Date: Sun, 02 Jan 2000 11:50:41 -0600 From: "Robert L. Nuckolls, III" Subject: COZY: Re: battery failure >i am considering a dual alternator, single battery electrical system, as >shown in the aeroelectric drawings. > >is there a "weak link" only having one battery? in other words, is there a >failure mode of the battery (or wiring) which would make the alternator(s) >fail also? is it the same for PM alternators? Back in not so good ol' days of flooded batteries, there was a failure mode that would raise some concerns for single battery, dual alternator ops . . . SHORTED cells. The plates of flooded batteries as a matter of routine would drop conductive flakes into an open space under the plates (a sort of bilge where junk was stored). If the battery's service was so long that the space was used up, trash would short the plates of the cell together and turn a 12v battery into a 10v battery. IF flooded batteries were maintained as we're all going to maintain our RG batteries (replace battery when useful capacity falls below useful electrical endurance with respect to fuel aboard) then I suspect we'd see no more shorted cell batteries even in flooded technology. RG battery plates don't molt . . . shorted cell phenomon is gone. With two alternators, battery capacity is moved down a not in importance so you can run the battery longer but I'd still try to get it out of the airplane when it's no longer able to carry e-bus loads for at least a hour. If you use the architecture shown in the latest article http://www.aeroelectric.com/articles/allelect.pdf you will note that the auxiliary alternator does not tie to the battery via the battery contactor rather it uses a dedicated control relay to gain access to the battery. This means that even if the battery contactor is lost (open wire, etc), the aux alt will work in conjunction with the battery and e-bus alterate feed path to keep the e-bus running indefinitely. I've studied this drawing extensively and i've got other folks looking at it too. At the moment, we can find no single failure (except shorted cell in battery) that would put a pilot into an uncomfortable position. Use an RG battery, replace it regularly and this low cost approach to an all electric airplane should serve you well. Bob . . . http://www.aeroelectric.com From: "Russ Fisher" Subject: COZY: Re: Grounding Date: Wed, 26 Jan 2000 23:18:42 -0500 >Hi, >If the article describes "other proven methods I would appreciate >receiving a copy too. Would be pleased to exchange something of equal >value to cover your costs. If article does not describe would appreciate >lead info. >Yours indebted, >Joe Toop Joe, I'll be happy to fax a copy to you. In the mean time, let me share with you and the group a couple of paragraphs from the article. -- In composite aircraft or aircraft equipped with fiberglass fuel tank(s), the fuel tank filler neck(s) may not be grounded. A reasonable precaution for homebuilders of such aircraft is to attach an internal grounding wire from the tank filler neck to the aircraft's metal ground bus, and this, in turn, should be grounded to the metal in the landing gear so as to be accessible to the ground cable of a fuel truck. Since the integrity of this grounding scheme cannot be assured in every case, caution should be used when approaching the filler neck with the nozzle. The electrical potential for spark may still be present. Before removing the filler cap, the nozzle of the dispenser should first be grounded to the metal filler neck of the aircraft to dissipate any static charge while no fumes are present at the filler neck. This can be done by holding the nozzle in one hand and touching the closed filler neck with the other hand, or by simply touching the nozzle to the closed filler neck. The nozzle should be kept in continuous contact with the filler neck throughout the filling process to create another path by which electrical charge can escape. If the nozzle is not touching the filler neck, a spark could jump the air gap that separates them. -- The reason I dug this article out was that I remembered that they had said fuel is non-conductive and I wanted to point this out to Michael. It wasn't until I read your message that I did a more thorough scan of the article and discovered that they recommend the same thing as I had (connecting the ground to the filler neck). The other "proven methods" I mentioned came from (I believe) an FAA pamphlet that I picked up at a safety seminar. I will have to dig it out (if I still have it), but won't be able to until this weekend. If I can't find it, I'll call a friend of mine at the Rochester FSDO and see if she has one. Regardless, I'll see if I can get you a copy as well as post the title of the report here so others can order one. Russ Fisher - Date: Wed, 02 Feb 2000 21:47:02 -0600 From: "Robert L. Nuckolls, III" Subject: COZY: Re: Panasonic Batteries >This is a question for Bob Nuckolls. Are the Panasonic sealed lead acid >batteries that are for sale in the Digi Key catalogue suitable for aircraft >use, and are these RG batteries? Yes and yes. For engine cranking you need to pick a product that will allow you to draw hundreds of amps from the battery . . . fast-on tabs are just too small. There are gobs of places to buy batteries perfectly suited to light aircraft. Here are just a few: Powersonic: PS-12180 http://www.power-sonic.com/12180.html Hawker: Check out the first 6 batteries on this page . . . http://www.hepi.com/products/genesis/genprod.htm Panasonic: particularly the LCRD1271P http://www.panasonic.com/industrial_oem/battery/battery_oem/images/pdf/lc-rd 1217p.pdf http://www.panasonic.com/industrial_oem/battery/battery_oem/chem/seal/seal.htm Yuasa-Exide: Check out the NP18-12B at this site . . . http://www.yuasa-exide.com/np-prod.html Handle these like any other lead-acid battery. Bus volts no less than 13.8 - 14.2 is about ideal - no more than 14.6 Bob . . . -------------------------------------------- ( The only time you don't fail is the last ) ( time you try something, and it works. ) ( One fails forward toward success. