From: "Doug Shepherd" Subject: COZY: Air conditioning Date: Mon, 6 Dec 1999 21:45:41 -0800 In order to produce bench seats in my plane, I have shortened the hot air duct to 2" tall and will use it for throttle cables and wiring instead of hot air ducting. I've considered at least three different ways of to providing heat: electric, oil cooler, and heat pump. I'd really rather not run hot oil through the fuse (and besides you need the oil cooler the most on the dog days), and electric heaters are pretty wimpy and require a huge alternator and high-current components and wiring. John's right, a compressor is heavy and requires horsepower to turn, and I'd add that you'd probably have to run freon lines through the fuse and the cowl would have to be bigger , but I'm seriously thinking about a heat pump because it can provide heating AND cooling. I'm not looking forward to sitting under that full bubble on the taxiway in a San Diego august. From: "Capps Family" Subject: RE: COZY: Re: Air conditioning Date: Tue, 7 Dec 1999 02:31:33 -0600 They marine industry makes small, light weight, portable air conditioners for small boats, could one of these be retrofitted in the strake and serve the same purpose. This unit would be electric, so as long as your engine was running, you would have cool air. AND, since it takes hot air to make cool air, you might have your heat source as-well. Larry Larry A. Capps #829 Naperville, IL capps@mediaone.net -----Original Message----- From: owner-cozy_builders@betaweb.com [mailto:owner-cozy_builders@betaweb.com]On Behalf Of JStricker Sent: Tuesday, December 07, 1999 12:03 AM To: cozy_builders@canard.com Subject: COZY: Re: Air conditioning John, I've toyed with this idea as well, and since you've opened yourself to the flames of those that say you don't need it, so will I so we can share the heat. 8-) I looked at it early, and right now I've rejected it, but I did enough preliminary work on the idea to answer some of your questions. I'll try to be fair in the answers and not taint them, although I think my reasons for rejection will show through. First, the compressor will be driven by the engine at the prop end. Piper used a system of A/C in aircraft as lowly as the 140. The weight added to the Pipers is on the order of 70# complete, but you can do better. All of the weight of the compressor will be located, approximately, in the location of the current alternator CG-wise. The Piper's used either a York or Tecumseh (one or the other of those is aluminum, and that's what they used). A newer compressor, namely the Sankyo or Sanden, is much lighter and more efficient. But the compressor alone will still weigh a bit over 12 pounds. You need to add to that the weight of the mounting bracket(s), belt, and heavier drive pulley. Maybe another 3 or 4 pounds. You will need to find a flywheel with the two groove pulley. One groove will be substantially smaller (that is a thinner belt). That belt goes to the alternator, the thicker one to the compressor. Your alternator alignment will have to be PERFECT or you will flip belts over and they'll last only a few hours. You get to pull the prop to replace this belt. Many Piper owners have a spare belt safety-wired in place, but out of the way of any moving parts. It's a problem. The hoses will weigh about 8 or 9 pounds, more or less. Depends on how and where you run them. I figured to run them beneath the rear seat and blow cool air in the heat duct. For reasons I won't get into here, that area is possibly going to be empty in my aircraft. If you use the standard gear, yours won't be so you have to do something else. You will need, most likely, a freon charge of about 4 pounds. You will have to penetrate the firewall in two places, unless you can figure a way to run them in an existing hole. I couldn't. The hoses will measure about a little over 1" in diameter for the low side, and 3/4" for the high side. You're up to a minimum of 29 pounds so far, and you still need to add an evaporator (5#), expansion valve (1#), receiver-drier (3#), blower (5#), condenser(8#), electric fan for the condenser (5#) if you plan ground operations, and controls (2#). You might be able to do better on some of these weights, but I bet you do worse on others so the total will still be pretty close. The total weight comes to a minimum of 58 pounds for a well done installation. At cruise speeds, you can expect it to suck up only about 3 or 4 horsepower. The new compressors are much more efficient than the old ones. I'd have a manual off switch, as well as a momentary on the throttle quadrant that opened the compressor