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Jet-A Powerplant

George is right

...
If you deviate from Van's Aircraft plans and install some custom engine you will spend 100's or 1,000's of hours hours of extra build time and 1000's of dollars more than if you just went with the Lycoming.
This was exactly my experience with a subaru "kit". Wasted about 50k, and many hours. Today I'm flying behind a 180hp io-360 from Mattituck, AFP FM200, dual pmags, burning unleaded avgas (UL91, https://www.aviation.total.com/fuels/avgas-ul-91) and it's working really well so far. Just under 50 flight hours.
 
....What I see as the big benefit is taking off from an airport at 9000' on 100 degree days without having to leave your luggage or take on less fuel....

This ought to be possible with a stock RV-10. It most certainly is with my C180. Climb is reduced and take off distance is longer. The airport had enough runway (doesn't take much with a C180, longer with an RV-10) and a clear departure.

That said, 100 F at 9k feet is not all that common. Is that truly your need?

Dave
Colorado
 
A lot of you have stated a very good point. The RV-10 as designed seems to be a very capable aircraft. Sure we all could build it by the numbers and end up with a very nice plane that performs the mission. There's nothing wrong with that.

I feel a lot of us choose to build our own plane so we can build it to our desire and put our own personal touch in it. That is at different levels, some choose to only change the paint scheme or interior design, some choose to add mods like rudder trim or A/C. Some people get a little more extreme and start customizing engines, fuel tanks, or adding recovery chutes, etc.

For me personally, I'm starting with the -10 because of it's reputation, build process/quality, and the community. However, I have a desire to experiment with a different engine conversion. I do plan to setup the engine on a test stand with prop and cowling and run it as much as possible while I build the rest of the plane. I realize there will points along the way, that I may change my mind and go with an aircraft engine. But, I will give this a try.

I'm not trying to make the -10 go faster. My third build may be a jet, LOL, and that would start with an airframe that is designed to go fast. My second build will probably be a STOL aircraft. :)
 
Rob, when we start out as unknowing builders we don't fully appreciate just how much time it can take to build one of these aircraft. I was certainly guilty of that. As I have gotten farther into my build I have realized what others are pointing out here. If you go off the plans you will be spending extra time figuring out custom solutions. I have done many customizations and in a way wasted many hours going down those multiple paths. I am still happy with what I have selected and of course that is the whole point of this type of endeavor, to build what you want as the builder. However, I still don't have a plane that I can fly. So it comes down to the amount of time that you can dedicate to the project, the amount of money you can invest to do things multiple times and your end goal for your sense of accomplishment. Just keep in mind it may seem cool to do your custom development but will you be happy with the end result if you have to start all over from square one. I'm certainly not trying to deter you but we don't know what we don't know.
 
I'd love to have a complete and well supported firewall forward kit for a compression ignition piston or turbine engine. Something that will burn Jet-A. I'm not enough of a gear head to tackle the challenge of doing that work myself. Just don't have the time, money or technical ability myself. Certainty envious of those with that capability.

Maybe Van's will offer the DEL-120 from Lycoming as a factory supported option. Although at 360lbs, it's an awkward weight. Heavier than an angle valve 4 cylinder, but lighter than a 6 cylinder. Plus it's a turbo, and we all know how Van's feels about turbos.
 
This was exactly my experience with a subaru "kit". Wasted about 50k, and many hours. Today I'm flying behind a 180hp io-360 from Mattituck, AFP FM200, dual pmags, burning unleaded avgas (UL91, https://www.aviation.total.com/fuels/avgas-ul-91) and it's working really well so far. Just under 50 flight hours.

I share Mickeys pain, experience and similar costs.

Really if anyone is considering developing their own power plant I would seriously suggest that you don't bother building the airframe at all. Just develop the power plant, and when it's perfected then find or build an airframe to put it in.
 
I think you are wrong with respect. Peter is a talented guy who is doing amazing work.

First self disclosure, in the last 35 years I have followed, researched many (many) auto engine conversions. I'm not a big fan but admire the effort. The best engine conversion is to take $35,000 and converted it into a Lycoming ( significantly less $$$ is you source a used engine).

With that said with Peter's never give up attitude, apparently endless time and money, methodical approach, he show Auto Engine conversions require tremendous amount of extra time and no real money savings in an aircraft that's not going to perform as well with a Lycoming.

Peter had no real world experience in aircraft design, structures, system design, powerplants, turbocharging or aerodynamics and the results show- the aircraft is double the projected weight from 2013, has twice the projected fuel burn and will be 90 knots slower than projected. Every target has been missed by a mile...

You also don't start an engine development program like this compound turbo, Audi diesel without a deep mechanical, engine and turbo background. It produces less than stock hp, doesn't cool, doesn't last, is really heavy and complicated, making it essentially useless for powering an airplane.

Peter is certainly tenacious, however his approach isn't methodical, more of a guessing game and shotgun approach simply because he lacks a proper background in multiple disciplines. You can eventually solve issues like this but you'll be very old or dead before you fix them all.

As far as auto engines go, I've published 2 YT videos featuring 10 successful Subaru powered aircraft, one that goes 220+ knots and another with over 2300 flight hours on it. They can work well if done right, or poorly, like Peter's experiment, if done wrong.

Anyone contemplating doing their own homespun diesel for powering an RV-10 had best possess the proper mechanical background and experience if they hope to have a good chance of success- and even that background doesn't guarantee it. Otherwise I'd suggest one of the Conti diesels, developed by professionals.
 
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Good advice.

Great advice, Ross but few will heed. I flew my -10 for 11 years with an Aerosport IO-540, with multiple trouble free trips to the Bahamas and back, listening to that engine purr.

It has a new home near Atlanta, still humming along after 700 hours.

Regards,
 
A lot of you have stated a very good point. The RV-10 as designed seems to be a very capable aircraft. Sure we all could build it by the numbers and end up with a very nice plane that performs the mission. There's nothing wrong with that.

I feel a lot of us choose to build our own plane so we can build it to our desire and put our own personal touch in it. That is at different levels, some choose to only change the paint scheme or interior design, some choose to add mods like rudder trim or A/C. Some people get a little more extreme and start customizing engines, fuel tanks, or adding recovery chutes, etc.

For me personally, I'm starting with the -10 because of it's reputation, build process/quality, and the community. However, I have a desire to experiment with a different engine conversion. I do plan to setup the engine on a test stand with prop and cowling and run it as much as possible while I build the rest of the plane. I realize there will points along the way, that I may change my mind and go with an aircraft engine. But, I will give this a try.

I'm not trying to make the -10 go faster. My third build may be a jet, LOL, and that would start with an airframe that is designed to go fast. My second build will probably be a STOL aircraft. :)
I am not trying to be a jerk but you should consider the advice.

