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Turbotech engine video from AOPA
- Thread starter Walt
- Start date
I’d like one but would wait until there is a 180hp version
Shawn.m.halbritter@gmail.
I'm New Here
wish there was a price tag
With how expensive piston engines are it wouldn’t be that far off from a thunderbolt build. If TBO is truly 3000 and as reliable as a PT-6 it would be even closer.
Toobuilder
Well Known Member
“….Could this mini turbine engine revolutionize general aviation…”
Forgive me for being a bit skeptical, but I’ve heard this line many times before.
That said, I am certainly rooting for one of these guys to actually come out with a viable product.
Forgive me for being a bit skeptical, but I’ve heard this line many times before.
That said, I am certainly rooting for one of these guys to actually come out with a viable product.
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I heard Sport Class ( or what ever their revised name is) is updating their allowable engines to include turboprop & other powerplants so maybe eventually we will be seeing some huff&puffin racers turning pylons in New Mexico soon.
Maybe a Turbotech may be one of them.
Maybe a Turbotech may be one of them.
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The idea here isn't new regarding heating oxidizers (and fuel for that matter) to increase fuel efficiency for sub-sonic combustion. I'm envisioning the "weak point" as far as maintenance and parts life expenses moving from the Hot Gas Path/Turbine section to the heat exchanger. I'll wager money on it even. There's really a big three of parameters that guides actual xfer; internal and external film coefficients and the parent material conductivity. The thinner the HEx walls, the better. Of course being less "robust" will affect their service life. Would also guess that most related operator service interval life limits will wind up being starts based vs hours based.
BTW, the efficiency gains comes at a net power decrease as compressors are fixed volume machines. This is just a fact and ignores potential other limitations.
The air heating approach isn't new. It works well on paper and in a performance test. Like many abandoned projects, the fuel costs savings probably won't match the HEx expenses.
I wish them well.
BTW, the efficiency gains comes at a net power decrease as compressors are fixed volume machines. This is just a fact and ignores potential other limitations.
The air heating approach isn't new. It works well on paper and in a performance test. Like many abandoned projects, the fuel costs savings probably won't match the HEx expenses.
I wish them well.
If no one even tries then we will be stuck with 60+ year old tech forever…
No they don’t behave like piston engines. They are actually super simple once you understand the differences.
NORDO Industries LLC
Well Known Member
I reached out to Gogetair a few months ago for pricing, and the TP-R90 engine/prop option was an extra €170k. At current exchange rates that's ~USD$193k
Freemasm,
I read about it. I too was intrigued the price suggested was $100,000 US. So, not too much more. High altitude benefits, smooth & quiet.
It is the fuel efficiency that was previously a deal breaker.
This could be it.
Daddyman58
That’s interesting I too thought it might have been in the $100k-120k range. I guess it is almost double that.
Toobuilder
Well Known Member
Well, unfortunately many firms completely bypass the "try" part and move straight into bold claims and pre production deposits. These guys get a lot of credit for having flying hardware, but the "revolutionize GA" part remains to be seen.
Just remember that under current rules, E-AB aircraft with turbines require an approved maintenance plan (that must be followed, including implementing factory service bulletins) and an “Experimental Aircraft Authorization” (a type rating for an aircraft without a Type Certificate). Additionally, with the exception of single seat, single engine turbines, you have to have an annual check ride with an appropriately rated check pilot (probably a DPE because there won’t be anyone else qualified….). Ever wonder WHY the Subsonex and BD-5J’s are singe seat with one engine?
Now rules can be changed…just look at teh implementation of MOSAIC as an example…or maybe don’t…..
Now rules can be changed…just look at teh implementation of MOSAIC as an example…or maybe don’t…..
Physics and metallurgy are both undefeated. Numerous attempts incorporating this cycle have been attempted. The typical scenario is elation -> reality -> disappointment -> abandonment -> removal. If a HEx cannot be made to be reliable in a ground bound, weight not an issue, ugly AF, industrial gas turbine, what are the chances of it being successful in an aero application?
You can invest in AC Aero as they're supposedly back in business. They've been telling the public they've figured stuff out that no one else has for many years now. I'm sure they'd take your money.
Hill said the same thing when asked why the GT50 didn't have a recuperator. It's been tried but never works out for flight usage.
Wonder how many acts of ccongress it would take to change that, as it is a major inhibitor for options like the one posted here. I somewhat understand the ratings and checkrides for a turbo-fan, but really doesn't make a lot of sense for turbo-props.Just remember that under current rules, E-AB aircraft with turbines require an approved maintenance plan (that must be followed, including implementing factory service bulletins) and an “Experimental Aircraft Authorization” (a type rating for an aircraft without a Type Certificate). Additionally, with the exception of single seat, single engine turbines, you have to have an annual check ride with an appropriately rated check pilot (probably a DPE because there won’t be anyone else qualified….). Ever wonder WHY the Subsonex and BD-5J’s are singe seat with one engine?
