Diesel powered helicopters
Avoid imitations
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The problem with "Gas / petrol" fuelled engines for European use is that the fuel (AVGAS) itself is so expensive, also fewer outlets are now supplying it. AVGAS is environmentally unfriendly due to the high lead content (much higher than motor fuel ever contained, despite the "LL" suffix).
The modern aviation diesel engines are being specially designed to use Jet A-1 fuel which is much cheaper and available at many more airports.
A diesel engine cannot suffer from carb icing (there is no carb) and has no ignition components to fail in flight. There is also no mixture control to worry about.
I am certain diesels are the best way forward (pun not intended!) for light aircraft.
The modern aviation diesel engines are being specially designed to use Jet A-1 fuel which is much cheaper and available at many more airports.
A diesel engine cannot suffer from carb icing (there is no carb) and has no ignition components to fail in flight. There is also no mixture control to worry about.
I am certain diesels are the best way forward (pun not intended!) for light aircraft.
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Torsional vibrations
So you have a little more insight to the issues.
leemind
I am aware of these engines. Yet the engine does have a reduction gearbox and a torsional vibration damper fitted as well which more than likely only matched to the MT propeller. This part of the adaptation probably accounts for 30% of the weight. Add in the torsional vibes from a rotor system and you have some major issues.
Ideally of course the drive system will need better integration to achieve the desired result - read clean sheet.
So you have a little more insight to the issues.
leemind
I am aware of these engines. Yet the engine does have a reduction gearbox and a torsional vibration damper fitted as well which more than likely only matched to the MT propeller. This part of the adaptation probably accounts for 30% of the weight. Add in the torsional vibes from a rotor system and you have some major issues.
Ideally of course the drive system will need better integration to achieve the desired result - read clean sheet.
Avoid imitations
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Of course there are normally some problems with any new direction of technology. I'm certain the problem of vibration can be dealt with by design.
For example, one could even drive the gearbox with a couple of rubber bands. On second thoughts, no-one would fly in a helicopter driven like that, would they?
For example, one could even drive the gearbox with a couple of rubber bands. On second thoughts, no-one would fly in a helicopter driven like that, would they?
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The Rand Cam and Dyna-Cam engines certainly are a lot smoother in their torque delivery than a conventional piston/crankshaft recip. One or the other could easily find its way into that 250 - 400 SHP market as an economical alternative to a small turbine.
BTW, a 2-stroke diesel does not suffer from the same efficiency problems as its premix/petrol brethren. Their power/weight ratio goes up a lot, while their fuel-for-hp rate gets only a little worse. If you need the power, 2-stroke diesel is the way to go!
BTW, a 2-stroke diesel does not suffer from the same efficiency problems as its premix/petrol brethren. Their power/weight ratio goes up a lot, while their fuel-for-hp rate gets only a little worse. If you need the power, 2-stroke diesel is the way to go!
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diesel heli engine's
what do you guys think of putting a diesel engine in heli's?? i am thinking of putting one in mine. www.copter.com.ua ,
here are the engine's:
http://www.smaengines.com/index.html
http://www.zoche.de/
http://www.dynacam.com/Index.htm
http://www.deltahawkengines.com/
http://www.centurion-engines.com/c17/c17_start.htm
some of these are close to certification with the FAA and some are not.. what are your opinions??
although the Dynacam engine is very radical, it is just simply a cool looking engine!!
here are the engine's:
http://www.smaengines.com/index.html
http://www.zoche.de/
http://www.dynacam.com/Index.htm
http://www.deltahawkengines.com/
http://www.centurion-engines.com/c17/c17_start.htm
some of these are close to certification with the FAA and some are not.. what are your opinions??
although the Dynacam engine is very radical, it is just simply a cool looking engine!!
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This helicopter you want to put the diesel in looks like a 269 or 300.
How can you have solid landing gear with a 3 blade rotor? Is it rigid like a BO105?
What is the current engine?
Thanks
Clayton A.
How can you have solid landing gear with a 3 blade rotor? Is it rigid like a BO105?
What is the current engine?
Thanks
Clayton A.
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Diesels are typically quite heavy because of the 17 to 1 or so commpression ratio.Helicopters have favored low weight engines even if thirsty for fuel.
If a long range helo is desired, then a diesel may make some sense, because the fuel weight savings could offset the heavy engine.
My diesel tractor seems to leak almost as much fuel as it burns (just kidding) 5 gallons will run it all day.
Diesels have good low rpm torque and that would help reqain low rotor rpm in flight.
Consider the shaft dynamics and stresses that would be very different for a diesel.
If a long range helo is desired, then a diesel may make some sense, because the fuel weight savings could offset the heavy engine.
My diesel tractor seems to leak almost as much fuel as it burns (just kidding) 5 gallons will run it all day.
