Raptor Aircraft, Vaporware?

[frcabot]

Total BS. No way this is ever getting produced.

 

[Blatham489]

When someone does a slick low "flying wing", I'll start considering those kind of numbers.

BTW, the hole diameter is not the greatest issue, total wetted surface is the larger factor there which is why you see modern designs with larger diameter cabins and wasp thin tails.

Open minded and willing to learn. But the formula I learned has the area (A) and coefficient of drag (Cd) as both linear factors, so in that sense wetted area (which I think impacts Cd) is of the same importance as the cross-sectional area. However, in comparing this design to something like a Velocity, it seems unlikely they could improve (reduce) Cd by 50%, whereas making the area (A) 50% bigger is obviously possible. So I still say making it 50% wider overrides any minor reduction in Cd.

School me, I enjoy this kind of geek banter.

 

[Henning]

Open minded and willing to learn. But the formula I learned has the area (A) and coefficient of drag (Cd) as both linear factors, so in that sense wetted area (which I think impacts Cd) is of the same importance as the cross-sectional area. However, in comparing this design to something like a Velocity, it seems unlikely they could improve (reduce) Cd by 50%, whereas making the area (A) 50% bigger is obviously possible. So I still say making it 50% wider overrides any minor reduction in Cd.

School me, I enjoy this kind of geek banter.

It has to do with the shape of the exit and drag. An egg with a slim tail having the same total surface area of a typical taper in, taper out design of a smaller cross section will have less drag.

 

[ktup-flyer]

I don't think the eggs I eat have tails. I would think a shape similar to a sailfish would be most efficient. Not nearly as practical as a bullet shape, though.

 

[Henning]

I don't think the eggs I eat have tails. I would think a shape similar to a sailfish would be most efficient. Not nearly as practical as a bullet shape, though.

Nope, sperm shaped is the most efficient. A sail fish if is the way it is due to the restrictions imposed by muscles. Tuna are fast too.

 

[Blatham489]

I get the concept and understand there are ways to improve Cd (shapes, wetted area, whatever) my main point was any aerodynamic improvements Raptor made over the Velocity design would have much less impact on power/efficiency than the 50% increase in the frontal area.

 

[Henning]

I get the concept and understand there are ways to improve Cd (shapes, wetted area, whatever) my main point was any aerodynamic improvements Raptor made over the Velocity design would have much less impact on power/efficiency than the 50% increase in the frontal area.

Most definitely, they made no change of any great significance in drag in anything they were putting up in art.

Now if they came out swept flying wing with maybe a swallow tail for positive control, I could maybe put some kind of belief in their claim. What they show? Nope, just not seeing it.

 

[ibgarrett]

So here's my thoughts on this.

The design of the aircraft is very similar to the Velocity TXL which has a 310hp Continental TSIO-550-C engine in it. The Audi 3.0L will have around 250hp or so, so the Audi certainly (from what I was able to find) has fewer horsepower. I know from personally speaking with Velocity TXL owners that they are getting upwards of 275kts true in their aircraft, and these planes were designed back in the 80's and haven't been altered since. The Raptor is using modern design techniques, modern materials and improved engineering to design the plane.

So the question is - why wouldn't this airplane be an overall improvement? For the naysayers out there I'm sure there were plenty of people telling Orville and Wilbur "that thing ain't never gonna fly" and yet - it did.

If you actually sit down and watch the videos and read what has been published to the website, what is being said is plausible. I'm still skeptical of the price point, but at the same time I'm willing to risk the $100 in escrow to put down my money on it. The absolute WORST that is going to happen is I'm out $100. The best? Well, I get a phone call and they say "Mr. Garrett - you're plane is ready".

I can't fault someone for trying to make a difference and improve things - especially if they can come close to hitting the price point they are setting out for.

 

[kyleb]

300 knots on 250 hp is an insane claim. A Cirrus cruises about 180 knots on 75% of its 310 hp (75% power is 232 hp). Because power required goes up proportionally with the cube of airspeed, it would take the Cirrus roughly 4.6 times that power (or about 1100hp) to go 300 knots. The Vapor, um, Raptor has less than a quarter of that HP, meaning to go 300 knots it would need to have less than a quarter of the drag of the Cirrus.

I fail to see how anyone can build a 4 or more place aircraft with less than a quarter of the drag of a Cirrus.

