No4

Sorry Aaron, I got myself in way too deep there. That's the induced drag calculation, so at a guess W is weight, and maybe b is a lift coefficient. I got that from here: http://www.me.ttu.edu/faculty/oler/me4356/website/Notes/total%20drag.pdf and you might want to also look at this : http://www.desktopaero.com/appliedaero/appliedaero.html I'm just studying a Gas Turbine course at the moment, very interesting after our discussions on turbochargers. Made your mind up on the cozy yet? I'm going to get started in about 3 weeks. Hopefuly my group of slaves aka Dust style will include a 747 Flight Engineer, an aircraft mechanic, and at least 5 other student CPL pilots. DUST ; Cheers for the nod on the 337 pusher prop, I found a bored almost identical to this one for the Skymaster, but it's very quite, maybe we should send Marble over?

That's easy Marble, if the aircraft is in equilibrium the thrust must equal the drag. Really easy to find the drag just use this equation D=1/2pV2SCd+1/1/2pV2(W/b)2 1/pi e. Are you still planning on the twin ducted fan's? or have you worked out yet that propellors are far more efficient than a jet of air until they approach high Mach numbers. Kinetic Energy = 1/2mV2 (1/2)* 1kg air accelerated 10m/s(2) = 50 watts (1/2)* 10kg air accelerated 1m/s(2) = 5 watts Both have the same thrust of 10 kg.

I quite often fly a Piper Arrow with a 200hp IO-360. If you have the electric fuel pump on and full fuel flow for too long (5 seconds) at start up, it will flood and a big pool of avgas appears behind the nose wheel. If that was trapped in a hot cowling I'd be moving the other way reasonably fast. They can flood badly, you have to be very careful starting those motors, go easy on the pump and mix, and give it plenty of throttle. Also they vapour lock if you try to restart when they are hot. I'd also say to make sure the vent is nowhere near the exhaust pipe.

Ahh, the good old my engine is better than your engine argument. I used to sit in an auto day and night running 75% power for hours on end, that engine never missed a beat whether it was 140', blowing a hurricane, or I was scraping frost of the windshield. The only trouble is that particular Cummins produces 750 hp and the weight might be a bit much for the Cozy. I don't think some of the figures about gearbox power losses are quite right. If it is done right 5-15% max. If anyone's planning on using a Subaru, there's a company here www.sub4.co.nz , but I don't know about pushers. Back to the original thread, Are there any pusher constant speed propellor units about, electric or hydraulic?

Looks very speccy, I wonder if the plans are available?

Some of these moving map GPS systems you guys are building sound very speccy indeed. I'm not so flash with computers, so wouldn't dream of trying it myself. But if someone else cracks it, then I'd really like to know more. Over here in NZ, legally you can't use GPS approaches without an ADF or a VOR. As for my opinion for what it is worth, I think you would be nuts to go IFR without a VOR, twin ADF, and a DME. The thought of relying on a homebuilt GPS set up for IFR navigation gives me the jitters. Therefore I could use any old GPS and not worry wether it is certified or not. I plan to have an HSI ( Direction Indicator, VOR, ADF, and ILS in one dial), a twin fixed card ADF, a backup basic VOR, a DME, and then a hand held GPS. If I get lost with that lot I guess I shouldn't be flying and I'll take up knitting. Good Luck with your fancy moving maps!

Thanks for the info guys. The Infinity rig looks very speccy, almost exactly what my minds eye had conjured. What are they like as a company? Any reports on what the gear is like operationaly? Cheers

I don't think it was a great idea to post in all the topics, but in his defense, Marble was just playing follow my leader to someone who did likewise. As for the value of this site, I'd say it is enlightening, I would have been very nervous about building a Cozy without it. I have learn't a great deal here already , listened to people who have been there and done it,( and also spotted the people with no idea what there talking about). I expect this site will save me somewhere around $1000 or more, and probably 100 hours or more from listening to you guys, and learning from your tips. Keep up the good work trendsetters. By the way, I'm English, what does signal to noise ratio mean?

I'm quite keen on the idea of retractable under carriage. Is it possible on the Cozy? I see aerocad sell a retract, and velocity, can their systems be integrated to the Cozy? Cheers

My friend pulled up next to me in his old Bedford safari truck at a campsite in Namibia. "Coming for a beer I asked?" "I'll just fill up the running tank", he said. Came back at 1 am full as a boot to find all our kit sitting in 1000 litres of diesel.

