply these devices for general power distribution tasks that satisfies our desire for positive protection and annunciated faults. The polyswitches are packaged to mount inside a product . . . soldered to an etched circuit board. The EXPBus does exactly that. The problem is that manufacturing costs for utilizing the Polyswitch make it more expensive to install and drives up parts count. Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= Date: Sat, 18 Oct 1997 12:48:51 From: "Robert L. Nuckolls, III" Subject: COZY: Lessons in self preservation . . . A titbit gleaned from another source but worthwile reading for all of us . . . ------------------------------------------------------------------ Recently I posted a message about alternator whine in my headsets. Its appearance coincided with spark plug R&R, so I suspected cause-and-effect. Today I fixed the problem. He're how: 1. Whine disappeared when Alternator switch turned off, so I discounted the spark-plug noise theory. 2. Measured resistance of less than 0.1 ohm between alternator housing to battery'spositive terminal--nothing wrong with that. 3. How to check for bad voltage regulator? Disconnected wire from the regulator 'F' terminal and connected a D-Cell flashlight battery from the wire to ground. This produces a tiny charge on the meter, but--and here's the important part--I could still hear a whine in the headsets. Regulator is therefore not the cause of whine. (I never seriously considered it, but it was so easy to check...) 4. I now suspected the rectifier diodes in the alternator. Removed alternator (discovered a cracked mounting bracket). Connected the D-Cell flashlight battery from the Field terminal to ground. Attached oscilloscope to output terminals, then spun the pulley with my Makita (knew that buffer pad attachment would come in handy some day). The output should look like series of contiguous humps. Instead, every-other hump (or was it every third?) was missing. Diode bridge is bad. 5. Took alternator to highly regarded alternator/starter shop in SF Bay Area, which had the exact replacement part in stock. As I watched, technician replaced diode bridge and bench-checked the alternator under full load. He said brushes and bearings were still fine. Cost: $12.40 for part, $17.50 labor. 6. Local AI welded bracket for $15 and later signed off my reinstallation of alternator. (I didn't ask him to sign off the *repair* of the alternator.) 6. Test flight. Voila! No more headset whine. Home in time for lunch. I now have a green-tagged alternator for $29.90. ---------------------------------------------------------------- Name withheld to protect the guilty. Folks, here's an excellent example of an investigation to determine the real cause of an effect based on step-by-step trouble shooting and analysis. I might have taken a different approach but the end result would have been the same. An important point is that very FEW a/p mechanics have the skill to successfully carry out this kind of investigation. Every year, hundreds of thousands of dollars are spent on labor hours and parts-not-needed on GA aircraft because the mechanic is guessing and trouble shooting by subsititution. And, of course, once a part is installed on your airplane, it's your's whether you needed it or not. Lest anyone misunderstand, I recognize that there some fine, skilled mechanics out there who do an educated, honorable job of working on people's airplanes. But how do you KNOW which ones they are? The ticket hanging on the wall of the shop office guarantees nothing. You have but one good defense, take the time to know more about your airplane's inner workings. Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= From: TRCsmith@aol.com Date: Sat, 18 Oct 1997 17:07:25 -0400 (EDT) Subject: Re: COZY: It's not just fuses vs. breakers Hi All While flying as a Air Force Reserve Flight Engineer on C-5's for 9 years, we were taught that if a an item quit working check the C/B, if popped reset it one time. It may of had a voltage spike or what ever that tripped it. If a breaker related to fuel popped, DO NOT RESET IT! Tom LongEZ Date: Sun, 19 Oct 1997 09:41:17 -0400 (EDT) From: whittaker@mindspring.com (Glen Whittaker) Subject: COZY: The Great Fuses vs Circuit Breaker debate Cozy Builders: There is another way to protect electrical circuits without using mechanical circuit breakers and wire fuses. About a year ago I received a data sheet for RAYCHEM's PolySwitch Resettable Fuses. A PolySwitch will trip when an overcurrent condition is present. The PolySwitch will reset only after it has cooled and the fault condition has been corrected. There's no need for manual resetting or replacement. These devices are available with trip points as low as 0.120 amps and as high as 9 amps. Littelfuse, which makes auto fuses, has a similiar product called Positive Temperature Coefficient(PTC) Resettable Devices. RAYCHEM and Littelfuse both appear to be using some type of conductive polymer in their circuit protectors in lieu of wire links and moving parts. Glen Whittaker Cozy Mk IV 0563 Date: Thu, 23 Oct 1997 09:53:32 From: "Robert L. Nuckolls, III" Subject: COZY: Electric Trim Runaway > I tried sending this once before, but got no mail for 3 days and never saw >it when I started receiving it again. I am one of many who have electric >elevator trim. If you have a stuck switch or relay, in other words a runaway >trim. I for one would like to be able to reach over and pull the breaker >before the situation becomes critical. Now I suppose I could wire in a >cuttout switch if I wanted to, but that would fall under complicating the >system. I know for a fact if the trim were all the way to one extreme you >would have a hell of a time bringing the airplane back in one piece. I would >consider this a saftey of flight item. > Thanks for staying with it. The matronics.com URL fell of the edge of the world a few days ago and everybody's input to the list was bounced or disappeared. There are still some funny things going on as I've had to post one or two pieces twice to get them through the pipe. Computers is wunderful! Here's a case where I think complicating the system has good foundation in pilot versus airplane ergonomics. Pulling a breaker on trim runaway is too time consuming and there's a lot of window for error. If your trim breaker is located in a whole nest of other breakers, the possiblity of pulling the wrong one in time of "tense pilot response" is great. Pulling the wrong one may no have electrical consequences for flight for inadvertently shutting down another system but it adds still more delays in perception and resolution of multiple problems . . . all design and/or pilot induced. In any case, pulling the breaker is far more time consuming than some alternatives. During trim runaway, time is of the essence. The longer you delay in effecting shutdown, the further out-of-trim the airplane is going to be when the motor stops running . . . we need to shave tens of milliseconds off of the perception-reaction-action time needed to bring things under control. I'm working on an article that suggests powerful electric trim systems should require two switch actuations for operation . . . not unlike requiring your starter current to also pass through the battery contactor. You have a way to deal with a stuck starter contactor by shutting of the battery master. Suppose you had a stick grip with the usual coolie-hat trim button and a second, "arm" button for all electric trims. The arm button would have positive control over electrical power to all trim systems and would have to be held closed at the same time you are commanding trim. The advantage is that you hand is already on the control necessary to disable the trim when the runaway happens. Even if the trim relay stuck at the conclusion of your last trim operation (latent, unannunciated failure) then as soon as you pressed the "arm" button, you'd get an un- expected trim operation and your reaction to release the button is a few hundred milliseconds away from successful trim shutdown . . . you can't do it any faster any other way. For airplanes with autopilots and powerful servos, the situation is a bit different. Here we have mulitiple, electrically driven systems with the ability to drive flight controls. The common wisdom here is to fit the aircraft with an "autopilot disconnect" button on the wheel or stick. When you think about it, the pilot's first reaction to countering an unexpected input from electrically powered flight controls is to grab the stick to keep the dirty side down and the pointy end forward. It stands to reason that all the controls necessary to corral the runaway system should be on the stick or wheel too . . . the "autopilot disconnect" or "master trim disconnect" button would have positive control over all electrical devices connnected to flight controls. When things are back under control, the pilot may elect to experiment a bit to see if it was trim or autopilot that caused the upset and shut down the offending system (perferably with panel mounted, clearly labeled switches . . . not little black buttons hiding in a flock of other little black buttons). >. . . I know for a fact if the trim were all the way to one extreme you >would have a hell of a time bringing the airplane back in one piece. If this is true, has your trim system been fully evaluated for both speed and travel limits? I have several builders I'm working with now trying to get them to revise the mechanism that connects servos to tabs. Trims in a mechanical limit on these airplanes produces a barely flyable airplane. This conversation goes right to the issue I raised a few weeks ago with the Great Breaker Debate . . . we've commonly viewed and many of us have been REQUIRED to compensate for POOR SYSTEM DESIGN by fiddling with breakers. IMHO, no matter what fails or how it fails in your airplane, your reaction should be no worse than, "Oh fudge . . . is that thing broke again! I think I'm gonna have to find a better part." My brothers in the certified world would like to design airplanes with that philosophy but are prevented by a host of regulatory and bureaucratic walls and mountains. Unencumbered by such obstacles here in amateur-built world, we're going to build the best airplanes that have ever existed. Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= Date: Thu, 23 Oct 1997 11:05:43 From: Bob Nuckolls Subject: COZY: RE: Electric Trim Runaway om> >I built my own actuator with the spring tube as an integral part. This >allows the elevator to move to either stop with the actuator at either >end of its travel. I realize it will take a bit of force to overcome >the spring but it can be done and I feel comfortable I can handle it for >enough time to get back to ground level. > > I hope someone can show me where I went wrong with my >interpretation of Vances design, I came to my conclusion by measuring >the pushrod travel on my yet unfinished A/C as well as measuring the >geometry of the system and doing the trig calculations to figure out the >movements needed for full travel. I am assuming 15 deg up and 30 deg >down travel that Nat demands be met in the plans. John, This is exactly the kind of deductive reasoning it takes to narrow the field of choices and failure modes. You may find after you've flown the airplane that the 1.75" stroke can be restricted still further. My first dual instruction was in a Ercoupe with rudder pedals. Pilot, passenger and fuel were right on the CG . . . the trim system was a tiny tab on the elevator operated through a Bouden (sp?) control not unlike the manual choke on a carburetor. From full up to full down trim, one could hardly feel the effect and as a student trainer it really sucked . . . was I surprised a years later when I finished my ticket in a B-77 Beechcraft and itty-bitty movements of trim had a demonstrable effect on pitch. A hundred or so hours later, in the company A-36 I discoverd that pitch trim limits in either direction produced a barely manageable airplane if BOTH pilots could push and pull on the wheel together. Know your airplane and be ready to make changes when you discover situations with potential for grief. Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= From: Epplin John A Subject: RE: COZY: Electric Trim Runaway Date: Thu, 23 Oct 1997 10:40:31 -0500 > > [Epplin John A] See Bob Nuckolls post for the story. I completely agree with the two path, two movement philosophy here. This is too critical an area to trust a single component or single movement. The real aircraft that I have been involved in had such a system. A lot of large A/C have more trim than elevator control, if the trim fails at 40+ thousand, landing is going to be real interesting. Redundant servos and power connections are common. I am just completing a variation of the Vance Atkinson EZ electric trim. I don't know if the LongEZ has the same geometry in the elevator control or not so cannot speak to the Long installation. However, in the Cozy Mk4 the system as he describes seems to me to be able to restrict the elevator travel. I made the spring tube very similar to his but limited the travel of the actuator to 1.75 in. I built my own actuator with the spring tube as an integral part. This allows the elevator to move to either stop with the actuator at either end of its travel. I realize it will take a bit of force to overcome the spring but it can be done and I feel comfortable I can handle it for enough time to get back to ground level. I hope someone can show me where I went wrong with my interpretation of Vances design, I came to my conclusion by measuring the pushrod travel on my yet unfinished A/C as well as measuring the geometry of the system and doing the trig calculations to figure out the movements needed for full travel. I am assuming 15 deg up and 30 deg down travel that Nat demands be met in the plans. My intentions are to have a arm switch actuated by a finger and the trim then actuated by a thumb switch. Both must be closed for the motor to run. Also intend to use this servo for the autopilot when I get to that phase. The autopilot disconnect logic would include any movement of the trim switch. John epplin Mk4 #467 From: "astrong" Subject: Re: COZY: Electric Trim Runaway Date: Thu, 23 Oct 1997 11:14:23 -0700 ---------- > From: EpplinJohnA@JDCORP.deere.com > To: Alex > Subject: RE: COZY: Electric Trim Runaway > Date: Thursday, October 23, 1997 7:16 AM > > > > > > > > [Epplin John A] > See Bob Nuckolls post for the story. > > I completely agree with the two path, two movement philosophy > here. This is too critical an area to trust a single component or > single movement. The real aircraft that I have been involved in had > such a system. A lot of large A/C have more trim than elevator control, > if the trim fails at 40+ thousand, landing is going to be real > interesting. Redundant servos and power connections are common. > > I am just completing a variation of the Vance Atkinson EZ > electric trim. I don't know if the LongEZ has the same geometry in the > elevator control or not so cannot speak to the Long installation. > However, in the Cozy Mk4 the system as he describes seems to me to be > able to restrict the elevator travel. I made the spring tube very > similar to his but limited the travel of the actuator to 1.75 in. I > built my own actuator with the spring tube as an integral part. This > allows the elevator to move to either stop with the actuator at either > end of its travel. I realize it will take a bit of force to overcome > the spring but it can be done and I feel comfortable I can handle it for > enough time to get back to ground level. > > I hope someone can show me where I went wrong with my > interpretation of Vances design, I came to my conclusion by measuring > the pushrod travel on my yet unfinished A/C as well as measuring the > geometry of the system and doing the trig calculations to figure out the > movements needed for full travel. I am assuming 15 deg up and 30 deg > down travel that Nat demands be met in the plans. > > My intentions are to have a arm switch actuated by a finger and > the trim then actuated by a thumb switch. Both must be closed for the > motor to run. Also intend to use this servo for the autopilot when I > get to that phase. The autopilot disconnect logic would include any > movement of the trim switch. > > John epplin Mk4 #467 John, you are on track with regards to Vance`s design. Four years ago when we went from Copperstate to Salisbury MD. we already had the Strong Pitch Trim installed though it was battery operated.on final at Auburn AL. the battery went out, I had a spare but no time, I landed manually over riding the set trim, a little stiff but manegable, I have since flown and landed the plane with the Pitch Trim in both extremes. Before I started selling the Strong Pitch Trim I contacted Vance since he published his idea first, he had no objection to my selling the device and wished me luck. The geometry on the Veri-EZ, Long-EZ, Cozy II , MKIV and Berkut are similar however the E-Racer and Velocity with there Single center control stick required a longer Motor mount. I hope I was of some help. A.R.Strong Homepage "http://www.canard.com/trim" Date: Wed, 29 Oct 1997 09:36:30 From: "Robert L. Nuckolls, III" Subject: COZY: Re: Master Switch >Date: Wed, 29 Oct 1997 09:31:33 >To: "trogers@utech.net" <40304@utech.net> >From: "Robert L. Nuckolls, III" >Subject: Re: Master Switch >In-Reply-To: <3456D551.2982@utech.net> > >At 10:18 PM 10/28/97 -0800, you wrote: >>Bob, >> >>First off I visited your web site, it's great. I'll kindly explain why >>I, others and many manufactures feel an avionics master switch is useful. > > . . . there's a difference between "useful" and "necessary" . . . > >> First off, it's nice to be able to turn on everything with just one >>switch but that does have it's draw backs as you know. > > . . . not the least of which is single point of failure for every > electronic item. Further, contemporary bus architectures don't > accomodate essential goodies with a second, totally isolated > power path . . a few folk have installed a second switch across > the first path, "just in case." > >> . . . . I'm not sure just >>how much avionics you've installed but my guess is very little. > > True. I've not been personally involved in installation of > off-the-shelf products in many airplanes . . . perhaps a large > gap in my education or I would have discovered earlier how > bad some of these products are, to