 

[Velocity173]

This is a 400 hp TXL that does 250 KTAS @ FL250. That's an accurate claim. It's airframe is shorter than the Raptor and not as wide. It also has less wing area than a Raptor. Whatever whizz bang aerodynamic clean up mods the Raptor has over the TXL isn't going to make it exceed it by 50 kts with 140 HP less, especially since some of its HP is being robbed for pressurization.

http://www.kitplanes.com/magazine/fixedwing/Flight_Review_Velocity_TXL5_9334-1.html

Then the 130K cost? Even with a cheaper auto engine, I have serious doubts that they can keep the completed cost below 200K. Here's what speed really costs:

http://velocityaircraft.com/images/Cost of A T-XLRG-5 Top Of The Line 2014.pdf

 

[RJM62]

So here's my thoughts on this.

The design of the aircraft is very similar to the Velocity TXL which has a 310hp Continental TSIO-550-C engine in it. The Audi 3.0L will have around 250hp or so, so the Audi certainly (from what I was able to find) has fewer horsepower. I know from personally speaking with Velocity TXL owners that they are getting upwards of 275kts true in their aircraft, and these planes were designed back in the 80's and haven't been altered since. The Raptor is using modern design techniques, modern materials and improved engineering to design the plane.

So the question is - why wouldn't this airplane be an overall improvement? For the naysayers out there I'm sure there were plenty of people telling Orville and Wilbur "that thing ain't never gonna fly" and yet - it did.

If you actually sit down and watch the videos and read what has been published to the website, what is being said is plausible. I'm still skeptical of the price point, but at the same time I'm willing to risk the $100 in escrow to put down my money on it. The absolute WORST that is going to happen is I'm out $100. The best? Well, I get a phone call and they say "Mr. Garrett - you're plane is ready".

I can't fault someone for trying to make a difference and improve things - especially if they can come close to hitting the price point they are setting out for.

I wish them the best. Canards are very aerodynamically complex, however, and also very unforgiving if done wrong. There are reasons why they're not more common than they are, despite the theoretical efficiency advantages.

The non-certificated engine doesn't bother me in the least. (Then again, I've flown ultralights powered by chainsaw engines, so yeah...) The inherent aerodynamic complexity of canards does. I'd be more comfortable with a canard design from someone like Rutan who spent his life figuring it out than from a couple of guys I never heard of.

Still, I wish them all the luck in the world. It's entirely possible that these guys will pull it off, and I hope they do.

Rich

 

[Blatham489]

Edumacate me, what's so complex about canards?

The front one stalls, the back one doesn't, pretty simple stuff from what I can tell. They're both just airfoils. Lift = Weight. The biggest drawback I see is the lack of flaps for short field op's. I think the lack of prevalence has more to do with something new than aerodynamic complexity.

 

[Henning]

There is only so much power 7gph buys, and it doesn't buy that speed in anything that hauls more than one person unless you want to deal with absurd runway lengths and take off or landing speeds. This thing does not have a variable geometry wing does it?

 

[FastEddieB]

I think the lack of prevalence has more to do with something new than aerodynamic complexity.

Something new???

 

[Henning]

Something new???

Same goes for that "new fangled" tricycle landing gear.

The reason you don't see many pure canard designs around is because canards are "one trick ponies" and lack flexibility in speed range without great complexity. The reason you don't see them is their time has come and gone.

Hybrid canard and tail applications prove out much more functional, and see most of the advantages gained in the canard designs while maintaining the ability to deal with a large pressure shift with high lift devices. The Piaggio Avanti and Katmai 182 prove out the conceptual superiority at both ends of the scale.

 

[German guy]

There is only so much power 7gph buys [...]

1 gallon Diesel or Jet fuel contains around 50 hp-hr. Even a modern diesel has a thermal efficiency of only between 40 and 45%: 7 * 50 * 0.45 = 157.5 hp

Even 75% of the rated power of the Audi's 250 hp engine would only be 187.5 hp.

Velocity claims that their TXL does 250 kts @FL250 with a 310 hp engine and 75% or 232.5 hp power.

Frankly, the performance Raptor claims just don't sound reasonable.

This thing is however also vaporware for a very different reason: Audi will never, never, NEVER ever sell their engines for such an application as a 'kit', with a ECU and everything else that is needed. To just buy it as a spare part will also not work, because the engine control is so deeply integrated into the entire vehicle electronics, that it is pretty much impossible to even get is started outside of the vehicle, into which it belongs. To run such modern engines on a test bench, engineers use specifically programmed ECUs, which are not publicly available. With the modern Diesels, you can also not just throw the factory ECU away and replace it with a aftermarket unit, like the ones which are available for (older) gasoline engines.