clutch circuit any time full throttle was selected. You need a pretty substantial blower. Cold air does not move as well as hot air. Piper got away without a condenser blower because the evaporator was in the propeller slipstream. You're not going to have that luxury, so if you want ground ops you need a blower. Here's how it came out for me: PROS--- Cool Air Comfort Blower for Hot and Cold Air CONS--- Extra Weight of at least 58#, probably more. 15 or more pounds of that weight where you want it the least. Higher Maintenance. Unless you're ASE certified (I am) you can't service it yourself More penetrations through the firewall Double the risk of belt breakage and passing through the prop Complications in ducting and air movement both in the cockpit AND somewhere outside the cockpit for the condenser air. Increased Electrical load from the blower and compressor clutch. (I figured that to be about 15 amps for the blower, 15 for the condenser fan, and 10 for the compressor. This is NOT a minor issue.) Potentially bigger alternator required to support electrical draw. There are ways to minimize the impact of all these things, but not eliminate them. It looked to me like it could very easily take an extra month or more of steady work to get a reliable system running, and I've installed custom air units on several pieces of equipment, starting from scratch, before. If you haven't, it will take you longer. Can it be done? Sure. Is it worth it? Not to me, and I fly in Kansas where 100+ days are common from June through August, 90+ from May well into September. I can taxi with the canopy open, don't forget the propwash is behind me so it's not as uncomfortable as having the prop blow in front. And once I'm off the ground, I don't intend to stay low very long. FWIW, I trained in a Warrior with Piper A/C. It really worked well. When we did pattern work, it DID make it more comfortable and a LOT more comfortable if you have long waits for take-off clearance, but there was an added landing and takeoff checklist item "A/C-OFF" that we did. But that really just cycled the A/C more than anything else. You might look around on the ramps in your area. There are very few of the Pipers that kept the factory air. Most owners removed them to get back the 70# in useful load when they found they really didn't use them as much as they thought. If you are still seriously thinking about this after digesting the above information, contact me and I can help you with some resources and go into more details of all the things that I'd worked through before I decided against it. I wouldn't do it, but then again I'm not building your airplane and I'm sure you wouldn't do some of the things I've got drawn out for mine. 8-) John Stricker jstricke@russellks.net "I didn't spend all these years getting to the top of the food chain just to be a vegetarian" ----- Original Message ----- From: "John Slade" To: "Cozy builders" Sent: Monday, December 06, 1999 9:51 PM Subject: COZY: Air conditioning > Builders, > I've searched the archives on the issue of A/C and found one request for > information and one "put down" in '97. I'd like to pick this back up again. > Lack of A/C in Florida can be a real pain when taxiing or "toodling around" > at under 3000 feet. I'd even say it can be dangerous - I've had situations > in spam cans when I could hardly see for sweat dripping into my eyes. > > Anyway, Some Mooneys have A/C and many Mooneys use Lycoming 180 HP engines. > I presume the compressor is driven by a belt. Any other suggestions for how > it could be done? > > To save the onslaught, here are the reasons not to do it: > > 1. All you have to do is climb to cooler air. Sorry. Doesn't work for > taxiing, low level cruise or approach. > 2. It adds too much weight. I'll go on a diet. Anyone know how much weight > is involved? > 3. It costs too much power. How much? I'll turn it off for take off. I don't > care if it costs me 10kt and a gallon / hr on cruise. > > Does anyone have anything to contribute to my quest for an air conditioned > Cozy? > > Regards, > John Slade, Cozy MKIV #757, progress: http://kgarden.com/cozy > West Palm Beach, FL > Date: Tue, 07 Dec 1999 10:46:35 -0500 From: Neil Clayton Subject: Re: COZY: Air conditioning For me it would be a safety issue on the "not to do it" side; When I lived in South Africa, the local club bought a new Piper 180 with A/C. The visor had a warning in big letters plastered on it "A/C not for use during take-off or landing" (Someone had also added "regard thine airspeed, lest the Earth arise and smite thee"). I flew it several times and always