You are talking desires and reality. First your RV10 will not be fast with a VW Audi V6 TDI diesel or any other car engine I can think of, I can guarantee it. The reputation of the RV3, 4, 6, 7, 8, 10 are all based on Lycoming power. Deviations from Lytc power have had some mixed results, mostly poor to bad, with rare individuals like RV6guy and his buddies up in Canada... So if slowing down and reducing payload carrying ability in your dream RV10, is your goal, you will succeed with a prop bolted to a PSRU driven by a boat anchor, water cooled, car engine. There is no experiment. It has been done and the results are known. Why do you think your results will be different?

Before working on your 2nd STOL plane build, you might want to try your 1st to plane. The most sage advice given to new builders is "stick to the plans". You assume you will have good performance with a VW/Audi TDI V6. (BTW I have been driving a VW TDI CR 2.0L Diesel for 10 years and still do, love diesel, but many companies with vast resources have tried to make diesel work specifically for light planes with various degrees of success and failures, sometimes technical success and just sales failures. Diesel option is more expensive, is always heavier and does not offer a huge advantaged in a plane. In a car, pickup truck, semi truck or large boat diesel rules, but then weight is not as big of an issue.)

BTW I don't know your finances, but airplanes are expensive you may have heard. I assume you are a pilot. I recommend sometimes buying a fixer upper C140C150/152/170/172, Piper (any Pacer, Cherokee, Tomahawk) and being an aircraft owner. If you want a equivalent RV10 then a Mooney, Beech Bonanza, C182. If you never owned a plane it might enlighten you to the reality of airplane care and feeding. To spread the cost out, getting a partner to split the fixed cost (tie down/hanger) and expendables (oil, tires, brakes) is also a good thing. Some people who build never owned a plane and might be surprised. It is like the old joke a man is happy they day he buys his boat.... but that man is truly happiest when he sells his boat.

The down side of owning and flying is this is a distraction in time and money from building. Obviously you can't experiment with a certified plane as an amateur built kit plane, without getting the FAA involved. Bottom line work on your airmanship and have fun... or stay on the ground dreaming. Many have had the same thoughts as you and spent a lot of time an money not flying. However many people prefer to not fly and dream, build and tinker. I have seen some spectacular car engine conversions in planes collecting dust as they work on it, run it up in front of the hanger but never fly.

Up to you. I like both building and flying.... but flying is the goal not nursing a hanger "experiment" queen.

Only plane I know of in "large" (qualified as a few dozen planes a year) production with diesels is the Diamond DA62 light twin with two Austro Engine AE 330 turbocharged common-rail injected 2.0 liter diesel engines rated at 180 HP each, using EECU single lever control system. Keep in mind this is 180HP. It seems many "aircraft" diesels shoot for the under lower 1800 HP range when designing a diesel. The nominal HP a Lyc 540 puts out is 250 to 350 HP, more with tweaking. (Note a 2021 Diamond DA62 is $1,135,000. Yes over a million. Dimond now offers the diesel in a single engine DA50 for $700,000.)

You are 100% out on your own designing a new. Do you have the background, skill, equipment, time and money to make it work. Dreaming is one thing and flying is another. Many have dreamed and failed. However the dream with a Lycoming is less risk and most likely to lead to success and known excellent performance (real world performance not pipe dreams). Also you will have a valuable plane you could sell. Most car engine planes do not sell well or are discounted well below a Lyc powered example.

There are so many challenges to adapting a car engine intro a plane, the PSRU, cooling, fit, prop, weight, fit, mount, cowl.... With a Van's kit it is all designed and laid out (for a Lyc). Even then sticking to plans, keeping it simple, with diligent constant work you will have 2000 hours building it (if you are an efficient builder. Part time work that means a few (to many years). Now going your own you will make many parts over and over to make it work. Is it worth building? YES!!! However at the end you want a plane that performs and is valuable to you and even in resale, since you will put in well over $100,000 into it plus your time.

With that said UP TO YOU. Good luck.

By the way Lycoming's and Continental's can easily be turbocharged for high altitude. As was said a RV10 with weight and runway limits can operate at high density altitudes with descent payload. The B737's and other Boeing jets I flew out of Denver were also weight and runway limited when ambient was hot. Are you going to do gross weight T/O's at 9000 ft often if ever? If you want Jet A get a P&W PT6. However it is cheaper to buy a used TBM700.... and you would have much more of a plane than a RV10. They can be bought for less than $1M.

Do you want to fly or dream. The quickest way into the air besides buying a finished RV is buy the kit, pound rivets, stick to the plans and drawings, keep it simple. If you have your heart set on putting a car diesel in a plane do your research. First find someone who has done it and has 100's of hours flying it. I almost guarantee you will have a hard time finding this person. This should be a hint? :) (I know of a 2.0L VW TDI in a Cessna in Europe and has been flying for a few years. How much it has flown besides the YouTube Video of first flight, performance don't know.)

All the best and keep us informed of your progress...
 
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First your RV10 will not be fast with a VW Audi V6 TDI diesel or any other car engine I can think of, I can guarantee it. Deviations from Lytc power have had some mixed results, mostly poor to bad, with rare individuals like RV6guy and his buddies up in Canada...

All it takes to be faster than a Lycoming is more power and that's easy to come by. Gary Spencer's Long Ez, Russell Sherwood's Glasair, Phillip Johnson's Cozy RG and Shane Getson's RV-7 are all faster than their Lycoming powered counterparts.

I have no corner on success in auto conversions, many others from around the world have done a lot better than me which was a main reason to create the 2 videos, showing this success.

There are hundreds/ thousands of successful auto conversions flying, from VWs to LS V-8s, I've documented but a few. I just received an email this morning from an old customer with 700 hours on his Subaru Quickie and he's doing a 2.5 turbo for his new Q200 because the first one served him so well.

Most of the well proven certified diesels are based on automotive diesels, showing that Austro and Continental believe this was the best path. I think this validates the concept.

I did a technical comparison of many engines here: https://www.youtube.com/watch?v=GJy93vrbvw0&t=1s

It can be done. It can be powerful, reliable and durable. It WILL be a lot of extra work. It may not work well if you don't get all the details right.

It's technically interesting and personally satisfying to make a conversion work well. Lots of folks would rather explore different paths than the well trodden one. You just have to be prepared to encounter a few thorns and stumps along the way...

If you'd like to experiment and learn a lot, a conversion might be right for you, otherwise if you just want to fly with the least amount of trouble and time spent, the Lycoming is the way to go IMO.
 
Peter had no real world experience in aircraft design, structures, system design, powerplants, turbocharging or aerodynamics and the results show- the aircraft is double the projected weight from 2013, has twice the projected fuel burn and will be 90 knots slower than projected. Every target has been missed by a mile...

You also don't start an engine development program like this compound turbo, Audi diesel without a deep mechanical, engine and turbo background. It produces less than stock hp, doesn't cool, doesn't last, is really heavy and complicated, making it essentially useless for powering an airplane.

Peter is certainly tenacious, however his approach isn't methodical, more of a guessing game and shotgun approach simply because he lacks a proper background in multiple disciplines. You can eventually solve issues like this but you'll be very old or dead before you fix them all.