 

[Henning]

1 gallon Diesel or Jet fuel contains around 50 hp-hr. Even a modern diesel has a thermal efficiency of only between 40 and 45%: 7 * 50 * 0.45 = 157.5 hp

Even 75% of the rated power of the Audi's 250 hp engine would only be 187.5 hp.

Velocity claims that their TXL does 250 kts @FL250 with a 310 hp engine and 75% or 232.5 hp power.

Frankly, the performance Raptor claims just don't sound reasonable.

This thing is however also vaporware for a very different reason: Audi will never, never, NEVER ever sell their engines for such an application as a 'kit', with a ECU and everything else that is needed. To just buy it as a spare part will also not work, because the engine control is so deeply integrated into the entire vehicle electronics, that it is pretty much impossible to even get is started outside of the vehicle, into which it belongs. To run such modern engines on a test bench, engineers use specifically programmed ECUs, which are not publicly available. With the modern Diesels, you can also not just throw the factory ECU away and replace it with a aftermarket unit, like the ones which are available for (older) gasoline engines.

The parts are available in the racing aftermarket. To pare down the controls to the ecu for outside applications is not impossible. I keep watching the salvage for a cheap Q7 with the big Diesel.

 

[JimNtexas]

I'm old enough to have been excited about the BD-5. This is like deja vu all over again, but with Kickstarter.

 

[German guy]

[...] To pare down the controls to the ecu for outside applications is not impossible. [...]

I used to work for a company which did all kind of vehicle tests. Volkswagen / Audi was a big customer. I remember that even the Volkswagen / Audi engineers struggled to get get the engines running on the test bench, because of relatively simple stuff like the engine immobilizer of because the control unit(s) were looking for sensors, like those for the electronic stability program, which were simply not there on the test bench.

My understanding was, that these development ECUs and the required knowledge to program them is entirely centralized in one single department. Even if somebody only wants to have a software version which gets rid of the engine immobilizer, this department would have to do it. As far as I know, this is the same at all car manufacturers.

I admittedly don't know much about the racing aftermarket. If a solution for turbo charged direct injection Diesel engines would exist, this might indeed be the easiest solution. This solution would however also have to be redundant, particularly for the use in such a fast airplane.

Personally, I would rather wait for the more powerful version of the new Gemini Diesel by Superior. Superior has the financial resources, a good track record and the design seems to be pretty mature. Their 100 and 125 hp versions sound good, stronger versions are planned for the future: https://youtu.be/7bAR5tjNWOk

I also wouldn't bet on (V)Raptor and instead rather get a Velocity. Their numbers seem to be a lot more realistic and their design is proven.
Actually, if our runway would not be just 2,300 ft long, I could see a Velocity as our next plane.

 

[RJM62]

Edumacate me, what's so complex about canards?

The front one stalls, the back one doesn't, pretty simple stuff from what I can tell. They're both just airfoils. Lift = Weight. The biggest drawback I see is the lack of flaps for short field op's. I think the lack of prevalence has more to do with something new than aerodynamic complexity.

It would be pretty simple if flying were a static sort of thing. It's pretty complex to make it happen that way while keeping the airplane stable throughout the full range of operational variables.

To do so requires compromising the very design characteristics that make the canard theoretically more efficient. The rear wing must stall after the canard, which usually means some combination of a longer span and a lower angle of incidence on the wings; and a higher aspect ratio, higher loading, and a greater angle of incidence (to put it closer to its critical angle of attack) on the canard.

All of these requirements add drag to the design, thus at least partially defeating its inherent theoretical efficiency. But if they're not done right, the aircraft will be unstable in normal flight and irrecoverable in a stall. So it's a balancing act in both the literal and figurative senses.

Obviously, it's not impossible to get it right. It's just more difficult. And although these fellows might well be able to do it, I wouldn't be in any hurry to buy or fly in one of their canards until there was more than the usual amount of real-world testing behind it.

Rich

 

[Blatham489]

Not an aeronautical engineer, but I do understand it's not a static design environment. I still don't see any statement in your comments that isn't essentially true for a conventional design? Get those wrong and you have the same problems. Tail has to have lower incidence to maintain authority in a stall, has a different aspect ratio and loading than the main wing, get the CG wrong and it's unstable, etc, etc. I still don't see it being more difficult, just different. Teach me.