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com Date: Thu, 24 Feb 2000 08:43:11 -0600 From: "Robert L. Nuckolls, III" Subject: COZY: Re: CHT Lead Length At 06:25 PM 2/23/00 EST, you wrote: > >Bob, > >I posted this basic question to the RV-list and got no response... Sorry, I must have missed it. I scan through about 300 pieces of list-server traffic a day looking for items on which I can be helpful . . . they slip by from time to time. . . >I have a single cylinder CHT system. I'd like to buy 3 more thermocouples >and run four thermocouples to a 4 way switch, then through a ~6" wire to the >gauge. > >I usually see dire warnings about changing the length of the thermocouple >leads. What's the scoop? Thermocouple lead length is critical only for the old, self-powered termocouple instruments of WWII vintage. Many of these instruments had accessory resistors mounted external to the instrument so that the installer could change the lead length and then recompensate using the external resistor. ANY electronic instrument that reads thermocouples is not so crippled. You can get a short tutorial on thermocouples at: http://www.aeroelectric.com/articles/excerpt.pdf >Also, IF I can't do it that way, could I determine a baseline with a CHT >probe installed per plans, write down those readings, then hook up the >(innacurate?) 4 cht system with the switch to see relative differences for >the purpose of balancing CHT's through baffle mod's? After balancing the >temps, I could go back to the one CHT system. It's both practical and not too difficult to put a two pole, 4 position switch in your thermocouple pathways following the guidlines in the above article. To make the termocouple wires solderable with ordinary tin-lead solder for switch connections you need to first "tin" the ends with silver solder. The silver solder will make the thermocouple alloy solderable with ordinary materials at more benign temperatures friendly to the rotary switch. There are commercial, off the shelf thermocouple switches that allow you to simply strip the wire and capture it under a screw driven clamp. Most of these are bulky ol' hogs . . . not terribly friendly to a modern, tightly spaced lightplane panel. >Thanks in advance, > >Kyle Boatright > > Bob . . . -------------------------------------------- ( The only time you don't fail is the last ) ( time you try something, and it works. ) ( One fails forward toward success. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com From: "Reid Siebert" Subject: Re: COZY: Ground service connection Date: Wed, 29 Mar 2000 12:38:47 -0600 John, I installed a ground service port on a Seawind using a cigarette lighter outlet, and a 10-amp circuit breaker. The outlet is wired to also charge two batteries (through 35-amp diodes). I then wired the male plug of the outlet to an automotive battery charger. With this circuit I am able to keep the batteries charged, while powering the airplane in the hangar. The outlet is also available for powering hand-held equipment (while ship's power is on or off) when its switch is turned on. It's been working fine for a year. On my two battery - two bus - two alternator Cozy I have a four wire trailer hitch plug that is wired to allow me to charge, one, or both, batteries. Two wires are positive, and two are grounds. The positives run to the battery side of each master solenoid, with diode protection. I'm mounting the plug's receptacle under the cowling's oil service door, so that I can use another of the plugs, with only two long ground wires attached, for my anti-static fueling ground. Mounting the receptacle in the cowling allows me to keep the canopy closed, and also avoids cutting another access hole in the fuselage. The plug, and receptacle, are keyed to prevent improper connections. When the airplane sits in the hangar I will have two small trickle chargers (one for each battery) plugged into the wall, to keep the batteries topped. Reid From: mbeduhn@juno.com Date: Wed, 29 Mar 2000 16:18:13 -0800 Subject: Re: COZY: Ground service connection I don't do anything (they are 4" apart), but plastic caps could be put on one of them if this was a concern to someone using this idea. Mark > Mark, do you protect the tabs from accidental short? > Bulent On Wed, 29 Mar 2000 14:34:06 -0400 Bulent Aliev writes: > > > mbeduhn@juno.com wrote: > > I installed two copper tabs under my strake near the firewall > (they stick out about an inch). On the inside of the plane I ran #4 wire from > each tab directly to the battery. The copper tabs are mounted > horizontally so have little effect on drag, but allow standard jumper cables or > charger clamps to clip on to them. It is light, and works well for me. > Keeping my battery charged or jump starting my plane is no problem. I do > not consider hand propping my IO-360 to be an option. > > > > Mark Beduhn > > Cozy N494CZ From: "Tim" Subject: COZY: Battery Date: Wed, 12 Apr 2000 16:02:38 -0500 I took a look at a new battery that advance auto parts is selling. It is a rolled type lead that is sealed. The battery is made by champion. The battery is rated at 46 amp hour or 700 cranking ampsat o degrees and 900 at 32 degrees. It is supposed to handle 3 times as many starts as conventional batterys. The deminsions are lenth 9 5/16 width 6 13/16 height 7 5/8 weight 33.1 pounds The price of the battery is around 100.00. It weighs the same as a conventional 35 amp hour battery. The