used the A/C in cruise. Very nice! Everyone remembered about the take-off bit, but one day a student and his instructor were making an approach with it on. The student got too low about a mile from the threshold. It's thought they piled on the power but not soon enough (Jo'berg is 6600' above sea level and density altitude is always an issue). I saw the wreckage after it was dug out of the ravine where they both died. Florida is at sea level but one day I'll be flying into Denver... Neil C From: "david vollrath" Subject: Re: COZY: Air conditioning Date: Tue, 07 Dec 1999 08:15:35 PST > >Does anyone have anything to contribute to my quest for an air conditioned >Cozy? The first step to a cooler envirerment should be to keep more heat out. Our Cozys are very efficient heat colecters, and this is quit handy is winter, but a great hardship in the summer. A sunshield is the area above your head and aroud your shoulders helps greaty, and block off the rear windowes with stick on removable sunshields. I have never flown in a cozy with tinted bubble conopy, but often wish that I had one when flying into the afternoon sun. Perhaps others can "shed light" on this subject. Till then, carry a glass of ice to chew on, or fly high and cool. David Vollrath Cozy III N22AZ ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com From: "JStricker" Subject: Re: COZY: Re: Air conditioning Date: Tue, 7 Dec 1999 12:15:11 -0600 David, Actually, I'm quite sure that a system COULD work well on the ground. The systems I've built are commonly used on farm equipment with groundspeeds of 6 or 7 mph, many with the condenser completely self-contained and away from the engine cooling airflow. And they will keep a cab bathed in 220 degree engine heat with more glass than a Cozy cockpit cool on a 110 degree day. It's all a matter of sizing the components and providing sufficient airflow through both the evaporator AND the condenser. And I have a good idea which components would work, from a functionality standpoint, and which ones wouldn't. That said, I'm still not convinced that the brief time cooling is required is offset by the many problems and hit one would take on useful load. But that's my opinion. John Stricker jstricke@russellks.net "I didn't spend all these years getting to the top of the food chain just to be a vegetarian" ----- Original Message ----- From: "David Domeier" Cc: Sent: Tuesday, December 07, 1999 8:02 AM Subject: Re: COZY: Re: Air conditioning > > John Stricker gave many reasons why he decided not to pursue air > conditioning in the Cozy. I'll give one more - it probably won't work > on the ground anyhow. In-flight with lots of air flow it might be OK. > > I've been on very expensive machines with very sophisticated > environmental control systems and on hot days, they don't cool much on > the ground either. About the only thing that really works is a big pipe > bringing cold air from a ground support machine. > > I've flown around St. Louis on days over 100°F and it is no fun, but > doable with the canopy open until take off. I have very large eye ball > vents which take much panel space which I do not like, but they provide > enough air to blow charts to the back seat. Once in the air, the > airplane is reasonably comfortable. > > John Slade, I think you're going to have move north or bight the > bullet and sweat. > > dd From: Epplin John A Subject: RE: COZY: Re: Air conditioning Date: Tue, 7 Dec 1999 13:47:33 -0600 Just a crazy thought. Turbine powered A/C usually use an air cycle machine for heating and air-conditioning. Does anyone know of some sort of compressor that could be driven from our Lycoming etc engines that would power a shrunk down system that could be used on light aircraft? Would have to be high volume at a moderate pressure to be effective. The old Gulfstream I used a roots blower on one engine. Worked sort of OK but the APU was much more effective. Just another hair brained idea. John Epplin Mk4 #467 From: "Doug Shepherd" Subject: COZY: air conditioning Date: Tue, 7 Dec 1999 20:44:10 -0800 One more note: A far-out possibility I considered was using Peltier devices, but the numbers don't work out. You'd have to run huge amounts of current to get any cooling at all. Besides, you'd have to have one heat sink inside the fuse to provide the cooling, and one outside in the airstreem to dump the excess heat. (You can read about Peltier devices on http://www.tellurex.com/resource/txfaq.htm) From: "JStricker" Subject: Re: COZY: Re: Air conditioning Date: Tue, 7 Dec 1999 22:46:33 -0600 Bulent, You may be right about the Velocity builder. But before