 

[RJM62]

Not an aeronautical engineer, but I do understand it's not a static design environment. I still don't see any statement in your comments that isn't essentially true for a conventional design? Get those wrong and you have the same problems. Tail has to have lower incidence to maintain authority in a stall, has a different aspect ratio and loading than the main wing, get the CG wrong and it's unstable, etc, etc. I still don't see it being more difficult, just different. Teach me.

You'll need to find someone both smarter and more current than me if you want to be taught. My knowledge of aeronautical engineering is limited to two courses in aerodynamics I took in the 1970's and what I've learned from helping (predominantly) amateurs build ultralights. I'm not an engineer by any stretch of the imagination.

I'm also not "against" canard designs. It's simply my understanding, based mainly on what I've been told by people smarter than myself, that they're harder to design in ways that make them flyable while minimizing losses of the design's inherent efficiencies, as well as inducing performance sacrifices.

For example, it doesn't take an engineer to understand that the absolute necessity of the canard always stalling first also limits the AoA, and therefore the lift potential, of the main wing. That this must always happen irrespective of airspeed, thrust, trim, attitude, gusts, shear, or any other conceivable variable also means that efficiency during "normal" flight is likely to be sub-optimal. More safety and stability mean less efficiency. So where do you draw that line?

And we haven't even touched upon the vertical axis. You still need a vertical stabilizer and yaw control, and the authoritative surfaces and controls need to be aft of the CG and vertical axis. You can do that with a tail as the Piaggio does, but that adds drag. Also, I believe that the Avanti is not a "true" canard anyway because as far as I know, the canard is a lift surface, not a control surface. The aft elevator is authoritative for pitch.

Or you can mount the vertical fins and rudders on the wing tips like the Starship and Rutan's designs, but that means that the wings need to be swept back so the tips are behind the CG, which means a sacrifice in slow-flight performance. It also seems to my non-engineer self that the lack of propwash past the rudders also means that they would have to be bigger to accomplish their purpose, which would also increase drag.

Again, none of these considerations are insurmountable. Engineers have managed to design canards that fly quite well. But I'd feel more confidant with engineers who have already done so successfully with proven designs than with two fellows who haven't yet (to my knowledge) been able to build a 1/4 scale model of what they have in mind.

I'm not saying that they can't do it, mind you, but only that they haven't; and even as someone who's flown some pretty odd-looking contraptions, I'd hesitate to be a test pilot for a canard designed by anyone without a proven track record in that configuration.

Rich

 

[Henning]

I used to work for a company which did all kind of vehicle tests. Volkswagen / Audi was a big customer. I remember that even the Volkswagen / Audi engineers struggled to get get the engines running on the test bench, because of relatively simple stuff like the engine immobilizer of because the control unit(s) were looking for sensors, like those for the electronic stability program, which were simply not there on the test bench.

My understanding was, that these development ECUs and the required knowledge to program them is entirely centralized in one single department. Even if somebody only wants to have a software version which gets rid of the engine immobilizer, this department would have to do it. As far as I know, this is the same at all car manufacturers.

I admittedly don't know much about the racing aftermarket. If a solution for turbo charged direct injection Diesel engines would exist, this might indeed be the easiest solution. This solution would however also have to be redundant, particularly for the use in such a fast airplane.

Personally, I would rather wait for the more powerful version of the new Gemini Diesel by Superior. Superior has the financial resources, a good track record and the design seems to be pretty mature. Their 100 and 125 hp versions sound good, stronger versions are planned for the future: https://youtu.be/7bAR5tjNWOk

I also wouldn't bet on (V)Raptor and instead rather get a Velocity. Their numbers seem to be a lot more realistic and their design is proven.
Actually, if our runway would not be just 2,300 ft long, I could see a Velocity as our next plane.

All the components work to standard protocols. You don't need the Audi ECU at all, you just need to program the triggers to your design functions and use the fuel mapping you want. It can all be run with a laptop and PLCs now.

The phenolic block V-12 would be an awesome aircraft engine for utility and short haul flights.

 

[Neal Howard]

Audi will never, never, NEVER ever sell their engines for such an application as a 'kit', with a ECU and everything else that is needed. To just buy it as a spare part will also not work, because the engine control is so deeply integrated into the entire vehicle electronics, that it is pretty much impossible to even of the vehicle, into which it belongs.