As far as auto engines go, I've published 2 YT videos featuring 10 successful Subaru powered aircraft, one that goes 220+ knots and another with over 2300 flight hours on it. They can work well if done right, or poorly, like Peter's experiment, if done wrong.

Anyone contemplating doing their own homespun diesel for powering an RV-10 had best possess the proper mechanical background and experience if they hope to have a good chance of success- and even that background doesn't guarantee it. Otherwise I'd suggest one of the Conti diesels, developed by professionals.

Fair enough, but none of us were born with experience. I have a degree in Engineering, ATP, build kit planes and I am still learning... However your point on being methodical and using knowledge (dare say scientific) based approach is excellent. Agree.

To your other points, yes this plane "Raptor" is not the high flying, long range, fast, 4 place, pressurized "turbo prop" performance he promised. It is not even close, to down right awful. The plane is so heavy, I believe it is at gross weight with just him and an hour of fuel. Slow? In the few videos I saw it has really poor climb (under 1000 fpm) and slow level airspeed of 140kts (cruise I guess). The handling seems almost unstable with pitch and roll oscillations so bad on the first flight it made me airsick the first time in my life just watching it... It was scary. However he seems to have mellowed that out.

Back to the OP's desire for a "jet fueled" engine that is not a Pratt & Whitney PT6. Although there are some Eastern European Turbo Props based on RC model airplanes people have used, but forget that for now (they are expensive and burn fuel like crazy for same performance as a Lyc). Peter's Raptor is using a VW/Audi CR TDI V6 diesel. He designed his own belt driven PSRU... It is mated with a MT prop that is hydraulically controlled... The hydraulic control issue was what killed his engine with a seal leak. He lost engine oil and then damaged the engine. Getting oil into a prop with a belt drive is a good trick, but one that failed here. That is why a good PSRU should have it's own oil supply or be bullet proof.

The gear box PSRU is a better choice if you want to go with a hydraulic prop, but this requires precision engineering, harmonic dampening, design, manufacturing and advanced materials and processes. PSRU's are one of the biggest weak points, adding complexity & weight over a Lyc direct drive. For the DYI'er to make their own PSRU is a challenge. Belt drive is simple and works, but Peter added the hydraulic prop to his belt drive. Clever but not so reliable. He would have been better with an electric prop, safer least risk of losing engine oil. Many car engine adaptations use fixed pitch props for this reason and are restricted from aerobatics.

To your other points could not agree more.... You know I admire what you do with your Subaru powered RV and your electronic ignition you offer for sale.

With that said the OP'er is a dreamer. Nothing wrong with that (to a point except when safety is involved). I hate tinkling on anyone's dream, because sometimes dreams come true. Wright Bros, Apollo Moon missions, Elon Musk Tesla/Space X. With a sarcastic slant the Wright's only flew a few 100 feet. Apollo, for all that money we got rocks (and amazing spinoff technology). Elon and his Tesla has a whopping 250 mile range and then parked for and hour or many hours to fully charge... All this for a car that cost $70,000 to $130,000. My VW TDI diesel gets 50 mpg, 700 mile range and can be "recharged" in 5 minutes at most street corner filling station or most freeway off ramps. Space X self landing reusable boosters is pretty cool to say the least, but was preceded with spectacular fails. However all of these dreamers lead others to even bigger and better technology and accomplishments by others.

Your gang flying Subaru's in Canada are totally an exception to the rule and the right way to do it. Anyone interested in the right way checkout RV6guys YouTube channel. He has a great series on all the challenges in adapting car engines, cooling, PSRU and examples of the right way with very good results. Your buddies Glasair is cool and fast. This is not to be confused with defuncted Eggenfellner engine kits. These guys in Canada have highly engineered installations using sound physics and continuous improvements and testing. This is my point, not everyone has these skills and capabilities or resources in time to do this innovative work. The issue is planes need to be made around the engine... like the P-51 was with v12 water cooled engine. To retro fit a water cooled automobile engine on an airframe made for a direct drive air cooled Lycoming results in compromises and or massive modifications. A bolt on plug and play car engine substitute for a Lycoming (that fits in same envelope, with same weight or lighter, and has as much or more trust as a Lyc) is not possible. Car engines were made for cars. Aircraft engines were specifically made for aircraft with all the optimal trade offs in the design incorporated.
 
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Your gang flying Subaru's in Canada are totally an exception to the rule and the right way to do it.

This is not to be confused with defuncted Eggenfellner engine kits. These are highly engineered installations using sound physics and continuous improvements and testing.

My videos featured aircraft from all over the world and several Eggenfellner based conversions which have accumulated several thousand flight hours to date. With some attention to detail, these have proven reliable as well. The ex NSI conversion from TX in the latest video has over 2300 flight hours on it- that's pretty successful in my view...
 
Jet A

To Rob-the-Builder:
I had your same dream in 2004! Since that time, I've built a diesel RV9 that my son and I have flown over 600 hours. We've had a blast with it. The plane ended up lighter than its Lycoming (O-235) equivalent, something Van's (and many on this forum) said was impossible. It performs as well as the Lyc, on less fuel.

I enjoyed the diesel RV9, but my son needed the plane. So in 2013 I built a Glasair Sportsman with a Continental CD155 diesel. It has been a wonderful, trouble-free plane. I've flown it 800 hours so far. Yes, it's slightly heavier (empty) than it's Lycoming (O-360) counterpart. But, when fueled for the same mission, it's lighter (more payload), since it requires MUCH less fuel to go the same distance. In almost all respects, it performs equal to an Avgas Sportsman, burning at least 25% less fuel.

Now I'm building another aircraft with a CKT 240TD turbodiesel. This engine has been developed by CKT Aero Engines in the UK based on the Subaru EE20. I've been impressed with the quality and design of the complete package. I've weighed it against an identical airframe with a traditional engine (O470) and it is within 5lb. If it runs as advertised and tested, it should perform quite well in an RV10. The size and weight are just right. We'll see how it goes. By the time you're ready for an engine, we'll know if the CKT does the job... I should have it in the air in the next few months.

So don't lose hope, Mr Rob-the-Builder! I can tell you that Jet A piston aviation is real, and there are a lot of advantages to flying a diesel. Don't let the naysayers in this forum kill your dream. They're doing what they think is the responsible thing to do, and for the most part, they are RIGHT. This type of "experimentation" isn't for everyone; it can be costly, time-consuming, and risky. But, as Ross points out, if done carefully and methodically, it can work well. At least it has so far for me.

Feel free to PM me if you've got questions. I'm a real diesel aviation nutcase; I might be able to help you avoid some pitfalls...

Kurt
 
.....Maybe Van's will offer the DEL-120 from Lycoming as a factory supported option. Although at 360lbs, it's an awkward weight. Heavier than an angle valve 4 cylinder, but lighter than a 6 cylinder. Plus it's a turbo, and we all know how Van's feels about turbos.

Actually the quoted 360 lbs doesn't include intercooler and radiator with 2-3 gals coolant which would put it around 400 lbs installed.

