Seneca with diesel engines?
 

My neibor just bought a Piper Seneca and was telling me over a bottle of beer that he is putting on diesel engines!
The advantage is that he can run 'em on jet fuel and double his range. (Same tanks, less GPH)
Also Jet A is cheaper than Avgas for more "savings".
TBO is also increased from 1800 hrs to 3000 hrs.

Sounds pretty wild to me.
Anybody else heard about installing diesel engines on aicraft?

(I know the Germans did some of that during world war II, but did not think it was very succesful)

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Men, this is no drill...

I recall seeing some articles last year about Continental working on a diesel that runs on Jet A but thought they were still a long way off.

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Per dementia ad astra

This'll be the new diesel engine being developed by the French - Not in production yet, but has been test flown on the tobago. I believe it is aerospatiale's work but can't remember. All I know is that it will be the future of GA - impressive performance and runs on Jet A1, diesel etc. as mentioned above.

Yup, the engines to go on the Seneca will be the French ones.
Air cooled and 235 HP. (If I remember correctly)

The owner does not have a multi engine rating yet and asked me if I would teach him.
Hmm, don't know if I want to be the test pilot and flight instructor at the same time.
Does anybody know if an airplane for a FAA check ride can have an STC like above with unproven and maybe not certified engiens?

Interesting times ahead.

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Men, this is no drill...

I believe Renault is working on the engine and Aerospatiale is modifying a Tobago or Trinidad.

Sounds great.


¿How many times did your car engine (diesel or petrol shut off by itself?

It will be interesting to see the response times of these new diesel engines and how large or small their power band will be- can you imagine shoving a handful of throttle in on a go round only for not much to happen very quickly?. However, they will be a boon for the GA community due mainly to cheaper running costs and I'm sure will only require a small amount of conversion training..

Quite a few times actually.

On my wife's Ford station wagon (fuel injected, 1994 model) the engine would quit and leave us stranded. Then start again 10 minutes later.
I expected vapor locks in the injection system or some such invisible thing.
After the 5 or 6 time we traded it in for a newer vehicle under warranty.

As for the diesel engine in my sailboat, it has never failed us yet, except the time I foolishly ran it out of diesel approaching the dock.(A Perkins 4-108, the best product the Brits have ever made. Hats off.)

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Men, this is no drill...

I seem to remember somebody relaying a second-hand anecdote to me about some bloke who got a 3 cylinder diesel engine for a single. He said the middle cylinder kept overheating, and his engine had failed on him literally more times than not. I can't remember the manufacturer, but I think it must have been French.

Pie http://www.pprune.org/ubb/NonCGI/tongue.gif

Airtaxi, don't know how the French are doing it but I do know that turbocharging a diesel can give it acceleration that is comparable to conventional normally-aspirated motors. Mercedes used the technique for its early diesel models.

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Per dementia ad astra

There has been a bit of discussion on this topic in other forums. I have to admit that the concept of re-engining piston aircraft and helicopters is extremely interesting, very practical and is definitely going to happen.

Apart from the amazing simplicity and reliability of the engine, the ability to build a product to known weight, performance and dimensional requirements to slot into existing products is a very practical business concept. The fact it uses a fuel that is now more common than Avgas at most airports, is just another benefit!

There has been some quite reasonable rumours regarding a helicopter manufacturer designing their first piston product in about 40 years, as the cost of turbine engines is so exorbidant. Whilst the reliability of piston engines has increased dramatically (er...maybe excepting Continental crankshafts) the reliability of small turbines has remained about the same - only the cost of owning and operating them has gone through the roof. A diesel engine in a small helicopter would be a very strong selling point.

I think this is an excellent programme and will lead one of the greatest technological aviation advancements of the next decade.

Former PPRuNe thread, with links to all the major manufacturers programmes: http://www.pprune.org/ubb/NonCGI/For...ML/000280.html

Any ideas how this guy intends to certify this TD? Experimental category, or is he going to be the STC fleet leader?