Diesels have good low rpm torque and that would help reqain low rotor rpm in flight.
Consider the shaft dynamics and stresses that would be very different for a diesel.
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I favor the DynaCam, as it has the best pwr/weight ratio and will also provide the smoothest rotational power. I think it also provides the easiest packaging options. However, it is a gas engine (albiet one that will run on mogas or avgas).
On the diesel side, I like the Zoche and the DeltaHawk, both 2-strokes with four-cylinder 90-degree opposition which will also provide acceptably smooth rotational power. However, the Zoche line seems to be missing an engine right where you would want one, in the 180 - 220 HP range. Also, you would have to devise a cooling-fan arrangement for the Zoche.
I think the flat-four 4-stroke diesels will be too heavy and their power pulses too strong for your use.
On the diesel side, I like the Zoche and the DeltaHawk, both 2-strokes with four-cylinder 90-degree opposition which will also provide acceptably smooth rotational power. However, the Zoche line seems to be missing an engine right where you would want one, in the 180 - 220 HP range. Also, you would have to devise a cooling-fan arrangement for the Zoche.
I think the flat-four 4-stroke diesels will be too heavy and their power pulses too strong for your use.
Last edited by Flingwing207; 27th Mar 2005 at 16:24.
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Another to consider
On the subject of compression ingnition engines for helicopters then how about the realy excelent engine from Wilksch?. This is a very clever modular designed engine that has fantastic power/consumption/torque figures. This engine would be a fantastic replacement for the aging lycoming fitted to light helicopters such as the R22. Advantages would be the fuel consumption (and lower price of Jet A-1!) and total lack of any dependancy on electrics to fuction. With direct injection there is no danger of any form of carb icing. There would also be long term savings in maintenance costs with no plugs,leads or mags to worry about.
The engine is a bespoke design rather than an adapted car or truck engine and considering it is by a Cosworth trained designer, comes with the very best of pedigree. It can only be a matter of when rather than if that we will convert to this type of engine. If ,in America, you had to pay UK fuel prices then it would be here now! www.wilksch.com
The engine is a bespoke design rather than an adapted car or truck engine and considering it is by a Cosworth trained designer, comes with the very best of pedigree. It can only be a matter of when rather than if that we will convert to this type of engine. If ,in America, you had to pay UK fuel prices then it would be here now! www.wilksch.com
Last edited by sparks and stuff; 27th Mar 2005 at 21:02.
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I think diesel is the way to go.
Automotive diesel is relatively cheap and readily avialable. Jet fuel is also readily available, I think there may come a time when avgas becomes difficult to find.
Automotive diesel is relatively cheap and readily avialable. Jet fuel is also readily available, I think there may come a time when avgas becomes difficult to find.
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Industrial diesel engines are big, because they are expected to have a service life of 15'000 hours and must meet emission standards (ie low RPM). I have uncovered some interesting facts:
Rudolf Diesel intended to achieve 240 Bar in his engine, with fuel injected to achieve isothermic expansion. This would get around most emission problems, allowing much higher RPM. Modern diesels are up to 170 Bar and so, with improved injection technology, can spin at higher RPMs. Some way to go though...
The limiting factor on pressure is the small end bush. This must package into the piston, and is splash lubricated. Ceramic coatings are allowing higher bearing stresses, with less cooling requirements. Larger pistons, however, allow more heat to be rejected at TDC, resulting in less benefit from higher pressures.
Cylinder liners can be coated in ceramic material, to reduce heat rejection. Higher pressures become more practical. This also allows lower friction losses, improving efficiency. Liners also result in a block that weighs no more than a gasoline engine.
The practical upshot is that diesel engines are the fastest evolving engine technology out there. A 2-stroke turbo diesel could be thought of as a 2-stage gas turbine, with very high pressure ratios. I expect that not only will all (small) helicopters go diesel, but some may even go diesel/electric hybrid! This allows optimum rotor design for many different mission profiles, without the complexity (say) of multiple engines...
Mart
Rudolf Diesel intended to achieve 240 Bar in his engine, with fuel injected to achieve isothermic expansion. This would get around most emission problems, allowing much higher RPM. Modern diesels are up to 170 Bar and so, with improved injection technology, can spin at higher RPMs. Some way to go though...
The limiting factor on pressure is the small end bush. This must package into the piston, and is splash lubricated. Ceramic coatings are allowing higher bearing stresses, with less cooling requirements. Larger pistons, however, allow more heat to be rejected at TDC, resulting in less benefit from higher pressures.
Cylinder liners can be coated in ceramic material, to reduce heat rejection. Higher pressures become more practical. This also allows lower friction losses, improving efficiency. Liners also result in a block that weighs no more than a gasoline engine.
