Single engine 300-400hp pusher

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Mac790

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I don't see a problem in a long, unsupported shaft if you have a big diameter. A 5" thick, 10' long carbon shaft, with a wall thickness in the order of 1/4th of an inch doesn't seem unrealistic
Here is Orion's comment, big diameter vs small one
orion said:
There isn't a lot written on the torsional characteristics of this type of prop driveline, mainly because there really aren't that many airplanes that are configured in this manner. In looking at the problem, you have two choices: One, you can design a very rigid system, which is then coupled to the engine through a flexible coupling designed with a low frequency visco-elastic characteristic. Your shaft would most likely have to be something like a graphite wrapped aluminum unit (very rigid and very light) - these used to be manufactured by Spicer but I'm sure there are others.

One coupling manufacturer is Vulcan, which I think is an Austrian company (or at least they handle a line of Austrian produced couplings). The difficulty though is finding one that will work in your application. Most of these couplings are designed for the high magnitude impulses generated by Diesel engines. For aircraft, the unit does not to be that big but finding a small light one will be somewhat a challenge.

The second approach to this is to have a torsionally flexible system, such as is often used for powering the tail rotor of a helicopter. Here they use a small diameter shaft, suspended by a series of bearings along its length. The small diameter has very low torsional stiffness characteristics and thus operates below the range of the system's natural frequency and most of its harmonics.
This might be useful too :) http://ibis.experimentals.de/downloads/torsionalvibration.pdf

Seb
 

TFF

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I will get some pix; give me some time on it. Yea, 20% to one of the rotors on a Ch46 or 47 is called a bad day.
 

KC135DELTA

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Thanks, I've never heard about that pusher either :), it reminds me Vk-30 with different tail and wings shape. Wonder which one was reverse engineered :roll:.

I've found one more pic of Stemme back coupling pix1, one thing only makes me wonder did they use something else, in a car between the engine and the gearbox, there is a clutch with springs (for obvious reason), it would be nice to see also Porsche 928 "installation" (it has engine at the front and gearbox at the back).

After looking at Stemme pix2, "ultimate" pusher pix3, and helicopter boom pix4 (of course different RPM, different loads/forces, etc), one thing coming to my mind, wouldn't be easier to build the front section of a pusher plane out of composites and the tail section (with an engine mount) out of 4130 tubes? It would be easier to calculate and design for sure, better maintenance (removable tail section shells), etc.

edit

After looking at the manual, seems that there is a kind of centrifugal clutch? there, page 4 http://www.stemme.de/man/s10vt/mm_uk/amendment13.pdf

Seb
What is the aircraft in the 3rd picture of your post? It almost looks like a mini mirage f1.
 

autoreply

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I always found that style very appealing for a side by side two seater but never had an idea it could look as good as this one.
It's quite a complicated aircraft (cowl flaps, RG, turbo, variable pitch, flaps). A pilot I know commented that it was comparable in systems management to a Bonanza or a light twin. Maintenance and complexity are there as well.

There's also no point in putting the outline that way for a powered aircraft. If the engine is in the middle; a pusher prop makes much more sense. The only reason the Stemme doesn't have a pusher prop is the folding blade requirement.
 

Mac790

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Not exactly pusher, but it also has a drive-shaft, it's Isatis AEROJAMES | ISATIS 01 | ULM | FRANCE, I would love to see some pixs of the propulsion system, drive-shaft, couplings, etc, it has a BMW motorcycle engine.

btw found one more pix of the Stemme S6 engine, with coupling unfortunately quality of it isn't very good, but comparing it with a conventional Rotax engine pix5, I would say that there is nothing more there, besides that rubber coupling.

Seb
 

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Mac790

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Jarno I don't know what is your sight condition, but I need to go to the optician :gig:.

Do you know that it's Limbach engine on the picture not Rotax (this pix is from first manual http://www.stemme.de/man/s10v/afm_us/altern_pages_fix.pdf page 20), you wrote that nr 6 is a torsional vibration absorber, it was torsional vibration absorber for the Limbach engine. Take a closer look at this engine, it's a direct drive Limbach (check out this head cover, there is single cover on each side, Rotax has 2 on each side).

The Rotax has a gearbox, it has torsional vibration absorber between the engine and the gearbox, like Marcotte pix1, Aerotech pix2 (seems that they also use BMW donuts, check out pix 5 for BMW rubber), Mistral pix3, and any other pix 4 (as I was expecting they use BMW donuts Rotary Wing Forum - View Single Post - VW Redrive). Molt used a Flexidyne coupling because he had too, same with Orion 801, and I bet same with VK-30, all those planes had direct drive engines.

I'm not surprise that I couldn't find big difference between those two Rotax engines which I posted in post 69, the only difference between them is that flexible rubber coupling, I also bet with you about a bottle of Heineken, that you will find similar coupling in that Isatis, which I posted also in post 69.

Seb
 

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Starman

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It's quite a complicated aircraft (cowl flaps, RG, turbo, variable pitch, flaps). A pilot I know commented that it was comparable in systems management to a Bonanza or a light twin. Maintenance and complexity are there as well.
I'm sure the designers and customers are all impressed with the complication too, it's like getting gold plated doors for your fireplace.

There's also no point in putting the outline that way for a powered aircraft. If the engine is in the middle; a pusher prop makes much more sense. The only reason the Stemme doesn't have a pusher prop is the folding blade requirement.
I can think of a LOT of reasons for putting the prop in front, and if it can be made to look good enough (like the S-10 does) when the engine is in the middle then it's a Done Deal!

Let me tell you I'm really glad that side view of the S-10 was posted here because I always wanted to do that and when I reconsidered it for my design it's like it all fell perfectly in to place.

So my plane is now a tandem wing tractor rather than a tandem wing pusher, the design hardly needed to change to accomplish it - and it looks better.
 