But, with Van's being Lycoming's biggest customer (or close to it), this could be the most viable diesel option to date for our market.

The RV market could be a great way for Lycoming to dip a toe into bringing that engine into the civilian marketplace. Van's would of course have to develop a firewall-fwd kit, but they ought to have enough expertise today to pull that off.
 
A 205hp turbo diesel RV-10. I wonder if there's an appetite for that. Not too different than the Continental IO360 that was offered initially, but not popular and dropped. The turbo would make up for it at altitude, and if the ECU was programmed to do so, it could limit boost to be comparable power to the 260hp. Flat rated to only 8000' or so, then both engines develop ~200hp at 8000' and decreasing in a similar fashion above that.
 
That would be cool if Lycoming would offer the DEL-120 (also based on automotive design BTW) for Experimentals, especially working with Van's. Might open a fair market for them and offer some competition to Continental. Continental has 3 diesel offerings now. From their page on this engine, looks like they may be open to working with airframers on installations. Van's, how about it?

Would be even better if they offered a 300 hp range 6 cylinder diesel around the same weight as an IO-540. I think that would interest some RV-10 and Lancair folks.

Kurt, good to see you are on to yet another engine. Let us know how that works out. You are the man with aero diesels! :)
 
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Ross, you won't sell very many ignition systems to the compression ignition crowd :D

True, but I don't think everyone will be installing one. Aero diesel costs generally far exceed the SI offerings. I'd just like to see some viable/ proven/ different choices out there.
 
Now I'm building another aircraft with a CKT 240TD turbodiesel. This engine has been developed by CKT Aero Engines in the UK based on the Subaru EE20. I've been impressed with the quality and design of the complete package. I've weighed it against an identical airframe with a traditional engine (O470) and it is within 5lb. If it runs as advertised and tested, it should perform quite well in an RV10. The size and weight are just right. We'll see how it goes. By the time you're ready for an engine, we'll know if the CKT does the job... I should have it in the air in the next few months.

Thanks for the insight on this engine. I don't recall coming across this before. I'll be very interested to hear more about it, how it performs, and what roadblocks you run into. You are correct, I won't be ready for an engine by the time you get this flying.
 
To Rob-the-Builder:
I had your same dream in 2004! Since that time, I've built a diesel RV9 that my son and I have flown over 600 hours. We've had a blast with it. The plane ended up lighter than its Lycoming (O-235) equivalent, something Van's (and many on this forum) said was impossible. It performs as well as the Lyc, on less fuel.

I enjoyed the diesel RV9, but my son needed the plane. So in 2013 I built a Glasair Sportsman with a Continental CD155 diesel. It has been a wonderful, trouble-free plane. I've flown it 800 hours so far. Yes, it's slightly heavier (empty) than it's Lycoming (O-360) counterpart. But, when fueled for the same mission, it's lighter (more payload), since it requires MUCH less fuel to go the same distance. In almost all respects, it performs equal to an Avgas Sportsman, burning at least 25% less fuel.

Now I'm building another aircraft with a CKT 240TD turbodiesel. This engine has been developed by CKT Aero Engines in the UK based on the Subaru EE20. I've been impressed with the quality and design of the complete package. I've weighed it against an identical airframe with a traditional engine (O470) and it is within 5lb. If it runs as advertised and tested, it should perform quite well in an RV10. The size and weight are just right. We'll see how it goes. By the time you're ready for an engine, we'll know if the CKT does the job... I should have it in the air in the next few months.

So don't lose hope, Mr Rob-the-Builder! I can tell you that Jet A piston aviation is real, and there are a lot of advantages to flying a diesel. Don't let the naysayers in this forum kill your dream. They're doing what they think is the responsible thing to do, and for the most part, they are RIGHT. This type of "experimentation" isn't for everyone; it can be costly, time-consuming, and risky. But, as Ross points out, if done carefully and methodically, it can work well. At least it has so far for me.

Feel free to PM me if you've got questions. I'm a real diesel aviation nutcase; I might be able to help you avoid some pitfalls... Kurt
Would you be willing to share the actual performance (climb, cruise, top speed) and cost and empty weight of your RV9/Glasair Sportsman powered by Continental CD-155 diesel. Sounds interesting. I see the CD-155 spec claims 152.9 HP and shy of 295.4 pounds (134 kg). I do not think that is including cooling system and fluids. BTW for Ref the Lyc O-235 is 50 lbs lighter (245 lbs) and requires no radiator, hoses or fluids. Rotax powered RV9 would be lighter. Did you do something special to save weight (no paint, interior, min equip). The cost of the CD-155 engine I found was $48,000.00 and C-172 retro fit $78,000.

I think we are missing the point of the OP and many auto engine conversion fans, and that is not buying a $50K commercially available engine. They dream of going to the automobile salvage yard, buying a used engine for a few $1000's from a wrecked vehicle and throwing it in their sky scooter, and beating the snot out of Lycoming powered planes with their "modern" engine. He wants to tinker and develop not buy off the shelf (I think that is what he is saying). Commercial certified aviation diesels like the Austro E4 in the Diamond DA62 light twin are great (I think never flew one)... but the plane cost over $1M USD.

Second question why the CKT 240TD by CKT Aero Engines if happy with the CD-155? I see they claim 200 HP continuous and weight 230 Kg (507 lbs). That is a hefty engine for 200 HP... Just saying. The cost is not stated and it is still in development. I wish CKT luck, but that looks like a big expensive heavy engine with no history. Personally I would not fly behind an engine without a proven service history, certified or not. Which leads me to another point.

To continue to be the wet blanket and crush hope (kidding big fan of diesel but lets be real). several aviation diesel engines have been announced and in development for years (decades) in the past. DeltaHawk and Gemini come to mind. The DeltaHawk has been around for over a decade with many announcements, next year they will have certification or something, year after year. It is a 2-stroke diesel, and they have prototypes flying. A few years back they offered them for RV builders, FWF $80K or $90K I recall, and they install it. This is 100% FWF, systems and instrumentation. You are their test bed for getting it certified, which it is not yet as far as I know. It is 180 HP and weights about what an angle head IO-360 weighs, they claim. DeltaHawk is a direct crank to prop drive, no PSRU, saving weight and complexity. Two stroke diesel there is no valve train. I would love to see that come to market at a reasonable DIY kit price. Anyone flying a DeltaHawk?

And these diesel engines are better than a Lyc IO360 or IO540 why? One reason I see is Av gas (leaded) may be restricted or ended if some groups have their dream.... It is likely Kerosene / Diesel / Jet-A, will remain in production longer for trains, ships, semi trucks and John Kerry's Biz jet.. I don't think this will happen in our life time, but 2020 a lot changed fast. The promise of much better diesel fuel economy? OK sure but the pay back time saving a gallon or two an hour will be long for the extra cost, especially flying just a few hundred hours a year. You don't see many diesel engines claiming big fuel savings. Frankly judicial use of power and mixture in Lycoming can reach pretty excellent SFC (specific fuel consumption).
 
From their page on this engine, looks like they may be open to working with airframers on installations. Van's, how about it?