you jump to any conclusions, it may be that it wasn't working very well, or that he wasn't proud of the installation. I know when I've done some things that were on the different side, if it didn't work out too well I preferred to keep them to myself unless I saw someone else heading down the same path. BTW, if you're really serious about giving up the back seat, I KNOW I could get an A/C in there, with a flat floor over the top of it for a baggage compartment. It was one of the things I considered at one point, but decided I didn't want to give up the seating. John Stricker jstricke@russellks.net "I didn't spend all these years getting to the top of the food chain just to be a vegetarian" ----- Original Message ----- From: "Bulent Aliev" Cc: "Cozy Builders" Sent: Tuesday, December 07, 1999 8:43 PM Subject: Re: COZY: Re: Air conditioning > > > Capps Family wrote: > > > They marine industry makes small, light weight, portable air conditioners > > for small boats, could one of these be retrofitted in the strake and serve > > the same purpose. This unit would be electric, so as long as your engine > > was running, you would have cool air. AND, since it takes hot air to make > > cool air, you might have your heat source as-well. > > I have installed few of the units in boats. They are 110V and water cooled. > That's what makes them so compact. They are totally unacceptable for airplane. > Don't get me wrong. I'm one of the pilots that is willing to give up the two > back seats for the benefit of A/C here in S. FL. > IMHO the auto conversions are easier to install A/C. I have it on my wish list. > Few months ago on one of my cross country flights to Immokalee in FL, I > stumbled on one Velocity with Franklin engine and full Air conditioning system > . The owner was still ground testing the plane and was very uncooperative when > asked about details on his air conditioning. I assume he is one of the people > that wants to make money one day from his "invention" ? Hate b--t holes like > that. > Bulent > Date: Tue, 07 Dec 1999 23:07:23 -0600 From: "Joseph H. Hart IV" Subject: COZY: Re: Air conditioning OK, I'm the one that brought this topic up a year or two ago and I was completely shot down. Thanks Carl! : ) I haven't been able to work on my plane for quite some time but am about to get back to it so I've been silent for the past nine months or so. Anyway, I'm glad to see this topic brought back up. What I've noticed this time around that differs from when I originally made my inquiries is that there have been representations by some in the past few days that they had a good idea of what specific components would be required. IMHO, it would be productive to start discussing this issue in technical, rather than general, terms. In other words, does anyone have the expertise to calculate the thermal properties of the fuselage, canaopy, etc. and figure out how to maximize the benefit and minimize the weight of an A/C system for a Cozy? It seems that we might be able to kill two birds with one stone here; insulate the plane to maximize its insulating properties and minimize its cooling/heating capacity requirements while simultaneously minimizing noise and vibration. Any HVAC engineers out there? Jody Hart New Orleans, LA http://members.home.com/jodyhart/index.html Date: Tue, 7 Dec 1999 21:08:32 -0800 (PST) From: "Ray D. Congdon" Subject: Re: COZY: air conditioning Even farther out is the possible use of a "Vortex Technology" heating/cooling system. Several years(1980-3) ago I worked in the marine services industry. Workers involved in sandblasting the paint off of the decks and bulkheads of ships wore a full suit of very heavy material. Attached to the back of the suit was a small unit fed with compressed air that put out cold (REALLY COLD!) air from one port and Hot air from a second. I don't recall many details, but the cold air was routed into the suit to provide A/C for the worker. It worked very well. I've been out of that trade since then, don't know if it is still in use. my 6 bits... ===== Ray D. Congdon N7HQK ISA-USA Inc. 5529 N 4400 W Cedar City, UT 84720 rayc@inxsnet.com __________________________________________________ Do You Yahoo!? Thousands of Stores. Millions of Products. All in one place. Yahoo! Shopping: http://shopping.yahoo.com From: "JStricker" Subject: COZY: Re: Re: Air conditioning Date: Wed, 8 Dec 1999 00:23:11 -0600 Jody, I don't think that a HVAC engineer is really required. You can make some pretty educated guesses by looking at what works now in existing vehicles. The big problem isn't insulation, the foam/glass aircraft are