wit: > >> . . . . . . If >>you've ever installed a GEM, IIMorrow 360, Shadin air data computer or >>BFG 900 in a 4 cyl Lycoming powered aircraft and started it with the >>avionics on you will scramble the software and at least one of the above >>items. Often you can reset the instrument by just shutting the avionics >>master switch off and then back on. > > Why do you purchase and install this kind of stuff in your airplane? > As I mentioned earlier, I've been designing electronics systems for > aircraft for a long time (25+ years). The gizmos ranged from simple > low voltage warning systems to a servoed trim speed controller > that's currenty flying on the majority of the Lear fleet. I'm a > consultant to several manufacturers of modern, microprocessor > based components for aircraft and other vehicular applications > (you can't escape them any more, microprocessors are everywhere). > This type of behavior is unacceptable to my customers and unacceptable > to me as a designer. If you don't box these things up and send > them back, you've told your supplier that his design is "acceptable". > If the computer on which I write this barfed like that more than > a few times, it would be back in the box . . . or at least worked > on to fix the problem. My microprocessors don't go dumb with every > hicup on the bus, why should I accept it that anyone else's does? > >> . . . . . If the battery is weak, then the >>problem is worse. I haven't seen avionics software scramble with the >>master switch left on as much with the big bore continentals. This is >>probably because they are 6 cyls and low compression. Put and "O" scope >>on the avionics buss and start a Lycoming, you will see spikes not just >>low voltage. > > How "big" and for how long? > >>I don't think radios were designed to work during most piston aircraft >>starting, this is not ordinarly. I sent Mike Busch a couple of notes >>from King and Collins stating that an avionics master was desired. . . > > I'd like copies of those letters . . or the name of the person > at the bottom. > >>DO-160 is not revelent to all avionics such as GEMS and sorts. > > DO-160 is relevant to any piece of electrical equipment the manufacturer > chooses to apply it to. It's not a specification but a test method. > If you have any gizmo capable of being an antagonist or victim to > other equipment, DO-160 outlines test methods for various conditions > found aboard an airplane. It's applicable to ANYTHING you want > investigate for suitability of use on aircraft. > >> . . . . . I don't >>know of any current aircraft that doesn't have an avionics master from >>the factory, even the new Cessna models. I just got out of a Citation 5 >>and the check list had "Avionics Master Off" BEFORE the start button was >>pushed. > > I don't doubt it. I was working at Cessna when we put the first ones > in the airplane and based on what we knew then, the fragility of the > radios, the lack of design standards, and the general attituded that > "more gizmos is better" I thought it was a good idea then too. The > thing that mystifies me is why, in 30 years since, we've not > learned as designers to do any better and why as consumers, we > put up with what ever the manufacturer wants to sell us. > > After designing to meet performance specifications, the #2 design > item on my list is stand up to EVERYTHING the airplane can throw > at me. I can also tell you that the task is trivial compared to > other design requirements. I just finished qualifying a new > autopilot for a military program. This piece of hardware would > survive quite nicely in any single engine airplane too . . . the > autopilot costs about $9,000 to build. The cost of components to > insure survival from bus induced hazards is under $10. > >>Is an avionics master needed??? In my opinion it is, nor will I do an >>installation without one but you definately can have your own opinion. >>That's called America:) > > But here's the ace-kicker. The avionics master switch is a > check-list item. I cannot count how many times I've stepped into > a rental airplane and found the avionics master switch still on. If > a missed or ignored check-list item truly puts some very expensive > part of the airplane at risk then I'll suggest there's a SERIOUS > design problem here, would you disagree? Don't pilots have enough > responsabilites as pilots without burdening them with guardianship > of fragile or balky electronics? In virtually EVERY segment of > consumer electronics from Matel Toys to the fire-breathing, byte > thrashers on my desk, the value and capability of electronics-for- > the-people gets better almost daily. Yet we as pilots and owners > of airplanes take it in the shorts because there's some aura about > "aircraft quality" or "certified" hardware that has put our best > senses as consumers to sleep. > > You say you have documentation from manufacturers wherein they > recommend an avionics master switches. You also allude to special > action on the part of the pilot to coax pieces of equipment into > normal operation. Wouldn't it be better to encourage, nay INSIST > that manufacturer to live up to a trivial responsability? A 1960's > attidude of avionics consumerism puts little pressure on them to > do better. I work with hundreds of individuals who are assembling their own > airplanes. We design and fabricate systems that are failure tolerant > and free of trash that exceeds the capability of DO-160 qualified > stuff to SURVIVE. Since we're building the best single engine airplanes > that ever were, I counsel my friends to not tolerate any lapse in > supplier responsabilities to provide equipment suited to the task. > This includes both matters of survivability and operability. > > Your constituency is pretty much stuck with "what you see is > what you get" from the aircraft manufacturing community. Customer > relations of these firms may claim to have customer's best > interests in mind but I'll suggest they demonstrate otherwise. > When the kind of products you describe are allowed to continue > to flow into new applications, it's a glaring example of breakdown > in supplier consumer relations and manufacturers responsabilities > to REDUCE pilot workload not increase it. > > I really like to get some names of contacts you can supply for > any firm that suggests that an avionics master switch is useful. > > Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= Date: Sun, 02 Nov 1997 19:49:33 From: "Robert L. Nuckolls, III" Subject: COZY: re: avionics master switch > . . . . I plan to have one. >However, I will provide a fused alternate power source direct from the >unswitched terminal on the battery contactor through an on-on switch to the >avionics bus and the turn coordinator/auto pilot. . . . And perhaps some minimal panel lighting . . . a one-bulb flood?? > The other side of the on-on switch will be powered off the main bus. The problem with a single switch is that it's a SINGLE switch. One failure kills both paths. >(I know that I could use a blocking diode arrangement instead of an on-on >switch, but then I trust a seldom used switch . . . What is your basis for this judgment? As I write these words, I have a consulting customer who is suffering hundreds of failures of brand new switches every month; rolling belly up because they are too LIGHTLY used. There's a really cheap, 69-cent rocker switch in my desk drawer. If I handed you this switch and asked you if you thought it was an "aircraft quality part" you'd probably laugh at me. Well, it came out of an airplane, a 1968 model Cessna 150. It died after nearly 30 years and was the FIRST switch to fail in the airplane. It was also the most lightly-loaded and least used. It controlled the DOME light. Please don't fall victim to the notion that wear and tear is the only cause of switch failure. >more than a constantly used diode arrangement that may also fail and >burn out the alternate feed fuse as soon as you turn on the alternate feed >switch.) I use 20 amp diodes in a circuit that's loaded to about 5 amps. The semiconductor diode is the oldest piece of semiconductor technology on the surface of the planet and is 100 times more reliable than mechanical switches . . . if used within their ratings. A failue in the diode is pre-flight detectable. If you're basing your judgment about diodes on tales of woe about alternator diodes, keep in mind that 95% of alternators flying on single engine airplanes were designed in the 60's . . . the replacment parts are conformed to original designs by FAA mandate. There's no reason for parts selected 30 years later to suffer the same defects. > If either the master contactor or avionics master switch fails, Even if the avionics switch is a single device? How about the wire and all installing hardware between switch and avionics bus. How about the switch's internal mechanism? These all constitute single points of failure . . . you can design them out of your system. >I will still be able to power the avionics bus. Along with this, I will have >battery back-up to both the Micro-Encoder (airspeed, altimeter, compass, >vertical speed, and encoder functions) and Micro-Monitor (engine and fuel >info). I think that this will provide a fairly good (and not too complicated) >system for my expanded VFR equipped airplane as I don't consider any other >electrical item essential. I'd recommend two switches . . . normal path "avionics master" and alternate path switches and leave the diode in place to prevent inadvertent overload of alternate path fuse by having both switches closed. Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= Date: Wed, 05 Nov 1997 09:10:39 From: "Robert L. Nuckolls, III" Subject: COZY: Parts versus system reliability > I guess I have once again "lost the bubble" on one of your threads. Let me >recap my understanding of what has passed here and you can tell me where I >reached the wrong conclusion. > >1) There was a copy of a message to Avweb posted by someone with >acknowledged expertise advocating the use of an avionics master to protect >any/all installed avionics in an aircraft during engine start. > The keyword here is "protect" . . . the AMS was birthed 30 years ago. Avionics have evolved through 4-5 generations of technology advancements but our way of thinking about them has not. >2) There was a reply from you stating that the avionics master is an >anachronism that has no place in a homebuilt using modern avionics and >electrical system layout/design techniques. >3) Flurry of responses from listers saying, "yeah but if the switch cost so >little and could potentially save me thousands of dollars in repairs on my >avionics, why not use it?" Because, if it's the ONLY power path to all the radios, then it's far more likely to be the source of failure for all radios than to be the guardian angel for any radio. If one wants an AMS, by all means have one but do good systems design and ASSUME that all wiring and components are subject to failure. Any such failure kills all radios. Radios, (and a few other "essential" items should be supplied via independent power paths. See or Sport Aviation, Feb 93, p.80 for a more detailed discussion. >4) Ongoing debate amongst you and various listers stating that manufacturers >should be forced by the laws of supply and demand economics to provide >avionics that are impervious to any power supply anomalies. They already are. The thrust of my words was to suggest that if you don't believe it, ask 'em. If any manufacturer admits to some form of fragility in their design beyond gross overvoltage, ask them why they don't conform to the industry standard testing regime DO-160. I'm working on an article about DO-160 which I will publish on our website and elsewhere. > I guess its #4 above that prompted my post. I was under the impression from >your postings that there is still avionics gear on the market that is >subject to problems during engine start. . . . if there are, I'm unaware of them. I've asked everyone to show me documentation from any manufacturer that requires pilot intervention to "protect" their product from ordinary airplane systems operations. Starting the engine seems pretty ordinary. Further, I'd like to know about it. I'll write or call them and get the scoop. I did write to Terra some years ago about a statement in their installation manuals alluding to an AMS . . . the engineer said, "Oh, we just stuck that in there because everyone seems to expect it. Sure, we've done our homework for input power conditioning." > . . . . . . Your response to my post implies >that this is not the case. If that is so, then how do you explain the Avweb >post that started this whole thing? Was that guy just plain wrong? Not for 1970, but for 1997 I'll have to say, "yes". > . . . . And what >was the point of your repeated posts calling for change to be forced on >avionics manufacturers by the marketplace? I guess I am no less confused >about what you are trying to say than I have been all along. The "call to arms" was intended as an inducement to consumers of expensive, complex equipment to find out for themselves if the ol' mechanics and pilot's tales are worthy of consideration. If you've got a concern about it, call the manufacturer. If you don't like what they tell you, I'd like to hear about it. The Avweb article was simply a repeat of a 30 year old mantra. Quite frankly, people who build this stuff don't care much one way or another. It doesn't HURT their product for you to "mother" it. However, based on points in the article referenced above, the "mothering" circuitry has a potential for bringing the whole system down. Further, an electrical system FMEA shows there are times when you may want to shut down both normal battery and alternator circuits for best utilization of a finite quatity of energy in the battery. This ALSO calls for the second power path to essential goodies. All technology based products experience quantum jumps in performance and value happen every few years. Gizmos that run from automotive dc power systems are included. There's not 2 cents worth of difference between the dc power system in your airplane and the one on your garden tractor or car. EVERYBODY in these markets have had access to transient supressors, high voltage silicon transistors and high quality capacitors for over 15 years. For a very nominal cost, today's products can thumb their nose at ANYTHING the dc power system throws at it . . . including overvoltage to the tune of 20 volts for 1 second . . . plenty of time for an ov system to react and tame the runaway alternator. > Please understand that I dont intend this as any type of flame. I have no >knowledge of avionics whatsoever. The various standards that you have >referred to in this thread mean nothing to me. I, as do many other listers, >rely on the expertise of others such as yourself to attempt to make an >intelligent decision. When expert advice from 2 different sources conflicts, >what are we supposed to do? I'm simply trying to avoid making a very >expensive mistake. I fully understand and no offense taken. I also understand your problem. As spam-can owners, we have had to take comfort in the reams of regulation and decades of tradition (I prefer to call it mired in the ruts). Now you're a one-man airplane factory and you're getting some exposure to a few of the issues that were once left to unseen gurus. If you're more comfortable having an AMS, put one in. But the REAL issue here is SYSTEM reliability which goes far beyond concerns for "spikes" . . . real or imagined. If I have a mission here, it's to ask people to focus less on the minutia . . . it's admittedly easier to do and we all used to take great comfort in spec'ing the bejabbers out of everything bolted to an airplane. But what good is it to put a $100 mil-spec switch on a landing light bulb that you KNOW is going to burn out? What we're really interested in is comfortable completion of every flight. I work toward that by assuming that EVERYTHING is subject to failure and I'll either have (1) a backup or (2) don't need it. My real heartburn with the classic AMS has nothing to do with "spikes" . . . it has to do with system reliability in that it goes against well considered design. There are a number of articles on our website that speak to these issues. Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= Date: Fri, 07 Nov 1997 08:48:14 From: "Robert L. Nuckolls, III" Subject: COZY: Re: battery cable At 10:46 PM 11/6/97 -0900, you wrote: >Sir Rabbit, > >I had occasion to talk with a professional aviation electrician today about >the proposed wiring scheme for my GS. Took the opportunity to ask your >question. This is what he said (illustrated by a visit into the hangar to >show samples of welding cable he removed from a Super Cub, as well as the >aviation cable). The main safety difference is that the insulation of >welding cable, which is black rubbery stuff WILL support combustion and >gives off very noxious, toxic fumes (think burnig rubber tires and worse) >while the aviation cable insulation will not not burn. The insulations are indeed different . . . tefzel and cousins don't support combustion but they give off equally noxious if not downright toxic fumes when the wires they contain are overheated. We're talking red-heat type temperatures here too . . . not impossible to generate in a battery cable with an RG battery but very difficult. > >Another difference is the size of the individual wire strands; much coarser >in welding cable, very fine in aviation cable. I'm thinking the "welding" cable he was comparing was not welding cable but some other material. All the welding cables I've worked with are designed to be VERY flexible and able to withstand a lot of abuse (trucks run over them, they get handled a lot). The wire stranding is VERY fine in order to achieve both flexibility and resistance to flexure stresses. If the cable he was showing you had fewer, heavier strands, it WASN'T welding cable . . . got it off a golf cart maybe? >This makes a difference >because the prefered route of electrical conduction is on the surface of >the conductor and the finer the component strands in a cable, the more the >surface area to conduct electricity and the lower the resistance. Total BS. So called "skin effect" comes into play in the megahertz frequency range and is insignificant below tens of megahertz. It doesn't happen at DC. >He couldn't offer any specific comparison in terms of Ohms per foot however. >Lastly, the connectors are available