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Subaru diesel EE20 aircraft RV-7

S

Syncrogreg

I'm New Here
Hello all,

I have accumulated a good amount of experience over the last 3 years concerning the Subaru Diesel EE20 engine. I have ran last June the engine over 14000 Ft successfully on Jet A when I raced Pikes Peak with my Subaru diesel race car http://subiesport.tv/site/2013/07/impreza-22b-diesel-pikes-peak/ . I'm now confident and interested to put together a FWF for the rv-7.

What I have:
- EE20 Engines
- Bosch MS 15.1 ECU ( jet A and diesel map)
- SS exhaust
- 180 HP with 450 Nm of torque at 2800 RPM
- Estimated weight of engine 320 LBS.
- integrated gear pump ( no fuel pump needed)

What I need:
- Direct drive plate + bearing to release stress on the crank
- Same engine mount as EJ25
- Same cooling as EJ25
- correct propeller

Let me know if you have any ideas of source for the parts or recommendation concerning the setup especially propeller and direct drive plate design.

Thanks

Greg
 
For the prop at least, I'm sure Craig at Catto could help with that. Since you know the engine spec and target cruise speed it shouldn't be all that hard. The big test will come from dealing with the different harmonics produced from that engine vs current FWF packages.

I would love to see a viable, reliable, affordable diesel FWF package for the RV line. It sounds a little heavy, but not bad (not sure whats included in the quoted weight). I would love to have a diesel on the front of my plane if it could match the performance and reliability of the Lycoming. Best of luck to you putting this together!!!!
 
Engine looks heavy on paper, but when compared to an IO-360 and a C/S prop it's right on point if not a little lighter.

I'm with Colin, would love to see a light, reliable diesel option for the Rv's.

No reduction required, and 180HP? This will be interesting.
 
With a turbo, you'll probably want a C/S or VP prop to get best performance. Probably stuck with an electric MT composite one which are very expensive. I wouldn't use a metal prop unless you are going to instrument and do a vibration study on the crank and prop.

What sort of pressure ratio are you running at 14K on the turbo? OEM or aftermarket turbo?
 
I love my Diesel....Truck, dont forget to add 40 ish Lbs extra for fuel.
 
bret said:
I love my Diesel....Truck, dont forget to add 40 ish Lbs extra for fuel.
Click to expand...

Apples to apples? Isn't the specific energy of diesel fuel higher, such that you get additional range compared to avgas for a given weight (not volume)?

--
Stephen
 
fatherson said:
Apples to apples? Isn't the specific energy of diesel fuel higher, such that you get additional range compared to avgas for a given weight (not volume)?

--
Stephen
Click to expand...

I think he is talking about how much the fuel weighs per gallon.

100LL - 6 lbs per US gallon
Diesel - 7.1 lbs per US gallon

That is 44 extra pounds just in fuel load for the same volume.
 
What is the cruise bsfc for this engine? 2700 RPM seems like a pretty low piston speed for that engine too. Does the diesel version have a longer crank with thicker cheeks and better L/D ratio for bearings? I looked up specs but did not see internal details.

Maybe the weight gets made up in less onboard fuel for typical 700nm mission.

Looking forward to following your project, keep us informed!
 
Syncrogreg said:
Let me know if you have any ideas ...direct drive plate design.
Click to expand...

Have you determined how much length you can accept, crankcase flange face to prop flange face?

Are you planning to run a flywheel on the crank end?
 
N941WR said:
I think he is talking about how much the fuel weighs per gallon.

100LL - 6 lbs per US gallon
Diesel - 7.1 lbs per US gallon

That is 44 extra pounds just in fuel load for the same volume.
Click to expand...