The practical upshot is that diesel engines are the fastest evolving engine technology out there. A 2-stroke turbo diesel could be thought of as a 2-stage gas turbine, with very high pressure ratios. I expect that not only will all (small) helicopters go diesel, but some may even go diesel/electric hybrid! This allows optimum rotor design for many different mission profiles, without the complexity (say) of multiple engines...
Mart
Last edited by Graviman; 28th Apr 2014 at 17:25. Reason: Cause I got bored of designing non aviation equipment.
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Hi Nick,
a little late for a reply, but better late than never!
Congrats to your new post!
Are we goin' to see some Gulfstream-helicopters soon?
To the Rotary engine:
Seals are not a problem any more - actually since decades.
Also Mistral will probably offer Ceramic seals as an option in the turbo engines, which should outlast the TBO of the engines.
Also the Mistral gasoline engines are on par or slightly better than the Lycosauros on BSFC. If you are interested I can forward you some test data from Mistral or put you in direct contact with them.
The missing data is from Lycoming, as they do not publish any consumption data over 70% power!! But what is available shows at least even or better efficiency on the Mistral. However you probably cannot compare these numbers with anything on the road - on the other hand anything from the road would never last in the air at the required power levels.
To all:
The real problem with the diesel is that after you pass a power level of around 135- 160 hp, the engines become rather heavy.
Thielert promoted his V8-turbo diesel at 300 hp. Now it is out at max-cruise 260hp - around 600 lbs !! And no TBO, but TBR (time before replacement)
You can't compare car engines with aviation engines. The duty cycle in a car engine is roughly 35-40%. In an aircraft engine you have it running between 70-100% all the time.
Toyota certified its V8 gas engine at 300hp max cruise - TBO 300 hrs!!
The one exception is the rotary engine as it is very compact and robust - if configured it will outlast any other piston.
For now the best you can hope for is something like Mistral - Jet-A burning with ignition - potential power level that can be reached easily is around 450 hp max continious, after that the price/weight/power relation probably favors the turbines again.
Just a side note: Hartzell never made a heavier prop than the one for the SMA diesel ( for the power transmitted) the lighter props would shatter after a short time due to the power pulses from the engine!!
Cheers,
3top
a little late for a reply, but better late than never!
Congrats to your new post!
Are we goin' to see some Gulfstream-helicopters soon?
To the Rotary engine:
Seals are not a problem any more - actually since decades.
Also Mistral will probably offer Ceramic seals as an option in the turbo engines, which should outlast the TBO of the engines.
Also the Mistral gasoline engines are on par or slightly better than the Lycosauros on BSFC. If you are interested I can forward you some test data from Mistral or put you in direct contact with them.
The missing data is from Lycoming, as they do not publish any consumption data over 70% power!! But what is available shows at least even or better efficiency on the Mistral. However you probably cannot compare these numbers with anything on the road - on the other hand anything from the road would never last in the air at the required power levels.
To all:
The real problem with the diesel is that after you pass a power level of around 135- 160 hp, the engines become rather heavy.
Thielert promoted his V8-turbo diesel at 300 hp. Now it is out at max-cruise 260hp - around 600 lbs !! And no TBO, but TBR (time before replacement)
You can't compare car engines with aviation engines. The duty cycle in a car engine is roughly 35-40%. In an aircraft engine you have it running between 70-100% all the time.
Toyota certified its V8 gas engine at 300hp max cruise - TBO 300 hrs!!
The one exception is the rotary engine as it is very compact and robust - if configured it will outlast any other piston.
For now the best you can hope for is something like Mistral - Jet-A burning with ignition - potential power level that can be reached easily is around 450 hp max continious, after that the price/weight/power relation probably favors the turbines again.
Just a side note: Hartzell never made a heavier prop than the one for the SMA diesel ( for the power transmitted) the lighter props would shatter after a short time due to the power pulses from the engine!!
Cheers,
3top
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There is plenty of technical data here and from an overview it would seem that helicopters like cars are heading for diesel power as the better way of powering small light helicopters.
I have to admit that I prefer the diesel car to it's gasoline brother for the better fuel consumption, longer life and better torque. Emissions also are environmentally more friendly.
My question is 'Who will be the first manufacturer to provide a diesel (Jet A1) powered helicopter'. Will it be Frank?
I have to admit that I prefer the diesel car to it's gasoline brother for the better fuel consumption, longer life and better torque. Emissions also are environmentally more friendly.
My question is 'Who will be the first manufacturer to provide a diesel (Jet A1) powered helicopter'. Will it be Frank?
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It should be borne in mind that diesels have a much narrower power band than petrol engines - hence the need for a 16 ratio box on a large truck, and why car drivers comment that they are more frequently changing gear in a manual box diesel.
Would this characteristic have a bearing on rotary suitability?
Would this characteristic have a bearing on rotary suitability?