Diesel engines?

Discussion in 'Engines' started by Lucky13, Nov 12, 2012.

  1. Lucky13

    Lucky13 Forum Mascot

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    Have to ask, what was the idea behind using diesel engines for aircrafts, was there ever any success?
     
  2. R Pope

    R Pope Member

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    A number of German flying boats used Junkers diesels, and in the US, Cuthbertson made a radial that was, I believe, based on a Continental engine.
     
  3. davebender

    davebender Well-Known Member

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    Reliability and low operating cost. Important factors for civilian passenger and cargo aircraft.

    The military typically wants maximum power from the smallest possible size so you don't see many military applications.
     
  4. R Pope

    R Pope Member

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    Diesels don't do well at high altitudes, either, which is why the Cuthbertson was tried in some tanks.
     
  5. tomo pauk

    tomo pauk Creator of Interesting Threads

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    Haven't the Jumo diesels operated well at high altitude in the Ju-86s?
     
  6. davebender

    davebender Well-Known Member

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    Why not?

    With the right supercharger any engine should run ok at high altitude.
     
  7. Lucky13

    Lucky13 Forum Mascot

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    Cheers for the replies lads?

    Aye, didn't that high flying Ju 86R use diesels?
     
  8. tomo pauk

    tomo pauk Creator of Interesting Threads

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    25000 posts ?? Time for an even better avatar? ;)

    They did.
     
  9. Shortround6

    Shortround6 Well-Known Member

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    diesels were actually easier to rig with turbo-chargers as their exhaust gases are cooler than the exhaust gases from gasoline engines. Since turbine inlet temperature was rather critical to turbine blade/bucket life even a few hundred degrees made a big difference. Engines in the JU 86R used turbos feeding regular engine driven superchargers ( two stage).
     
  10. dobbiemiko

    dobbiemiko New Member

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    Looks like diesels are getting another lease on life. Lycoming is in production for general aviation diesels...the big problem with diesels at high altitude is restarts, but theyve come up with some pretty ingenious ways to work around that for FAA approval. Weight to hp ratio was also an issue but has been addressed. Lycoming's diesel has both a turbocharger and a mechanical supercharger. Whats pushing all of this new development is that 100LL fuel may not be readily available in the very near future. Cessna is due to come out with a diesel powered 172 next year.
     
  11. engguy

    engguy Member

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    I don't see anything about a Lycoming diesel on their website.
    Certified Engines - Lycoming

    Maybe you meant the Chinese manufacture Continental Motors inc, has a diesel aircraft engine?
    https://en.wikipedia.org/wiki/Continental_Motors,_Inc
     
  12. johnbr

    johnbr Well-Known Member

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    #12 johnbr, Nov 23, 2012
    Last edited: Nov 23, 2012
    Here is a USA Diesel engine.

    Picture URL
    BB Code

    deschamps v 3050 sectional view
    The Deschamps V 3050 was an inverted, 12-cylinder, diesel, aircraft engine of all aluminum construction. The engine was built by the Lambert Engine and Machine Company in Moline, Illinois and completed in 1934. The cylinder banks were arranged in a 30-degree Vee to minimize the engine’s frontal area. With a 6” bore and 9” stroke, the engine had a total displacement of 3,052 cu in. The liquid-cooled, direct drive engine produced 1,200 hp at 1,600 rpm for take-off, and 950 hp at 1,500 rpm for cruise. Fuel consumption was 0.41 lb/hp/hr. When built, it was one of the largest and most powerful diesel aircraft engines in the world.

    The compression ratio of the V 3050 was 16 to 1, and air was forced into the cylinders by two gear-driven GE superchargers. The centrifugal superchargers were driven at 13.5 times crankshaft speed (21,600 rpm) and provided air at 12 psi. Cylinder scavenging for the two-stroke cycle required 8 psi and 4 psi remained for boost. A small portion of the air entering the superchargers was taken from the crankcase to to provide ample ventilation and burn away any fuel vapors. Sea-level power could be maintained to 10,000 ft altitude.