Stephens point, is if you want to go the same distance, you can carry less Diesel/Jet A. So the weight increase is a wash (or close to it). If you want to go 1:1 on avgas vs diesel in an RV with the same volume, the diesel will go farther (but yes will weigh more at the start)
 
The engine consumption is 45 mpg in my car. I'm not to worried about operating at High altitude as I already got this case checked. The vibration is minimal if not even existing.

http://www.youtube.com/watch?v=ZEKUWMWxvC4


So, I'm not thinking of using a heavy flywheel but a flywheel that is just strong enough to handle the cranking from the starter. The turbo is the stock one. I'm working on a larger Garrett unit for the next year race at Pikes Peak. I'm very curious on how a direct drive is usually done and what type of hardware is used. I understand that a plate is needed to hold a bearing that has the purpose to handle torsional stress. So the bearing need to handle Axial and radial loads. Do you know what type bearing it is???

The Subaru diesel engine is 17" deep from transmission flange to front of the engine so It could fit in any EJ25 or EG33. From there I guess the direct drive shaft would need to be cut to length to meet the original prop position.

Let me know you thought!

Thanks

Greg
 
Google the name Reg Clarke, and Dragonfly name Expresso -------he was very successfully running a direct drive turbo Subie back in the 1980s or 90s------and I am pretty sure he is still around with a new plane.

Perhaps he could provide you some direction.
 
Ok Thanks I will. I think he does not hold the prop:

drageng.jpg


Greg
 
You might check with Ross, I suspect he may have contact info for Reg------or knows about the need for thrust bearings already.
 
Greg,
This was a past project, a fixed pitch shaft to convert surplus M14V-26 helicopter engines to sport aircraft use. Conceptually, you want to do something similar. It won't look the same of course, but there are lessons.

Note how the tail of the propshaft is centered within the end of the crankshaft, a standard practice. In this case it is pressure lubed, but that's just a holdover from the geared application. The lube does little more than prevent fretting, as there is no relative rotation difference between the crank and the shaft. You could pilot the propshaft tail in a small bolt-on crank extension if the stock crank provides no useful purchase. The extension could hold a proper bearing surface.

Here torque is transferred from the crank to the shaft via a external splines and a coupler. In your case the coupler could be solid, as this is, or could incorporate a torsional spring rate, i.e. one of the torsional couplers specifically designed for diesel drive systems. I suspect you'll need it.

The big ball bearing at the front carries both the radial and the thrust loads. See the engineering section in any good bearing catalog for guidance. This one is oil lubed and happily deals with a thrust load well over 1000 pounds.

voqy5v.jpg


There are other ways to skin the cat of course. For example, a quill shaft might bolt directly to the crank end, which would eliminate the coupler and provide a measure of torsional softness.

Have fun.
 
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Maybe doesn't need a damper?

If a prop can take the 2-per-rev pounding of a lycoming at 2700 rpm, then it may also be able to take the 2-per-rev pounding of a diesel at 2800 rpm (as long as there isn't a blade resonance there).

It is not the same requirement that is needed to protect the gears of a speed reduction gearbox, right?

So, perhaps he doesn't need a coupling with a damper in it.

Ross can help with replacing the ECU that has all kinds of car-friendly, but non-airplane-friendly failure-protection modes.

Is there still the classical concern of running at max power for long times, as opposed to typical automotive duty cycles? Or are diesels so stout that this would not be a concern?
 
scsmith said:
<snip>
Is there still the classical concern of running at max power for long times, as opposed to typical automotive duty cycles? Or are diesels so stout that this would not be a concern?
Click to expand...

Typically, the fatigue life may be ok if operated within its "normal" limits, but continuously elevated temperatures would be the area of interest. The light duty diesels in automotive are already hugely different (i almost said compromised) compared to an engine designed for heavy continuous service, so installation in an airframe and appropriate consideration to loads, torsionals etc seem like an intelligent path to evaluate this engine in this application.

Facts and data will need to be gathered here. I don't want to speculate on its success as there are many ways to mitigate issues and potential issues. This is a "development" project with no obvious prediction of the final result. I am sure the process will be interesting, and success would be a big positive step forward for a diesel engine option.
 
With a DD diesel, the boost pressure is being upped to be able to develop around the stock hp at a prop friendly, lower rpm. This means total thermal loads are not much different than stock. Even the light duty diesels of today have most of the tricks their heavy brothers have like anodized or steel inserted ring lands, under piston oil jets etc.