name of the battery is vortex. Just thought I would pass it on. Tim Kilgore Cozy Mark IV 372 Date: Thu, 04 May 2000 10:24:16 -0500 From: "Robert L. Nuckolls, III" Subject: COZY: Re: Odyssey Battery - Voltage Regulator At 07:53 AM 5/4/00 -0500, you wrote: >--> RV-List message posted by: "Jones, Bryan D." > >Isn't the Odyssey a dry cell type battery? If so, what type voltage >regulator does it require? Same as for lead-acid battery? The Odyssey is not a dry cell, it has liquid water and sulphuric acid in it. It's also a lead-acid battery. It requires no special attention in terms of voltage regulation. see http://www.aeroelectric.com/articles/rg_bat.html The majority of my builders are using a 17 a.h. recombinant gas batteries which which can be found on hte following links. These batteries can be purchased from a variety of battery specialty shops. We have some little convenience store sized Battery Patrols around Wichita that handle these batteries for $60-70 each. Powersonic: PS-12180 http://www.power-sonic.com/12180.html Hawker: Check out the first 6 batteries on this page . . . http://www.hepi.com/products/genesis/genprod.htm Panasonic: particularly the LCRD1271P http://www.panasonic.com/industrial_oem/battery/battery_oem/images/pdf/lc-rd 1217p.pdf http://www.panasonic.com/industrial_oem/battery/battery_oem/chem/seal/seal.htm Yuasa-Exide: Check out the NP18-12B at this site . . . http://www.yuasa-exide.com/np-prod.html Handle these like any other lead-acid battery. Bus volts no less than 13.8 - 14.2 is about ideal - no more than 14.6 Bob . . . -------------------------------------------- ( Knowing about a thing is different than ) ( understanding it. One can know a lot ) ( still understand knothing. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com Date: Sat, 13 May 2000 12:13:23 -0500 From: "Robert L. Nuckolls, III" Subject: COZY: OV protection w/built in regulator >My experience has been that most of the hardware old enough to use an >external regulator is also less reliable. Note that I said 'my >experience' and 'most.' I went through 4 externally regulated >alternators & at least that many regulators in about 4 months before >switching to an internally regulated alt. almost 5 years ago, with not a >single glitch since. None of the above failures were of the o/v nature & >none damaged any avionics. Agreed . . . and MOST of the externally regulated alternator hardware out there is specific to aircraft and designed/certified 20-30 years ago. Check the service difficulty reports using keyword "alternator" and then filter for single engine aircraft . . . Everything that might be deduced in the way of alternator failures happens every month in a TC aircraft . . . "casting broke, thru-bolts stripped, brushes worn out, windings burned, bearings siezed, diodes shorted, etc. etc." FBO's love 'em . . . regulated job security well into the new century. On the other hand, when you take a brand new, Nipon-Dienso, 40 or 60 amp alternator, disassemble for modification to run external regulation, balance the rotor to about 10x tighter specs than they come out of the factory and re-assemble with due care, you end up with an alternator that runs well for a very long time. I have first hand knowledge of 2,000+ such alternators sold over the last 8 years . . . not one has returned for wear-out or repair. It's the difference between a 1990's product and a 1960's product. >I don't use o/v protection, but if I did, it would probably be the very >simple zener/fuse arrangement. I'm sure Bob's solid state system is more >sophisticated & works better, but as the guy used to write in BYTE >Magazine, 'Better is the enemy of good enough.' The zener fuse combo was certified onto early American and subsequently Grumman-American aircraft. It's a sort of poor-man's crowbar ov protection scheme. When I first heard of it, I was skeptical. It has been about 15 years since I brass-boarded this system onto an alternator-battery system in the lab. Here's what I found. Proper operation of the system depended heavily on two things. (1) A fuse (fast acting) had to be used upstream of the zener and (2) the zener had to be a 1W glass encapsulated device - p/n 1N4745. It works like this: In an ov condition, the zener tries its best to keep the bus voltage from rising above 16 volts. In so doing, internal disipation rises well above the diode's 1W rating and it commits electronic suicide by becoming a dead short. The resulting short opens the fuse and corrals the runaway alternator. Over the years, folk who did not understand the "balance of power" implicit the this design made well meaning-changes to this scheme with the unintended consequences of degrading performance or even making the system ineffectual. Common errors include: (1) Replace pesky fuse with a real circuit breaker: Opening times for breakers vs. fuses is 10x to 50x longer. The slow response of the breaker stresses the zener to explosive destruction. The altenrator runaway continues unabated. (2) Substituted any ol zener with the number "1N4745" printed on it: Plastic parts were unable to withstand the rapid onset of heat dissipation and explosive destruction of the zener results. The runaway continues unabated. (3) Substitute a really husky 16 volt zener for the itty- bitty 1W device. This change was often combined with a change from fuse to circuit breaker. The general idea was to make the protection scheme "reusable" . . . no fuses -or- zeners to replace: The general effect of this modification was to push the time-constant for tripping OV protection out by hundreds of milliseconds to perhaps several seconds. Contemporary OV protection is designed to react to a step from 14-20 volts on the bus in 50 milliseconds or less. >My personal