Definition
Cylindrical metal components inside a reciprocating aircraft engine that slide up and down within the cylinders. Driven by the expanding gases of combustion, pistons convert the pressure produced by burning fuel and air into the linear motion that, through connecting rods, turns the crankshaft and ultimately drives the propeller.
Plain English
The plug-shaped parts inside an engine's cylinders that get pushed by the burning fuel-air mixture. Their up-and-down movement is what makes the engine produce power.
Context Anchor
Seen in aircraft engine descriptions, preflight discussions, maintenance reports, and explanations of how a reciprocating engine makes power.
Derivation
From the Italian 'pistone' and Latin 'pistare,' meaning to pound or crush. The original sense was something that pushes or strikes with force, which fits well — a piston is repeatedly pushed down by combustion pressure.
Why Pilots Care
Pistons are critical to engine operation; their fit, rings, and movement directly affect power output, fuel efficiency, and the risk of engine failure.
Intuition Check
Do not think of pistons as the whole engine. Pistons are individual moving parts inside the cylinders; they move back and forth and help turn that motion into usable engine power.
Example Sentence 1
In a typical four-cylinder aircraft engine, each piston completes a power stroke once every two revolutions of the crankshaft.
Example Sentence 2
A pilot checks compression to confirm the pistons and rings are sealing the cylinders properly.