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Turbine on RV ?

I just got quoted from a lycoming dealer for a brand new IO-360-M1B, I mean factory new with new parts/metal…96k without the core and a year wait. So it is VERY comparable with a piston engine if you compare apples to apples. You are not buying factory reman or factory overhaul for that jet.

Fun fact, I had to specifically request brand new pricing, he said they don’t even quote it because it is so astronomical and most people don’t even bother buying it.

Yeah, no. I'm not buying that one, considering that you can order the brand-new same engine from Vans today for $42,850, and an IO-540 for $67,650. Care to share who your lycoming dealer was?

The year-long wait on a new engine I will believe, yes, but your price is about 2X.
 
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I just got quoted from a lycoming dealer for a brand new IO-360-M1B, I mean factory new with new parts/metal…96k without the core and a year wait. So it is VERY comparable with a piston engine if you compare apples to apples. You are not buying factory reman or factory overhaul for that jet.

Fun fact, I had to specifically request brand new pricing, he said they don’t even quote it because it is so astronomical and most people don’t even bother buying it.

The price i quoted was factory new from Lycoming sold through VANs. Check the VANs web site. It’s there OAM pricing which you get when you build an RV.

So the comparison was apples to apples for any RV builder.

Oliver
 
Here's an important point I rarely see discussed: Think of tech progress like inverse inflation, a $1 MEMS gyro is orders of magnitude more reliable than a vacuum pump mechanical gyro. In other words a dollar today buys you more safety margin because of tech advances. That means sticking with the same hopelessly outdated tech is making our engines LESS safe over time, when adjusted for technical progress. Really think about it. The advances in materials, manufacturing, sensors, computing power, modeling, AI models for early warning of failures, real-time oil analysis, exhausts gas analysis, vibration characterization, and on and on. All that innovation is slipping past us and we will pay for that the same way we always do, with blood.

I'm incredibly excited to see ANYONE working on ANY type of forward progress for GA powerplants. Turbine, modern mogas/diesel, electric (though turbines take the cake on cool-factor). I'm building a 14, and unquestionably the absolute most disheartening things for me is how hopelessly outdated my powerplant options are, followed closely by the truly disgusting cost of avionics. The price is eyewatering and brutal, but it's something I can at least work at paying for. The fact that my $50-70k engine will be more similar to the Wright Brothers engine than modern technology though... that just crushes my soul. I don't attribute malice to Lycoming or the people there, I fully expect they are fantastic individuals with the best of intentions. But they have absolutely no economic pressure to innovate. Quite the opposite in fact, because pilots are so overly conservative and negative about new tech. And that's where I really challenge pilots to question their attitude.

We lost the spirit of innovation somewhere between the Wright Brothers and today. As an engineer that makes me sad. I wish anyone innovating in GA the best of luck, and will support them with my wallet.
 
Here's an important point I rarely see discussed: Think of tech progress like inverse inflation, a $1 MEMS gyro is orders of magnitude more reliable than a vacuum pump mechanical gyro. In other words a dollar today buys you more safety margin because of tech advances.

All those $1 MEMS devices are orders of magnitude less stable than mechanical gyros
ahrs%20technology.JPG


As the "modern" aviation engines are concerned, you might want to check recent accident reports related to various types of diesel powered Diamonds. Falling from the sky one after another, HP fuel pump failure being the probable cause. Those engines are unreliable, expensive, heavy and relatively weak.
 
The fact that my $50-70k engine will be more similar to the Wright Brothers engine than modern technology though... that just crushes my soul.

Go look at SDS or EFII - you can drag that Lycosaurus kicking and screaming into the 21st century pretty easily.
 
Go look at SDS or EFII - you can drag that Lycosaurus kicking and screaming into the 21st century pretty easily.

Agree.
I’m excited to get the full SDS on my lycoming.
Thought about mags and mechanical fuel injection, but thought. Why?
 
…and

All those $1 MEMS devices are orders of magnitude less stable than mechanical gyros
ahrs%20technology.JPG


As the "modern" aviation engines are concerned, you might want to check recent accident reports related to various types of diesel powered Diamonds. Falling from the sky one after another, HP fuel pump failure being the probable cause. Those engines are unreliable, expensive, heavy and relatively weak.