Only some extended hard running will prove how stout the design is for aviation use however.

Engines like the early Thielert often had a lot of ring and ring land distress in only a few hundred hours. The high continuous boost often takes its toll in aviation use. Hopefully the Subaru is tougher than this.

You'd certainly want a different turbo on there for high altitude too and you need a very high pressure ratio capability compared to an SI engine.
 
scsmith said:
If a prop can take the 2-per-rev pounding of a lycoming at 2700 rpm, then it may also be able to take the 2-per-rev pounding of a diesel at 2800 rpm (as long as there isn't a blade resonance there).
Click to expand...

Blade issues are low priority, assuming the experiment begins with a sensible fixed pitch prop, like laminated sugar maple. If seriously stressed the blades will generally split and delaminate with plenty of warning, unlike a metal prop.

There may be a requirement to increase the the peak instantaneous torque/nominal torque factor used in calculating frictional torque transmission capacity of the prop hub. It's conservatively 3 for piston radials. I suspect the diesel will require more...needs a trip to the library.

It is not the same requirement that is needed to protect the gears of a speed reduction gearbox, right? So, perhaps he doesn't need a coupling with a damper in it.
Click to expand...

Same requirement, resonant torsional vibration of the shaft system. If we assume the diesel crank is quite stiff and ignore blade root bending (not unreasonable for a fixed pitch), the system can be roughly modeled as two inertias and one connecting stiffness. Makes the natural frequency math very simple. Will it need a soft torsional element? You can't know for sure without the math, and you can't do the math without the shaft stiffness and the inertia values. It's primary purpose would be to lower the fundamental natural frequency below the operating range. It's secondary purpose would be reducing the amplitude of the pounding noted above, as transmitted through the system. After all, it is a spring, an energy storage device. It is not a damper, a term which would mean it removes energy from the system, usually as heat. A soft rubber element acting in that manner would simple melt. Yes, I know, even the coupler manufacturers will often refer to the products as dampers, but it doesn't help understanding.

I'm guessing the system will need a soft element or a slip clutch. Heck, I'll bet one US dollar on it. Any takers? ;)
 
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The heavy truck diesels today run boost levels so high that the pre-cooler temps burn the paint off the tubes. Paint browns around 400F. The pistons are all steel now to handle the 3000psi+ firing pressures. These engines can run 1000 hours at max loads/rpm and when dissembled the parts still all look new. If they don't, they won't make the 8000 hour + life expected (some twice that). And that is just for the Class 8 truck engines.

Still, I have seen some light duty engines with aluminum heads go 1000 hours all near peak torque, and at their altitude limit. (Typically 1400 F exhaust temps. The big guys will use 1200F limit for continuous duty.) They did not look pretty when torn down, but they made it. These automotive engines have come a long way in the last 20 years, especially the Japanese engines.
 
On a Mission...

There is hope, and it's spelled SMA.
This year at Oshkosh my New Tribes Missions friends Jeff and Michael stopped by our ITEC Maverick Flying Car booth. Close behind them were two French engineers from SMA, talking up the recently converted NTM Cessna 182 that was on display at the IAMA tent. http://en.wikipedia.org/wiki/SMA_SR305-230
NTM recently began seeking donations to upgrade a small number of their aging Cessna aircraft to SMA Diesel power as AvGas is nearly unheard of in the remote regions where they operate. They installed a SMA Diesel engine in a test C182 aircraft and flew it extensively under the most difficult conditions to simulate Mission Field flying. It passed and the first one is entering service this Fall alongside their Kodiak already flying in Indonesia. Currently for most of us it's cost prohibitive, hopefully this is just the beginning.

Good news indeed...

V/R
Smokey
www.itecusa.org


NTM Diesel C182
http://www.youtube.com/watch?v=6mFgT_hXndg


SMA Diesel engine
 
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Did you get to talk with the engineers about mods or fixes they have made to the design? Others using the original engines in Africa for similar work found they developed oil leaks from fretting case halves and the engines were being pulled after a few hundred hours to be replaced. I believe someone flying these posted that info here on VAF a year or two back.
 