Largeprime, The Volvo D5 is a new kid on the block, and apparently has Mercedes, BMW, and Volkswagen/Audi crying in their breakfast cereal. Standard it is 160 hp, but some jermans make an ecu upgrade for 190hp. It is based on the T5 petrol engine which makes 300hp out of the box. Not much is available about the motor, and everything I have read is just hearsay from websites. It weighs about 165 kg without extras. I'm a truckie from way back, and worked on Roadtrains in Australia, several operators had 600hp stock motors turning out 900hp +. With a diesel you don't worry about detonation, because it's always detonating, when it stops you have to worry. I'm reliably informed that the way to go is reduce the compression ratio severely, allowing a good increase in boost, big fat intercooler, ceramic coat the piston face, teflon coat the liners, put in the strongest rods, piston, and crank you can find. I'm hoping for maybe 250hp for take off, and then 170 hp cruise. I used your Ray Hall turbo chart, it comes out spot on for my Skyline, but fiddling with the temperature did nothing. Again I'd say that it seems turbo equipment seems to work on pressure ratios, so adding a bit of altitude ruins sea level calculations. Aaron A kit car v's a cozy eh? I thought the speed limit was 50 mph in the states, you don't need a turbo mazda for that, or are you good friends with the local constable? My Skyline has my license hanging by a thread, I'd much rather have 250 Knots ground speed showing on the gps. Again about wastegates it seems they may work on pressure ratios. Maybe the manual one is not so crazy, look at all those switches in a 747! If I said I was thinking about making mine a two seater mkIV, what would people say? I say this because I think the Volvo is relatively big and heavy, I don't want to squeeze the cooling, I want to fit a CSU propellor with reduction drive, a tricky twin turbo set up, an oxygen system, and even dare i say it a retractable undercarriage; and then head for the flight levels (250 KTAS at FL200 and 1500nm range ?). I fly a Piper Arrow 200 rg, and the extra 20 hp over a 180hp Archer, added to the CSU and retractable gear make it a far superior aircraft. With a fixed pitch prop you have only one speed when everything is working efficiently, and as drag is a function of true airspeed, then the extra weight of a retract should pay off. The oxygen is obviously a neccessity above 10 grand. Maybe I'm just lining myself up for headaches, but I quite fancy a plane that is regarded as "the dog's bollocks".

Cheers Aaron, It's amazing what you can learn from the internet. I always thought a wastegate was on the inlet side. What i described is obviously a manual wastegate I now realise. I've never seen one, just learn't about it in CPL Air Tech. Yes it can get quite chilly down here in The Land of the Long White Cloud. 26'F is an International Standard Atmosphere figure. In Winter, which is just around the corner for us, it goes below freezing every day, so at 10,000 feet it can be -22'F or less. The sea level air pressure also goes up to 31 inches, pretty good for the motors and wings. I read yesterday that a Reno Air Race Merlin was running 150 inches mercury manifold pressure, and was jetting water onto the intercooler and radiator, and mixing water and methanol into the fuel to stop it detonating. I think that must make about 4000 hp. I'll really have to make that trip. How's your Cozy going? and what motor are you intending on using? I havn't started yet, waiting for a visa and finishing my CPL first, then right into it. I'm planning on the Volvo turbo diesel, but they havn't arrived here yet, I'll probably wait for someone to wreck one in the UK. Don't know what sort of MAP it runs, but I'm guessing it won't use much up to 140hp, then about 15inches for 200hp.

Thanks for the garrett link Aaron, fantastic stuff. Pick a flow rate and you are away with a 2:1 compression ratio, 3 at the max. The only thing I will have to ask garrett is about the exhaust turbine. I think at 9000 feet and 25 inches MAP, the ratio would be about 4 to 1 and would have it screaming it's nuts off, and ruining the compressor performance. I'm guessing that a larger turbine would reduce the pressure difference. I wonder if this also affects waste gates and dump valves? In your example @ 10000 I think the temperature should be 26'F(ISA), giving extra density and lower exhaust temps. Someone was surprised about the bypass gate in the exhaust. If you are only using the turbo for altitude compensation you will be risking overboost, increasing the air temp, increasing the exhaust temp, creating back pressure on the exhaust, losing power for takeoff, and whistling and hissing away as you taxi down the ramp dumping all that boost. With the bypass, when you reach 3500 feet you flick a switch, and you have a turbo trimmed for those conditions, with reduced risks of over boost and over heating, not to mention improved lifetime. If you are using an engine that needs boost at sea level, you either wouldn't use this at all, or you could use two turbines in harmony. I guess two turbos in parallel would double the flow but not the pressure, whilst two turbos in series would double the pressure but the flow would remain the same.The Rolls Royce Merlin (Spitfire & Mustang)had a two stage altitude compensating supercharger giving 57inches MAP for take off , then still boosting at FL450! I wonder how a cozy would feel up there? pretty frightening I'd imagine.

