Date: Wed, 02 Apr 1997 15:27:05 -0800 From: berkut@loop.com Subject: Re: COZY: Cabin Heat (fwd) "Marc J. Zeitlin" wrote >If I remember correctly from their literature, this is a 600W device. >Maybe I'm wrong, and it puts out as much heat as a big honking hair dryer >(1500W). Either way, at 12 - 14 volts, you'll be sucking down anywhere >from 43 to 125 Amps. Good luck running anything else off of your >alternator, or keeping your battery alive for any length of time. I also >remember reading reviews in the CSA regarding electric heater of this >size, and people stating that they couldn't even tell that they were on, >even in a L.E. > I'm working on a heating system right now - no details till I prove that it works or that it doesn't. The thing I really need is a 12 volt blower that moves some real air (I've tried all the muffin fans, none are nearly powerful enough) but isn't as big as a basketball. The local surplus stores have plenty at 28 v/dc and 110 v/ac, buy none at 12. Any ideas? -- Czech Sikhs! Richard Riley "Heavier than air flying machines are impossible." Lord Kelvin, President, Royal Society, c 1895 See the Berkut at http://www.berkut.com Date: Thu, 3 Apr 1997 03:30:05 -0500 From: Bill Theeringer Subject: COZY: Electric Cabin Heat Greetings to the group. I have been a silent absorber of knowledge here for several months enjoying the open discussions of opinions and facts being bandied about. There is a tremendous amount of collective knowledge on almost every subject available here and my mind is a constant sponge. (Full of holes :)) I am a retired E.E. and fly a Long that took me 8 and 1/2 years of full time labor to build. I had only been a pilot 2 years when I started building it. It won awards at Sun-N-Fun, Watsonville etc. so I stopped showing it and started flying it, averaging about 300 hours a year. (Fulfilling a promise I made to myself when I was 11.) Its color is yellow and it can be seen on JD's web page. My reason for coming out of my hole is to correct some mis information that some of the members may have on a product that I designed for use in my airplane and subsequently made available to others at their request. BACKGROUND: My first cross country in really cold conditions. Hastings, Nebraska. October. Feet so cold that they were numb. Are there brakes or not? Can't tell. No feeling at all. I got it stopped but I can't stand up. The nice man at the FBO got me warmed up and delivered me to an un named motel. I tried hot water on the feet then used my portable hair dryer. Hey, this thing works! Hmmmmm. No, the extension cord would be too long. LATER: Back home in Santa Barbara. K-Mart. I bought a half dozen various hair dryers and tore them apart to see how feasible that idea was. I think they call that a feasibility study. I found one that looked promising and tried various ideas over the following months. The only thing usable was the motor and frame. I used heavier nichrome wire from some 1800 watt 120 volt cooking units and built a prototype which looks like hell but is still in the Long working just fine. It draws 35 Amps at 13.8 volts which is 483 watts. Several life tests on other units showed at least 1000 hours before the fan bearings cried out for oil. Incidently, that 1600 watt hair dryer you have was dubbed 1600 watts by the marketing department. Engineering designed it as a 1200 watt dryer. The low position is 400 watts, high is 1200 watts. Engineers and marketing people don't use the same math. MUCH LATER: I have a list of about 6 people that would like to have me make them a heater when I get around to it. i.e., land the plane. It is subsequently entirely re-designed with dual overtemperature sensors, automatic over temperature shut down circuitry, 40 Amp self reset circuit breaker, solid state controller, panel mount temperature select switch, reg/green bi-color status lamp, removable dust filter and draws 33 amps at 13.8 volts. (450 watts.) A 28 volt model is also built that allows the fan to run slightly faster and comes in at 600 watts. I have never built any other voltages or currents (powers) for aircraft other than these two. Friends suggested that I go into business manufacturing and selling them. I did. SUMMARY: All of my literature starts out by