Single engine 300-400hp pusher

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autoreply

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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.
I was told by a DLR employee that he couldn't recall an aircraft that needed less paper mass than engine weight. For such an aircraft we're talking tenthousands of pages...
 

KC135DELTA

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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.
I do not know where you came up with your 2,500lb number. Most modern medium/heavy duty diesels (5.9L 6.0L 6.6L 6.9L 7.0L 7.3L) weigh in the neighborhood of 1,000lbs with Iron blocks, heads, internals, and non optimized accessories.

I do not think I can "out-do" those 'other guys'. However no one has really tried this concept. The VK-30 wasn't completely optimized for high speed or high altitude flight, It wasn't even turbocharged. Plus it was about 10% larger than what I have in mind. The IVP has exceedingly good performance however its approach speeds are too fast for certification.

Although the continental engine does produce 310 liquid cooled horsepower. I don't think it would be enough. Plus the 100LL situation isn't pretty. I apologize if this response seems snide or poorly coordinated, I'm in a rush.
 

Starman

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I checked into diesels, you can get a drop dead reliable V8 pickup truck diesel (used, from a wrecking yard, stock + turbo) to put out 500hp for around 800lb. You can make that same engine, in fresh condition with maybe stiffer valve springs, give you bursts of 800hp without breaking it or wearing it out much faster either. As long as your cooling system can handle 600hp you're good for some 800hp heat soaks ... add more water :D

I mean, they even have a 'limp home' backup engine control system, stock, how cool is that?

I'm almost talking myself into a diesel ...
 
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autoreply

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I do not know where you came up with your 2,500lb number.
From several truck engines we discussed before on this forum. The only Diesels in the neighborhood of 500HP were far over a tonne:
http://webapp109.scania.com/i/IndustrialMarine/DL-DP_Industrial/DC1374A_331kW.pdf
1200 kg when turning. That's over 2500 lbs. The smaller engines simply aren't designed to output 500hp.

Here's some more discussion about diesels:
http://www.homebuiltairplanes.com/forums/firewall-forward-props-fuel-system/3645-diesel-engines.html#post74794
 

Noah

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I know slow turning engines are well loved in aviation, but coming from cars I have to point out the short stroke engines vibrate less, make more hp per pound, and sound more exotic.

Inline 6, flat 6, or 12 cylinder engines make great power plants because they are mechanically stable.

BMW set the naturally aspirated hp/liter record in 2001 with its m54 333hp in an all aluminum engine maybe 350lbs. Their newer turbo 335i versions are even better. HPF sells 1200+hp off the shelf turbo kits for 30k. They have 750hp bolt on (stock engine!) kits for 15k These prices are off the top of my head but I think they install for those prices as well. They have proven very reliable over the last 5 years.

Another example is the Toyota Supra engine or 2jz. Like the BMW its a 3l, 9000rpm turbo motor that can handle excess of 1000s of horsepower. Iron block in this one. They can be on ebay for 10k. Youtube is loaded with videos of 8 second quarter miles. Porsche makes fantastic flat 6s that are even better than the previous two. They are obviously much more expensive.

I can't praise the turbo inline 6 enough. Seriously look into it. Also, 91 OCTANE GASOLINE.

If you want a V8 I promise you should use a Chevy LS engine variant. (ls9,3,2,6,1 in order) The commie v8s are all aluminum and dirt cheap. They get around 100k miles in a car and make 300-400hp all day. A cam/head package will add 100hp and thats with crap gasoline and good throttle response; we need neither. 10k new? 400lbs? Probably the route I'd go unless I had double/triple the budget for an engine then BMW.
 

autoreply

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If you want a V8 I promise you should use a Chevy LS engine variant. (ls9,3,2,6,1 in order) The commie v8s are all aluminum and dirt cheap. They get around 100k miles in a car and make 300-400hp all day.
No, they don't. Even a big (50 tonne) truck only burns 100HP or so continuously, with maybe 300-400HP for those that drive in the mountains. There's a reason they have such rugged engines for those power ratings... there is a vast difference between peak power and continuous power.
A serious pick-up truck uses what, 30-40 HP at high speed continously? So you're effectively loading an engine at 10 times it's design load. Geez....

On this forum too, you'll see endless discussions about those "dreaming engines". Yeah, great, let's put in a bad-ass car-engine in our aircraft and make a PSRU ourselves. Let those nay-sayers whine in the corner.