for the aviation cable but do not fit >on the #2 welding cable as well. Perfectly suitable connectors are available for ANY size wire. >Many resort to soldering which produces a >low resistance joint at first but which leads to fatigue failure presenting >as increasing resistance across the solder line until it fails altogether. Again, not consistent with the physics of the matter. See I've been soldering things together for over 35 years including some wiring that carried over 1000 amps . . . I can't even imagine the failure mode being described here. >It seems to me that with a well planned electrical system (assuming battery >on the firewall) you ought only to need 3-4 feet of #2, so the cost >difference is only on the order of $10. Go with the good stuff. True . . . ACS gets about $3.75/ft for #2 and we get $1.75 when we have it in stock (which reminds me, I'm about out and need to chase down anohter spool). However, for airplanes with the battery in back, runs are longer. Canard pushers with battery on opposite end of airplane from engine need two long runs. Here the weight is a bigger factor. #2 welding cable is heavier and bulkier but it's very soft and much easier to work with. In fact, if you want to run #2 wiring throughout the cranking circuit, I would RECOMMEND welding cable be used for connections to the battery. These connections tend to be short jumpers between battery and ground or battery and contactor. #2 aircraft wire is so stiff that it's hard to work with on short bend radii and stresses it's terminals more. Use #2 aircraft wire everywhere else but nice, flexible battery connections are very nice to work with. The afformentioned hazards are about as remote as your wing falling off so for my money, it's a toss up. If you can stand the weight difference and wish to use REAL welding cable (go buy new stuff from a welder's supply), I don't perceive any great sins happening here. >Switching circuits here, I need a bit of guidance. Auto engines with auto >type ignition systems rely on external power so the design for such a plane >must include a separate, uninterruptible power supply that will function >right through an alternator failure. I would like to talk to people who >are flying with automotive style ignition systems to hear how they've dealt >with this. I am not on the RV net, nor any other systems. Every airplane has an un-interruptable source of power . . . called a battery. This pre-supposes that the battery is maintained well. We tend to treat batteries pretty badly in airplanes . . . run 'em until they refuse to crank an engine any more. By that time, their usefulness as a backup power source has been gone for months. Run periodic capacity checks on a battery, and replace it at 50% of capacity (or some higher number you choose). If you don't run capacity checks, then put a new battery in every two years. For airplanes with total dependence on electrical power, we suggest two half-sized batteries with alternator-out loads distributed between the two batteries depending on system needs. In this case, we suggest replacing one battery every year. This way, you always have one battery less than 1 year old, no battery is more than 2 years old. If you can go "total electric panel" there are options for replacing the vacuum pump with a 20 amp aux alternator. This permits total redundancy of power generation and storage for very little weight penalty compared to classic alternator/battery/vacuum pump installations. Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= Date: Sat, 08 Nov 1997 10:04:47 -0500 From: David Domeier Subject: Re: COZY: re: avionics master switch Bob, re "What is your basis for this judgment? As I write these words, I have a consulting customer who is suffering hundreds of failures of brand new switches every month; rolling belly up because they are too LIGHTLY used." On the subject of switch reliability, I have a brand new master switch, right out of the box that does not work. I installed the thing when running wires and went bonkers trying to figure our why I couldn'd power the bus when it should have worked. Finally, I ended up at it and it was the culplit. Power in but no power out. I firmly believe in KISS. (keep it simple stupid, for you new guys) The fewer switches and relays there, are the fewer there are to fail. dd Date: Sat, 08 Nov 1997 15:31:10 From: "Robert L. Nuckolls, III" Subject: Re: COZY: re: avionics master switch > re "What is your basis for this judgment? As I write these words > I have a consulting customer who is suffering hundreds of failures > of brand new switches every month; rolling belly up because they are > too LIGHTLY used." > >> On the subject of switch reliability, I have a brand new master switch, >>right out of the box that does not work. I installed the thing when >>running wires and went bonkers trying to figure our why I couldn'd power >>the bus when it should have worked. Finally, I ended up at it and it >>was the culplit. Power in but no power out. > >> I firmly believe in KISS. (keep it simple stupid, for you new guys) >>The fewer switches and relays there, are the fewer there are to fail. In this case, I'll counsel getting it a little more complicate because making sure the normal feed path (via AMS, Diode -or- AMS-Diode combination) needs a backup for a variety of other systems ills in addition to AMS failure. Thanks for publishing this Dave . . . Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= Date: Sun, 23 Nov 1997 16:11:13 From: "Robert L. Nuckolls, III" Subject: COZY: Power Source Reliability >Bob's book is a usefull reference but does not cover auto engine >conversions and the problems associated with the reliable power source >requirements for ign etc. Dual batterys, charging systems with internal >regulators, etc. are not covered. The typical cont/lyc acft flys after a >total electrical system failure. Actually, the latest revision to the book added a foldout diagram showing how to architecture dual alternators and batteries. . . . total redundancy in power generation. There are also several articles in Sport Aviation (some downloadable from our website) and on our website where we've described dual battery installations along with maintenance for continued airworthiness. IMHO, attaining reliable power sources in an airplane to support total electric engine requirements is no problem . .. in fact quite simple. Just add a second battery, battery contactor, and active notification of alternator failure. Then, split critical engine loads between the batteries such that no single failure brings the engine to a halt. Having said that, I'll point out that most of the automotive conversions flying still use single ignition and fuel injection systems . . i.e. failures in these systems are not backed up by standby equipment. Bad? Not necessarily. You don't have back up spars, propellors, crankshafts, etc. If probability of failure for any critical component is sufficiently remote for the way we intend to use it, then it's no bigger a deal than say, structural integrity of the flight control system. This is my personal heartburn with some of the single failure vulnerability hardware flying . . . I'm not sure anyone has gathered more than anecdotal information with respect to reliability. I know that of the three cars I've owned with EFI systems, only one has had a problem in a total of 250,000 miles on the three cars . . . the problem was caused by insulation flaking off the wiring in a bundle causing conductors to short to each other in a small-radius bend. At first blush, I'd say there's good reason to belive that current automotive technology for ignition and fuel systems is reliable enough . . . something on the order of one failure in say 10,000 hours (Feds would require much higher reliability in flight for hire aircraft). It would be very helpful to see a refereed study to confirm this. > >By all means get Bob's manual but then you also need the info that is >published in CONTACT mag. This publication is strictly auto engine >conversions. Past issues are rich with how others solved (and is some >cases failed to solve) the problem of reliable electrical power. I read the magazine but I guess I've not picked up on anyone's complaint about power reliability . . . as long as you don't flog a battery until it fails to crank the engine, a pair of batteries with very ordinary installation hardware can offer very reliable power sourcing. Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= Date: Mon, 24 Nov 1997 09:11:45 -0500 From: David Domeier Subject: Re: COZY: Power Source Reliability Bob, I'm sure this info is available if I would take the time to find it, but off the top...can you have 2 batteries in parallel and charge them with one alternator system? dd Date: Mon, 24 Nov 1997 14:13:36 From: Bob Nuckolls Subject: COZY: re: paralleled batteries At 12:49 PM 11/24/97 -0500, you wrote: >not good to have two (batteries) in parallel, if 1 shorts youve got a tremendious drain >on the other in an instant, check out the recreational veh. people they have >battery isolators. Let's look at the physics of the matter. How do batteries short? (-) to (+) terminal or one-cell-at-a-time? If a 12-volt battery shorts a single cell, it becomes a 10-volt battery. Now the ideal charging voltage for the battery becomes 11.5 volts as opposed to the 13.8 or so that exists on the bus. How does the system react? The battery becomes another load on the system. How much of a load? Consider the following: If ideal charging voltage is 2.3 volts per cell (13.8/6) and we've now got a 10 volt battery (13.8/5) the voltage applied to each cell is now 2.76 volts . . . an increase of .46 volts per cell. Hmmmm, how much current will a cell draw if "overcharged" by .46 volts? We could find out by applying 16.5 volts to a fully charged battery. When this test was conducted in the laboratory on the B&C RG batteries, the charging current eventually fell to less than 1 amp and the battery temperature rose less than 10 degrees C. The battery quietly went south. From experience, I'll guess that it won't exceed 20 amps and that for only a short time. If it's a "flooded" battery, the liquid in the working cells begins to disassociate rapidly into hydrogen/ oxygen gasses . . . plates get bubbles on them and internal resistance tends to rise. RG batteries have so little water in them that severe abuse tends to "poof" the littel bit of water out the pressure relief valves and it's all over. Flooded batteries will vent a lot of hydrogen/oxygen in this mode and quite frankly, THIS is the real hazard to continued flight. They may spit liquid water/acid out the caps too. This is why they need a battery box. The RG battery will sit there and quietly die . . . you won't know it happened until you check the battery during next preflight. Now, let's assume there's another battery in parallel with the first. The alternator is probably going to carry the excess 20 amps or so needed to supply the extra demand of the failing battery. Bus voltage will stay up where it belongs and except for an abnormally high alternator loadmeter reading, you probably won't notice anything. If the added load causes the alternator to go into current limit, the bus voltage sags. How far? Depends on the total load and some alternator characteristics. If below 13.0 volts you SHOULD get a low volts warning light to tell you something is amiss. But in any case, the votage isn't going to drop enough to even begin to discharge the battery that's still okay. Recall that a battery can DELIVER energy at 12.5 volts or LESS. Once you get a low-voltage light, if you want to play airborne systems analysis and/or mechanic, you could turn the batteries off one at a time to see if the low-volts light goes out. When you do de-select the failed battery, the bus will come back up and light will go out. On the other hand, if you have developed a "plan-b" for electrical systems malfunctions, flipping three switches at most automatically selects the alternate mode of operation and you get back with the piloting task at hand. The important item to note from this analysis is that while one battery is dying, the otherone is not affected in any way that requires immediate attention from the pilot. basicaly two high current diodes, alt power goes into the >common and comes out as 2 isolated outputs 1 for each battery. worked great >on my race boat and rv, now its my planes turn. Battery isolators have been around for years for a variety of applications none of which have anything to do with protecting one battery from the ravages of another battery. They are commonly used in situations where there is minimal instrumentation and no need for "Plan-B" development and implimentation. Their primary value is to allow one to charge a battery in a trailer/boat from the towing vehicle system while preventing the towed appliance from loading the vehicle battery. I had an uncle who stuck himself way out in the boonies because he'd run down BOTH batteries while sitting and could not start his truck. The reason we use paralleled batteries in airplanes is so that they may share engine cranking duties by virtue of high-current, hard connections to the system via battery contactors. By making them the same size, we can rotate the installed batteries once a year . . . put a new one in the main slot, move the 1 year old main to the aux slot and put the old aux battery in your lawn mower. Next year, repeat the exercise. When no battery is more than two years old and one battery is always less than one year old, the likelyhood of the shorted cell scenario even occuring is very, very close to ZERO. If it should happen, it's no big deal. In the mean time, you enjoy a VERY reliable power generation/storage system for keeping essential goodies running. Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= From: "norm & monda" Subject: Re: COZY: Power Source Reliability Date: Mon, 24 Nov 1997 12:49:34 -0500 not good to have two in parallel, if 1 shorts youve got a tremendious drain on the other in an instant, check out the recreational veh. people they have battery isolators. basicaly two high current diodes, alt power goes into the common and comes out as 2 isolated outputs 1 for each battery. worked great on my race boat and rv, now its my planes turn. norm Date: Mon, 24 Nov 1997 22:25:11 -0500 From: Bill Theeringer Subject: COZY: Power Source Reliability Dave; You can indeed put two batteries in parallel. You will wind up with the total capacity of both units combined. I.E. Two 50 amp hour batteries i= n parallel will give you 100 amp hours of capacity. The problem with doing= this is that two batteries never have the same capacity. If the off line= float voltage of one is say 12.65 volts and the second was 12.25, then th= e first battery would discharge itself into the second and assume the capacity of the second. Also, while you have increased the total capacit= y of the system and significantly lowered the battery impedance (good thing= s) you have also increased the probability of a battery system failure. The= probability of failure goes up proportionately with the number of batteri= es in the string. It matters not wether they are in parallel or series. A way around this is to diode isolate the two batteries. This would allow both batteries to see the same _voltage_ when in the charge mode (99.99% = of the time), but be isolated when not being charged. They would effectivel= y be in parallel except during times of no current flowing into or out of them. The charge _current_ would be determined by the state of charge of= each battery independently. In a properly designed and operating electrical system the alternator supplies all of the aircrafts electrical= requirements. The battery should never be supplying any energy for your airplanes electrical system while the engine is running. One of the neat= things that I have designed over the years is a diode system as just described. It consists of a dual Shockley diode rated at 80 amps per leg= with a peak rating of around 400 amps. The voltage drop would be about 0= =2E6 volts at max rated current. All that means is that the voltage regulator= should be set up 0.6 volts higher than normal. Telephone companies do th= is all the time. They have two separate battery systems diode summed so tha= t if one battery goes down the load is absorbed by the other remaining battery. Viola! The best of both worlds. Ain't electricity neat? = Computers are cool too. Bill Theeringer N29EZ Composite Aircraft Accessories HOME: 805-964-5454, SHOP: 805-964-5453, FAX: 805-683-8577 INTERNET: Composite_Aircraft_Accessories@Compuserve.com PO Box 21645 Santa Barbara, CA 93121 Serving Sport Aviation=92s Cabin Heating Requirements Since 1991. From: "Boykin Ed (C)" Subject: COZY: looking for electronics wiz Date: Tue, 25 Nov 1997 10:43:51 -0500 Hey folks, I have jsut about put together a list of equipment I will need for a homebuilt cockpit instrument system. Basically I will be using a PC/104 modular PC for the main CPU, an A/D card with enough channels to support the number of sensors I want to collect info from,possible a sound card for audio outputs(warnings, reminders, maybe radio playback), GPS, and some other misc. stuff. The problem I am running into is this: I can receive air data one of two ways. I can buy a device already designed to do this (why I was asking about RMI's uEncoder) or build my own device to measure static and dynamics pressures. I would like to build the system myself. I think RMI's systems is awesome but I am trying to do as much integration as I can of the system and having external devices doesn't fit this profile. Anyway, after reading over as much literature I could get my hands on, I have found that even building a simple airspeed, altimeter, and v-speed indicator is a dauting task. All my experience in data collection has been with off-the-shelf parts.I would like to build a PC/104 baord that contains the sensors and a microprocessor to do all of the calculations before sending the data to the main CPU. What I am looking for is someone who would like work on this with me. I want to keep the costs of board to a minimum but I definately would sahre the design openly (I have no desire to sell it) Anyway, all help on the matter would be appreciated. ps: I already have the pressure sensors I want to use. They are a set of Motorola MPX5100's They are calibvrate, temperature compensated and amplified on the sensor. One is packaged for to measure absolute(static) pressure and the other is packages for differential(dynamic) pressure. Ed 'What's a circuit' Boykin aviator@mindspring.com From: Marc J. Zeitlin Subject: COZY: looking for electronics wiz (fwd) Date: Tue, 25 Nov 97 11:20:53 EST Ed Boykin wrote; >........ What I am looking for is someone who would like work on >this with me. I want to keep the costs of board to a minimum but I >definately would sahre the design openly (I have no desire to sell it) >Anyway, all help on the matter would be appreciated. Since I am in the midst of buying all my instruments, laying out my panel, and putting it together, I am particularly interested in this topic (more from a theoretical standpoint than a practical one, but interested nonetheless). However, this is only peripherally related to COZY's and is certainly applicable to ANY aircraft. There's already a mailing list for "glass panel's", which was run by: Eberhart, Steven newtech@newtech.com who's on the COZY list as well. For the small number of you that are interested in this topic and want to work together, please contact Steve (you're welcome, Steve :-) ) and get on his mailing list, if it's not moribund. If there's no list, please work together via direct email, rather than on the COZY list. If there's enough people that mailing directly is a problem, I can set up majordomo to run a parallel list for COZY builders working on electronic/computerized panels. No archives, no web pages - just email distribution to the small # of people interested in the topic. If either Ed or Steve could coordinate this off-line and keep me informed as to the consensus, I'd appreciate it. Thanks. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Tue, 25 Nov 1997 13:10:16 -0600 (CST) From: Steven A Eberhart Subject: COZY: Glass Panel Info On Tue, 25 Nov 1997, Marc J. Zeitlin wrote: > Ed Boykin wrote; > > >........ What I am looking for is someone who would like work on > >this with me. I want to keep the costs of board to a minimum but I > >definately would sahre the design openly (I have no desire to sell it) > >Anyway, all help on the matter would be appreciated. > > Since I am in the midst of buying all my instruments, laying out my > panel, and putting it together, I am particularly interested in this > topic (more from a theoretical standpoint than a practical one, but > interested nonetheless). > > However, this is only peripherally related to COZY's and is certainly > applicable to ANY aircraft. There's already a mailing list for "glass > panel's", which was run by: > > Eberhart, Steven newtech@newtech.com > > who's on the COZY list as well. For the small number of you that are > interested in this topic and want to work together, please contact Steve > (you're welcome, Steve :-) ) and get on his mailing list, if it's not > moribund. If there's no list, please work together via direct email, > rather than on the COZY list. > > If there's enough people that mailing directly is a problem, I can set up > majordomo to run a parallel list for COZY builders working on > electronic/computerized panels. No archives, no web pages - just email > distribution to the small # of people interested in the topic. > Mark, I am not maintaining the list directly but I have a "browsable archive" on the Multi-Tasking Aero Computer page that I do maintain. There is a mail list set up for discussing airborne computers and glass cockpits. There hasn't been very much activity lately but now is a good time to get some more discussion going. Rutan's son, the one that did the Boomerang's computers has monitored the list in the past. You can subscribe via glass-panel@van.inc.net just send email to glass-panel-request@van.inc.net with the word subscribe in the body of the message, just as with all majordomo lists. I have an archive of some of the previous posts on my Aero Computer Multi-tasking web page at http://www.evansville.net/~newtech Steve Date: Wed, 03 Dec 1997 21:10:31 From: "Robert L. Nuckolls, III" Subject: COZY: Automotive Alternators >According to Bill at B&C, the problem is heat under the cowl. Seems auto >alternators often do not get enough cooling under there and so they and/or >their internal regulators go south. Lesson: provide your alternator with >a supply of cool air adequate to keep it health and happy. There is, of >course, the issue of "abusing" the alternator electrically which has been >addressed elsewhere. > >Gary Crane > > I'm not sure that "heat" or any other stress can be identified as the single worst effect on an alternator. I guess I didn't see the threads on "electrical abuse" of alternators and I'm mystified by that notion . . . how does one electrically abuse an alternator? We know intuitively that doing some extra things like a cooling air source is a "good" thing. Necessary? Without measurement data we don't know. B&C's ultra-balancing procedure on their rotors is a strong selling feature . . . not one bearing failure in thousands of units sold? Necessary? There was no measurements taken of relative vibration levels versus failure rates for B&C alternators . . .in fact, no very few B&C alternators figured into the decision but observations of other automotive conversion product's problems prompted the rather expensive decision by B&C to do the ballancing. Irrespective of the discussions on which alternator or how it's installed or if one should worry about abusing it, there's a consideration that transcends all others. Question: After you applied all the best advice, applied your best craftsmanship and educated yourself on it's application, are you now betting anything on the notion that it will never fail? "Never fail" means 100% reliability . . . like your wing spar or elevator control push rod. A nice thing happens when we do failure mode effects analysis and develop satisfactory alterantives to all failures, the discussions about "cooling this just right, or not abusing that" become much less significant. Much of what is brought forward as advice is based on anecdotal information. Nothing wrong with anecdotal information, it's the best we have in many, many design situations but it does not lend itself to analysis for cause/effect or quantified performance and stresses. A lot of B&C's manufacturing decisions are based on anecdotal input. Once you've acquired a component from B&C or any one else, the prudent approach is to assume that any of these parts are going to fail anyhow and develop well a reasoned "plan-b" for the situation. Reliability studies are conducted on critical components of machines like the space shuttle and for commercial air transport of people. Believe me, you cannot afford such efforts on the convenience accessories in your airplane. I recommend you treat EVERYTHING electrical as a convenience item, each backed up by "plan-b" alternatives for the way you intend to use your airplane. Without elaborating here, may I recommend these two pieces availble for viewing elsewhere? By the way, our weekend seminar schedule for 1998 is beginning to shape up. See Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= From: AlWick Date: Thu, 4 Dec 1997 13:02:18 EST Subject: COZY: home made strobes Organization: AOL (http://www.aol.com) Since it's getting cold outside, I'm planning on making my own strobes using instructions from march 1990 kitplanes article. Was tempted to etch a circuit board. Having a little difficulty finding all of the components. Anyone tried this? Seems like it would be fun way to save a few hundred bucks. -al Date: Thu, 04 Dec 1997 11:05:51 -0800 From: "LCDR James D. Newman" Organization: INFINITY Aerospace http://www.flash.net/~infaero Subject: COZY: Re: Home Made Strobes Hi Al and All, >Since it's getting cold outside, I'm planning on making my own strobes using instructions from march 1990 Kitplanes article. Was tempted to etch a circuit board. Having a little difficulty finding all of the components. Anyone tried this? Seems like it would be fun way to save a few hundred bucks.