Lubricity

You need to run some long term tests on the injectors as Jet A1 does not have the same lubricity as diesel.
 
Oui!

rv6ejguy said:
Did you get to talk with the engineers about mods or fixes they have made to the design? Others using the original engines in Africa for similar work found they developed oil leaks from fretting case halves and the engines were being pulled after a few hundred hours to be replaced. I believe someone flying these posted that info here on VAF a year or two back.
Click to expand...

Ross,
Short answer, yes. The French Engineers were full of great information unfortunately my French stinks. Good news is one of them spoke enough English to share your exact concern as one of their major fixes when they pulled them from the market 3 years ago.
NTM had very specific requirements and specifications they wanted proven (as did Cessna) before they invested donated mission funds for the product. During the proving flights and test stand hours, NTM reps and the FAA monitored their findings and the end result was impressive, albeit expensive.
My friend Jeff is an NTM Pilot/Engineer and I will ask him to keep me updated on the C-182D's numbers in the field.

V/R
Smokey

PS: Steve, NTM agrees with you and will primarily run Diesel in the 182, vice Jet A. Diesel is available even in the most remote regions. Interestingly enough, the Quest Kodiaks PT-6A-34's run very well on Diesel.
 
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WAM120RV said:
You need to run some long term tests on the injectors as Jet A1 does not have the same lubricity as diesel.
Click to expand...

You make a good point. However, diesel engines that are developed to run in Japan have their fuel systems durability tested with Japanese kerosene, a very very light fuel, it looks like water. If a system tolerates J-K, then Jet A would not be an issue.
 
smokyray said:
Ross,
Short answer, yes. The French Engineers were full of great information unfortunately my French stinks. Good news is one of them spoke enough English to share your exact concern as one of their major fixes when they pulled them from the market 3 years ago.
NTM had very specific requirements and specifications they wanted proven (as did Cessna) before they invested donated mission funds for the product. During the proving flights and test stand hours, NTM reps and the FAA monitored their findings and the end result was impressive, albeit expensive.
My friend Jeff is an NTM Pilot/Engineer and I will ask him to keep me updated on the C-182D's numbers in the field.

V/R
Smokey
Click to expand...

Good that they think they have that issue fixed now but one wonders after all this time this engine has been on the market, how did they validate the design in the first place? Seems like any engine, certified on not, should simply be beat on with many hot and cold cycles between running at max continuous power until it either reaches TBO or breaks.

The earlier in service SMAs were pretty poor. A fellow here had one in a 182 and it was nothing but problems, being removed at least twice in less than 300 hours. Pretty much mirrors the experience reported by the guy in Africa. Makes me wonder how they were tested initially. If they only tested to meet the FAA certification minimum which is pretty paltry, they were asking for trouble down the line.

I would have loved to talk to those engineers but my French is about as good as my Japanese and Mandarin- meaning not very.:(

While we are off topic here, I understand Lycoming is developing a heavy fuel engine called the DEL-120 for UAV use primarily. I wonder if they have GA plans for that design or something similar.

Some interesting non-avgas stuff in the works anyway.
 
DanH said:
Greg,
This was a past project, a fixed pitch shaft to convert surplus M14V-26 helicopter engines to sport aircraft use. Conceptually, you want to do something similar. It won't look the same of course, but there are lessons.

Note how the tail of the propshaft is centered within the end of the crankshaft, a standard practice. In this case it is pressure lubed, but that's just a holdover from the geared application. The lube does little more than prevent fretting, as there is no relative rotation difference between the crank and the shaft. You could pilot the propshaft tail in a small bolt-on crank extension if the stock crank provides no useful purchase. The extension could hold a proper bearing surface.

Here torque is transferred from the crank to the shaft via a external splines and a coupler. In your case the coupler could be solid, as this is, or could incorporate a torsional spring rate, i.e. one of the torsional couplers specifically designed for diesel drive systems. I suspect you'll need it.