I've had a few conversations (both voice and email) with James Ball (Sales Manager) at Continental, he told me that they would indeed be interested in working with someone to develop a FWF package, and they have approached Vans several times about doing so, and Vans has told James they have no interest in doing so. That was November of 2020.

Continental will not sell to the experimental market without a developed FWF kit.
 
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I've had a few conversations (both voice and email) with James Ball (Sales Manager) at Continental, he told me that they would indeed be interested in working with someone to develop a FWF package, and they have approached Vans several times about doing so, and Vans has told James they have no interest in doing so. That was November of 2020.

Continental will not sell to the experimental market without a developed FWF kit.

I was thinking more of Lycoming here but perhaps Van's doesn't see enough demand for Jet A engines to be worth it?
 
It's really a catch-22. It's probably not worth the cost and liability to Van's to develop the FWF package, because it's a substantial change from a traditional engine, and I'm guessing they don't envision sufficient demand. Plus, the diesels are pricy. They'd probably become a lot cheaper with larger production volumes, but those won't come without being proven. They can't prove it unless they sell a lot of them, and they can't sell a lot of them until they're proven.
 
I'd buy a CD-155 tomorrow if I could for my airplane. For my typical mission it's a perfect fit.
 
Would you be willing to share the actual performance (climb, cruise, top speed) and cost and empty weight of your RV9/Glasair Sportsman powered by Continental CD-155 diesel. Sounds interesting. I see the CD-155 spec claims 152.9 HP and shy of 295.4 pounds (134 kg). I do not think that is including cooling system and fluids. BTW for Ref the Lyc O-235 is 50 lbs lighter (245 lbs) and requires no radiator, hoses or fluids. Rotax powered RV9 would be lighter. Did you do something special to save weight (no paint, interior, min equip). The cost of the CD-155 engine I found was $48,000.00 and C-172 retro fit $78,000.

I think we are missing the point of the OP and many auto engine conversion fans, and that is not buying a $50K commercially available engine. They dream of going to the automobile salvage yard, buying a used engine for a few $1000's from a wrecked vehicle and throwing it in their sky scooter, and beating the snot out of Lycoming powered planes with their "modern" engine. He wants to tinker and develop not buy off the shelf (I think that is what he is saying). Commercial certified aviation diesels like the Austro E4 in the Diamond DA62 light twin are great (I think never flew one)... but the plane cost over $1M USD.

Second question why the CKT 240TD by CKT Aero Engines if happy with the CD-155? I see they claim 200 HP continuous and weight 230 Kg (507 lbs). That is a hefty engine for 200 HP... Just saying. The cost is not stated and it is still in development. I wish CKT luck, but that looks like a big expensive heavy engine with no history. Personally I would not fly behind an engine without a proven service history, certified or not. Which leads me to another point.
Love the CD155. Doing the CKT because I want a larger plane to haul 4 people and gear to the back country. And I'm impressed with the engine and I want to give it a try. There isn't anything else available at the right HP and weight.
To continue to be the wet blanket and crush hope (kidding big fan of diesel but lets be real). several aviation diesel engines have been announced and in development for years (decades) in the past. DeltaHawk and Gemini come to mind. The DeltaHawk has been around for over a decade with many announcements, next year they will have certification or something, year after year. It is a 2-stroke diesel, and they have prototypes flying. A few years back they offered them for RV builders, FWF $80K or $90K I recall, and they install it. This is 100% FWF, systems and instrumentation. You are their test bed for getting it certified, which it is not yet as far as I know. It is 180 HP and weights about what an angle head IO-360 weighs, they claim. DeltaHawk is a direct crank to prop drive, no PSRU, saving weight and complexity. Two stroke diesel there is no valve train. I would love to see that come to market at a reasonable DIY kit price. Anyone flying a DeltaHawk?

And these diesel engines are better than a Lyc IO360 or IO540 why? One reason I see is Av gas (leaded) may be restricted or ended if some groups have their dream.... It is likely Kerosene / Diesel / Jet-A, will remain in production longer for trains, ships, semi trucks and John Kerry's Biz jet.. I don't think this will happen in our life time, but 2020 a lot changed fast. The promise of much better diesel fuel economy? OK sure but the pay back time saving a gallon or two an hour will be long for the extra cost, especially flying just a few hundred hours a year. You don't see many diesel engines claiming big fuel savings. Frankly judicial use of power and mixture in Lycoming can reach pretty excellent SFC (specific fuel consumption).

Vans RV9/Wilksch 120 hp diesel. 974 lb empty. 900-1000 fpm climb. Cruise 140ktas, 5 gph. top speed 148ktas or so. Engine cost $18,000. I did nothing special to make it so light. The engine is 220 lb, or about 25 lb lighter than an O-235 of equal HP.

Sportsman/CD155 diesel. Empty 1501 lb. 1000 fpm. Cruise 135ktas @ 6.1 gph. Top speed 142ktas. Cost around 45K, but I spent more because I was developing the first installation on a Sportsman.

You are absolutely right about "rolling your own" engine from a junkyard. Not a good idea. It can be done, but be ready to spend a LOT of money and time making it happen, again and again, until you get it right.

With regard to the weight of the CKT package, maybe I didn't explain it well. The advertised weight of 506 lb. includes EVERYTHING FWF except the prop. I have personally weighed it side by side with a Continental O-470 FWF package w/o prop and the weight is within 5 lb. From what I've been able to find, a Lycoming IO540 "installed" weight is about the same. Because of the turbo, the CKT will maintain 200 hp continuous power to above 10K', so it'll be pretty close to an IO540 WOT at 7500', and better at higher altitudes.

I have followed DH and many others for years. Also some gasoline engines. Shows just how difficult it is to develop a new engine and bring it to market. Not for the faint of heart or pocketbook.

Who said diesels were better than Conti or Lyc? I only said they had some advantages. Fly one for awhile and you'll understand. Here are a few: 1. Ease of operation. No mixture, no plug fowling, no hot start issues, no carb heat, no prop control (at least on some), no priming, no LOP/ROP concerns. 2. Safety. MUCH less chance for a fire in case of an accident. Jet A / diesel is much less volatile. Diesel exhaust fumes won't kill you like CO will. It'll make you sick, but you'll live to fly another day 3. Better for the environment. No lead, less NOX, less fuel burned. 4. Much more efficient. In some cases this also means more payload because less fuel is required. 5. As you mention, Avgas isn't going to be around forever; JetA will be with us a lot longer.

Folks, I'm not here to say diesels are better. I fly a Cirrus and a Cessna 180 with Continentals. I love them. They're great. They have advantages over the diesel. But I am enamored with diesels, and since this is the "Alternative Engine" forum, it's fun to discuss alternative engines.
 
...and

As with everything, with the advantages, diesels have some disadvantages, too.

An honest discussion about the merits of diesels must also include the disadvantages in order to make an informed decision...

I follow the diesels, too. I would LOVE to see a viable option for the Rv-10!
 