This. As soon as they learn that somebody is wanting to use their engines in a aircraft, their lawyers will put an abrupt halt to the possibility of engine sales as well. I'd be surprised if you could even buy a brand new engine from VW/Audi/Porsche without providing the VIN number of the vehicle it's supposedly to be a replacement for, and such an engine would only be shipped to an authorized service center.

Didn't Siemens also just recently put the kibosh on selling electric motors to Pipistrel when their lawyers learned the motors were going to be used in production airplanes?

 

[Henning]

This. As soon as they learn that somebody is wanting to use their engines in a aircraft, their lawyers will put an abrupt halt to the possibility of engine sales as well. I'd be surprised if you could even buy a brand new engine from VW/Audi/Porsche without providing the VIN number of the vehicle it's supposedly to be a replacement for, and such an engine would only be shipped to an authorized service center.

Didn't Siemens also just recently put the kibosh on selling electric motors to Pipistrel when their lawyers learned the motors were going to be used in production airplanes?

Junkyards...errrr Auto Recycling Institutions... don't give a rats ass what you're gonna do with what you buy.

 

[Neal Howard]

Junkyards...errrr Auto Recycling Institutions... don't give a rats ass what you're gonna do with what you buy.

This is true, but the TDI 3.0l engine in particular is going to be exceedingly rare to find in junkyards, and each one that finds itself in a junkyard will probably have a waiting list of customers bidding on it.

 

[Henning]

This is true, but the TDI 3.0l engine in particular is going to be exceedingly rare to find in junkyards, and each one that finds itself in a junkyard will probably have a waiting list of customers bidding on it.

I would imagine in Europe they're pretty plentiful, they're in a bunch of rentals. 4.2 as well.

 

[German guy]

I would imagine in Europe they're pretty plentiful, they're in a bunch of rentals. 4.2 as well.

While stronger Diesel are indeed quite popular as company cars in Europe, particularly Germany, it is not like that people wreck them so often that used engines are available in larger quantities. Also, because the cars a pretty expensive, even severely damaged cars usually get repaired. And, if a VW/ Audi / BMW / Mercedes is beyond repair in Germany, they get sold to eastern Europe or Russia.

Frankly, to me this appears to be a pretty shaky source for aircraft engines. Even if I would get one, I would not want to depend on a race ECU without any redundancy. Other then the functional principle, modern Diesel engines don't have much in common with an old tractor engine. If the ECU dies or the power supply breaks down, the engines quits. The same with the high pressure pump, which is not unlikely to fail, but which is, like the ECU, not easy to backup with a redundant system.

It also appears a whether the Jet fuel provides significantly less lubrication than Diesel what requires massive modifications and testing of the engine. Unless, of course, somebody is willing to haul in Diesel to the airport. Then again, particularly the modern high performance Diesels are really picky when it come to fuel quality. To run them in combination with a home-brewed map certainly does not contribute to the reliability, either.

The fact alone that Raptor plans to use a Audi engine tells me that they have no clue of what they are doing...

 

[Henning]

How many engines will he need? 3-4 a year? There's plenty. Some German dude will pay for his supplying engines.

 

[LevelWing]

How many engines will he need? 3-4 a year? There's plenty. Some German dude will pay for his supplying engines.

I'm not sure I want to purchase a brand new airplane that has an engine from a car that was in an accident. No matter the condition of the engine, it isn't new out of the box but coming from a junk yard instead. Now if he wanted to use one for testing his aircraft to prove the concept, that's alright by me as long as it's not what's being sold to the public.

 

[Henning]

I'm not sure I want to purchase a brand new airplane that has an engine from a car that was in an accident. No matter the condition of the engine, it isn't new out of the box but coming from a junk yard instead. Now if he wanted to use one for testing his aircraft to prove the concept, that's alright by me as long as it's not what's being sold to the public.

I prefer a seasoned block to a green one to build an engine on.

 

[Velocity173]

I don't recall in the advert but aren't they selling the kit with a new 3.0 TDI engine? Anyone got a price on one?

 

[dans2992]

$16k according to what I was told at their OSH booth.

Another concern is that an auto engine isn't meant to be run flat out (or 75%) for long periods...

 

[Henning]

$16k according to what I was told at their OSH booth.

Another concern is that an auto engine isn't meant to be run flat out (or 75%) for long periods...