The big ball bearing at the front carries both the radial and the thrust loads. See the engineering section in any good bearing catalog for guidance. This one is oil lubed and happily deals with a thrust load well over 1000 pounds.

voqy5v.jpg


There are other ways to skin the cat of course. For example, a quill shaft might bolt directly to the crank end, which would eliminate the coupler and provide a measure of torsional softness.

Have fun.
Click to expand...

This is essentially the concept ULPower uses on their direct drive engines. You can see it here on page 12 and 29. A ball bearing works as a thrust bearing and also takes lots of radial loading I guess.
 
SvingenB said:
This is essentially the concept ULPower uses on their direct drive engines...A ball bearing works as a thrust bearing and also takes lots of radial loading I guess.
Click to expand...

The designer opted for a thrust/radial ball bearing rather than the long plain bearing and thrust face in our Lycomings. However, it's not a separate shaft. It would still allow bending loads to reach the crank, and it would not provide any way to tailor torsional issues. I'm suggesting a light bellhousing bolted to the Subaru, with separate prop shaft, for those reasons.

BTW, everything in the previous cad drawing is standard M-14 design, except for the flanged shaft and two custom coupler parts. The concept of a separate shaft supported by a ball bearing at the front and a sleeved tail is common to geared radials worldwide. Here, for example, is an P&W R-2800 C-series:

2880c9j.jpg


2uhtwk6.jpg
 
Syncrogreg said:
- Same engine mount as EJ25

Let me know if you have any ideas of source for the parts or recommendation concerning the setup especially propeller and direct drive plate design.
Thanks Greg
Click to expand...

You could contact the Cozy-Girls for a source for engine mounts...they have taken over production of mounts in the Mazda 13B / Renesis world...

http://www.cozygirrrl.com/aircraftparts.htm

Doug Lomheim
RV-9A Mazda 13B / FWF (on hold to complete RV-3 restoration :) )
 
DanH said:
The designer opted for a thrust/radial ball bearing rather than the long plain bearing and thrust face in our Lycomings. However, it's not a separate shaft. It would still allow bending loads to reach the crank, and it would not provide any way to tailor torsional issues. I'm suggesting a light bellhousing bolted to the Subaru, with separate prop shaft, for those reasons.
Click to expand...

OK. I thought he wanted a direct drive. If a separate shaft is needed, then I would believe it is better to increase RPM on the engine to get the torque (and torque pulses) on the engine down, and decrease the RPM on the propeller to get the efficiency up.
 
SvingenB said:
OK. I thought he wanted a direct drive. If a separate shaft is needed, then I would believe it is better to increase RPM on the engine to get the torque (and torque pulses) on the engine down, and decrease the RPM on the propeller to get the efficiency up.
Click to expand...

I believe you are thinking in spark ignition engine performance terms. The diesel typically has a naturally high efficiency region mid to low speed and 80% of max torque. If this engine is in that region at 2700, then it will get much better bsfc there. Using DanH type of drive, the "drive shaft" can be tuned to reduce the reaction torque impulse to the airframe by softening the drive linkage to the prop. Since steel is quite efficient, it may also need a torque limiting clutch for starting and shutdown, and a visconic damper or dual mass on the engine to attack torsionals.

Also, the prop may be better with shorter blades as 72-74 inch running at constant 2700 may be approaching mach at colder temps, thus hurting efficiency. This is based on comments by a prop manufacturer engineer. A 3 blade might end up a better trade off.
 
BillL said:
The diesel typically has a naturally high efficiency region mid to low speed and 80% of max torque. If this engine is in that region at 2700, then it will get much better bsfc there.
Click to expand...

Can't speak for the OP's modified engines, but here's the stock output....

http://subdiesel.files.wordpress.com/2011/05/powergraphsubaru.png

Using DanH type of drive, the "drive shaft" can be tuned....
Click to expand...

Exactly the point, plus remove all prop loads from the crank.
 
