Diesel Debate
Joined: Apr 2003
Posts: 581
Likes: 0
From: Bordeaux, France
Just to throw in a tangental but related question, all the reports of diesel engines in aeroplanes have related to touring aeroplanes.
Has anyone put a diesel in an aeroplane that goes upside down yet?
Regards, SD..
Has anyone put a diesel in an aeroplane that goes upside down yet?
Regards, SD..
Joined: Jul 2003
Posts: 139
Likes: 0
From: Minnesota
FFF, et all,
Some interesting points, lets take a look at some of them.
Durability. True, in Europe small diesels have been traditionally used in commercial applications, but I have been involved in many fleets in the U.S. that have and still do, use 'medium' sized petrol engines (up to 5 liters) for these same duty cycles with great success. The reason they use them, fuel costs aside, is because they are cheaper! (compare the replacement cost of a diesel engine with a similar size petrol engine, and you will see a huge cost difference). In the same duty cycle, they last as long as a diesel engine, often exceeding 400,000 miles with regular oil changes the only maintenance. (Belts and platinum plugs the only exceptions) I know many will argue anecdotal evidence that diesels will last longer still ,but in my experience of many fleets and many years, small diesels do not.( Large diesels are another matter, and will now regularly exceed the million mile mark, with proper maintenance, in over the road applications in the U.S.)
Ignition systems: The Distributor, often the problem in older ignition systems, is now gone. Modern petrol engines have computer controlled ignition systems. Each spark plug has it's own coil unit so no chance of a single ign coil failure causing a complete loss of spark, if one does fail, it will only affect that one cylinder.
Magnetos are simply a self contained ignition spark producer and distributor in one, they still use points, or contact breakers, still have rotors. and a cap, all of which are subject to burning, cracking, vibration, and of course are still susceptible to moisture problems. Modern ignition systems are sealed against moisture incursion, have no point's, no distributor, no cap, no rotor, no plug wires, and are as a consequence very reliable..
Running upside down? No reason why not.
Avgas mechanical fuel injection systems use much lower injection pressures than diesel direct injection systems, which can be as high as 2600-3000 psi. Modern computer controlled fuel injection systems are port injected, the injector is actually mounted in the intake manifold, and directs it's spray into the cylinder when the intake valve opens. Therefore the injector is not subjected to the pressures and heat of direct fuel injection, and are therefore much more reliable. System pressure is only about 55 psi, and I have seen very few failures of these injectors since their introduction back in the mid 80's.
Once again, I do not have any problems with diesels, but things have moved along on more than one technological front. Fuel costs, although a consideration are, as has been discussed, a tax issue, and as all things political are "subject to change without notice". Our focus should be on providing our fellow G.A. pilots with the most reliable, powerful and fuel efficient engines possible, whatever fuel it uses.
More grist for the mill?
Regards,
W.B.
Some interesting points, lets take a look at some of them.
Durability. True, in Europe small diesels have been traditionally used in commercial applications, but I have been involved in many fleets in the U.S. that have and still do, use 'medium' sized petrol engines (up to 5 liters) for these same duty cycles with great success. The reason they use them, fuel costs aside, is because they are cheaper! (compare the replacement cost of a diesel engine with a similar size petrol engine, and you will see a huge cost difference). In the same duty cycle, they last as long as a diesel engine, often exceeding 400,000 miles with regular oil changes the only maintenance. (Belts and platinum plugs the only exceptions) I know many will argue anecdotal evidence that diesels will last longer still ,but in my experience of many fleets and many years, small diesels do not.( Large diesels are another matter, and will now regularly exceed the million mile mark, with proper maintenance, in over the road applications in the U.S.)
Ignition systems: The Distributor, often the problem in older ignition systems, is now gone. Modern petrol engines have computer controlled ignition systems. Each spark plug has it's own coil unit so no chance of a single ign coil failure causing a complete loss of spark, if one does fail, it will only affect that one cylinder.
Magnetos are simply a self contained ignition spark producer and distributor in one, they still use points, or contact breakers, still have rotors. and a cap, all of which are subject to burning, cracking, vibration, and of course are still susceptible to moisture problems. Modern ignition systems are sealed against moisture incursion, have no point's, no distributor, no cap, no rotor, no plug wires, and are as a consequence very reliable..
Running upside down? No reason why not.
Avgas mechanical fuel injection systems use much lower injection pressures than diesel direct injection systems, which can be as high as 2600-3000 psi. Modern computer controlled fuel injection systems are port injected, the injector is actually mounted in the intake manifold, and directs it's spray into the cylinder when the intake valve opens. Therefore the injector is not subjected to the pressures and heat of direct fuel injection, and are therefore much more reliable. System pressure is only about 55 psi, and I have seen very few failures of these injectors since their introduction back in the mid 80's.
Once again, I do not have any problems with diesels, but things have moved along on more than one technological front. Fuel costs, although a consideration are, as has been discussed, a tax issue, and as all things political are "subject to change without notice". Our focus should be on providing our fellow G.A. pilots with the most reliable, powerful and fuel efficient engines possible, whatever fuel it uses.
More grist for the mill?
Regards,
W.B.
Avoid imitations
Joined: Nov 2000
Aviation Qualifications: ATPL
Posts: 15,116
Likes: 1,091
From: Wandering the FIR and cyberspace often at highly unsociable times
Whitebear,
You said "Remember in terms of equivalency the diesel engine would need to be larger than a petrol engine to produce the same power".
Not necessarily so, if you use a 2 stroke design.
