Peter congratulations on your progress so far. I am amazed by the width of your skillset and your tenacity. I am a pilot who operates a turbocharged 350 HP Continental with a four blade prop in a pressurized aircraft. I'd like to share some thoughts and hope they will help you. I have installed temperature probes in the engine compartment and made a number of observations. The most striking one is the following: compressor discharge temperature or CDT (i.e. the temperature of compressed air AFTER the turbo and BEFORE the intercooler). This increases in a linear fashion with altitude. In my aircraft, at 20'000 ft, it hits 150 Celsius (300 degrees Fahrenheit) above ambient (so if ambient were 0 F it would be 300 F). I was using 37.5 inches of manifold pressure and 2500 RPM during this test. Despite gradually colder outside air, the air that's fed into your intercooler gets hotter and hotter as you climb. The cause is that as the air gets less dense, the turbo works harder to deliver the desired manifold pressure and the compressed air gets much hotter for several reasons. The intercooler will shed part of this heat, but the intake air will still get hotter and hotter as you climb and typically reach critical levels above 15'000 ft. If you look at the operating instructions of aircraft engines in this class of power, you'll see fairly consistent power limitations with altitude. Thats' why. Conclusions: - It is not enough to test the engine at sea level and ambient temps, you need to see what happens as the inlet air gets much hotter due to the above. One economical way of doing it would be to bypass the intercooler... - It is critical to make the best possible design for the intercooler setup - you need maximum intercooler efficiency during climbout, so you should tune intercooler aerodynamics for this vs for cruise. Pusher aircraft have huge challenges in this regard, but a lot of knowledge is available. Make sure you read this stuff early on. - I also recommend you explore the thermodynamics of engine combustion and make sure whoever is programming your software is fully aware that it will operate at 1/3 sea level pressure and makes appropriate provision. Example: at full power (350 HP) my Continental engine needs 37 gallons per hour, more than double what your Audi seems to achieve. But a big portion of the Continental's fuel consumption is actually used for two critical tasks: shifting the engine's parameters away from detonation and cooling the cylinders through fuel vaporization. Granted, the Continental engine has no FADEC, but i think that the bulk of the excess consumption is unavoidable if you are to keep combustion parameters in check at high altitude with very hot intake air. - Now add insult to injury and simulate a take off from Las Vegas on a hot day. More generally, I respectfully encourage you to think "I have one third of an atmosphere up high - how will this part/system behave". An example - one of your "competitors" Evolution Aircraft recently lost an aircraft after the (bonded) windshield departed in flight. In my (certified) aircraft all windows and the windshield are bonded AND held by hundreds of heavy stainless steel screws. The weight and cost penalty certainly was not approved lightly. All the best. Antoine
? This might be a silly question. Is your 4 blade adjustable? If so, my question is giving the air is thinner can or do you increase the pitch? Or does the hp loss cancel that out?
Hi Antoine, I have a couple of questions out of curiosity: 1) Would a larger turbo be more efficient at altitude thus reducing temperatures with the same amount of intercooling? 2) Is there any drawbacks to up-sizing the turbo, especially the on the compression side within reason in an aircraft application? 3) Would a compound turbo setup be better able to control the air temp if you design it for efficiency at altitude as the work is split between the turbos and you can keep a more or less constant air density at both sea level and altitude by controlling the waste-gates electronically in accordance to elevation?
The Raptor will have a very distinctive sound on departure. For the VERY short time the plane is close enough to the ground to be heard..lol Nice work.
It will probably sound just like a Velocity, certainly a distinctive sound. It comes from the disturbed airflow off the wings. There's an angled downwash and one side hits the prop at a different angle than the other.
Not something from the engine, but just dust and debris from floors and benches. The 2 highest precision instruments in the shop are the most irreplaceable. Your eyes.
Thank you for the video on the performance of your engine. Were the results obtained using diesel fuel or JetA fuel. The figures obtained were impressive and your aircraft should be a beautiful aircraft to fly. Once again, thank you.
Could you let me in on how you got an ecu to run that out of the car? I have been racking my brain thinking of how to put that engine into my 4x4. Any links would be super use full. Thanks.
It's great seeing the incremental progress on the engine. I must say that this looks video looks like one of those OSHA worksite safety videos- would definitely recommend addressing the run of hoses / cords on the floor and fashioning a protective fence to avoid inadvertent trip ups toward a spinning prop. Want to keep you around to see this thing through, Peter.
I would be interested to see what happens to an engine that was designed for short bursts of power, driven at full or close to full power for hours. Do you have any updates on the reliability ? How do you limit the EGT and engine oil temp?
When/If choosing a new prop, the shorter in diameter you go the less efficient it becomes, you probably already know this but just throwing that out there! Awesome update, looking forward to the progress!!
this engine is smooth! i looked at the start up 10 times and can hardly see any deferential between the movement of the engine and engine mount frame. i was looking because i see the prop end of the reduction drive seems to be mounted to to the frame and wondered how would it handle these stresses. what belts are you using for the reduction drive? i really enjoy ur videos.
Keep up the good work very nice to see this motor being used ! I have the same motor in my race car I very highly doubt you'll break the crankshaft or rods im pushing 60psi of boost making almost 600whp
@@RaptorAircraft that is peak gauge pressure these tdi engines are very durable i dont run 60 continuous with a long pull i could see egts of 1200 Celsius but that is way to hot during your testing what were you seeing for sustained egts at high rpm? Also are you running standalone or factory edc17?
