Noun
piston engine (plural piston engines)
Any of several types of engine having cylinders containing reciprocating pistons, in which a crankshaft is turned by pistons moving up and down within cylinders.
All parts rotate moving in one direction, as opposed to the common reciprocating piston engine which has pistons violently changing direction. Source: Internet
A further advantage of the Wankel engine for use in aircraft is that a Wankel engine generally has a smaller frontal area than a piston engine of equivalent power, allowing a more aerodynamic nose to be designed around the engine. Source: Internet
All engines exhibit oil loss, however the rotary engine is engineered with a sealed motor, unlike a piston engine that has a film of oil that splashes on the walls of the cylinder to lubricate them, hence an oil "control" ring. Source: Internet
Armstrong subsequently developed a piston engine instead of a rotary one and decided that it might be suitable for driving a hydraulic crane. Source: Internet
A piston engine does not move the aircraft by itself (the propeller does that), so piston engines are usually rated by how much power they deliver to the propeller. Source: Internet
A reciprocating piston engine with equal power to a Wankel will be approximately twice the displacement. Source: Internet