pretty well insulated as compared to cars and farm equipment. The real problem is radiation heating through the canopy and that's not unlike farm and industrial equipment cabs that are in excess of 80% glass. Other than the few obstacles I've already mentioned (grin) there is another problem that I never could get resolved to my satisfaction. That being the problem of airflow. In order to get the evaporator to do a good job of cooling, you need to move some significant air. If you don't, you have problems with the evaporator first freezing up externally, and then not doing a good job of thermal transfer internally. So we need to move quite a bit of air to do a good and efficient job. No problem, you might think, just put a bigger blower on it. But it's not that simple. First off, the bigger blower draws more amps. Most A/C alternators aren't sized for this kind of load. Particularly when you consider that when you'd REALLY want it would be on the ramp and taxiway with the engine mostly idling around. Also, Electric motors are heavy. I'm just as willing to trade weight for comfort as the next guy, but for my use I don't intend to be down that low for that long a period of time. The cost/weight/benefit ratio just doesn't come out that well for my tastes. You don't want real high air pressure in your ducts that deliver the air. In fact, ideally you want low pressure and high volume. This keeps the noise level low and the comfort high. It's very uncomfortable to have a "blast" of cold air hitting you in one spot. You also have very different requirements on WHERE the air is delivered. In the "cool" mode, you want the air delivered as high as possible, the canopy ceiling if you can figure out how. This will cause it to mix with the hot air that is up there and also keep the areas that are most sensitive to heat, namely your head, cooler. If your head and face stay cool, you stay comfortable even if your feet are nearly cooking. OTOH, in the "heat" mode, it's just the opposite. Once your feet and hands get cold, the comfort factor drops quickly. Think about it. On a cold winter day, you can go outside and as long as your feet and hands stay warm, you can stand a LOT of cold. So we need ducts low for heat. This means that we have to have two separate sets of ducts, ideally. While you could get away with ducts in the panel for the A/C if you keep them near the top, compare the size of the standard eyeball vent to those in your car. The reason they are so big is that there needs to be a lot of area to move the air through since it takes MORE air and COLD air doesn't move as easily as hot air does. If you can integrate this behind the panel of the Cozy, then I'd love to see your drawings because I could never get it done. Now we move outside. The smallest condenser you can get away with will be about 12 inches square and 3 inches deep, without the fan figured in. I can find a condenser like this, in fact I use 5 of them on the farm on equipment. But their not automotive and you won't find them in any automotive catalog. They also list for about $400. You can find them used and the going price for anything used off farm/industrial equipment is 1/2 list, so that's about $200. You need to find a place to put it. A Piper Navajo has the condenser in the nacelle, with a little scoop that pops up when the compressor kicks on. You'd have to have something like that, independent of your engine cooling airflow since that's marginal in the Cozy anyway (reference all the questions and problems on cooling). You'll also need a fan to push or pull air through it when using it on ground operations. The condenser I'm referring to has the fan, as well as the receiver dryer, all in a rectangular unit about 12X12X7 or so. You're not going to find anything much smaller than that. Of course, you'll have to figure out the ducting and such, and a way to block it off for no drag penalty when the unit isn't operating. None of this stuff is impossible, if you're willing to take a lot of time, about $600 (minimum) to $1000, and live with the loss in useful load. If that's acceptable to you, and you've got some creative ductwork ideas, then I wish you the best of luck. But after many hours of thinking about it myself (it wouldn't cost me anywhere near that, as I have nearly all the components on the shelf as spares) I decided it wasn't worth it to me. John Stricker jstricke@russellks.net "I didn't spend all these years getting to the top of the food chain just to be a vegetarian" From: "Doug Shepherd" Subject: COZY: air conditioning Date: Tue, 7 Dec 1999 23:40:09 -0800 Looking at the