Engines aren't animals. As long as you manage the heat, an engine is happy to run at design power for the entire time until the wear out. It's change that stresses engines, not continuous loads.

 

[German guy]

Engines aren't animals. As long as you manage the heat, an engine is happy to run at design power for the entire time until the wear out. It's change that stresses engines, not continuous loads.

Well, you might want to talk to some road warriors in Germany, who tend to go full throttle on the Autobahn whenever possible. I was one of them for many years. While I never had a mechanical failure of the engine itself, the turbochargers usually crapped out after around 120 - 150 tKm, I also had 2 or 3 failed ECUs. I had to be towed 7 or 8 times over the years and don't even recall anymore, how often I barely made it to the garage, with the engine running in fail safe mode. My cars were always from VW / Audi, other brands however did not seem to do much better.
Despite of the extensive driving on the Autobahn at +200 Km/h , the trip computers still just showed an average speed of only around 50 km/h over the last 10.000 Km or so. The average load on a passenger car's engine is just a fraction of what an aircraft engine has to endure, even if the car is driven on the Autobahn.

All of this happened over a total of around 800,000 Km or, at an average speed of 50 Km/h, 16,000 hours.
One complete breakdown every around 2,000 hours and the engine running in fail-safe mode, which allows the car to barely accelerate to 100 km/h, every few hundred hours? This alone would be unacceptable for me in an aircraft. Now, replace the extensively tested, mass produced ECU with a race ECU, which is produced in small series and put between 5 - 10 times the average load on the engine, for what is was designed and tested for. Next, put this beautiful package, of course in combination with a home brewed cooling and exhaust system, in a super fast canard without flaps.

What could possibly go wrong...

 

[Velocity173]

Oh the autobahn. I used to think I was going fast doing 120 mph in my A4 then you get passed by a Mercedes or BMW like you're standing still!

 

[Henning]

Well, you might want to talk to some road warriors in Germany, who tend to go full throttle on the Autobahn whenever possible. I was one of them for many years. While I never had a mechanical failure of the engine itself, the turbochargers usually crapped out after around 120 - 150 tKm, I also had 2 or 3 failed ECUs. I had to be towed 7 or 8 times over the years and don't even recall anymore, how often I barely made it to the garage, with the engine running in fail safe mode. My cars were always from VW / Audi, other brands however did not seem to do much better.
Despite of the extensive driving on the Autobahn at +200 Km/h , the trip computers still just showed an average speed of only around 50 km/h over the last 10.000 Km or so. The average load on a passenger car's engine is just a fraction of what an aircraft engine has to endure, even if the car is driven on the Autobahn.

All of this happened over a total of around 800,000 Km or, at an average speed of 50 Km/h, 16,000 hours.
One complete breakdown every around 2,000 hours and the engine running in fail-safe mode, which allows the car to barely accelerate to 100 km/h, every few hundred hours? This alone would be unacceptable for me in an aircraft. Now, replace the extensively tested, mass produced ECU with a race ECU, which is produced in small series and put between 5 - 10 times the average load on the engine, for what is was designed and tested for. Next, put this beautiful package, of course in combination with a home brewed cooling and exhaust system, in a super fast canard without flaps.

What could possibly go wrong...

I guess you only fly turbines.

 

[German guy]

I guess you only fly turbines.

After how many hours can one expect, in average, an catastrophic engine failure frrom an Lycoming or Continental aircraft eingine?

 

[RJM62]

After how many hours can one expect, in average, an catastrophic engine failure frrom an Lycoming or Continental aircraft eingine?

Aircraft engines are better-inspected and -maintained than are car engines, and problems that could cause catastrophic failures are therefore much more likely to be caught and remedied before that happens. Show the same TLC to the mechanical parts of a well-made car engine and I think the results will be impressive.

The ECU is another issue, however. As with any computer system, there will always be a SPOF even if you design it with failover redundancy. That's not to say that it's impossible to achieve acceptable reliability, but it would have to be a purpose-built ECU with built-in redundancy, plenty of headroom, and exquisite attention to quality; and it still wouldn't be as reliable as a Continental or Lycoming with dual ignition.

Rich

 

[Henning]

After how many hours can one expect, in average, an catastrophic engine failure frrom an Lycoming or Continental aircraft eingine?

TBO is between 700 and 2300 hrs depending on which engine you're talking about. Something in this power range with turbos and gear drive is in the 700-1600 hr range. How long the engine actually lasts depends on operation, maintenance, and luck.