saying that "electric cabin heat is not the only way and may not be the best way to heat an aircraft cabin." The formula for the amount of heat removed from a heat source is Q=MC delta T, or energy removed is the product of the change of the sources temperature times its mass (roughly). C being a constant of 1 for water. It becomes obvious that a red hot exhaust has 13 zillion times more energy than the 200 degree oil, which itself has gobs more energy than the puny electric heater. The advantage to electric heat is it is cheaper and lighter (than oil, in the EZ's), and works very well in a suitably insulated (foam / fiberglass!) aircraft that is well sealed. I have sold more than 600 heaters since 1991. My policy is if you don't like it I will refund your purchase price, no questions asked. 3 have been returned. I did ask. A kitfox in North Platte Nebraska, (no way!) an over extended visa card from Florida, (no problem) and a dead unit 2 years old. Way out of warranty. I fixed it no charge. It belonged to Tim Merrill and was in his 1996 Oshkosh Grand Champion Cozy MK IV. He said it worked perfectly in his plane. I have a file full of unsolicited letters praising the heater. All of these people have volunteered their names to be used in support of the heater. I have NEVER used them. I have one complaining. (The Kitfox). I have never had any negative feedback from any source. If I did I would cease making them. The waiting time for delivery right now is 6 weeks. I have pulled my advertising from Kitplanes and Sport Aviation because I cannot keep up with orders. Aircraft Spruce will continue to handle them. (They have the wrong photo in the catalog). Please do not buy one! I will send an infopack which has color photos free to any members of this forum though, unless Marc says it is solicitation which is verboten here. See JD's last comments for my address. I'm outa breath. Bill Theeringer N29EZ Composite Aircraft Accessories EAA Chapter 527 past president EAA Chapter 527 newsletter editor EAA Chapter 527 Tech Councillor, glass Ham operator & electronic tinkerer 44 years Date: Fri, 4 Apr 1997 00:47:22 -0500 From: INFINITY Aerospace Subject: Re: COZY: Cabin Heat Hi Dick and All, >Is fogging an issue on the canopy. I had never given the matter much thought before but could see difficulties in landing if the canopy is opaque.< On start up, taxing out and take-off until everything gets warmed up, may be a concern also. Any of you guys flying have any experience and ideas? I have adjustable canopy defog tubes with holes around the perimeter of the canopy using a squirrel cage fan to push the warm air through the tubes and holes. This is similar to how it is done in the T-2C, TA-4J, F-14A and F-4J/N/S, so I'll let you know how it works for me. Infinity's Forever, JD Date: Sat, 5 Apr 1997 01:05:04 -0500 From: INFINITY Aerospace Subject: COZY: Canopy Defog and Anti-ice Hi Dick and All, >I saw an anti-fog chemical from the same folks who make Rain-X. I didn't buy it but the idea was that you would apply it to your car windshield and it would prevent fogging. I wonder if this would work on a canopy.< The Rain-X works pretty good on the car glass windows. I too wanted to try it on a canopy, but first I wanted to test it on plexiglass, lexan and acrylic to make sure it didn't craze or somehow destroy the canopy and / or the landing light covers over time. Has anyone already tried this? I've also heard of a chemical that one can put on the leading edges of our pride and joys that helps prevent ice from forming. Anyone heard of this or tried it? Infinity's Forever, JD From: SMilesCozy Date: Sun, 7 Dec 1997 16:32:51 EST Subject: COZY: Heater? Organization: AOL (http://www.aol.com) Dear group, After reading my post I thought of some things that may need clarifying in order to use the data provided. In a message dated 97-12-05 23:32:01 EST, I wrote: > I estimate that at zero degrees F outside, it will take aprox. > 8500 btuh to maintain 72 degrees in the cabin, 4500 btuh to maintain 50 > degrees, 2500 btuh to maintain 32 degrees, 1200 btuh to maintain 15 > degrees. Four people seated doing light work generate 400 btuh ea. = > 1600 btuh, solo 400 btuh, the way I see it I need to get 2900 - 4100 > btuh from somewhere to