Definition
An internal-combustion engine used in aircraft in which pistons move back and forth inside cylinders, with that linear motion converted by a crankshaft into rotary motion that turns the propeller. Fuel and air are burned inside each cylinder in a repeating cycle of intake, compression, power, and exhaust strokes.
Plain English
An aircraft engine that uses pistons sliding up and down inside cylinders to spin the propeller. It works on the same basic principle as a car engine.
Context Anchor
Seen in aircraft systems, engine operation, preflight, and maintenance discussions, especially for small training airplanes.
Derivation
‘Reciprocating’ comes from the Latin reciprocare, meaning ‘to move back and forth.’ The name describes the engine’s defining motion: pistons travelling back and forth in their cylinders, in contrast to a turbine engine where parts spin continuously.
Why Pilots Care
Most training aircraft use reciprocating engines, and pilots are expected to understand how they work, how to operate them correctly, and how to recognise problems such as detonation, carburetor icing, or improper mixture settings — all of which directly affect safety and performance.
Analogy
Think of a bicycle pump handle moving in and out. A reciprocating engine has pistons moving in a similar back-and-forth way, but the engine uses that motion to turn the propeller.
Intuition Check
Reciprocating does not mean the whole engine moves back and forth. It means the pistons inside the engine move back and forth.
Example Sentence 1
The Cessna 172 is powered by a four-cylinder aircraft reciprocating engine driving a fixed-pitch propeller.
Example Sentence 2
Most light training airplanes are powered by a four-cylinder aircraft reciprocating engine.