You said "Remember in terms of equivalency the diesel engine would need to be larger than a petrol engine to produce the same power".
Not necessarily so, if you use a 2 stroke design.
Joined: Jan 2004
Posts: 6
Likes: 0
From: 4th Planet
Hi,
I've been following the diesel issue with interest. Break even on the SMA seems to be about 500hrs (C182), thereafter you keep money in your pocket. I also found a interesting engine on www.dynacam.com. Its a diesel, weights the same as a Lyc. 360 (about 300lbs) same power 200HP double the tourque with an 18 inch diameter (round like a turbine) FAA approved for Helicopters, busy with fixed wing. Reason for this is for a fixed wing you need to approve the prop also.
I've been following the diesel issue with interest. Break even on the SMA seems to be about 500hrs (C182), thereafter you keep money in your pocket. I also found a interesting engine on www.dynacam.com. Its a diesel, weights the same as a Lyc. 360 (about 300lbs) same power 200HP double the tourque with an 18 inch diameter (round like a turbine) FAA approved for Helicopters, busy with fixed wing. Reason for this is for a fixed wing you need to approve the prop also.
Guest
Posts: n/a
http://www.centurion-engines.com/c17/c17_start.htm
The engine really does make the equivelent Lycoming look rediculous. I quite like the TBO arrangements too - check out the FAQ.
Also, checkout the consumption and endurance figures!!
The engine really does make the equivelent Lycoming look rediculous. I quite like the TBO arrangements too - check out the FAQ.
Also, checkout the consumption and endurance figures!!
Joined: Nov 2003
Posts: 31
Likes: 0
From: over the moon
Funny no ones mentioned the volatility issue,
Avgas is more than likely to see you Crash in a firey wreck, Jet A1/Diesel is much harder to ignite.
Weight for weight, Jet A1 is more calorific, Diesel more so.
The diesel engine will go further on the same weight of fuel.
Volume for volume, JetA1/Diesel is denser, so a diesel engine will take you much further. So a converted Cherokee, with the same tanks will have far greater range and endurance, yet suffer a load penalty for full tanks.
I believe the figures for the Diamond Katana are 32 litres /hour on avgas with an O-360, and 20 litres/hour with the Thielert diesel, travelling at the same speed.
The Thielert engines, which are conversions of the Mercedes Benz 4 cylinder, and V8, are turbo normalised to around 15,000 feet and come as standard with a Constant Speed propeller, yet only a single lever in the cockpit.
Modern diesels produce less power than modern auto petrol engines because they only rev to half the maximum of the petrol engine, for the same size engine.
Diesel engines have a peak torque much lower in the rev range, giving improved climb and cruise performance.
As far as I am concerned, comparing a Lycosaurus to the Thielert is a no brainer. Comparing modern diesels with modern auto engines is somewhat of a waste of time, as these can only be fitted to experimentals, and for certified avgas engines we are at the mercy of Lycoming/ Continental.
For our American friends, unfortunaley, most of the rest of the world pays far more for "Gas" than you do, and might I suggest with the current shenanigans in the Gulf, your days may be well and truly numbered.
I am building an experimental homebuilt from plans, and will be using an auto diesel conversion.
Avgas is more than likely to see you Crash in a firey wreck, Jet A1/Diesel is much harder to ignite.
Weight for weight, Jet A1 is more calorific, Diesel more so.
The diesel engine will go further on the same weight of fuel.
Volume for volume, JetA1/Diesel is denser, so a diesel engine will take you much further. So a converted Cherokee, with the same tanks will have far greater range and endurance, yet suffer a load penalty for full tanks.
I believe the figures for the Diamond Katana are 32 litres /hour on avgas with an O-360, and 20 litres/hour with the Thielert diesel, travelling at the same speed.
The Thielert engines, which are conversions of the Mercedes Benz 4 cylinder, and V8, are turbo normalised to around 15,000 feet and come as standard with a Constant Speed propeller, yet only a single lever in the cockpit.
Modern diesels produce less power than modern auto petrol engines because they only rev to half the maximum of the petrol engine, for the same size engine.
Diesel engines have a peak torque much lower in the rev range, giving improved climb and cruise performance.
As far as I am concerned, comparing a Lycosaurus to the Thielert is a no brainer. Comparing modern diesels with modern auto engines is somewhat of a waste of time, as these can only be fitted to experimentals, and for certified avgas engines we are at the mercy of Lycoming/ Continental.
For our American friends, unfortunaley, most of the rest of the world pays far more for "Gas" than you do, and might I suggest with the current shenanigans in the Gulf, your days may be well and truly numbered.
I am building an experimental homebuilt from plans, and will be using an auto diesel conversion.
Joined: Jun 2003
Posts: 393
Likes: 0
From: Southampton
Guys,
I'm not an authority on diesel engines in aircraft, but in the course of my vibration and prop balancing work I came into contact witha guy called Mark Wilksch (If memory serves ) of Wilksch Airmotive. I can't remember much more in the way of contact details, but anyway, Mark has done a lot of work / study into the use of diesels, and is probably a good man to speak to in reference to this thread.
Perhaps somebody knows him?
I'm not an authority on diesel engines in aircraft, but in the course of my vibration and prop balancing work I came into contact witha guy called Mark Wilksch (If memory serves ) of Wilksch Airmotive. I can't remember much more in the way of contact details, but anyway, Mark has done a lot of work / study into the use of diesels, and is probably a good man to speak to in reference to this thread.
Perhaps somebody knows him?