feeling about external regulators & o/v protection is this: >Once I reach a certain (hard to define) comfort level about the >reliability of a system, I'd rather not add failure modes. Over-voltage >type failures in self-regulated alternators seem to be so rare that you >hear about every one. Generator/regulator & alt/regulator failures are >so common that they are treated like dry vac pump failures, you know >they are going to happen sometime in the near future. No argument about comfort levels . . . I'll suggest that the greatest body of experience with aircraft alternators comes from the world of certified aircraft. My best recommendation is to see what's happening with true state-of-the art designs and fabrication techniques. There's a mistaken perception that the certified aircraft world is benefiting from the advance of technologies in all respects . . . I'll suggest it happens only in area of things you bolt into holes on the instrument panel. Stuff under the cowl has evolved very slowly if at all in 50 years or so that have passed since the first generator was bolted to a single engine airplane. If you want to know what a modern alternator can really do for you, you'll have to limit your observations to the real leading edge of aviation technologies . . . check out the flight line at OSH. Bob . . . -------------------------------------------- ( Knowing about a thing is different than ) ( understanding it. One can know a lot ) ( still understand knothing. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com Date: Mon, 22 May 2000 18:31:47 -0500 From: "Robert L. Nuckolls, III" Subject: COZY: Re: Switches >Somewhere in the recess of my mind, I recall something being said about a >difference between store bought switches and aviation quality switches. I >have looked through all my library and cannot find any reference that >directs an answer to this ponderence. Tony Bingelis says that there are >probably many 'Radio Shack' switches out there in homebuilt aircraft, but it >bothers me to go 'downtown' for switches if I am supposed to be getting >aircraft switches. What's an "aircraft" switch? Never saw one with that terminology marked on it. There's plenty of advertising hype designed to convince folk that a particular offering is more suited to aircraft than another product . . . but no matter how much you spend for a switch, does that guarantee that it will never fail? If it might fail, what is your "plan-b" for dealing with the failure? If you've GOT a plan-b, then is the absolute quality of the switch all that important? I can tell you that the row of rockers that went into tens of thousands of single engine Cessnas cost them under $1.00 each. The vast majority of those installed at the factory are still operating 20+ years later. > . . . Even 'Electric Bob' seems quiet on this topic other than >to say that the switch should be heavy duty and a snap action switch which >is rated for the load to be placed on it. Where is the reference that I >remember about AC and DC rated switches? Can anyone point the way? I just got back to Wichita after a week of errant electron stomping in CT . . . working a proble with the de-ice system on the Beechjet. Took the day off from RAC to try and catch up on duties at home. You can download a copy of an article I did for Sport Aviation a few years ago at: http://www.aeroelectric.com/articles/swtchrat.pdf Bob . . . -------------------------------------------- ( Knowing about a thing is different than ) ( understanding it. One can know a lot ) ( still understand knothing. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com Date: Fri, 23 Jun 2000 09:35:46 -0500 From: "Robert L. Nuckolls, III" Subject: COZY: Re: Radio Stuff At 07:46 AM 6/23/00 -0400, you wrote: > A couple weeks ago, Michael Harter, John King, and I flew to the Va. >State Fly-in. I flew with John, in his plane, and we followed Michael. We >flew off his aft stbd quarter (nautical talk) most of the way and Mikes >transmissions were very weak and garbbled to the point, we could barely >understand him. John said, they had experienced the problem before when >flying in formation. We were well within visual distance of Mikes plane. >If we changed position a little, the problem seemed to get better. > Is this mearly a "positioning" problem? Both radios in question were >built in and not handhelds. It is not uncommon for closely positioned radios NOT to communicate well with each other . . . the receivers are designed to pick very tiny signals out of the etherial trash. After going to a lot of trouble to hear the weak signals, the radio may be prone to overloading from VERY strong signals. Try an experiment where you back off from the transmitter that's difficult to hear in incerments. You may find some separation where the receiver "recovers" and you can now hear what used to be garbled. Further, radiation patters around an airplane can have marked peaks and valleys in their intensity, you may discover that your position in azimuth around the > Speaking of handhelds, I saw in, one of the catalog's, an "amplifier" >for handhelds. Are they worth the money to improve comms with a handheld? >If I remember, they weren't cheap???? Generally these devices only boost your transmitter performance although some may have receiving pre-amps built in too. By-in-large, receivers in hand helds are nearly as capable as receivers in panel-mounted radios when it comes to sensitivity. It may lack capabilities in overload resistance but generally speaking there is little gain to be realized by puting a pre-amp on a hand held radio's receiver. Transmit amplifiers will indeed make you heard further but there are cautions. Low power hand held radios, because they are low power, don't have to work so hard to suppress UNWANTED output from their transmitters . . . and EVERY transmitter puts out energy on frequencies other than the one you're using to communicate. An amplifier will boost both the desired and undesired outputs which may cause you to become a nuisance to folk using other parts of the spectrum. An external antenna is much less expensive, needs no power from ship's systems, and will generally let you talk to any station you can hear. Bob . . . -------------------------------------------- ( Knowing about a thing is different than ) ( understanding it. One can know a lot ) ( and still understand nothing. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com Date: Tue, 27 Jun 2000 10:07:07 -0500 From: "Robert L. Nuckolls, III" Subject: COZY: Partially broken co-ax cable >While working at the wing tip preparing the winglets for attachment, the >coax from the com antenna buried in the winglet took a lot of bending back >and forth where it emerges from the micro in which it's buried and the >insulation and shielding is cracked in one place . (Idiot!!!!) >The shielding and the core are still electrically connected to the copper >foils, (per my ohmmeter) but while it's still un-glassed I'd like to make >it good. There isn't enough free wire length emerging from the winglet to >put in a co-ax connector. >Anyone know of a cable industry trick to take care of a situation like >this?? Maybe some kind of continuity clamp that would pierce the outer >insulation and connect the shielding but not touch the core? My mental image of your description is that you have a few of the shield wires broken and that the center-conductor is 100% intact. Keep in mind that the center conductor is but 19 strands of wire while the shield will have dozens. The larger number of shield wires are necessary for physical COVERAGE of the inner conductor. When you get to the end and need to attach the coax for antenna currents to flow, the number of strands of wire needed for shield attach are no greater than for the center conductor. I'd make sure no loose strands are touching the opposite connection (trim them off) and go ahead with covering it up. Bob . . . -------------------------------------------- ( Knowing about a thing is different than ) ( understanding it. One can know a lot ) ( and still understand nothing. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com Date: Sun, 02 Jul 2000 21:33:05 -0500 From: "Robert L. Nuckolls, III" Subject: COZY: Re: Wire crimp >Bob.. the URL you showed is bogus... >Dennis Douglas Oops . . . was logged into the hard-drive version when I captured the URL to my clipboard. You can find it on my website at: http://www.aeroelectric.com/articles/matenlok/matenlok.html Thanks for the heads up! >"Robert L. Nuckolls, III" wrote: > >> At 02:00 PM 7/1/00 -0700, you wrote: >> >Amp makes a tool available through Newark Electronics or you can order >> >direct from Amp on their web page. I recall that both of these connectors >> >take the same crimper. It's called a Service Tool II but I don't have a >> >part number. >> >> I was going to stock this tool . . . tried to order a couple >> dozen and was informed that AMP has discontinued it. It was >> one of best values around in a low-cost open-barrel crimper. >> Very well made compared to some of the tools I've been evaluating >> over the past month. >> >> We've finally decided on one and have inquiries out to >> several warehouses that stock them. See how it works at: >> >> file:///D|/0_WEBSIT/articles/matenlok/matenlok.html >> >> I hope to put this tool in our website catalog for about the >> same price as what the Service Tool II would have cost. Bob . . . -------------------------------------------- ( Knowing about a thing is different than ) ( understanding it. One can know a lot ) ( and still understand nothing. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com Date: Tue, 11 Jul 2000 10:32:30 -0500 From: "Robert L. Nuckolls, III" Subject: COZY: Re: Vacuum Instrument bashing! >If your alternator goes out, your battery dies or your buss fries, a >few suck type instruments would look mighty good up there in a murky sky. The 'dark panel' syndrome has been topic of many a hair-raising, wing-and-a-prayer hangar tale for decades. Virtually all of these experiences happend in a government approved, certified aircraft where the technology and design philosophy are carved into 1960's era regulatory stone. >With all electric, you could lose all instrments at once unless you have a >lot of back up electrical systems in place. There is no reason for a modern aircraft to suffer an electrical emergency of any kind. Wires are no longer cotton-covered-rubber or nylon-over-PVC insulation. Reasonably maintained batteries are dependable sources of power when and if the alternator craps. A second alternator capable of extended endurance engine powered flight costs less than a vacuum system and weighs 1/2 to 1/3 the pounds. Certified alternators repeately demonstrate 50-200 hrs limits before something breaks . . . modern alternators that ran the lifetime of the automobile they came out of are ready to go another thousand hours or so in your airplane. Simple departures from system architectures revered for decades provide operational alternatives to every simple failure of any component. Physics and facts don't support the rhetoric. Busses don't "fry", any battery that enjoys a modicum of preventative maintenance doesn't die in flight, and alternators (particulary two of them) are going to be there in one form or another when you need them. MOST importantly, YOUR airplane is going to be fabricated and maintined under aviation's finest traditions of craftsmanship and attention to detail. On an assembly line, the kid bucking rivets