BillL said:
I believe you are thinking in spark ignition engine performance terms. The diesel typically has a naturally high efficiency region mid to low speed and 80% of max torque. If this engine is in that region at 2700, then it will get much better bsfc there. Using DanH type of drive, the "drive shaft" can be tuned to reduce the reaction torque impulse to the airframe by softening the drive linkage to the prop. Since steel is quite efficient, it may also need a torque limiting clutch for starting and shutdown, and a visconic damper or dual mass on the engine to attack torsionals.

Also, the prop may be better with shorter blades as 72-74 inch running at constant 2700 may be approaching mach at colder temps, thus hurting efficiency. This is based on comments by a prop manufacturer engineer. A 3 blade might end up a better trade off.
Click to expand...

It's only a 2L engine. Max torque may start as low as 1500 RPM, but it is still only 2L, and there is only so much torque you can get out of it reliably. Max power is typically around 3500-4000 rpm, even though the torque is lower there. It is much better to have higher RPM on the crank shaft and lower torque than the opposite regarding forces on the crank. 3500-4000 rpm is still low for a 2L engine. If it was a 3L or more, things would be different because the shaft would be spec'ed to handle more torque.

In comparison the SMA is a 5L engine, 2.5 times the volume of the Subaru.
 
Is anyone still working on the Subaru Boxer diesel?

Is anyone still working on the Subaru Boxer diesel for use in the RV7?

What happened to this project? Was it not successful?
 
Subaru EE20

:)We are flying with Subaru EE20. We have direct drive and using WarpDrive propeller.

Thanks,
Rene
 
Rene said:
:)We are flying with Subaru EE20. We have direct drive and using WarpDrive propeller.

Thanks,
Rene
Click to expand...

I might add that another fellow contacted me this week and is also working on another DD EE20 powered RV project. Will be interested to watch the results and performance. Kudos to these folks actually doing this stuff. :)
 
Rene said:
:)We are flying with Subaru EE20. We have direct drive and using WarpDrive propeller.

Thanks,
Rene
Click to expand...

Hi rene :)

i'm planning a build using this engine.... any pictures/info you can offer would be helpful. did you keep the stock flywheel? i'm very interested in everything between engine crank & prop.

thanks
 
rv6ejguy said:
With a turbo, you'll probably want a C/S or VP prop to get best performance. Probably stuck with an electric MT composite one which are very expensive. I wouldn't use a metal prop unless you are going to instrument and do a vibration study on the crank and prop.

What sort of pressure ratio are you running at 14K on the turbo? OEM or aftermarket turbo?
Click to expand...

Give GT Propellers a call. They made me a custom electric constant speed prop for my RV-8 at half the price.
 
direct drive

Syncrogreg said:
Hello all,

I have accumulated a good amount of experience over the last 3 years concerning the Subaru Diesel EE20 engine. I have ran last June the engine over 14000 Ft successfully on Jet A when I raced Pikes Peak with my Subaru diesel race car http://subiesport.tv/site/2013/07/impreza-22b-diesel-pikes-peak/ . I'm now confident and interested to put together a FWF for the rv-7.

What I have:
- EE20 Engines
- Bosch MS 15.1 ECU ( jet A and diesel map)
- SS exhaust
- 180 HP with 450 Nm of torque at 2800 RPM
- Estimated weight of engine 320 LBS.
- integrated gear pump ( no fuel pump needed)

What I need:
- Direct drive plate + bearing to release stress on the crank
- Same engine mount as EJ25
- Same cooling as EJ25
- correct propeller

Let me know if you have any ideas of source for the parts or recommendation concerning the setup especially propeller and direct drive plate design.

Thanks

Greg
Click to expand...

check out https://www.facebook.com/raptoraircraft/

he has a device on the prop drive that would work PERFECTLY on your direct drive setup. (even though he's using it with belts).

have you weighed the engine with it stripped down of non-essentials yet? how much does it actually weigh? just curious. would love to do a build with this engine.
 
What airframe is this in?

Rene said:
:)We are flying with Subaru EE20. We have direct drive and using WarpDrive propeller.