…and the “cause that’s the way it’s always been done” attitude perpetuates the lack of any new progress.

Is the experimental part of our hobby for everyone? Most definitely not; most people want to follow and end up with a known quantity. They do not want or necessarily possess the required knowledge, will, or specific risk aversion, to go outside the box. That is perfectly fine.

Then, there are those who want to be leaders and Trail Blazers, knowing fully well that the outcome is not guaranteed and likely carries a greater risk. Also perfectly fine.

The issue that I have a problem with, is when the followers try to dissuade the leaders from trying something new, based on the “that’s how it’s always been done” attitude. Of course, this can be found all through history from the beginning of time.

Consider that if Van himself had not chosen to go outside the box and lead, there would be no RVs. The same can be said for others trying to move the hobby forward, instead of being endlessly stuck in the status quo loop.

I, for one, would be happy to see someone succeed with an alternative to ancient engine tech that we have now. There has to be a starting point, and there will be issues along the way but that’s how progress works.

Again, is it for everyone? No. For those whose choose to be on the leading edge, I respect your choice and hope for success.
 
But they have absolutely no economic pressure to innovate. Quite the opposite in fact, because pilots are so overly conservative and negative about new tech.

I would argue that litigation experience creates economic pressure on Lycoming against innovation. A $5 million judgment against Superior eliminated the Superior XP400 as an alternative to the IO390, and there really wasn’t any innovation involved at all - just “me too”. Innovation creates an even bigger bullseye for the attorneys.
 
Besting a Lycoming/Continental may be harder than most think ...

I don't think anyone is stopping you from designing and building your own engine and PSRU, just like they did. :)

To Matt's point ...

Take a look at the "Honda-nental" that was shown at Oshkosh (in the Continental booth) about 20 years ago.

As I recall when I saw it, 225HP and it looked alike a work of art! Lots of "innovation" (FADEC, 16 valves, liquid cooled(?), auto plugs, mogas or 100LL, etc.).

They had test run it on a Cessna 337, I think.

To my knowledge, it is still NOT available.

Now, if Honda, with its DEEP pockets either don't see the financial return, or they met unsurmountable problems, then this problem is not so easy to solve.

We may pick on the Lycomings (and Continentals) as being ancient technologically, but they work
 
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The issue that I have a problem with, is when the followers try to dissuade the leaders from trying something new, based on the “that’s how it’s always been done” attitude. Of course, this can be found all through history from the beginning of time.

Consider that if Van himself had not chosen to go outside the box and lead, there would be no RVs. The same can be said for others trying to move the hobby forward, instead of being endlessly stuck in the status quo loop.

To make it happen you need more than just the innovators. You need the early adopters that show success. Without the early adopters there is only one person with a great idea. Great example in Experimental aircraft is glass in the cockpit. It was originally in experimental but with the success shown by the early adopters it migrated into mainstream GA. On the other side an example may be the Eggenfellner Subaru conversions. Unfortunately the early adopters had issues.
 
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Take a look at the "Honda-nental" that was shown at Oshkosh (in the Continental booth) about 20 years ago.

As I recall when I saw it, 225HP and it looked alike a work of art! Lots of "innovation" (FADEC, 16 valves, liquid cooled(?), auto plugs, mogas or 100LL, etc.).

They had test run it on a Cessna 337, I think.

To my knowledge, it is still NOT available.

Now, if Honda, with its DEEP pockets either don't see the financial return, or they met unsurmountable problems, then this problem is not so easy to solve.

We may pick on the Lycomings (and Continentals) as being ancient technologically, but they work

Developing and certifying a new engine is a LOT of man-hours and money. If you succeed, it just gives you the engine; now you have to get it on airplanes, and that means finding a partner for production or doing your own STC (read: more time and money).

How big is the market? Really, really small. So small that you'll probably never come close to breaking even.

L&C engines are still around in large part because it's just too darned expensive to replace them. Just cranking out another one to an existing design incurs no R&D or certification cost.

The experimental market isn't burdened with all the certification costs and the associated requirements, so there's more freedom for new products (either components, systems, or whole engines) but the market there is even smaller still.
 