Now rules can be changed…just look at teh implementation of MOSAIC as an example…or maybe don’t…..
Paul, is that true for all turbines, or just turbojets? You know way more about this than me, and my memory of 61.58 is fuzzy, but I always thought it was written to include jets but not turboprops.
This is my reading of it as well. "turbojet" appears but I think this explicitly does not apply to turboprops.
Any thoughts Paul?
Well it’s always important to look at the latest versions of documents, and you’re right that currently, the Function Code references say “Turbojet”….but I have a copy saved from a while back that said “Turbine”…so I have some research to do…
Things like this get quietly changed from time to time - sometimes purposely, sometimes accidentally!
And, of course, to an engineer, a “Turbojet” is different from a “Turbofan”, so based on the current ruling, you shoudl be good with a high (or low) bypass fan!
Yes, I always thought this was silly as well, or at least the legal verbiage includes historical terms the engineering world finds imprecise. I believe it comes down to legal and regulatory spheres building upon specific language from many decades ago. But legally I'm just a layperson.
You are completely missing the point of my comment.
If no one ever tries anything new, then no progress will ever be made.
Consider that if Van himself never modified the first Playboy, the entire Vans line would not have been born.
And you're missing the point of mine.
They aren't trying anything new
They talk about the cycle (the easy part) but not how they've conquered the metallurgical challenges. I know which way to bet regarding any success.
Compared to other prime mover products in the market
Capitol Cost = Very High. At nearly $200K, nuff said..
Fixed O&M Cost = Probably even assuming no unexpected calendar life components.
Variable O&M Cost = Even at best I'm guessing, BSFC aside. Amortized/Levelized costs for Hot Gas parts would be higher but they are quoting higher TBO. Have not seen starts-based TBO numbers. The HEx will be a limited life, relatively fragile component. For that reason I'm going to expect the cost to actually be relatively high compared to the market.
This paints a very limited chance for any GA/EAB market penetration. The fact that the only offering is 140 HP significantly limits it even more.
Would like to be wrong here. I'll state again that I wish them success, as I do TurbAero and Delta Hawk.
Would the heat exchanger be susceptible of becoming a soot collector over time requiring regular cleanings to maintain its efficiency?
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Jjackh10
Well Known Member
Every exchanger I've been around needs periodic cleaning, I'd think this will be no different. Look inside a diesel pickup exhaust pipe. Even with a modern DPF system they get pretty dirty.
Jjackh10
Well Known Member
Is the reason to look at number of starts driven by thermal cycling the exotic alloy components? Or something else like extreme conditions inside while trying to get a turbine rolling? Or maybe both?
Would be hard to imagine any HEx in a similar application that wouldn’t foul. The soot (carbon) would at least be cleanable thus the heat transfer recoverable. I have no idea what the non-recoverable scaling and corrosive attack penalties would be over time. Would imagine JP-1 being way less aggressive than diesel which is certainly better than the #2 distillate common in my industry. There will be a performance degradation over operating time. Would assume design margin has been added for this. Of course, most any hard guarantee is based on a “new and clean” condition.
Yes. Thermal cycling is much harder on metallurgy than steady state conditions. Can probably consider this a universal truth though steps can be taken to lessen the effects.
Excellent video and I wish this company well. Improving the efficiency (bsfc) by using recuperators will be a key to their success. However, I'm old enough to remember the romance the auto and truck industries had with the Wankel engine and the gas turbine engine (1970s). Two excellent books from that era both by Jan P. Norbye: The Wankel Engine and The Gas Turbine Engine. Although almost all auto companies took out licenses for Wankel engines (John Deere went a long ways towards a practical aircraft Wankel engine) and most had development programs (Chrysler turbine car, Pratt and Whitney Canada snowplow truck and STP Indianapolis turbine car, Lotus 56) for gas turbine engines, very little came of the millions (when this was a lot of money) spent on these programs. And yes, recuperators (heat exchangers) were tried. So the auto, truck and light aircraft are "stuck" using 130 year old piston (ICE) technology. Perhaps piston (ICE) is the "sweet spot" for affordability (barely!), efficiency, power density and bsfc?
I do not disagree with your statements; my point is that there is ZERO chance of success if nothing is tried.
Even trying something that ultimately fails can lead to progress. Trying nothing GUARANTEES failure and ultimately, no progress.
