Definition
Piston-driven internal combustion engines used to power most light airplanes, in which fuel and air are burned inside cylinders to push pistons up and down. The pistons' linear motion is converted by a crankshaft into the rotary motion that turns the propeller.
Plain English
The most common type of small-airplane engine. Fuel burns inside cylinders, pushing pistons back and forth, and that motion is turned into the spinning motion that drives the propeller.
Context Anchor
Seen in fuel, oil, engine operation, and preflight discussions for many small propeller airplanes.
Derivation
Reciprocating' comes from the Latin 'reciprocare', meaning 'to move back and forth'. It describes the back-and-forth motion of the pistons inside the cylinders, which is the defining feature of this engine type compared with turbine engines, where parts only rotate.
Why Pilots Care
Pilots of these engines must manage mixture, monitor oil temperature and pressure, and follow specific starting and leaning procedures that differ from jet aircraft.
Intuition Check
Reciprocating does not simply mean propeller-driven. It specifically refers to the back-and-forth piston motion inside the engine.
Example Sentence 1
Most training airplanes are powered by reciprocating airplane engines that burn aviation gasoline.
Example Sentence 2
Before takeoff the pilot performed a magneto check on the reciprocating airplane engine to verify both ignition systems were working.