We lost the spirit of innovation somewhere between the Wright Brothers and today. As an engineer that makes me sad. I wish anyone innovating in GA the best of luck, and will support them with my wallet.

This is totally false.

There was likely naysayers about what the Wrights were doing and there has been throughout all of aviation history.
That didn't stop advancement then and it doesn't stop it now either.

The majority of that advancement has been paid for with other peoples money... along with just as many (or more) failures and loss of other peoples money.

Yes, sometimes even the failures produce beneficial advancement, but at this point in the game, the failure rate for development of small turbine power plants has been pretty much 100%.
That is a high enough failure rate to put some level of skepticism in people to wonder if it is even possible based on currently known science and properties of physics.
That will naturally have an impact on peoples willingness to gamble their hard earned money. Especially when the developer is taking deposits before they have even begun a flight and longevity testing program (it has happened more than once)
 
The Adept V6 is still crawling forward slowly and as it does so, the price now exceeds that of Lyconentals and will continue to do so as time marches on, costs add up and ROI gets further away.

Unfortunately, their intention to certify is likely to sink the project financially as it has with most other new aero engines in the last 2 decades.

Hope I'm wrong there. Would love to see this as another viable choice.

We're supplying two other companies with EFI on automotive based engines right now. Both in the prototype stage. We'll have to wait and see if they go anywhere.

Finally, Jack Kane of EPI fame has developed an O-200 replacement that looks excellent and is working on another new engine for a client. No details on the second project yet.

These projects are a lot harder to do and more expensive than most people think.

To truly succeed on a big scale, you'll also need to develop a proper support network as Lycoming, Continental and Rotax have done. Big $$ and time to do that past getting a reliable and durable engine built and validated.
 
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Looking at it another way

This is totally false.

There was likely naysayers about what the Wrights were doing and there has been throughout all of aviation history.
That didn't stop advancement then and it doesn't stop it now either.

The majority of that advancement has been paid for with other peoples money... along with just as many (or more) failures and loss of other peoples money.

Yes, sometimes even the failures produce beneficial advancement, but at this point in the game, the failure rate for development of small turbine power plants has been pretty much 100%.
That is a high enough failure rate to put some level of skepticism in people to wonder if it is even possible based on currently known science and properties of physics.
That will naturally have an impact on peoples willingness to gamble their hard earned money. Especially when the developer is taking deposits before they have even begun a flight and longevity testing program (it has happened more than once)

There are several small turbines, that have been around for a long time, that are successful. Maybe one of the issues is that we need an airframe designed around one of those instead of trying to adapt it to an aircraft designed around an ancient Lycoming design…
 
I don't think anyone is stopping you from designing and building your own engine and PSRU, just like they did. :)
I do not have the expertise to build my own engine, which is why I encourage other to innovate where I cannot. Avionics on the other hand... that's something I'm actively working on ;) Free and open source too.

All those $1 MEMS devices are orders of magnitude less stable than mechanical gyros
ahrs%20technology.JPG
This is a perfect example; this is the exact facile thinking that bothers me. MEMS gyros are definitively worse than mechanical gyros, no argument there, I have 4 sitting on my desk. They have a lot of noise and a strong (shifting) bias, non-linear responses, clipping and discrete integration errors. And here is where I see a lot of people pile on to new tech and write it off as a scam or at least not worth anyone's attention. As 'failed experiment'.

Now let's consider the previously unimagined world these inferior MEMS gyros have unlocked. You low-pass filter the data, then run it through a 15 error-state Extended Kalman Filter, and suddenly you have a super accurate gyro with several Khz response rates and zero drift. Couple that with 4 RTK GPS modules that have centimeter differential accuracy and a whole new world of possibilities open up (hint, remember how I was saying I'm working on an avionics project...)

In other words, taken as a whole, new technology always unlocks novel and unforeseen uses, and my frustration lies with measuring prototype-level tech innovation against the incumbent, number for number, then write it off as inferior. Exactly as this chart would imply of MEMS gyros. It's myopic, and it doesn't support innovation adoption, which is a key component of innovation. Even if a turbo is definitely worse in all metrics from a piston engine, you still can't say that it won't revolutionize GA. Maybe we find a way to very accurately determine when a failure is immanent with turbos, or find that they lend themselves well to a backup motor/battery to get you down safe. I would happily take that engine over one that could cut out at any time, even if it's "worse" in all other ways.
 