I’m with you. It’s probably the most interesting development in the EAB world. That someone doesn’t know anything about it except it won’t work isn’t helpful or interesting.
Jjackh10
Well Known Member
Maybe a future side hustle cleaning and solution annealing the HEx sections.
I was excited to watch this video but surprised at all the negativity in the comments. Outside of cost, this seems exciting to a low time GA pilot like me. Can someone explain to me what I’m missing?
The fact my engine was certified 70 years ago, costs more than a luxury car and isn’t necessarily “bulletproof” has irritated/borderline angered me since I became a plane owner. I feel like our power plants are in desperate need of innovation and this seems like a path forward, even if it’s not yet the answer?
The fact my engine was certified 70 years ago, costs more than a luxury car and isn’t necessarily “bulletproof” has irritated/borderline angered me since I became a plane owner. I feel like our power plants are in desperate need of innovation and this seems like a path forward, even if it’s not yet the answer?
I don’t think you are missing anything. There is nothing available that replaces the Lycoming 200hp range of engines for our aircraft. If they do make one that can be a swap in, it will more than likely consume more fuel per hour and cost more overall to acquire and run. I still want one. If they become as reliable as traditional turboprops for the big planes then I think more people will want them one day.
Over time, most engineering solutions tend to converge into a "sweet spot", which is the point I was trying to make. Over the history of small (less than 350-400 hp) aircraft engines, there have been radials, inline, vee, inverted vee, and horizontally opposed. There have also been air cooled and liquid cooled. So some of the "innovation" you mention has come in the form of better metallurgy, better geometry, better oil formulation and filter design, which increased engine life from say 1000 hours to 2000 hours, yet is invisible from the outside. Magnetos, which are self contained and needs no outside power, ignition was and is common for this reason. Perhaps 20 years ago, the manufacturer of fuel injection systems designed and developed a computerized FADEC system with spark and fuel control like contemporary automobiles. The market (cheap pilots and aircraft owners) proved extremely limited and this system is no longer offered.
By the time a designer with a clean sheet of paper (or computer screen) works his way through the design parameters - air cooled vs liquid cooled, direct drive or geared, two stroke or four stroke, inline, vee, radial or horizontally opposed, economical (relatively!) to manufacture, the tendency is to arrive at our current crop of air cooled horizontally opposed aircraft engines.
However, innovation is happening. Look at the Deltahawk inverted vee liquid cooled four cylinder two stroke turbo and supercharged diesel (runs on Jet A) in the 200 hp range. Also look at the Rotax series, with their current 916iS, four cylinder, four stroke gasoline fuel, air and liquid cooled, geared and electronically controlled, up to 160 hp.
Although I wish the Turbotech company in France success with their turboprop engine, and I think the recuperator is the way forward for small turbine engines for GA due to the increased efficiency, I don't think the Brayton (gas turbine) cycle will ever displace piston engines for small GA aircraft.
And don’t forget how hard they can be to start! Can you imagine putting up with “hot starts” in your car? “Now slowly ease in the mixture knob….”
Why not?
If you don;t already know it, most people have found the the best way to make a small fortune in aviation is to start with a large fortune - and the world of engines is a great example of that. I have been playing around with flying machines for over half a century, and the only “new” engine company to achieve total market penetration has been Rotax - and they spent several large fortunes to do it. They HAD the only because they were making millions of motors for jet skis, snowmobiles, and what-have-you, and could let their profitable activities pay for the development into new industries.
Based on what we see at the big shows (AirVenture, SnF, Aero….), at any one time, there are between half a dozen and a dozen companies developing completely new engines for aviation. The players change every couple of years as companies sink into the swamp of failure while new ones climb out of the primordial ooze to try and gain a foothold on dry land. And yet in the fifty years I have been watching, Rotax is the only one that has achieved the success of Lycoming, Continental, Pratt&Whitney, etc….
Why is that? If anyone knew the actual firm answer to that, they’d avoid the pitfalls, climb the leader of success, and be “the new engine company that is successful”. My personal theory is that it takes such a huge long-term commitment to persevere through countless failures and expenses that most people and financial backers give up and go for something with surer short-term gains. DeltaHawk has been doggedly working on their engine for twenty years or more, and are just beginning to maybe see the point where they can actually make and sell enoug engines to say that they actually have one. But to get to the number of engines in the field that Lyc, Continue, Rotax have? Won;t happen in my lifetime.