@@oooonlytdi7423 I haven't run high power for very long but around 1200f seems about usual for a decent power setting. I have seen as high as 1900f on one quick pull. The ECU is a Motec one.
@@RaptorAircraft yup 1900f sounds about right oil temps are critical as well helps keep the pistons cooled ! I was considering standalone for mine did you do all the mapping yourself? what is your engine code CATA? Your in north America correct?
@@oooonlytdi7423 CNRB is ours from a 2014 Q7. In my mind 1900f is really high because the Y pipe leading into turbo 1 was glowing a little red, probably ok but made me nervous. So far the engine hasn't missed a beat. We're running the Motec m141 ECU with a base setup that Motec provided. I have done some tuning but mainly just idle settings and fuel delivery per throttle setting. If you'd like to have a WhatsApp call at some point we could compare notes. We're in the U.S. what about you?
Hey Peter! Could you send your prop to a prop shop and have a different low pitch angle set to increase prop/engine speed? If needed, I can recommend a awesome prop shop.
If you change out the 4 blade prop for a 5 or 6 blade prop, you should be able to reasonably reduce the diameter and keep the same amount of efficiency. That is, to a certain point. There is inevitably a cross-section at which once passed you lose efficiency regardless. Other things that can help are changing the props design from thin and straight to thicker and curved, and finally, allowing for variable geometry at the prop can great help too.
VeteranAJ they already explained why they didn’t go with the 5 blade prop. It was very expensive compared to the 4 blade prop and the power to price ratio wasn’t worth the hassle. Maybe that will change later but as of right now that’s what they went with. If you watch the video of them first unboxing the 4 blade prop you can see this info from raptor. (It was probably several months ago. I can’t remember the exact date)
Good to see you've got a handle on the governor issue that's been slowing the engine development. The next engine issue yuo'll need to deal with is heat. As you pointed out, the temperatures were still rising, and I'm not sure if you've realised the fuel temp is going up as well as the oil and coolant
Will Audi still be producing this engine in 5 yrs and do they permit installation in an aircraft? Some companies don't want anything to do with the liability.
Peter, did you consider using electronic wastegate actuators controlled by the ECU? Might be lighter and less complicated than that manifold with all the braided hoses coming off.
The manifold is there because I have a digital and an analog gauge hooked up as well as the connections to the two wastegates. It's working well right now.
They are rated for 500,000 miles, and are known to have slow failures. I would feel comfortable with my own life with 250,000 miles worth of wear, although mine has double that and runs like a clock. Works out to about 1,100 hours. Given the reliability of these engine, it's no surprise. Careful with the turbo though, after about 15,000 feet, it will start spinning too fast to keep up with commanded boost so you need to derate the engine.
why hasn´t turbodiesel caught on for aircraft? aren´t those more rugget and dependable? i´ve also heard that they respond better to high boost esspecially in aircraft a very usefull feature, hasn´t a turbodiesel other economic advantages aswell? even before the fifties highpower turbodiesel recon aircraft were used.
@@RaptorAircraft The engine management and the reduction of the vibration cause by the diesel 'knock' has been the problem in the past. Multiple inj. sequencing seems to have solved that problem.
Steeltree - homesteading with a twist The aircraft is designed for high altitude flight. NA engine will lose power as it climbs. They also need a turbo to bleed compressed air to pressurize the cabin. The diesel will be more efficient and jet-a fuel is more widely available compared to aviation gasoline.
If something flies off the engine I'm probably going to need more than just eye protection. As I start doing long test runs I'll be back in the office monitoring remotely and no one will be in the shop space.
For the engine it's less than $15k. For the reduction drive it's around $25k because there has been some remachining of parts that were not done correctly initially. For the reduction drive it's also a one off presently so everything costs more.
For this setup, yes. But there is tons of room to bring the price down on the reduction drive. Possibly to $5k if we machine everything in house eventually.
Try to get some temperature readings off of those idler pulley bearings. They are going pretty fast for sealed bearings don't you think? I guess that as long as they last longer than the belts it's okay though. I know that similar setups last on other engines but they have spring tensioners to limit their load. Are you planning to put grease fittings in for the main tapered bearings in the prop shaft housing? Or are they going to get oil in the new design? Great work she sounds sweet!
Bill Wessels , that prop shaft isn't under much heat or load. It just takes the thrust and radial load from the prop and belt respectively. The heat radiates to the aluminum housing which is oil cooled or heated in this case. Those are huge tapered roller bearings, like semi-truck sized. The only issue I see is that they will need to be disassembled, cleaned, inspected, re-packed, reassembled, and properly preloaded at some point. Which means pulling the shaft and replacing the seals, might as well replace the belts and the idler pulley bearings while it's apart, the parts are cheap. Well except for the seals which are the things you will most likely damage. Matter of fact those huge bearings that look fine are pretty inexpensive and very flight critical so..... Don't mind me I've been fixing other people's bad designs for too long. Peter is doing a fantastic job, I just constantly think about failure modes and maintenance schedules. It's my nature I suppose.
Bill Wessels , thanks, just to be clear, contamination and/or incorrect pre-load, being dropped, etc will kill any roller bearing no matter how oversized it is. This is why every thing has sealed bearings these days, harder for uneducated factory workers to screw up.
