Definition
A unit of rotational speed expressing how many full turns a rotating component completes in one minute. In aviation, rpm most commonly refers to the rotational speed of the engine crankshaft or the propeller, displayed on the tachometer in the cockpit.
Plain English
How many times something spins all the way around in one minute. In an airplane, it usually tells you how fast the engine or propeller is turning.
Context Anchor
Seen on engine instruments, during engine checks, in power-setting instructions, and in aircraft performance information.
Derivation
The word “revolution” means one complete turn around a circle. “Per minute” means the count is measured over one minute, so “revolutions per minute” literally means complete turns each minute.
Why Pilots Care
Maintaining proper RPM keeps the engine inside its designed operating range, protects it from damage, and ensures the expected power output for each phase of flight.
Intuition Check
rpm is not aircraft speed. It is the speed of rotation of a part, usually related to the engine or propeller.
Example Sentence 1
During the run-up, the instructor set the throttle to 1,700 rpm before checking the magnetos.