I have a brand new 390exp119 on order for my 14. While it took some time, I'm at peace with that fact. Is what it is. It should be fine for 10 years or so.
However, for the long term, Vans needs to get together with Lycoming and design something that uses Jet A. For simplicity and viability, eventually there should only be on fuel pump at the airport.

https://www.aviationconsumer.com/industry-news/lycomings-diesel/
 
I think we are missing the point of the OP and many auto engine conversion fans, and that is not buying a $50K commercially available engine. They dream of going to the automobile salvage yard, buying a used engine for a few $1000's from a wrecked vehicle and throwing it in their sky scooter, and beating the snot out of Lycoming powered planes with their "modern" engine. He wants to tinker and develop not buy off the shelf (I think that is what he is saying). Commercial certified aviation diesels like the Austro E4 in the Diamond DA62 light twin are great (I think never flew one)... but the plane cost over $1M USD.

I'll start by saying I value your input and playing the devil's advocate. It helps everyone to stay grounded and remember it won't be easy to go against the grain. I don't feel there is a need to label anyone for wanting to think outside the box. Great ideas come from all sorts of places and we all know more ideas fail then become successful. But please, continue to prove why no one should fly an RV-10 behind an engine burning Jet-A. It makes for good conversation.

To address what it is you think I'm doing... I don't have a dream of dragging an engine from a salvage yard. Sure people do it, but I prefer to start with a new engine (aviation or other) to put into my plane. I want to know what abuse that engine has lived thru. I'd be perfectly happy to buy an off the shelf aviation diesel from a manufacture that has already gone thru the trouble to make it work. Do I have that option for an engine that is right for the -10? I'm open to suggestions.

Yes, right now my plan is to start with a non-aviation diesel engine and convert it to fit in an RV-10. I may find out very early on that I took the wrong path. I have a feeling that the weight of the FWF assembly is going to be the early killer. If I can make the weight work then I can continue moving forward. I'm not afraid to try and fail because I'm not going to ignore safety and be reckless. I'm simply looking at other options because I do feel like going to a Jet-A burning engine is the right choice.

Yes, I know doing something different is more time, more money, more headache, ... I like building things. Yes, I like to fly too. Some day my -10 will fly but until then, I can enjoy the build. :)

Cheers,
 
http://www.ac-aero.com/

AC-AERO is scheduled to begin deliveries of the HIGGS engines after EAA Airventure this year. According to Karl Grove Lead times are 12 weeks and they do have many reservations already in the hopper. So at this point delivery without a reservation is likely early 2022.


They also have a liquid cooled Lycoming cylinder that they offer if jumping on the "new" engine bandwagon is to "experimental"

.
 
I've looked all over the site and can find no information on these engines test running and validating durability and performance running on dynos or in airplanes.

It seems unbelievable to me that they can release so many engine designs simultaneously. Even the big aero engine companies don't do that.

It would be good for Karl or Andy to step in here and bring us up to date on these aspects.

I've talked to Andy at Reno a few years back and like the design innovation here, he's a smart guy. Hopefully it works out well but there are a lot of unanswered questions.

http://www.ac-aero.com/hawkrv10/
 
There would appear to me to be even more that creates questions.

The listed stroker kits make some some pretty substantial HP gain claims but no mention of torque improvements. Is there a torque curve that goes with that? I'd think that would be a big selling point.

Likewise, what are the torque values of the two cycle offerings; a common shortcoming of this application?

Literature is cleverly worded. Engine envelope is highlighted as are other comparative characteristics (weight). What are the expected added weight, cooling drag, etc. impacts from the filled water cooling system? Way more questions than answers even for a non-recip engine person like me. The carefully chosen wording in the releases really raises my skepticism but that is my nature.
 
Liquid-cooled cylinders as an aftermarket option for a Lycoming? That's definitely interesting, although I'm a bit skeptical, especially about the purported weight savings. You shave off the cooling fins, but then add a pump, hoses, radiator, and coolant.
 
Likewise, what are the torque values of the two cycle offerings; a common shortcoming of this application?

The 2 stroke should have very high HP compared to a 4 stroke of the same displacement- twice as many power pulses. HP is the quantitative measure of work, not torque.
 
I’ve got to be careful here as I’m discussing something with someone who is well respected by everyone including myself. HP is a factor of torque and rpm. It is as co-dependent a relationship as current and voltage. In my opinion, HP gets too much credit (or torque not enough) when it comes to turning a prop. To all of you ready to jump in (on me); Yes, I’m aware of the influence of fixed and CS props when converting shaft HP into trust. Flame away boys. I don’t mind being taken to school.
 
Higher torque means you don't have to spin up the engine to develop horsepower. Sure it makes 180hp at max RPM, but rarely do we cruise at 2700rpm. What RPM do we need to have 75%, or 135hp available? Do we need 2300rpm to develop cruise power, or is the torque curve look like a cliff and need 2500rpm?

Using typical units, hp = ft-lbs x rpm / 5252. So 180hp at 2700rpm is 350ft-lbs. If the torque curve is perfectly flat, that's still 150hp at 2300rpm. If the torque curve falls like a cliff and is only 250ft-lbs at 2300rpm, we only have 110hp or 61% available.

So yes torque is important, but RPM is important too. Volts x Amps = power. Torque x RPM = power.
 
I’ve got to be careful here as I’m discussing something with someone who is well respected by everyone including myself. HP is a factor of torque and rpm. It is as co-dependent a relationship as current and voltage. In my opinion, HP gets too much credit (or torque not enough) when it comes to turning a prop. To all of you ready to jump in (on me); Yes, I’m aware of the influence of fixed and CS props when converting shaft HP into trust. Flame away boys. I don’t mind being taken to school.

Torque doesn't tell you much which is why all aero engines are rated by HP rather than torque. HP is rate of work, torque is force over a distance.

Here's a video I did on the subject: https://www.youtube.com/watch?v=DXN9WW-qpV4
 
Torque doesn't tell you much which is why all aero engines are rated by HP rather than torque. HP is rate of work, torque is force over a distance.

Here's a video I did on the subject: https://www.youtube.com/watch?v=DXN9WW-qpV4

My line of thinking is more in line with David Z's. You can never divorce the two co-dependents but consider this. This is true in any system but more evident in synchronous or constant rpm applications.

The system balances out where torque meets counter-torque.

I'll state again that HP gets too much credit in our applications. Reference David Zs post. Low(er) torque in our aircraft engines would be like trying to accelerate your car with only high gears in your transmission. High(er) torque means being able to be more aggressive with your prop settings or twist for FP applications; thus, more thrust or vehicle speed for the given RPM (an operator selected variable with limits).

I would disagree that torque doesn't tell you much. I speaks volumes to me. I would expect some some helo pilots, ship engine room engineers, etc. would state similarly.

Why are things rated in HP? Probably convention. The unit of measure is actually quite dumb but it has deep roots. BTW, do our brothers in the true north think in HP or watts when talking among themselves? I'm serious.

A minor correction to what was posted.
Force over distance is the definition of work.
Force applied at a distance better describes torque.