Cyclic:

The guy converting the Seneca is going for an
STC.
I would think diesels engine be heavier than the gas (Petrol for the Brits) engines and consequently one would run into center of gravity problems.

Last time I flew a Seneca II the owner had a
50 lbs piece of metal for ballast in the aft baggage compartment. He said the airplane was to nose-heavy with only pilot and co-pilot onboard. Perhaps even more so with heavy engines bolted on?

Good luck to the project anyway.

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Men, this is no drill...

I'm a bit puzzled at the posts above that make disparaging remarks about a diesel engine's "acceleration". Do you mean throttle response time - which is likely to be more instant than a carburated petrol engine? Or are you thinking of the acceleration of the Volvo estate your inadequate bhp diesel was attached to, and not the engine at all? Perhaps youve never seen class one powerboats in action. Diesel vs Lamborghini on equal terms.

I hope you dont practice slam accelerations on your Lycomings or, God help you, Continentals - when would that ever be needed? Not too good for Bristol Mercurys either, I seem to recall.

A diesel made in Northamptonshire was displayed at the PFA Rally last year, going for certification & to run on Avtur. 2 cyl 2 crank double acting two stroke, 120bhp same size, weight and mountings as a Lycoming, Bolt it right into your C150. A masterpiece of engineering.

I hope they make a commercial success of it. It would open a huge market for small long range aircraft, and particularly bush operations where avgas is hard to find, but dieso & Jet A1 is everywhere.

In addition to diesels, a project is now underway to fit highly modified turbocharged Chevrolet V8 aluminum engines with fuel injection and electronic variable timing to a Cessna 421C. More power, much less fuel (28gph vs 38) and quieter. Inital cost is expected to be $60,000 per engine including the STC fee. Not a bad deal. The 421C is a very good aircraft now, with the STC it would be superb.

I think the best thing about having a diesel engine would be the potential reliability. After all it’s COMPRESSION ignition, i.e. no sparky bits required for ignition. Millions of truckers can’t be wrong..

I don’t believe weight would be so much of a problem. With modern engine block casting techniques the weight differential compared to a conventional power plant is negligible. According to Autocar, VW’s 1.9 TDI engine is only 15 kgs heavier than their V-5 engine yet produces considerable more torque.

Regarding throttle response times, just remember even if it is fractionally slower a conventional engine if a blower is required, it will still be a barn sight quicker than any jet engine.

Perhaps icing might present a worry? Diesel tends to turn to wax at lo temperatures.

Love the sound of a Chevy V-8 Cessna by the way. Nearly as cool as the Chevy V8 Harley…

With new style turbos on Diesel engines e.g. the new garrets and KKKs, a nozzle is used to angle the exhaust gasses at the turbine to keep the turbo unit producing peak boost from the compressor side through as much of the rev range as possible of the engine; therefore no waste gate actuator system required, achieving almost no lag; when compared with the older TD's.

I am quite certain that diesel engines are likely to be the future of light aviation.

Firstly, the reliability of a properly designed diesel engine is excellent. They have fewer working parts than spark ignition engines, having no magnetos or other ignition components to fail, as someone already pointed out. Provided the fuel pump keeps pumping properly, there is little to go wrong. Ask any truck or taxi driver. Most diesel engines clock up phenomenal mileages without problems.

Fuel consumption is excellent because of much better volumetric efficiency than petrol engines. Diesel engines do not have a throttle in the inlet so that a full charge of air is induced on each stroke; instead the power output is controlled by varying the output of the fuel injection pump. The very high compression ratios required to ignite the fuel/air mixture (over 20:1) also results in a more efficient thermodynamic cycle and low specific fuel consumption.

Diesels are not nearly as critical as petrol engines over fuel quality. They can run on anything from kerosene to re-cycled vegetable cooking oil! (However, I don't think that aviation engines would be certificated if they left a smell of fish and chips at the airport). The types of fuel generally used are not prone to vapour lock, unlike gasoline based fuels.