Peltier device specs again, now I'm wondering if they could be made to work reasonably well. If I run a 28 volt electrical system, I could drive a pair of the 16 volt devices wired in series; in cooling mode they would draw about seven amps and could move 100 watts or so of heat energy outside the plane. With an 80-amp alternator, I should be able to drive eight of the series pairs with some current left over for other loads. That would give me 800 watts worth of cooling -- not a lot, but it might be adequate if directed at the head/chest area. For heating, I'd get the 800 watts plus the 1500 watts worth of electrical power (eight pairs drawing seven amps each is 56 amps total; times 28 volts gives 1568 watts), or about 2300 watts, which I bet would heat the cabin pretty quickly. The cost: sixteen total Peltier devices, representing around $400, a blower of some sort, and higher-current electrical components, wiring, and alternator. The weight penalty: a heavier alternator, extra copper in the larger-gauge wiring, and the devices, blower and heat sinks. I would think no more than $1000 and 20 pounds, if that. Reliability would be outstanding -- the blower is the only moving part. The external heat sink is the sticky spot. At speed, a flat plate of aluminum would probably be adequate, but some serious fins would be necessary to prevent overheating when sitting still. Any thoughts? Comments? Doug Shepherd From: CCady@aol.com Date: Wed, 8 Dec 1999 05:45:30 EST Subject: COZY: Re: Air conditioning Living in FL I have thought of air conditioning in the summer! It is miserable. I have used a small portable water mister that helps some. In looking around I noticed the units that RV's put on their roofs. They are 115v but seem pretty small and compact. I'd hate to have one sticking out of the top. I wonder if you could mount one inverted on the belly? >>It seems that we might be able to kill two birds with one stone here; insulate the plane to maximize its insulating properties and minimize its cooling/heating capacity requirements while simultaneously minimizing noise and vibration. Any HVAC engineers out there? Jody Hart<< From: "Nat Puffer" Subject: COZY: air conditioning. Date: Wed, 8 Dec 1999 11:56:12 -0600 Cozy Builders, I have noticed that most of the discussion on air conditioning (and sometimes other subjects) is amongst builders who are not yet flying their airplanes. We have probably 1500 to 2,000 hours in 3 Cozys and our Varieze (I am not bragging, just trying to show that I am qualified to have an opinion) in the past 21 years, we live in an area where the ambient can hit 120 deg F in the hottest part of the day, and have been all over the country in our airplanes in the summer time, and yes, it can be hot on the ground. When it is hot, we are grateful we have an airplane. We plan our departures for fairly early in the morning, taxi with the canopy open, and we climb at 1000 fpm to 2000 fpm up to 8,000 to 14,000 ft where the temperature is usually quite chilly. When we come down to refuel in the middle of the day, like Montana, Kansas, New Mexico, Texas, Mississippi, or you name it, we open the canopy after landing, and after refueling, it only takes a few minutes to get up to where it is cool again. I haven't heard of anyone actually flying a Cozy who has suggested needing airconditioning, not that it isn't an interesting subject. Regards, Nat From: "John Slade" Subject: Re: COZY: air conditioning. Date: Wed, 8 Dec 1999 20:12:16 -0500 Nat Said: >the ambient can hit 120 deg F in the hottest part of the day Yea, but your humidity is low. Down here in S. Florida its not so much the heat but the humidity which is the problem. >anyone actually flying a Cozy who has suggested needing airconditioning, Maybe I'm hot blooded! What about Dave Higgins? He's down in Ft. Lauderdale. Anyone know his opinion? Nat, Are you saying that a Cozy at low level (e.g. pattern work) is typically going to be cooler than a spam can? Perhaps so with all the foam for insulation. >discussion on air conditioning ... >amongst builders who are not yet flying their airplanes. It makes sense to hold off on adding extra weight and complexity until after testing out all the other systems. I expect I'll do my 40 hours before adding the A/C. With a bit of luck, that will be in about 6 months - right in the middle of next summer. Based on that experience, I'll consider adding an A/C system. In the meantime, I'm still very interested in any ideas people may have for / installations of A/C. What about something you "charge" in advance and carry on board, thereby supplying the energy from