Nothing is usually heard of all their great plans afterwards. There is no magic. You can't beat existing engines by a big margin (in weight, power, efficiency) if you're using the same basic principles. Thousands went before you and failed. Some had incredible amount of skill, money and workforce. They still failed...

As one of the users here has as a quote "Your opinion doesn't change the facts"...
 

Kristoffon

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Running direct drive makes more sense from a reliability and weight standpoint,
No it doesn't.

From the reliability POV there are plenty of reliable redrives around. Not to say they're bulletproof but I trust a modern auto engine with redrive much more than any certified aero piston engine.

From the weight POV it's silly to even make that point.
 

Toobuilder

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... There is no magic. You can't beat existing engines by a big margin (in weight, power, efficiency) if you're using the same basic principles...
I agree with this, yet I am collecting parts to build an LSx V8. Why? Because I aim only to approximate the power of an aircraft engine. If I can achieve this goal (or exceed it and MATCH the output of the Lycoming 540), my main claim to fame will be that it was done at a significantly lower cost.

Yes, V8's have been done and redone, but they almost always use a redrive and other junk in an attempt to make 400+ HP. I'm more of a realist - just the thermal loading by itself is a nightmare - let alone the torsional vibration issues (not to mention the cost and weight) of the PSRU, the complex fuel systems, or other adapted accessories. I on the other hand are going to tread where (despite a proven track record) few have gone before - I'm going to take the biggest inch engine I can find and turn it really slow. Yes, I leave a lot of power on the table by doing this, but I also make things much easier. Further, I'm going to manage this basic architecture with a proven, unmodified aircraft fuel system and simple electronic ignition. From the pilot seat, engine operation will be completely transparent compared to a IO-540 (aside from the elimination of shock cooling).

The bottom line is that I intend to build with a reasonable alternative to the big 300HP Lycoming at a price of around $8000. If I bust through 10k, I'll consider it a failure and go with the Lyc.

I do think that a 400 or 500 HP diesel is highly ambitious, particularly if you are talking of "simply" making a new block from aluminum. I hope you crack the code on that one, because I would love to burn Jet A in my airplane.
 
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Toobuilder

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No it doesn't.

...From the reliability POV there are plenty of reliable redrives around...
Really? Name ONE design within a "reasonable" sample population that has a documented track record of running 2000 hours at 300+ HP without failure.

From the weight POV it's silly to even make that point.
A PSRU adds weght - it's a fact.
 

Mac790

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Starman

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No, they don't. Even a big (50 tonne) truck only burns 100HP or so continuously, with maybe 300-400HP for those that drive in the mountains. There's a reason they have such rugged engines for those power ratings... there is a vast difference between peak power and continuous power.
A serious pick-up truck uses what, 30-40 HP at high speed continously? So you're effectively loading an engine at 10 times it's design load. Geez....
You are good on theory, but in the real world ... we have mountains around here, REAL mountains, I guess you don't have them in Denmark so you may be excused, but out here in the real world people take trucks and load them above gross weight and then drive for five hours up a steep grade to get over the mountains running full throttle non stop for five hours to get every ounce of speed they can get going up hill.

Out here in the real world we also have people who drive across the entire state of Montana (which is bigger than Europe) in fast cars at full throttle. I guess in Europe (edit: used to be =) people don't drive fast on the Autobahn? Too much traffic? You haven't heard of them? Sometimes it helps to get your head out of a book and look around, I tried that twenty years ago and never looked back.

On this forum too, you'll see endless discussions about those "dreaming engines". Yeah, great, let's put in a bad-ass car-engine in our aircraft and make a PSRU ourselves. Let those nay-sayers whine in the corner.
You nay sayers never whine in the corner, but rather rush off to the next subject.
 
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Norman

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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.
Placing the prop behind structure is never the best choice for efficiency. The fuselage boundary layer will rob at least 10% of your power. Piaggio used about 2000 hours of wind tunnel time just to get the nacelle shape of the Avanti right and it still turns a lot of power into noise.
 