The problem of fuel waxing can affect the fuel filters of road-going vehicles in low temperatures. This however need not be a problem because the fuel used can be AVTUR, i.e. jet/turbine fuel. Even if a DERV type fuel is used, the formula can be adjusted to resist waxing as it is in European countries. Another remedy is to design in a fuel/oil heat exchanger as used in many modern turbine engines. These channel fuel en route to the engine around the oil filter casing, which heats the fuel aiding combustion or in this case also preventing waxing. This obviously also cools the engine oil as an added benefit!

The throttle response issue is not such a great problem as in cars because aircraft engines driving a propellor are required to operate over a much smaller RPM range. Diesel engines provide good torque at low speeds and are ideal for use in aircraft, as they are in marine applications. In any case, turbosupercharging overcomes the response and power output issues.

(Edit: One important thing I forgot to mention. Because there is no carburettor and no requirement to externally vapourise the fuel, not surprisingly there is no possibility of carburettor icing which is a significant safety advantage to light aircraft).

Ever seen or driven one of the latest Merc or BMW high performance diesel saloons? It is hard to believe they aren't petrol powered because all the disadvantages have been overcome. Even from the outside, they don't even sound like diesels any more.

I recently rode an experimental diesel powered motorbike. The engine, based on an industrial engine, was warranted for 3000 hours between oil changes. Work that out as far as how many miles you can travel between service intervals. Answer: at 60 mph you could go 180,000 miles! The manufacturer of the engine has apparently acknowledged that some industrial users removed the oil filters altogether so they didn't even have to bother changing them, and even this didn't result in reliability problems!

Well, I'd certainly buy one, as you have probably guessed by now!

ShyT

[This message has been edited by ShyTorque (edited 08 June 2001).]

Thank you, ShyTorque for your intersting post. Only in the past week I was wondering about diesel engines on motobikes and wanted to post something here or on the Engineers Forum to learn something about it but was not able to get my head together enough to ask the question sensibly enough. TTT.

TTT,

If you are interested in a novel diesel powered motorbike with a virtually maintenance free engine that will do over 200 mpg you could get in touch with Jim D'Arcy at Charnwood Classic Renovations, 107 Central Rd, Hugglescote, Leicester LE67 2FL.

Tel: (01530) 832634 Fax: 832357

Email: [email protected]

I am not connected with this company, just an impressed visitor!

ShyT

Modern diesels?... PFM!!!
Have just passed the 300,000 mile mark on my Citroen BX19 turbo-D - 90 mph+ at part throttle (for overtaking, you understand!!)and the critical 50 - 70 overtake is a more relaxed business than on anything else I've driven. However, DON'T PUT PETROL IN THE TANK!!! I did - cost me well over a grand to fix http://www.pprune.org/ubb/NonCGI/redface.gif

Okay gents.
Good replies to my initial question on diesel
engines on aircraft.

A friend who is presently building an RV8 said he has seen diesels demonstrated at Oskhosh Air Show but he is not considereing a diesel for his aeroplane because they sound terrible: A "cackling" exhaust tone turned him off.
Hmm, I guess an un-muffled diesel would sound strange, on idle power at least: The benefits
however should indeed silence any unpleasant noise? (Pun intended)

Somebody mentioned taxi and truck drivers:
Yes, agree: To save money towards flight school 20 or more years ago, I drove diesel powered Mercedes taxi cabs in Europe a few years and I sure did like 'em.
Would buy one for private use in the US if I could find and afford one.

As for not changing oil: Learning from my boat/diesel maintenace books, oil change every 100 hours is the most important preventive maintenace you can do.
Same with clean fuel. Much more critical on diesels than gas (petrol) engines.

Not sure how a diesel engine can be air cooled as the tolerances are much tighter in a diesel than a gasoline engine and a steady temperature (water cooled thermostat cooling system) will keep those tolerances within uh, tolerance.

My boat engine, the Perkins 4-108 1.8 liter 4 cylinder 47 HP diesel has 3000 hours on it.
Some sailor dudes say they will last up to 10,000 hours if given good care.
Any experience/opinion on longevity?



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Men, this is no drill...