an outside source - e.g. some kind of compressed air arrangement or something. Regards, John Slade, Cozy MKIV #757, progress: http://kgarden.com/cozy West Palm Beach, FL Date: Thu, 09 Dec 1999 16:45:51 -0800 From: "J. D. Newman" Subject: COZY: Re: air conditioning. Hi Wayne, > > John Slade wrote: > > It makes sense to hold off on adding extra weight and complexity until after > > testing out all the other systems. I expect I'll do my 40 hours before > > adding the A/C. > Wayne Hicks wrote: > ----------> If I remember correctly from the rules and regs (and the > excellent articles written by Ron Alexander), if you do anything to your > aircraft affecting weight and balance as a result of major modifications > or systems, the FAA may require you to enter into a new test period to > flight test the new system. Can anyone more knowledgable comment on > this too? True. If your Phase 1 is completed and your plane has been signed off for Phase 2, you will need to go back into the Phase 1 test area to check out your major mod (which wouldn't be that much trouble). The thing to do while you are still in Phase 1 is after you fly about 25+ hours, then add the AC, test that for the next 15 hours (or how ever long it takes) while you are still in Phase 1, then when you're satisfied with the AC tests (and the overall aircraft), apply for your Phase 2. HTH. Infinity's Forever ( http://www.flash.net/~infaero ), JD Date: Thu, 09 Dec 1999 19:30:53 -0800 From: Steve Hagan Subject: Re: COZY: air conditioning I've seen some venturi cold air systems designed to blow a jet of cold air past the work piece in certain types of machining. No moving parts, just a flexible, aim able tube. Perhaps at pattern speeds this system and a scoop would be effective enough (and keep the canopy open on the ground)? Steve Hagan From: cdenk@ix.netcom.com Date: Thu, 9 Dec 1999 21:27:00 -0500 (EST) Subject: Re: COZY: air conditioning. Re: airconditioning - I concur with Nat's observations, we fly early in the day, and with the excellent rate of climb and comfort at altitude, we actually have used cabin heat at 12 or 15 thousand feet when it was hot on the surface. We have already stayed on the ground due to density altitude with 6600 feet runway available. If you feel air conditioning mandatory, then you are building the wrong aircraft!! Its more important to pay attention to cabin heat, defrosters, and good fresh air to the right locations, all leave to be desired when built per the plans. From: cdenk@ix.netcom.com Date: Thu, 9 Dec 1999 21:37:20 -0500 (EST) Subject: Re: COZY: Re: air conditioning. was said Don't think that works, the paragraph from day one is there, and to be followed. As I read it, it requires a new airworthiness certificate. THere is no wording that says not required. The inspector does have some discretion as to what may be required, depending on how major (read as likelyhood of failure within how many hours) the alteration is. Date: Fri, 10 Dec 1999 08:16:04 -0600 From: Michael Pollock Subject: RE: COZY: air conditioning. Bulent wrote: >Nat, you should spend one summer here in S. FL and than we will talk :) We have been flying our Velocity (without AC) for 2.5 years here in Dallas and the surrounding areas (including FL in the summer) and only have one large NACA inlet for cabin air. I have flown airplanes with and without AC and feel that it is not needed. It only adds weight and another failure mode of operation. Once airborne in the summer, it only takes 2000-3000 feet to get to a comfortable flying temperature. With the Velocity or Cozy, getting to that altitude is not a problem. I sincerely believe in the KIS principle because mean time to failure is dependent on the number of components in the system. Michael.Pollock@wcom.com Flying Velocity N173DT Building Cozy MKIV #643 Date: Fri, 10 Dec 1999 08:42:34 -0600 From: Michael Pollock Subject: RE: COZY: air conditioning. Wayne Hicks wrote: >if you do anything to your aircraft affecting weight and balance as a result of major >modifications or systems, the FAA may require you to enter into a new test period to >flight test the new system. I believe the regs state that if you do anything to the aircraft that affects established W&B "limits" or "maximum" gross weight, then the FAA will require a new test period. The reason I know this is that we painted our aircraft and installed interior after the 40 hour test period. However, the aircraft was tested to the max and min CG and max gross weight prior to the installation and those parameters did not change. My DAR, who used to be an American Airlines check pilot, agrees.