Thanks,
Rene
Click to expand...

Congratulations.

What airframe and how many flight hours?

Also what propellor arrangement are you running(photos would be nice) with what RPM for take off and cruise ?

Edit: Online searches have found reports of 350 Newton Meters to 380 NM torq in a wide band around 2250 RPM. 380 NM is 518 ft-lbs of torque! At the same RPM that is only about 125 -135 Hp however in an RV 9 with a propellor matched to the application it looks like a very worthwhile venture. A bell housing prop flange and bearing, properly executed should provide for a long and reliable service life running at a low 2200 to 2500 RPM.
 
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One of the biggest challenges faced in using diesel engines for aircraft (apart from weight) has been the fact that the power pulses are far stronger than in a gasoline engine of the same horsepower. This creates great strain on the propeller, and is one reason so many recommend composite propellers.

One way around this has been 2-stroke engines like the Gemini now owned by Superior and slated to go into production this year. The turbo version will only be 125hp, but will be able to generate full hp at any altitude any of us are likely to be flying at. Its 3 cylinders act like a 6 cylinder 4 stroke with respect to the number of power pulses per revolution, and in addition the whole thing is naturally gear reduced (I believe 8:5, so the crankshafts turn 4,000 rpm to the propeller shaft's 2,500 rpm) for 12,000 power pulses per minute @ 2,500 prop rpm compared to 5,600 power pulses for a 4 cylinder Lycosaurus at 2,700 rpm.

The Gemini promises to be the simplest aircraft engine design out there, but unfortunately it will most likely be priced more like their XP engines.
 
If diesel is same as 2.5 Subaru, I would recommend talking to Vassil at air strikes about their reduction drive for 2.5 suby, rated for up to 180HP ,higher yet on air boats Tom
 
The floor models...

breister said:
One of the biggest challenges faced in using diesel engines for aircraft (apart from weight) has been the fact that the power pulses are far stronger than in a gasoline engine of the same horsepower. This creates great strain on the propeller, and is one reason so many recommend composite propellers.

One way around this has been 2-stroke engines like the Gemini now owned by Superior and slated to go into production this year. The turbo version will only be 125hp, but will be able to generate full hp at any altitude any of us are likely to be flying at. Its 3 cylinders act like a 6 cylinder 4 stroke with respect to the number of power pulses per revolution, and in addition the whole thing is naturally gear reduced (I believe 8:5, so the crankshafts turn 4,000 rpm to the propeller shaft's 2,500 rpm) for 12,000 power pulses per minute @ 2,500 prop rpm compared to 5,600 power pulses for a 4 cylinder Lycosaurus at 2,700 rpm.

The Gemini promises to be the simplest aircraft engine design out there, but unfortunately it will most likely be priced more like their XP engines.
Click to expand...

Bill,
Wow, some encouraging news, albeit apprehensive. A flyable/affordable Diesel powerplant in that HP range would be a quantum leap...
Having just chatted with a One-X flyer who got his turbocharged Aerovee example flying for under $25K, I'm cautiously optimistic about the future of Experimental aviation. Having thrown money at airplanes for a long time, I'm thinking financially more like the Piet/Sonex/Sonerai/Panther guys these days.

Flying shouldn't have to require appendage amputation for payment...:)
V/R
Smokey


https://www.youtube.com/watch?v=4j_eUjBJNbI
Then there's this...ciao!
 
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sub-diesel aircraft.

I found a guy in europe who's flying what looks like a UH-12 with this engine (2L sub. boxer diesel. direct drive). performance specs are impressive. i'd paste you some images, but i don't see a place in here to do attachment. his 'flight ready' weight, minus fuel is 311 Lbs. fuel consumption with throttle at 80% is 4.5 GPH. econo- cruise is 2.6 GPH! and this is a 2-seater aircraft.
 
How can I find out more, and maybe get in touch with the owner? I'm ready to give an EE20 a shot, but would like to educate myself as much as possible before buying an engine and getting started mounting it on my RV9.

Kurt
 
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