[GerritJ9]

Yes, a diesel
http://www.enginehistory.org/Diesels/CH4.pdf

[Zorin]

huh? a diesel? hock:

They were used on recon planes and sea planes, due to their low fuel consumption and reliability. Their slow reactions to rpm changes etc, made them unsuitable for fighter planes.

[dimlee]

huh? a diesel? hock:

They were used on recon planes and sea planes, due to their low fuel consumption and reliability. Their slow reactions to rpm changes etc, made them unsuitable for fighter planes.

also on bombers in USSR, where, as in Germany, aviation diesels were given much attention. there was one difference: germans developed diesels for reliability/reduced consumption, while soviets aimed to achieve max power output, first of all. another reason was better safety (less flammable).