BTW. What started this drift was the (lack of) info on the AC Aero website regarding the Higgs diesels.

Very respectfully submitted. Cheers boys.
 
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Torque doesn't tell you much which is why all aero engines are rated by HP rather than torque. HP is rate of work, torque is force over a distance.
Consider cars with Iternal Combustion vs. Electric drive. If you're looking to win a race, do you want a 200HP ICE? Or do you want a 200HP Electric? The peak HP is the same, but the torque curve on the Electric is pretty much flat (and high) from 0 to max speed. The ICE won't start building any torque (or HP) until the speed comes up. So every time the cars need to accelerate in a race, the Electric will walk away from the ICE. That's the torque curve working for you.
 
My line of thinking is more in line with David Z's. You can never divorce the two co-dependents but consider this. This is true in any system but more evident in synchronous or constant rpm applications.

The system balances out where torque meets counter-torque.

I'll state again that HP gets too much credit in our applications. Reference David Zs post. Low(er) torque in our aircraft engines would be like trying to accelerate your car with only high gears in your transmission. High(er) torque means being able to be more aggressive with your prop settings or twist for FP applications; thus, more speed for the given RPM (an operator selected variable with limits).

I would disagree that torque doesn't tell you much. I speaks volumes to me. I would expect some some helo pilots, ship engine room engineers, etc. would state similarly.

Why are things rated in HP? Probably convention. The unit of measure is actually quite dumb but it has deep roots. BTW, do our brothers in the true north think in HP or watts when talking among themselves? I'm serious.

A minor correction to what was posted.
Force over distance is the definition of work.
Force applied at a distance better describes torque.

BTW. What started this drift was the (lack of) info on the AC Aero website regarding the Higgs diesels.

Very respectfully submitted. Cheers boys.

Torque doesn't take rpm into account.

HP isn't used by convention, it's used to compare or quantify how much work an engine can perform. You can't do that with torque alone.

HP isn't tangible in the sense that you can measure it directly like torque and torque IS the motive force, however to be able to compare rate of work and one engine to another, HP (or kilowatts in SI units) is universally used by the engineers who design and test all types of engines. Maybe the engineers know something you don't...

If you compare engines based only on torque, take this example- PT6 engine with 90 lb./ft. of torque sounds pretty weak compared to a big diesel with 800 lb./ft. @ 1200 rpm however the diesel is only making 183 HP while the PT6 is making over 500 since the power turbine spins at around 30,000 rpm. The "weak" PT6 can do almost 3 times the work of the "torquey" diesel.

Torque is defined as a twisting force or torsion, over or at a distance from the center of rotation, however as demonstrated in my video, applying torque without movement results in zero work being performed. HP conveniently adds rate (rpm) to the equation to be able to quantify work done.

More torque at a given RPM= more HP.

My video does a real world acceleration test shifting at torque peak rpm vs. power peak rpm. Since we're accelerating a mass over time or distance, Work= F X D. Power= F X D/ Time (rate of work). This is little different in concept from amps X volts= watts which is power. Amps or volts alone tells you little.

Area under the HP curves defines how much work an engine can perform over its useful rpm range so coming back to the Higgs Diesel, that is what matters in motivating an airplane.

“Facts do not cease to exist simply because they are ignored” –
Aldous Huxley
 
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Guess I can be snarky too

Mr. Farnham. Understanding the differences and relationships between force/work/power/energy puts one's understanding of related ahead of most. Still, people hear what they want to hear; see what they want to see. To your comments

Torque doesn't take rpm into account.
I assume you're referring to my comment about system balancing where torque meets counter-torque. Yeah, I probably should have used the adjective "instantaneous" but it is still correct. An imbalance between the two and the system (rotating mass) keeps accelerating.

HP isn't used by convention, it's used to compare or quantify how much work an engine can perform. You can't do that with torque alone.
Sure it is. I was referring to the unit of power. I didn't say it should be rated in torque. Watts or Joules per unit time make much more sense. The unit is now ingrained so it is what it is

HP isn't tangible in the sense that you can measure it directly like torque and torque IS the motive force, however to be able to compare rate of work and one engine to another, HP (or kilowatts in SI units) is universally used by the engineers who design and test all types of engines. Maybe the engineers know something you don't...
Gee. I guess that's an insult. There's a lot I don't know. Once again, I was talking about the unit, Not saying it should be XXX torque rated@yyy. I've got background in liquid propellant rocket engines, gas turbines, and their related systems. I'm a pretty good engineer

If you compare engines based only on torque, take this example- PT6 engine with 90 lb./ft. of torque sounds pretty weak compared to a big diesel with 800 lb./ft. @ 1200 rpm however the diesel is only making 183 HP while the PT6 is making over 500 since the power turbine spins at around 30,000 rpm. The "weak" PT6 can do almost 3 times the work of the "torquey" diesel. Once again, never said that. Don't know where you pulled that one from. I did say HP gets too much credit or torque too little. Why don't we fly behind two cycle engines? Their SHP/weight is better. It wouldn't because of fuel issues and the four cycle path was chosen long before anyone really cared much about hydrocarbon emissions (where the vast majority of two cycles are down right criminal). Might have a little to do with the fact their torque curves flat blow. WOT would be the only real PP setting. Regarding the turbine example. Torque is the primary driver behind spool-up time. Metallurgical requirements further limit this

Torque is defined as a twisting force or torsion, over or at a distance from the center of rotation, however as demonstrated in my video, applying torque without movement results in zero work being performed. HP conveniently adds rate (rpm) to the equation to be able to quantify work done. This could be said much better though you did change the verbiage above slightly from the original. You initially posted that torque is force over a distance. I politely said that better described work and that force applied at a distance better described torque (both FxD). That is still true. One is integral and one is instantaneous. There's that word again.

More torque at a given RPM= more HP. Yes and no. The mathematical relationship is indisputable. The physics and kinematics are not as linear as the math. Two of your countrymen pointed out as have I, it's not just about HP. Between two prime movers with equal HP@RPM ratings, give me the one with the better torque curve every time

My video does a real world acceleration test shifting at torque peak rpm vs. power peak rpm. Since we're accelerating a mass over time or distance, Work= F X D. Power= F X D/ Time (rate of work). This is little different in concept from amps X volts= watts which is power. Amps or volts alone tells you little. I actually watched it. It was well done. It still falls back to your established view point, See above and below

Area under the HP curves defines how much work an engine can perform over its useful rpm range so coming back to the Higgs Diesel, that is what matters in motivating an airplane. Once again, you state an indisputable mathematical relationship but it shouldn't be applied here. I can integrate as well. A better example of a proper application would be the required mission SHP integrated over time, not just the acceleration. Your one fellow countryman gave the electric motor comparison. Apply it to your logic/example here. The constant torque would provide a very steep acceleration curve that would then flat line. Using your method, integrate that area for the same time that your Bimmer took. A curve that approaches a pseudo box shape gives you way more area thus calculated work versus your ICE triangle. I look forward to reading your replies to both of your fellow countrymen that weighed in. Sorry. If a Higgs diesel is a two cycle engine, show me both the HP and torque curve. The website sure doesn't.