Two types, air to air and water to air. air to air looks like a normal radiator but shiny alloy. Compressed air is ducted from turbine to inlet, cooled by passing airflow then it's off to the outlet and to the manifold. These can range from 6*4*1 for a tiddler to 40*24*4 for a monster. water to air uses a wet radiator cooled in the airflow with a pump sending the water to a cooling bath for the induction air. try this link. http://www.superchargersonline.com/intercoolers.asp What size you need depends on the boost, and therefore charge temperature rise, and outside air temp. Then you have to ask is it worth the extra ducting drag and weight.

Dust, you seem like a pretty cautious guy, and good on you. I'd have to say to be very cautious with this turbo business. With an incorrect set up you can grenade an engine in seconds. I think you really need to start thinking in manifold pressures, fuel flows, exhaust gas temperatures, rpm settings, density altitudes. I fly a Piper arrow with a 200hp IO 360 C1C Lycoming. It is considered overboosting the motor if the MAP goes above 26 inches, 29 being sea level. Your choice of motor would then only be able to accept boost above maybe 5000 feet, and then where do you want to cruise? 9500? The pressure gradients across the exhaust and induction turbines are much different up there. But at sea level you'll be dumping boost or needing a gate in the exhaust manifold to divert the exhaust gas from the turbo. If boost gets away on you and you can't match it with fuel flow, severe detonation occurs. To match the fuel flow you'll need bigger pumps and injectors or carburettor. Then that creates more torque (remember torque), more horsepower, and higher exhaust gas temperatures, more rebuilds. Turbo motors usually run lower compression ratios to allow more boost. I think a standard lycoming is 8.5-1 and a turbo 7.5 to 1. A smaller pipe means higher pressure but less flow, a fatter pipe low pressure and high flow. You'll need to calculate a balance in your plumbing. Temperature is also important. 1 degree centigrade is equivalent to 120 feet in density altitude calculations. I degree drop in induction temperature is one degree drop in exhaust gas temperature. 24 inches at 2400 rpm at 10 USGph = 150 horsepower? with 4 inches of boost (4000 feet density altitude) and an intercooler dropping the charge air to -5'C (2400 feet density altitude). You'll be ripping along at 9500 feet. Two car turbos glowing red and spinning at 120,000 rpm? I wouldn't try it. A big spinner off a Kenworth? That's probably more like it. But definitely talk to someone who knows all about it first. I think the trick with twin turbos is to have two different turbos that complement each other, say in series as oppossed to parallel. Good Luck

It is the sweetest engine I have ever come across. It is a straight six, 24 valve, 2500cc motor. The standard motor is non turbo (GTS) 200hp, mine has a single turbo (GTS-T) 300+ hp, and there is the twin turbo (GTR or Godzilla)) of about 400hp. Mine boosts to about 50 inches total manifold pressure. Drag cars get 1000hp+ out of it, pumping some horrific boost, but obviously that's a bit different. I've never been able to hold full boost for too long because the speed limiter cuts in at 200kmh, but at 4000rpm and 50 inches it just howls. Maybe I should fill it up with half the Rugby team and tow a trailer full of rocks up in the mountains and see what happens. I'm not sure of the weight but it looks heavy, definitely 400 lbs plus.