has been working there two weeks. If something doesn't quite line up, he'll stick an awl into the hole and MAKE them line up. If something gets bent or broke, 3 supervisors and 5 inspectors will stand around for an hour and deduce the MINIMUM effort and expense that will allow the factory to LEGALLY put the airplane out the door. Is that how your airplane goes together? >So you install double alternators, double batteries, seperate busses and so >on. Also, if I am not off the bubble, electric instruments cost a lot more. True. But you save on vacuum system weight and installation time. The rat's nest of plumbing and hoses behind panel go away. Weight of system goes down. In 1965 while working at Cessna single engine engineering I was told that it was worth $100/pound to the end user to reduce the weight of an airplane. Each pound left OUT didn't have to be fabricated, installed, maintained nor was fuel burned carrying that extra pound of stuff around in the sky for the lifetime of the airplane. What is a pound of excess weight worth to you 35 years later? What's it worth to have reliability in a single engine airplane that rivals or exceeds that of a LearJet? What's it worth NOT to fabricate, install and maintain several pounds of plumbing? >Vac. pumps have been around for ever and to suddenly say they are no good >makes little sense. With Vac. pumps as with most other things, you get what >you pay for. Even one supposedly good for only three hundred hours would >run most pilots three years. It runs deeper than getting what you pay for . . . you can pay a lot of money for trash. If you endorse the "been around forever" philosophy then how about keeping dual VOR and an ADF in the panel? I know some folks that would make you a really good deal on a DME. I work daily within the morass of regulated aviation. A substantial portion of my time is expended trying to figure out how to fix a problem without opening the Pandora's box of recertification. The system works against truly effective solutions to problems. The very reguations offered up in the quest for aviation utopia are in fact making airplanes less friendly to the people who own, maintain and fly them. You don't know how refreshing it is to come home and work the folks who are building the finest airplanes to have ever flown. You may find comfort in a familiarity with "the devil you know". However a little study of aviation's history and some observation of truly modern and (more important) UNREGULATED evolution of aviation technology proves that "the devil you don't know" is really a pretty nice guy. Bob . . . -------------------------------------------- ( Knowing about a thing is different than ) ( understanding it. One can know a lot ) ( and still understand nothing. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com Date: Wed, 25 Oct 2000 16:41:03 -0500 From: "Robert L. Nuckolls, III" Subject: Re: Sticking relay with B&C starter. >There are two more considerations in connection with solenoids that you >should be aware of. >1) If you have low battery voltage, like too much resistance in the line, >or maybe one of the old-style lead-acid batteries, or do too much >cranking, you can weld the contacts together. Quite true . . . and it can happen to ANY style contactor. >2) The commonly used solenoids (Wicks et al) have bolt heads inside for the >contacts. If you twist the posts by tightening the electrical cables too >tight on the outside, the bolt head on the inside can turn, so instead of >the contacts being the flat of the bolthead, it is one of the points, and >that greatly reduces the contact area, and could cause welding of the >contacts. Not sure about what Wicks is selling if it looks like: http://www.aeroelectric.com/Catalog/switch/s701-1l.jpg then IT IS important to hold the nut up next to the contactor shell and keep it from turning while you tighten the wiring nut. ANY rotation of the threaded stud will render the contactor trash. If the contactor looks like: http://www.aeroelectric.com/Catalog/switch/s702-1l.jpg Then the studs are captive in the contactors molded housing. With this style, twisting the stud will break the housing but at least you KNOW when you've cranked down on it too hard. >B and C Specialties has a special contactor where the posts can't turn, and >it avoids this problem. Benoit, would you like Bill Bainbridge to send you >one of these which is garaunteed not to stick? Don't know about "guaranteed" but they're really hard to stick. However, starters with failed wiring inside or low battery voltage can weld the best contactor . . . > To amplify what I said in one of my earlier posts, the battery >solenoid is energized when you turn on the master switch, and nothing else >should be on at that time, so you aren't switching any current. Most airplanes have several amps of things that are on all the time but a battery contactor is generally rated to SWITCH 70 amps or better. Normal bus loads don't errode the battery master contactor to any significant degree. > . . . .But when >you energize the starter solenoid, you could be switching as much as 600 >amps, which is the cranking power of the battery. That is why the starter >circuit goes directly from the battery to the starter . . . This is not recommended. All of our drawings and virtually every certified airplane takes starter current through the battery master contactor . . . if the starter contactor DOES stick, then the battery master gives you a way to shut things down. While a battery master contactor is rated to SWITCH 70 amps, it will nicely CARRY the 200-250 amps common to starting an engine. I've had builders try to use one of my S701-1 battery contactors as a starter contactor and didn't get very good service life . . . however the battery contactor was ALWAYS there to bring a potentially bad situation under control. > . . . and not through the power bus and the 50 amp circuit breaker. Not sure what breaker this is . . . some folks have a fat breaker in their alternator b-lead output to the bus. By-in-large, there's no practical application for fat breakers anywhere else in the system. Bob . . . -------------------------------------------- ( Knowing about a thing is different from ) ( understanding it. One can know a lot ) ( and still understand nothing. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com Date: Wed, 25 Oct 2000 17:00:04 -0500 From: "Robert L. Nuckolls, III" Subject: Sticking Contactors . . . >There is something else to consider in installing solenoids (besides making >sure you have the right one in each application). You should install them >so that gravity assists the magnetic force in holding the contacts >together. Do not install them upside down! I recall a story circulated around OSH about ten years ago. Seems some show pilot landed and found a chewed up starter ring gear and his starter contactor was stuck shut. Some arm-chair engineering on the spot deduced that high g-loading during aerobatic maneuvers were responsible for "teasing" the contacts in flight and causing welding much like low battery voltage. The word went out like wildfire . . . tho shalt mount thy contactors UPSIDE down so that positive g-loading would not tend to close an open relay. The physics don't bear out any particular admonitions for orientation in the airplane. Once energized, a contactor has about 10x the force holding it closed than it takes to first move the contacts from a fully open position. Since a battery contact is ALWAYS closed, it's likely that you'll pull the wings off your airplane before you force the contactor open during a flight maneuver. Starter contactors (like our S702-1) have extra heavy springs to open them (to offset sticking tendencies) and extra heavy coils to close them (to offset contact bounce and subsequent damage from arcing while closing the high current load). G-loading effects on these contactors is even less significant than for the S701-1 continuous duty part. Further, starter contactors are normally mounted on firewall with base on vertical plane. This orientation puts g-loading sensitivity parallel to the longtitudinal axis of the airplane . . . don't fly into the side of a mountain, you might cause your starter contactor to close when you didn't want it to. By in large, all of the stories being circulated about contactor orientation and are not founded in the application or physics of the matter. IF the airshow pilot was using a poorly choosen device as a starter contactor (like our S701-1) AND it was oriented such that gravity helps close or keep the contacts closed, then it's thinkable that a 10g maneuver might have teased his starter contacts closed in flight. If he were using a REAL starter contactor installed accoding to recommendations, it would never happen. Maneuvering g-loads in airplanes you and I like to fly are not a risk to your various contactors. Bob . . . -------------------------------------------- ( Knowing about a thing is different from ) ( understanding it. One can know a lot ) ( and still understand nothing. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com Date: Wed, 25 Oct 2000 22:56:13 -0500 From: "Robert L. Nuckolls, III" Subject: Re: Sticking relay > Thanks for the overwhelming quantity of answers. It looks like it might be >a real problem. > I will answer to everybody in one message. > To be more precise on my configuration: > - The first starter relay I was using was the one sold by ACS (p/n 22735 on >their catalog) for homebuilders .It started to stick lets say after 3 months >of my initial testing ( I was already flying by that time) and was the one >used for the initial start of the engine when it was sometime a bit >difficult to start with a low battery. > - The second relay was bought in France to a company called Aerostock in Le >bourget airport. It started sticking after 15 days of use. I am now flying >quite often and the engine is firing very quickly and very nicely due to the >jeff rose ignition with a fully loaded battery ( I am flying a lot). > -I took it out and found out it a was a 24v relay. So I went back to >Aerostock and they changed it for a 12v one. The one I got looks very much >alike the master relay ( p/n 111-226 in ACS catalog). It started not doing >its job after a week. This explains it. NONE of heavy duty contactors in that package are suited to starter contactor service . . . for a time, RBM Controls, later White-Rogers, now Stancore built a series of intermittant duty relays with heavier coil wires and stronger closure forces but the way that contactor is designed internally, it just doesn't get the contact PRESSURE that modern automotive starter contactors enjoy. The contactor we sell (S702-1) is of this family of devices. > I know have two plans to attack that problem: > 1-A friend of mine gave me a brand new ACS 22735 relay he had in his >hangar. I might put that one on and keep the diodes that I had added on the >previous relay ( The first relay had a diode between the coil and ground but >not between the output and ground). Our conactor has the arc supression diode built into the contactor coil assembly. > 2-I recently bought a renault truck starter relay which looks impressive >(not to say massive) and very strong. I did not use it yet because I >measured the coil resistance and found out that it was 4 ohms. This would >mean that I would be pulling at least 3 amps through the triggering push >button and given the size of that button this would be way too much. So I >can decide to use it but