“Facts do not cease to exist simply because they are ignored” –
Aldous Huxley
"He who smelt it, dealt it!"
Anonymous

I still respect the heck out of your work and enjoy reading your posts
 
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Whether we rate power by Kw, HP, or ant pushes is irrelevant, choose your favorite power units, they all quantify RATE of work done.

More torque at a given RPM ALWAYS = more HP. The math is indisputable:

T x RPM/ 5252= HP T is a numerator. Prove me wrong.

I have no preconceived notion that HP is somehow "better" or more relevant than torque, I merely demonstrate the relationship between the two. You can't have HP without torque and you can't have power without movement.

If you can prove my statement wrong about area under the HP curve, please do- mathematically. I never said anything about peak hp which is rather meaningless.

I also wish Higgs would publish HP, Torque and details on the durability testing to date.
 
Turboprops set power with two gauges. The torque gauge and the prop RPM gauge. I'll pick on the Beech 1900D since I have a boat load of time flying them.

Takeoff power is 1279hp at 1700rpm and 3950ft-lbs. It goes like stink with both engines going full bore. Even with an engine feathered (sim experience), it's still climbing 500fpm and 125kias. There was an event several years ago where the crew did a go around, but forgot the prop levers at the cruise setting. They had both engines at 3950ft-lbs and 1400rpm. The RPM reduced by 300 cost them 225hp per engine, and scared the feces out of them. To make the same power at 1700 take-off RPM, it would have been 3250ft-lbs. Not surprised it climbed like a gutless wonder and scared the pilots.

The power turbine on that engine spins 27000 rpm, and is roughly 250ft-lbs of torque. That's less torque than a IO-320 at 2700rpm. Yet the 1900 power turbine is harnessing a huge amount of power.

Remember RPM x ft-lbs / 5252 = horsepower
 
Whether we rate power by Kw, HP, or ant pushes is irrelevant, choose your favorite power units, they all quantify RATE of work done.

More torque at a given RPM ALWAYS = more HP. The math is indisputable:

T x RPM/ 5252= HP T is a numerator. Prove me wrong.

I have no preconceived notion that HP is somehow "better" or more relevant than torque, I merely demonstrate the relationship between the two. You can't have HP without torque and you can't have power without movement.

If you can prove my statement wrong about area under the HP curve, please do- mathematically. I never said anything about peak hp which is rather meaningless.

I also wish Higgs would publish HP, Torque and details on the durability testing to date.

I could do another bulletized reply but I'll let the previous posts speak for themselves. I will say again that no one will argue validity of the aforementioned simple mathematical relationship. I stated the same is not true for the related kinematics and physics and stand by this statement. If that were the case, the very torque curve you published in your video would more linearized (both positive and negative slopes). I would both peak and cross a perfectly straight power "line" at 5252. Interesting
 
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Torque alone means nothing!

I could do another bulletized reply but I'll let the previous posts speak for themselves. I will say again that no one will argue validity of the aforementioned simple mathematical relationship. I stated the same is not true for the related kinematics and physics and stand by this statement. If that were the case, the very torque curve you published in your video would more linearized (both positive and negative slopes). I would both peak and cross a perfectly straight power "line" at 5252. Interesting

Here's something that I posted in response to another thread, but it's applicable here:

Torque alone doesn't make anything go! Torque is a measurement of force only and is but one component required to motivate something. To actually move something, we need to do "work" which is defined as force x distance. And doing that "work" in a finite amount of time requires "power" which is the amount of work performed in specific amount of time or work/time. For example, a car's brake can apply force or "torque" to the wheel(s) of a car parked on a hill to keep it from rolling, but it certainly can't apply torque while rotating the wheel (work) and it definitely can't rotate the wheel very fast...

Let's try a little though experiment:

Imagine a person with a long torque wrench, say like this 3/4" drive 600 ft-lb model Torque Wrench

With this torque wrench, we can apply up to 600 ft-lbs of torque to something...maybe even a prop hub. How much torque did you say that IO-550-N makes at 2700 RPM and 310 HP?*

OK, so said person (or people) can use that wrench to apply torque to our airplane's prop hub, but to make the plane move we actually have to turn that prop, i.e. do work on it. Of course, even though our torque wrench person is capable of applying a lot of torque with that torque wrench, he's probably going to get tired after trying to turn our propeller more than a few revolutions (doing all that "work") but more importantly, he probably can't turn it very fast while applying all that torque, certainly not 2700 RPM. I.E. he can't make much power.

So you see, torque is not what makes airplanes go!

*So the IO-550-N making 310 hp at 2700 RPM is producing 603 ft-lbs of torque. How much power do we get with 603 ft-lbs of torque at only 2000 RPM? About 230. Is the plane going to go as fast with that same torque at 2000 RPM? Not likely! Thus, as I said, it's actually power that makes our airplanes go fast.

Skylor

p.s. Horsepower = Torque*RPM/5252. Torque is our measurement of force, "revolution" is our measurement of distance (work) and "per minute" is our "over time". Power = work over time (work/time). The 5252 is simply a unit conversion factor of 550*60/Pi. Part of the reason that it's believed that "torque" is what makes things go is because aircraft engine output figures are very often compared at the same RPM (2700) and thus the torque values of engines of different power are directly comparable...but torque without a measurement of distance over time (RPM) does not tell us anything about the capability of an engine and how fast it can make an airplane go.
 
@David Z.Think about it another way. The props were set wrong increasing the counter torque required at their input shafts. Thus, the engine couldn't make or increase horsepower. Not having all of the details, a lower pitch setting would probably have been a better option at that point versus more available power. Can't say for sure without such but you still have to consider the whole system.

@Skylor. No one disputes the theory but the real world is full of alligators. Frictions, volumetric (in)efficiencies, unstable/inefficient combustion... a butterfly valve can only affect air mass flow so much in a constant volume machine (at a given RPM). If the world was so linearized and straightforward, anyone could be an engineer, which I assume you are. Liquid rockets are fun but scary. The saving grace is having a typical mission for one is usually less than 500 seconds. Large Industrial Gas Turbines are both more and less so. They don't have to be light enough to fly so there's a lot of design margin build in. They have their moments. When a generator main breaker opens and you've suddenly removed 580,000 ft*lbs of (instantaneous) torque, a 300MW machine can try and overspeed very quickly. That relationship follows the math. The centrifugal loads go up by the square of the speed It gets everyones attention. I'll also assume you're a bit younger than me. Please solve this weight and energy density battery technology barrier while we can enjoy it. Imagine having full rated torque and super quick full rated power available to an aircraft.

Anyway, going back to the original point. It ain't just HP. Torque curves in two cycle machines tend to blow. If AC Aero/Higgs had good numbers, I'd assume they'd publish them. The careful wording in their releases really peaks my skeptical nature. Hey, would love to be wrong there.
 
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