< Excellent idea. Call DynaArt (805) 943-4746 for laser printer transfer paper used to make circuit boards - works great. They should have everything you need to make one board, to going into production. I'm sure we'll all be looking forward to seeing what you come up with and the pics on Marc's Web Site. Infinity's Forever, JD Date: Thu, 04 Dec 1997 20:48:02 -0800 From: C Van Hoof Organization: Architect Subject: Re: COZY: home made strobes AlWick wrote: > > Since it's getting cold outside, I'm planning on making my own strobes using > instructions from march 1990 kitplanes article. Was tempted to etch a circuit > board. Having a little difficulty finding all of the components. Anyone tried > this? > Seems like it would be fun way to save a few hundred bucks. > -al Hi All, I wrote to the Author of this article (Kitplane Mag) to thank him and the following reply was received.... copied: Hi Chris: > > Thank you very much for sharing your knowledge with us. You're welcome. > > The Flashers will definitely be installed in/on (?) my Cozy MkIV - when > it's finished of course. I checked my mail to see if you've written me before - nothing found. So if I've sent you this info before, please pardon me. If you plan to build the flasher circuit, here are some errors I made in the article: I switched from floods to 15 degree spots. (Brighter during the day.) The 68K's I mention in the article are really the 100K's in the schematic. I forgot to show pin 1 on the 555 IC. It should be shown, and shown going to ground. The 2.2K to the gate of one FET is probably unneccessary, but makes for a nice jumper. The 2N2904 should really be a 2N3904. A 2N4401 from Radio Shack should work. And my reader's have pointed out that there are cheap p-channel FET's available, so you could do the ciruit with one wire to the lights, and ground them in the wing. (Not available from R/S tho.) Mike <>< Hope this helps chris #219 Date: Thu, 04 Dec 1997 20:54:52 -0800 From: C Van Hoof Organization: Architect Subject: COZY: Sorry re Strobes Sorry folks, the reading is OK, its the comprehension thats slow... My last eMail is an answer to Al Wicks thread about strobes...so i posted a fix to the Flashers in the latest Kitplanes Mag... sorry for cluttering the server. head hanging in shame chris #219 Date: Sat, 13 Dec 1997 22:48:37 From: "Robert L. Nuckolls, III" Subject: COZY: re: "dry batteries" At 11:14 PM 12/12/97 -0000, you wrote: >--> RV-List message posted by: Flyinghi@worldnet.att.net > >Is anyone familiar with the Black Panther dry cell battery collection? >They have a website at blackpanther.com and after haven seen the batteries, >they seem very interesting. The advantages of a dry cell battery seems >extremely favorable to me for aviation and the weights they post are very >respectable. Anyone have experience with these? Just visited their website. They're offering a lead-acid, recombinant gas battery not unlike the Concord RG series or B&C batteries. This technology is becoming quite commonplace and IMHO is the ONLY kind of battery to use in an airplane. There are DOZENS of other manufacturers out there offering similar technologies . . . virtually all manufacturers of un-interuptable power supply batteries now offer RG technology. "Gel" cells and flooded batteries are fading fast and I'm not sorry to see them go. Blackpanther takes a whack at Optima batteries which is only slightly justified . . . the stacked flat-plate designe does give one a slight edge on watt-hours per cubic inch. The Optima battery is a carry over from the ORIGINAL recombinant gas battery production by Gates from some 15 years ago. The patents have expired on this technology so lots of folks are getting into the act. Gates was having mechanical troubles with the "jelly-roll" cells when B&C was offering them to amateur airplane builders 10 years ago . . had to give them up. When Gates went to the stack-of-flat-plates design, they sold their tooling to Optima who now seems to have whipped the mechanical problems of years past. Looking at the Black Panther ad . . . Superior volumetric and gravimetric power density, offering more power in less space and weight Ultra-high-rate discharge capability Ultra-low internal resistance, allowing superior terminal voltage characteristics under fast rate discharges Under normal charging conditions, out-gassing is negligible. True of all RG products. Actually out-gassing is usually ZERO. Gases are fully contained and recombined within the battery, making it safe for installation in human environments, such as inside the passenger compartment (under the seat). RG batteries were VERY popular with the computer IPS builders . . . secretaries get really tense when foul fumes fill the office . . . or acid drips onto the carpet. 100% maintenance free copper/alloy terminals, making a true fit-and-forget battery Advanced manufacturing techniques, insuring high reliability and consistency True of most RG batteries . . . the technology is a proven concept. Problems with these batteries are generally attributable to manufacturing defects (still a LOT of hand assembly for most manufacturers). Use of very high purity lead grid (99.994%), translating into longer life VERY important . . . don't know about Concord but the battery B&C sells starts out with NEW lead. However, I've heard that metals recycling folk are getting better all the time with cleaning up OLD lead. Flame-retardent case and cover material, featuring an LOI> 28 and meeting UL94-VO requirements. Superior fast recharge capability, allowing 95%+ recharge in less than 30 minutes from 100% state of discharge Can be mounted in any orientation. Battery may be installed and operated in any direction, allowing greater flexibility in product design and use, due to the sealed, non-spillable construction, making it safe and approved by the USDOT for air transportation shipping worldwide True of every RG battery. Wide operating temperature range. Black Panther can handle the cold and heat, from -40o to +60oC Safety, All Black Panther product is UL recognized, as a component per UL standard 924 and 1778 Environmentally friendly; easily recyclable Nothing really outstanding here . . . but feel free to explore their range of products from a viewpoint of economics and installability. BTW . . . these are not "dry" batteries . . . their electrolyte is liquid water-sulphuric acid. It happens to be totally contained in not quite saturated separators. You can poke a hole in one and it won't leak but you can wring liquid out of a separator. I do note that the Black Panther battery is optimized for deep cycle service and claims 400+ cycles of endurance. This is a little misleading. ALL batteries begin a slide in capacity due to deep cycling immediately upon placement in service. Batteries designed for cranking (it only takes 1-2% of the battery capacity to start an engine) are generally good for 75-100 "deep cycles" (full charge down to 10% and back) before the full-charge value drops to 80% of original capacity. Depending on where Black Panther wants to call "end of life", their number of charge-discharge cycles can vary widely. For airplanes this is not especially important . . . 99.99% of the time all you need a battery to do is crank the engine. If you don't regularly deep cycle the battery (your alternator craps out every third flight or so) then the deep-cycle feature is not a compelling feature for purchasing Black Panther over any other battery. For more information on the RG batteries, see: Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= < Go ahead, make my day . . . . > < Show me where I'm wrong. > ================================= Date: Mon, 15 Dec 1997 21:42:19 From: "Robert L. Nuckolls, III" Subject: COZY: solar battery chargers At 08:03 PM 12/14/97 -0700, you wrote: >Bob, > >I see an add in Trade a Plane for a solar batter charger run off the >cigarette lighter. Are these any good or is it just a gimmick? > >Regards, >Tom Not at all. Cigar lighters on most cars are always hot which provides a convenient way to pump energy into the electrical system without getting under the hood or having any other accessories on. Most "chargers" are really pretty good "maintainers" as their output is simply too low to be a practical means for bringing a really dead battery up to full charge. Also, if left on too long . . . they can damage a battery. As a maintainer, the goal is to just offset the battery's internal self discharge rate . . . something on the order of 30-100 milliamperes depending on battery age and technology. Anything more than this will cause water to be driven off. I'm working on an article whereby one may use a derivation of our regulated dimmer assembly to put between the solar array and the battery to be maintained. Also, at OSH last year I spoke with Mr. Everett Yost who has several booths there selling all sorts of batteries including solar arrays. He is going to have some relatively low cost arrays capable of actually charging a battery . . . on the order of 1 amp output or so. These will indeed require some sort of regulation. I'll be working up a handout for him to describe construction of an appropriate regulator or get it off our website. Keep an eye on our articles index page for the information to show up. Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= < Go ahead, make my day . . . . > < Show me where I'm wrong. > ================================= Date: Thu, 18 Dec 1997 12:56:17 From: "Robert L. Nuckolls, III" >In order to use an LED for a warning light are there any additional >components necessary such as a resistor or DC to DC voltage convertor? > >I'm thinking I might use some LEDs for low fuel and low vacuum warning >lights. > >In addition I might susbstitute an LED for the incandescant bulb that comes >with the LR-3 regulator. LED's can be used to replace light bulbs by simply putting a resistor in series with the device to set the current through it. Most small LED's are rated at 20 milliamperes and they'll light up with about 1.8 volts across them. 13.8 - 1.8 means you need to drop 12 volts at 20 milliamps in a series resistor. 12/.02 = 600 ohms. You'll find that 560 ohms is a standard value (you need a 1/2 watt resistor) and will work for the majority of your needs. Some super bright LED's need 60 ma so the resistor drops to 200 ohms . . . but these are way too bright to be practical indicators. Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= < Go ahead, make my day . . . . > < Show me where I'm wrong. > =================================