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There are several small turbines, that have been around for a long time, that are successful. Maybe one of the issues is that we need an airframe designed around one of those instead of trying to adapt it to an aircraft designed around an ancient Lycoming design…

There is more to just existing, to make one viable for our applications.
At many times the current cost of a Lyc or Cont there is no marketability.
 
Developing and certifying a new engine is a LOT of man-hours and money. If you succeed, it just gives you the engine; now you have to get it on airplanes, and that means finding a partner for production or doing your own STC (read: more time and money).

How big is the market? Really, really small. So small that you'll probably never come close to breaking even.

L&C engines are still around in large part because it's just too darned expensive to replace them. Just cranking out another one to an existing design incurs no R&D or certification cost.

The experimental market isn't burdened with all the certification costs and the associated requirements, so there's more freedom for new products (either components, systems, or whole engines) but the market there is even smaller still.

My point exactly!

If the combination of Continental and Honda could not see their way through, even after testing the "concept" at OSH 20 years ago, it is not likely that someone much smaller is going to get a product through ALL of the "HOOPS".

Building a new, ground up, certified engine is a much bigger deal than modifying something that exists so that it can fit into the experimental world.

Even the innovations that are "add-ons" to the Lycomings (SDS, E-mag, etc.) have taken YEARS of work by some very sharp people.
 
My point exactly!

If the combination of Continental and Honda could not see their way through, even after testing the "concept" at OSH 20 years ago, it is not likely that someone much smaller is going to get a product through ALL of the "HOOPS".

Building a new, ground up, certified engine is a much bigger deal than modifying something that exists so that it can fit into the experimental world.

Even the innovations that are "add-ons" to the Lycomings (SDS, E-mag, etc.) have taken YEARS of work by some very sharp people.

Not from a technology standpoint; it’s all about liability…
 
I think in the case of the Honda and Toyota aero engines, they could have seen those through to production had they wanted to. Management/ board decisions changed the direction and nixed the projects. No way these would have been profitable in the near term for either, given the millions spent.

One wonders why they began in the first place with the increased exposure to liability. I maintain some people up high in both companies fancied airplanes and thought aviation could bring automotive marketing spinoff possibilities, brand cachet or perhaps it was just an engineering exercise and training ground for the younger engineers.

No doubt they learned a few things as they did in their racing programs but I can't imagine the cost/ benefit ratio was too good.

At least Honda went on to produce the HondaJet.
 
Looking at the latest announcements from TurbAero I was wondering why one would ever put a turboprop on an RV (There are airframes where a turbine obviously makes sense but I am asking about RVs in particular.).


My biggest concern would be weight. The biggest advantage of a turboprop is usually lower weight, in exchange for higher fuel consumption (compared to a piston). And you are now carrying heavier fuel as well.

If you need to put a bunch of ballast up front, and have to carry more fuel, probably better off with something designed for that to begin with. The other advantage of a turboprop is more power at altitude. But then you run into flutter as you get higher, so it may not matter that you have the power.

If it ends up weighing the same, and fuel burn isn't too bad down low, why not?
 
There is one more thing to consider when doing an alternative engine - you really cannot treat the engine as a stand-alone thing.

Sticking to piston-engines for now:

1: Much of the mechanical reliability comes from running closer tolerances. These are only made possible by a rather constant operating temperature, which in turn requires liquid cooling.

Now if you don’t want to modify your airframe (or further down the line: don’t want your customers to have to modify their airframes), then all you can do is stick some radiator(s) up front in the nose. Where they don’t work well. You need them under/in your wings or in some P-51 style pod. There is a reason why a Kitty Hawk with its huge cooling opening would not cool well, and a P51 did.

So you need to modify your airframe.

2: You need computer power to run them, if you don’t want to be stuck with 1970s technology (and that’s already half a century ago). For that you need electricity. Your typical homebuilt does not have a system that is optimized for electric reliability. So you need modifications there. Engine busses, alternate electric sources, or any other strategy.