The specifications I saw for the D5 mentioned that it has water cooled exhaust gas recirculation, I wonder if this can be disconnected/removed? This may add around 5 hp and save some weight. A lot has been discussed about engine weight, horsepower, and torque. The D5 should be capable of 200 hp for take off, which I think will be enough. I think lower rev torque is important for cruising at lower rpm settings, especialy with a CSU, but horsepower is ultimately the important number. If you changed the standard turbo set up to one tuned for altitude compensation, and used a tricky intercooler, the charge air temp can be cooled to well below zero. 29 inches manifold pressure at -20'C gives a density altitude of minus 4200 ft or equivalent 4 inches of boost. This means the motor has lower rpm, lower pressures and lower temperatures throughout (but more torque). But of course you'll need oxygen, a CSU, and be happy cruising at FL180. This altitude also gives a 215 KTAS cruise at 160 KIAS. I've just received plans 1124, and am provisionaly going for the D5, and then if not the motor out of my Nissan Skyline, but I'd hate to lose her.

Diesels, due to the chemical nature of the fuel, will produce more power per gallon than a gasoline motor. As a general figure, an efficient diesel engine will use about 200 grammes per kilowatt, or about 0.33 lb per hp. A Piper Cherokee Archer (180hp) running at 75% (135hp) uses 37 litres per hour, or about 10 gallons. A diesel at an equivalent hp setting should use 28 litres per hour, or about 7.5 gallons. The Volvo D5 is regarded as the best diesel auto motor on the market, so it should meet those expectations. The same motor with a petrol head produces 300 hp out of the box. Heico Sportiv of Germany sell upgrade ECU chips which give 190 hp and 282 lb/ft @ 4000rpm. http://www.heicosportiv.de/images-produkte/bilder-produkte/p26-d5-190-ps.pdf

I was looking at the specs on the starship and the document i see says 318 kts at FL350, @1600rpm with an 8ft 8in diameter prop. So Burt must know something we don't (stating the obvious). Flutter, I didn't know anything about it until I read your post, so I'cant really find a solution just yet, maybe re inforcing the airframe? I don't know. Money, well i'd rather eat my feet than spend $30,000 on a Lycoming or Continental, and I'm really finding a plane for the motor rather than a motor for the plane. I'd rather spend the money on a prop with whistles, lights, and bells etc. Will it happen? well there's only one way for me to find out, and that's to have a go. I just ordered my first ever credit card to pay for the plans and materials. I see on your profile it say's Velocity, Long EZ, and Cozy. How would you compare the three? and do you know anything about the eracer? I'd be grateful for your opinion. Cheers.

Thanks for the advice Jim, Where I come from a flutter is to go and waste your pay cheque betting on the dogs or ponies. Bad vibes eh? I'll keep well away. I'm planning on using a CSU with a reduction gearbox of about 2:1 .The Volvo torque peaks at 1750 rpm, and horsepower peaks at 4000rpm. That would make the prop 1000 rpm for cruise and 2000 rpm for take off and landing, running a fat 3 or 4 blade prop. Am I right in thinking that if the plane is already going mach 0.5, and critical speed is m0.8, then the tip speed must not be more than mO.3 greater than aircraft speed? I think that makes the maximum blade disc diameter possible about 66 inches, but now I'm into blade angles etc and my head hurts terribly. But i do know that the starship made 335kts with 5 blades, so I guess it must be possible. Anyway I'll chat with a fundi who makes props and see what he says, but it's a while away yet before I need it.

I'm about to start building a cozy, and will leave the fancy exhaust leading edge to my MkII. I had an idea to mount the turbo's in the wingtip and have the top of the wing as an intercooler, but am too lazy to work out if the exhaust gases would be useless by the time they travel that far, and doubt if the compression could generate enough heat anyway on the way back. It would be fantasticaly complicated, so I guess I'll just stay away from ice. Would having a heated ledge have an effect like a hot knife in warm butter, and create extra low pressure and raise the local speed of sound, or would it just ruin everything? i might be able to tell you in ten years.

How much horsepower will it make? and is it going to be us$30,000 plus?

I think making the exhaust pipe the leading edge is the way to go, but it wouldn't be an easy operation, and wouldn't solve the canard problem. I think the Hercules uses this system, bleeding the final stage turbine compressor and routing it into the leading edge, although they lose the equivalent of one motor when it is turned on.

Two at once eh? How come? Are you going for the Continental aero diesel? What are the specs on it?

Flat out at FL350 would be 325 kts,running 13 gph, that would do me just fine. I was hoping for a 250 KIAS vne. If you're interested here's a link to the Volvo D5 motor. http://www.volvocars.co.uk/d5/tech_specification.asp clicking on the bold in the beige box zooms in on each part seems to work once then dies. How is your cozy coming along? Hard work?