KC135DELTA

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Is everyone in consensus that this is possible?

2,000lbs empty
3,800lbs MTOW

400hp turbo-normalized to FL300
Carbon composite construction

270-280knt cruise

300knts~ max

The turbo normalized mooney is capable of 240knts on 280hp and it isn't nearly as clean of a design as this.
 

autoreply

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Is everyone in consensus that this is possible?

2,000lbs empty
3,800lbs MTOW

400hp turbo-normalized to FL300
Carbon composite construction

270-280knt cruise

300knts~ max

The turbo normalized mooney is capable of 240knts on 280hp and it isn't nearly as clean of a design as this.
Those weights might be a tad optimistic (a pusher has the driveshaft and stuff, so I'd expect it a bit heavier as a tractor).
No idea where to find a 400HP engine (350 is the max of the "known") engines and others are much heavier.
With that 350HP, the Lancair IVP achieves similar performance, so I don't think that's unrealistic:
Lancair IV - Wikipedia, the free encyclopedia
 

KC135DELTA

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Those weights might be a tad optimistic (a pusher has the driveshaft and stuff, so I'd expect it a bit heavier as a tractor).
No idea where to find a 400HP engine (350 is the max of the "known") engines and others are much heavier.
With that 350HP, the Lancair IVP achieves similar performance, so I don't think that's unrealistic:
Lancair IV - Wikipedia, the free encyclopedia
I have some prospects as far as diesel goes, but until then you can modify the IO-720 to be water cooled. It uses the same cylinders as the IO-540.

I'm not too concerned with getting it ~2,000 pounds either.
 

Kristoffon

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I have some prospects as far as diesel goes, but until then you can modify the IO-720 to be water cooled. It uses the same cylinders as the IO-540.

I'm not too concerned with getting it ~2,000 pounds either.
wouldn't it be saner to pick up a corvette engine with ~500 hp stock?

certainly the potential problems in transforming a lycoming to water cooling dwarf those with possibly unreliable psrus
 

Toobuilder

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...wouldn't it be saner to pick up a corvette engine with ~500 hp stock?...
If you run a redrive and allow the engine to spin then you can make more than 1000 HP with the LSx engine, but not for very long. Running direct drive makes more sense from a reliability and weight standpoint, but it looks like you are limited to about 315HP (normalized).
 

KC135DELTA

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If you run a redrive and allow the engine to spin then you can make more than 1000 HP with the LSx engine, but not for very long. Running direct drive makes more sense from a reliability and weight standpoint, but it looks like you are limited to about 315HP (normalized).

This engine (RED A03 Aero-Diesel) produces 500hp at 3,900rpm.



It is more power than I want and more expensive than what I am looking for but ultimately it proves the concept. As far as the long term goes I have found that making a straight six diesel used in large trucks useable for aircraft isn't that far of a stretch. A Custom aluminum block with iron sleeves, aluminum heads and accessories has been done before. This route we will have a proven, reliable engine that weighs ~500-600 pounds and produces ridiculous power/torque around 2,000rpm (Direct drive) and a long service life.


It might seem complicated but there are so many shops out their specializing in diesel engine modification I have no doubts that it is possible.
 

KC135DELTA

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The overall concept is to make the most aerodynamic airplane out of the lightest materials and power it via the most efficient power source. ---> Pusher configuration, carbon composites, diesel engines.

If it can cruise at ~300mph on ~20gph of JET-A I believe it would sufficiently kill the VLJ phenomenon. Not to mention the significantly reduced costs involved compared to a twin turbine jet. Also single engine pilots could fly it without a twin engine certificate or a type rating.
 

autoreply

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It is more power than I want and more expensive than what I am looking for but ultimately it proves the concept. As far as the long term goes I have found that making a straight six diesel used in large trucks useable for aircraft isn't that far of a stretch. A Custom aluminum block with iron sleeves, aluminum heads and accessories has been done before. This route we will have a proven, reliable engine that weighs ~500-600 pounds and produces ridiculous power/torque around 2,000rpm (Direct drive) and a long service life.
Yeah, all those paper engines. Maybe, because they're only paper engines they don't fly.
Seriously; a truck engines weights about 2500 lbs (500HP). You might be able to shave 1000 lbs of it, but that's already optimistic. You won't even get off the ground in your design then.

700 lbs for that "red" engine? Sorry, but I simply don't believe them. The lightest diesel that comes close is the 350HP Thielert 4.0. That's over 700 lbs with all accessorizes and pretty optimized.

Whether you guys put me at the "nay-sayers", or at the "common sense" group is up to you. Let me say just this. I'ts quite easy to think up an engine that's light, great, reliable and so on. Corvette engines are popular... for those thoughts. Nobody did it successfully though, and those who finally got it flying usually ended up more expensive, much heavier, less reliable. Actually, most threw out the engine finally and replaced it with a decent aircraft engine.
I'm not saying it can't be done. Just ask yourself whether you really can do that much better as all those other guys who tried.

If you're going for a Diesel; I see two reasonable routes:
*Lean the truck-engine. Still incredibly heavy and therefore performance (T/O run, climb) will suck
*Go with a proven car-engine (direct drive). That way it runs far below design strength. Think the big BMW engines or so. Still 600 lbs for 200 HP.
 

Topaz

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At this end of the power range, I'm all with Autoreply. Especially with a new design. And I'm hearing noises about "killing the VLJ phenomenon", which suggests production is in somebody's mind. If you want to sell it Part23 certified, you're going to need to have the engine certified, too. And you have not seen paperwork, I'm told, until you try to certify an engine for aero use. If there are any production plans in your mind, go with an already certified aero engine.

Of course, if 100LL goes south without a drop-in substitute, things get really interesting really fast.
 
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