I would have to trigger the coil of that new relay >through another relay, maybe the previous one that could accept that 3 amp >current easily. Is this overkill? No, the fact that you read the low resistance is FIRST indication that this is an intermittant duty contactor probably designed for higher contact pressures therefore much more suited to working with starters. Our S702-1 contactor is also a 4 ohm coil . . . The starter push-button we recommend is heaftier than most . . . or you can rig your magnetos to use switches and built the starter function into the switches. This is illustrated several ways in the diagrams at: http://www.aeroelectric.com/errata/R9Z_0400.pdf > I would like to thank for the LED advice. It is a very good one because I >had already implemented that in my bird and this is what allowed me to do >the identification of the problem.In fact , every switch has a Led that >lights up when it is on and the information is picked up trough a wire that >is coming from the back of the equipment the given switch is supposed to >energise.I like that set up a lot because I have an emergency power switch >that power a very minimum of what is needed ( to cover the alternator >failure) and when the switch is on "alternate" the LED's give me exactly >what is on. Do you also have some form of automatic disabling of the alternator in case of a failed regulator runaway? This needs to be an automatic function that operates in tens of milliseonds. Pilot monitoring of any instrumentation with the hope of adequately controlling a runaway by shutting the thing off is overly optomistic and potentially expensive. > Well, this is were I am . It is late now and I am going to bed as you guys >are now working. > May be I will find out more to morrow morning with maybe a direct advice >from Bill bainbridge. Just burry in mind that I am now so happy to fly that >bird that waiting 3 or more days for a part coming from the states is too >much. I want to fly to-morrow except if the wheather is bad (it might >happen). Bill is going to tell you that you need a REAL starter contactor like his, like mine or probably like the one you just bought . . . however, it's possible that our contactors are smaller and lighter. My S701-1 is 280 gm and fits inside a 6 x 6 x 6 cm cube. Bill's is very close to the same dimensions. Bob . . . -------------------------------------------- ( Knowing about a thing is different from ) ( understanding it. One can know a lot ) ( and still understand nothing. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com Date: Thu, 26 Oct 2000 12:20:07 -0500 From: "Robert L. Nuckolls, III" Subject: Some thoughts spike catcher diodes . . . A reader comments on the practice of putting diodes across the coil of a contactor . . > A diode connected in this way is usually suggested to clamp the inductive > voltage spike resulting from de-energizing the relay coil. The problem is > that it provides a path for the current caused by the collapsing magnetic > field. The net result is that the amount of time it takes to open the > relay *increases*. This exacerbates the issue of a sticking relay in that > a slower release time causes more arcing at the contacts. Yeeeaaahhh BUT . . . I've never been able to document much change in the contact spreading velocity of the contactors we sell and recommend when a diode is included in the contactor's coil circuit. I have been able to document wear and tear on the switch that controls the contactor and it's much worse if the diode is left off. On starter contactors, the spring tension that opens contacts is MUCH larger than for the continuous duty contacts. Further, given the higher coil current, it's more important that this stored energy be calmly dealt with than with battery contactors. Hence, our starter contactors come with the diode BUILT IN. I have to believe that the folks who make these by the millions for ground based vehicles find this a useful thing to do. Battery contactors are generally opened up with VERY mild loads on the main terminals . . . so again, it's more useful to tame the contactor's stored coil energy than to be concerned with contact opening velocity. > A better way is to dump the current of the collapsing field into the > battery. You can do this by connecting the diode across the starter > switch (cathode band to the battery side of the switch) rather than the > coil. This is a higher impedance path, and it allows the coil magnetic > field to collapse faster while still clamping the voltage. Not so. I've done an article on spike catching diodes and posted it to: http://www.aeroelectric.com/articles/spikecatcher.pdf It's rather large (500K .pdf file) and I appologize for the size but it has 4 pictures of oscilloscope traces taken from test setups on my bench this morning. If you want to get the straight skinny on this topic, I'll suggest it's worth the download time. Bob . . . -------------------------------------------- ( Knowing about a thing is different from ) ( understanding it. One can know a lot ) ( and still understand nothing. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com Date: Fri, 20 Oct 2000 11:08:59 -0500 From: "Robert L. Nuckolls, III" Subject: New Power Distribution Diagram I've had several requests over the past few weeks to incorporate separate concepts described with individual articles into a power distribution diagram illustrating their relationships to the whole airplane. See: http://www.aeroelectric.com/errata/errata.html Bob . . . -------------------------------------------- ( Knowing about a thing is different from ) ( understanding it. One can know a lot ) ( and still understand nothing. ) ( C.F. Kettering ) -------------------------------------------- http://www.aeroelectric.com