3: Unless you go with PWM pumps, an EFI system moves a LOT of fuel. Significantly more than mechanical fuel injection or a carburettor. If you don’t want to experience vapour lock misery, this means you need to place your fuel pumps very close to (or preferably inside) your fuel tanks. You really don’t want these pumps to suck the fuel in, as this pretty much guarantees vapour lock. Oh, and you need return lines. And maybe some header tank. So a redesign of your fuel system is called for.

4: You really need a constant speed prop for these to work well.

And by the time all is said and done, you’ve redesigned a significant part of your aircraft systems, plus a fair bit of the aircraft itself.

And then your next customer approaches you with yet another homebuilt design, and the whole process starts anew.

Like Ross said - this stuff is not simple and there is more to it than meets the eye.

When it works, it is soooooo good though! ;)
 
As others have pointed out, these are all technical challenges. While certainly significant, technical challenges are almost always solvable by clever engineers. The hard part will be everything else, namely getting early adoption. And they have to somehow do that while skirting around the Friends Against Aviation or letting the liability lawyers catch the scent of blood.

My biggest concern is how the engine will handle being started and stopped 10 times a day, while I sit in my RV and enjoy the beautiful music of a turbine spooling up over and over again :D
 
As others have pointed out, these are all technical challenges. While certainly significant, technical challenges are almost always solvable by clever engineers.

This is true, however with that comes the cost which has to be amortized over relatively low production numbers. Hence, new engine designs will rarely be cheap.
 
Standard, broken record type, economy of scale response =

Any new aircraft powerplant offering that doesn't utilize a vast majority of existing, repurposed parts and doesn't share an assembly line with another product line (non-aviation engine would be best) is not going to have a significant cost benefit.

I am cheering on the innovators but without the aforementioned, any market impact would be limited. Sucks but true.
 
Rotax has benefited from a very large manufacturing base across a variety of products. They are also non US based which helps a bit with US liability issues. The surge in drone demand has also benefitted them greatly. Until liability law changes in the US innovation will be stifled.
 
Rotax seems to have found a way...
Sailvi767 beat me to it.

Rotax has been around for about a century. Their growth was eccetually in a closed market. Their primary market these days is military drones if I had to guess (official #s aren't published). Side note = there was a lot of airfield thefts of their engines early in the Russia-Ukraine war due to export restriction/sanctions.

They make a good powerplant that gets efficiency benefits from the higher operating speeds. The $/BHP are in line with the traditional powerplants. Even with their newest 160HP offering, it's not a viable PP for the majority of the GA or EAB market.

So, still a niche (EAB) market and a long way from being a market disrupter.

Per some unofficial reports, 7-10K hrs is not uncommon on those Rotax drone PPs as their mission profiles are long duration.
 
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Until liability law changes in the US innovation will be stifled.

WHile clearly that is an issue, I still believe the primary roadblock is market size and investor requirements. buyers would be hesitant to adopt initially as the reputation builds. This means deep pockets from patient investors are required to float the R&D expenses for a relatively long time. At least relative to what most start up investors expect. Unfortunately due to the small market size, all of that patience doesn't really result in large profits even after the market accepts it. The type of investor this type of venture requires is very rare, as the profits don't really roll in until they have made serious dent in Lyc's marketshare and you are dealing with 3/4 of a century of brand recognition. One could build a business case, assuming price points of current competitors. However, the current market prices are SOOO inflated (greed vs labor and parts cost increases), that they would just drop them 30-50% once the new competitor gained traction, killing the mid term profitability. Lycoming did just that (50% price reduction) as soon as superior parts became accepted. Current Lyc cylinders that don't have competitive offerings are at least double in price today compared to those that do. Again, even more investor patience required. Doesn't take a harvard grad to recognize that a crankshaft selling for $9000 is about $8000-8500 in profit. A WHOLE bunch of room for short term radical price drops to wipe out new competitors before they really get started.

Once you deal with all of the above and become cash flow positive and paid off the debt, THEN you have to worry about the vultures of the legal system trying to take it away. Until you are there, no atty would bother, as there is nothing for them to take.
 
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