Starman

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... the real world people take trucks and load them above gross weight and then drive for five hours up a steep grade to get over the mountains running full throttle non stop for five hours to get every ounce of speed they can get going up hill.
Oops, if forgot the main point. The point is, people do that to their trucks four times a week for years with the same engine and hardly even change the oil if you get the point yet.
 

autoreply

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You are good on theory, but in the real world ... we have mountains around here, REAL mountains, I guess you don't have them in Denmark
I don't live in Denmark. In fact, I live about 7 times further from Denmark, than you live from Canada...
so you may be excused, but out here in the real world people take trucks and load them above gross weight and then drive for five hours up a steep grade to get over the mountains running full throttle non stop for five hours to get every ounce of speed they can get going up hill.
Sure. 300 HP for 50 tonnes gives you a climb speed of 0.25 m/s
5 hours is 18000 seconds, so we're talking 4500 m (15000 ft) climb. Can't recall any pass in the US that requires more than 6000 ft or so of straight and steep climbing...
Out here in the real world we also have people who drive across the entire state of Montana (which is bigger than Europe)
Well, you might want to restrain yourself from further (geographical) comments, though it starts to get hilarious, Europe is over 27 times larger than Montana...
in fast cars at full throttle. I guess in Europe (edit: used to be =) people don't drive fast on the Autobahn? Too much traffic? You haven't heard of them? Sometimes it helps to get your head out of a book and look around, I tried that twenty years ago and never looked back.
Well, that you never look back is clear, given your plans changing every 2 days. That you don't read a book is clear from your previous statements too...

But tell me, if you look around, which successful automotive engine conversions do you see flying around in the 200+ HP range? I count less than a handful and I wouldn't particularly call them succesfull...
You nay sayers never whine in the corner, but rather rush off to the next subject.
If people enthusiastically start discussing their dreamed up engines, I think a warning and reality check is at it's place.

Ow and please quit the personal flaming if you can't "win" the argument. I don't recall you actually building, repairing or designing an aircraft. I did. And for your information; last summer only I've driven 50+ passes that were over 6500 ft high ;)
[video=youtube;iqhtbXdxwLk]http://www.youtube.com/watch?v=iqhtbXdxwLk[/video]
(Sorry for going completely offtopic. Felt I had to lighten the mood a bit, not intending to make it mountain warfare ;-) )


Placing the prop behind structure is never the best choice for efficiency. The fuselage boundary layer will rob at least 10% of your power.
Well, I certainly wouldn't draw that conclusion. The pusher/tractor debate is a long one, where most pilots have strong opinions about and the nuances usually get lost. 3 effects play a role:
*The tractor blows an accelerated stream over the fuselage.
*The pusher sees turbulent inflow over the inside of the prop
*The pusher "sucks off" the boundary layer of the fuselage (adverse pressure gradient), lowering the drag.

Realizing that the ratio of prop and fuselage diameter plays a big role, a pusher certainly can be more efficient than a tractor, since it seriously lowers the boundary layer drag of the fuselage. What is usually omitted by the pushy folks though is that this requires a precise design, using this effect. For most aircraft, the configurational drawbacks (longer landing gear, debris in prop) don't out weight the small possible gain in efficiency. It can be made more efficient though and this is exactly the reason virtually every ship uses it.

@ Toobuilder; seems like a reasonable approach :)

@ KC135, my reply (http://www.homebuiltairplanes.com/forums/firewall-forward-props-fuel-system/3645-diesel-engines.html#post74794) I linked too might actually be the simplest approach to a diesel engine in that neighborhood. Less than 300 hp, 600 lbs or so, but you probably can get away with a bit of tweaking.
 
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Norman

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*The tractor blows an accelerated stream over the fuselage.
That's an old argument for pushers and has not been substantiated by experiment. In fact when this old assumption was finally checked experimentally it was found that, although there is turbulence in the blade wake, that the turbulent band only covers a thin spiral strip with laminar flow reestablished immediately. Besides that there isn't very much laminar flow on the fuselages of powered planes anyway. The nose gear destroys it on the lower surface and the canopy takes care of the top. That is to say IF you could somehow reestablish laminar flow after the edge of the cowling


*The pusher "sucks off" the boundary layer of the fuselage (adverse pressure gradient), lowering the drag.
Prop scavenging only results in a significant drag reduction if the aft fuselage was too blunt in the first place, in which case you're just spending power to fix bad aerodynamics.