    Each bank of cylinders had an intake manifold on the inside of the Vee to deliver air from the superchargers to the cylinders. The compressed air entered each cylinder via two poppet valves actuated simultaneously by an overhead camshaft driven at crankshaft speed.
     

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  13. johnbr

    johnbr Well-Known Member

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    Here is a cutaway
     

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  14. WJPearce

    WJPearce Active Member

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    I'm no expert, but I believe aircraft diesel development in the 1930s was based on a variety of different factors.

    1) Diesel was considered safer because of the non-explosive characteristics of the fuel. It was thought that fires could be virtually eliminated with the use of diesels.

    2) Diesel engines were 20-25% more efficient. Aircraft could have a greater range or require less fuel for the same range. Even though diesel fuel was heavier, there was still a net gain in overall efficiency.

    3) Diesel was less expensive than AvGas.

    4) Diesel exhaust was cooler and therefore easier to turbocharge.

    Keep in mind all that was in the 1930s. Most of the problems were solved with advances in technology and development just prior to and during WWII.

    1) Maybe planes do not catch fire as often or as easily as they used to.

    2) In the 1930s, 87 octane fuel was the good stuff. The octane quickly went up to 100 and then Performance Numbers up to 145. This drastically increased the efficiency of the standard engine, eliminating most of if not all of the diesel's (1930s) efficiency advantage.

    3) I don't know about cost, but maybe it was deemed too expensive to have a new fuel distribution/storage/delivery system in place next to standard AvGas, especially since the diesel's advantages had been minimized. Separate fuel systems were eventually done for the jet age, but the advantage and future rule of jets was very much undeniable.

    4) Better metals were developed and exhaust heat was not (or much less of) a turbocharging issue.

    Had diesels been developed sooner, I think they would have played more of a roll. They just happened to be developed at the same time all of the "problems" they circumvented were solved, allowing standard engines to continue. In addition, I think diesel development was basically abandoned during WWII. After the war, the jet was the future. Perhaps diesels were a victim of bad timing more than anything else.

    Today, there seems to be a second round of diesel development. The main push is because of the looming production halt of 100 octane AvGas (and its scarcity in some regions) combined with greater comparative efficiency.

    Below is an image from Packard’s DR-980 brochure that speaks to point 1 from a 1930s frame of reference:
    [​IMG]
     
  15. GrauGeist

    GrauGeist Well-Known Member

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  16. dobbie

    dobbie Member

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  17. engguy

    engguy Member

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    The date of that article is 2005, last I checked it is now 2012 and their website has zero, zip, nothing on any diesel engines they offer. That I see anyway.
     
  18. dobbie

    dobbie Member

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  19. Aurum

    Aurum Member

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    Thanks allot for such a nice photo of this prominent my favorite engine 8)

    This diesel was completed in 1934 and had so harmonic but mighty design that it had to be refined up to serviceable state in next couple years.
    It's hardly to imagine how could the war turned if B-17-ies and "Lightings" P-38 were equipped by these Deschamps V3050 diesels!!! For example they could reach Japan cities from Midway so Doolittle raid was not need to be done. :)

    Fuel consumption of Deschamps V3050 2-stroke deisel was about 185 g/h.p.*h and avgas engines had no less then 240-260 g/h.p.*h. Plus specific weight of solar oil is hither then avgas has, so tha same tank volume can contain +10% more of fuel. Plus air-drag of inverted 30°-angled Vee is about twice less then huge rounded Wright Cyclone R-1820 had. All these could add no less then 50% range to Boeing "Fortresses" B-17-ies!!!

    I have few more draws of Deschamps V3050 diesel, so i can post them if somebody needs
     
  20. tomo pauk

    tomo pauk Creator of Interesting Threads

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    That would be nice :)
     
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