Here’s the thing - all of the successful companies have taken decades of field experience - and failures - to reach a point where they have fixed the problems to reach a level of acceptable reliability. You have to have MILLIONS of accumulated hours before your engine is accepted as reliable enough to fly regularly. How do you get that kind of activity when GA is slowly shrinking? In the middle twentieth century, WW II provided unlimited government funding to help traditional companies build gobs of engines and through them into the field. I often tell people when I give talks that - historically - the greatest impetus to human technical development are wars and exploration. Right now, PBS (the maker of the little turbine engine that I fly) is learning a lot about their motor - and improving it - because they make them for drones being used in the Ukrainian conflict.
What will come along to push the development of the next GA engine?
Based on what we see at the big shows (AirVenture, SnF, Aero….), at any one time, there are between half a dozen and a dozen companies developing completely new engines for aviation. The players change every couple of years as companies sink into the swamp of failure while new ones climb out of the primordial ooze to try and gain a foothold on dry land. And yet in the fifty years I have been watching, Rotax is the only one that has achieved the success of Lycoming, Continental, Pratt&Whitney, etc….
Why is that? If anyone knew the actual firm answer to that, they’d avoid the pitfalls, climb the leader of success, and be “the new engine company that is successful”. My personal theory is that it takes such a huge long-term commitment to persevere through countless failures and expenses that most people and financial backers give up and go for something with surer short-term gains. DeltaHawk has been doggedly working on their engine for twenty years or more, and are just beginning to maybe see the point where they can actually make and sell enoug engines to say that they actually have one. But to get to the number of engines in the field that Lyc, Continue, Rotax have? Won;t happen in my lifetime.
Here’s the thing - all of the successful companies have taken decades of field experience - and failures - to reach a point where they have fixed the problems to reach a level of acceptable reliability. You have to have MILLIONS of accumulated hours before your engine is accepted as reliable enough to fly regularly. How do you get that kind of activity when GA is slowly shrinking? In the middle twentieth century, WW II provided unlimited government funding to help traditional companies build gobs of engines and through them into the field. I often tell people when I give talks that - historically - the greatest impetus to human technical development are wars and exploration. Right now, PBS (the maker of the little turbine engine that I fly) is learning a lot about their motor - and improving it - because they make them for drones being used in the Ukrainian conflict.
What will come along to push the development of the next GA engine?
“…learning a lot about their motor - and improving it…”
Exactly. If you never try you can never fail but you can never progress, either.
Two parameters that do not scale well going from large gas turbine engines to small ones are Turbine Inlet Temperature (TIT) an blade tip clearance (either compressor or turbine), both related to efficiency, or bsfc. Higher TIT improves efficiency, but requires internal blade cooling and exotic alloys to achieve which are expensive. As the turbine size is reduced, the blade tip clearance as a proportion of the blade length increases, reducing efficiency.
In the case of Turbotech, they have basically made and engine out of a turbocharger, with a centrifugal compressor and a radial inflow turbine wheel. Nothing wrong with a centrifugal compressor, Frank Whittle used one on his first W1 prototype. But the pressure ratio is limited with a centrifugal compressor, which again limits efficiency. The radial inflow turbine is a single stage element which is probably not internally cooled. In general, a multi stage axial blade turbine is better to extract the power needed to turn a propeller. Turbotech seems to have placed all of their faith in the recuperator (heat exchanger) to make up for these design choices.
Again, I wish them well, and they do have a flying engine for which I congratulate them. But until I see a light turboprop engine that is cheaper and has as good or better bsfc and TBO and overhaul costs in the power range of 150 to 250 hp, I think a piston aircraft engine is a better choice.
With the way the prices and wait times are going, you may not have to wait long…
Over 40 posts on this thread and yet I'm the first to mention the horrible fuel economy of jet engines. Paul will tell you that his SubSonex is not a practical traveling aircraft, due to fuel economy/fuel tank limitations. An RV will have the same issue.
Fuel consumption is discussed in the video in post #1 of this thread, and the associated article states:
Better fuel consumption through the magic of technology is kind of the whole point of this engine:
Reality is often a tough pill to swallow.
BIG Thanks to all the folks with practical knowledge in this area and sharing the realities of turbine engine design.
What we need is a scaled down PT6, of course that's not reality either.
Some folks would say what we need is a turbo compound rotary, but that's another can of worms. Really we need any innovation that can break the stranglehold duopoly/oligopoly the engine manufacturers have which is making prices insane. I'd love for that to be a small combined cycle turbine but we still have to obey the laws of thermodynamics.
That is what I get for commenting without watching the video. Hopefully, their claims are true!
For what it's worth, even if this engine costs $100k and has its own unique maintenance requirements, I could see it being quite attractive in the very light helicopter market. I have to imagine the Guimbal people (also in France) are keeping an eye on it, as the idea of replacing their derated Lycoming with a lightweight turbine makes a lot of sense.