maintain a cool but acceptable 50 degrees in the > cabin. This also only figures 10 cfm of infiltration air. (minimum > recomended for breathing) I doubt I will be able to limit it to only 10 > cfm. These figures are only valid if you reheat and recirculate the existing air with ONLY ten cfm of zero degree f outside "infiltration" air to heat. It would require some sort of blower or fan to move the air. To provide the air movement necessary to heat the area of a cabin, in a reasonable time frame, an automotive type blower, with the weight, may be necessary. > It would seem to me that capturing waste heat from the > engine is a more practicle way to get the kind of btuh's required. > Using exhaust or oil cooler is a personal preference, (does anyone know > how many btuh's can be expected from an oil cooler?) I'm leaning > towards exhaust because of the ready availability of lots of btu's, and > the ease of ducting air through the cabin. (I would definately get a > quality CO detector) The hardest part of this is guaranteeing a pressure > differential of about ½ " wc to get adequate flow through the cabin, > high pressure air coming into the plenum from naca inlet is easy, > exhaust into low pressure might be trickier, maybe out the top of > turtledeck or over the top of the strakes. This type system would have 100% infiltration, since it uses the ram pressure, at ambient (zero degrees f), as the motive force. A two inch by four inch duct at 1/2" wc pressure difference will allow approximately forty cfm of zero degree air into the aircraft. This will require an additional 2200 btuh to heat the zero degree air to fifty degrees for cool but comfortable. 40(cfm) X 50(temp. dif. in deg. f.) X factor of 1.1 = 2200 btuh. Add this to the 4100 btuh already required to maintain fifty degrees in the cabin and you get 6300 btuh minimum to maintain fifty. Someone had mentioned getting a fifty degree temp rise across an oil cooler. If you get fifty degrees rise, at zero f outside, you will only be generating 2200 btuh (depending upon static pressure and duct size), and still be 4100 btuh short of maintaining fifty in the cabin using outside air (Cozy MkIV only, EZ would be slighlty less, but not much), and 1900 btuh shy of maintaining fifty recirculating cabin air via a blower moving forty cfm. At fifty degrees rise, a blower that recirculates 75 cfm MAY be adequate. 75 (cfm) X 50 (temp rise deg f) X 1.1 = 4125 btuh. Since I'm considering using outside air and the exhaust muff approach, I guess the question is "what will be required to maintain fifty in the cabin?" At forty cfm, 143 degree temp rise will maintain fifty in the cabin. 6300 btuh / 1.1 / 40 (cfm) = 143.18 (degrees f temp rise). If we increase the duct to four inches by four inches (or use two 2X4 ducts), doubling cfm to 80, we need 97 degrees of rise to maintain fifty in the cabin. 8500 btuh (2200 extra because of the extra 40 cfm) / 1.1 / 80 (cfm) = 96.59. Hope this helps, sorry for the length, and as always YMMV. Happy Holidays, Steve Miles Cozy MkIV 272 From: cdenk@ix.netcom.com Date: Sun, 7 Dec 1997 17:28:13 -0600 (CST) Subject: Re: COZY: Heater? Steve Miles writes I get 12 degree F temp rise across oil cooler oil temp. The main problem is not being able to get air volume from the heat muff to the cabin for several reasons: 1. The air cannot get into the cabin unless air get out. Ask anyone who drove a VW bug in the winter, it was necessary to crack a window open to get the heat in. I have reverse gill vents at the firewall to allow air out. 2. The small aeroduct with its rough inside surfaces don't help with all the attendant friction losses. I use 2" aluminum tubing on both sides which have much less frictiopn losses. 3: On the ground and in climb additional force is required to move air forward. I use a globe motor tubeaxial fan. It moves 50 cfm if I remember right, at considerable pressure. This early afternoon Wife and I flew in from PDK (Atlanta) to 22G (Cleveland Ohio). Temperatures at both ends 35F. We flew at 9000, temp 19F IFR. I was in my shirt sleeves the whole way with the heat at less than maximum most of the way. Picked up 1/8" ice on decent on leading edges. It is only on very short flights that I wear a jacket any time of the year.