Realizing that the ratio of prop and fuselage diameter plays a big role, a pusher certainly can be more efficient than a tractor, since it seriously lowers the boundary layer drag of the fuselage. What is usually omitted by the pushy folks though is that this requires a precise design, using this effect. For most aircraft, the confrontational drawbacks (longer landing gear, debris in prop) don't out weight the small possible gain in efficiency. It can be made more efficient though and this is exactly the reason virtually every ship uses it.
Ships and torpedoes have relatively much smaller props AND thicker boundary layers. A ship's propeller is completely immersed in the BL and gains efficiency by operating in a much slower environment than the free stream. In other words a ships prop "sees" a nearly static inflow
 

Starman

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I don't live in Denmark. In fact, I live about 7 times further from Denmark, than you live from Canada...
Oops. Well then where the heck do you live?

Sure. 300 HP for 50 tonnes gives you a climb speed of 0.25 m/s
5 hours is 18000 seconds, so we're talking 4500 m (15000 ft) climb. Can't recall any pass in the US that requires more than 6000 ft or so of straight and steep climbing...
Out here in the West we exaggerate sometimes.

Also out here in the West we have mountains with ups and downs so the total altitude gain is higher for the trip than it would be for going over a theoretical pyramid shaped mountain that you might find in a book, for example :roll:

But you're right, there aren't any engines like that, till now :ban:

Well, you might want to restrain yourself from further (geographical) comments, though it starts to get hilarious, Europe is over 27 times larger than Montana...
That depends on how you measure it, from East to West Montana is a lot wider than Western Europe was from East to West, but hardly anyone goes that way anyway =)

Peace bro, I'm just funnin' ya.

Now I need to get to work.
 

autoreply

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That's an old argument for pushers and has not been substantiated by experiment. In fact when this old assumption was finally checked experimentally it was found that, although there is turbulence in the blade wake, that the turbulent band only covers a thin spiral strip with laminar flow reestablished immediately. Besides that there isn't very much laminar flow on the fuselages of powered planes anyway. The nose gear destroys it on the lower surface and the canopy takes care of the top. That is to say IF you could somehow reestablish laminar flow after the edge of the cowling
As for laminar flow, you're correct that you won't have that much on a tractor prop anyway. It can be achieved though (there's the "if properly designed" again) on a pusher, see many gliders. That laminar first part of your fuselage lowers drag (thinner BL) for the whole fuselage.

I wasn't talking about laminar/turbulent though, I meant the accelerated flow. A typical prop in cruise accelerates the air backwards. This is a pretty low acceleration (typically 10-20% faster than the cruise speed), but that does increase the fuselage drag. Since velocity is in the drag equation as a square, a 15% velocity increase leads to a 32% higher fuselage drag.
Prop scavenging only results in a significant drag reduction if the aft fuselage was too blunt in the first place, in which case you're just spending power to fix bad aerodynamics.
In a nicely streamlined flow too it lowers the boundary layer drag.
Ships and torpedoes have relatively much smaller props AND thicker boundary layers. A ship's propeller is completely immersed in the BL and gains efficiency by operating in a much slower environment than the free stream. In other words a ships prop "sees" a nearly static inflow
That last statement is absolutely wrong (I've witnessed numerous ships and believe me, they have massive flow around the prop/rudder, if the prop is stopped) The displacement boundary layer thickness of a 1000 ft container vessel for example is just over a foot.

But yes, on a ship, the efficiency gain is much larger, I've seen statements (not proof) of a 50% gain. We'll never achieve that in an aircraft, but we can certainly gain a bit. Whether that's enough is up to the designer, but I'd regard any claimed gain over 10% highly optimistic.

Out here in the West we exaggerate sometimes.
Yeah, I noticed several hilarious occasions before.
Here's another one:
That depends on how you measure it, from East to West Montana is a lot wider than Western Europe was from East to West, but hardly anyone goes that way anyway =)
Well, no. Absolutely not. When there was still Western Europe, West-East was 1800 km tops. Montana is 870 km tops. So still completely the other way around...
Europe is larger as the US. Heck, even Australia is as large as the US. Do you already feel tiny? :gig:
Peace bro, I'm just funnin' ya.
I don't mind, as long as you don't mind me correcting you.
 

Bigorneau

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But tell me, if you look around, which successful automotive engine conversions do you see flying around in the 200+ HP range? I count less than a handful and I wouldn't particularly call them succesfull...

:gig:i know one in France: E-Racer with automotive engine Land Rover V8 4.6 liters injection 240 HP and PSRU :lick: it's mine
flying between 62 knots to 216 knots tested.
:lick::lick::lick::lick::lick::lick:
 
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