Polmar agrees, and points out that the piston engines used in conventional light planes are ruled out for other reasons: they would fail if any water leaked into the cylinders.

Gas turbine engines use the Brayton cycle. Wankel rotary engines use the Otto cycle, but they do it in a very different way than four-stroke piston engines.

Only small aircraft, and those needing tough low-speed propulsion at low altitudes, for agricultural work and fire-fighting, still have piston engines.