Definition
A reciprocating aircraft engine designed and installed so that its cylinders point downward from the crankshaft rather than upward. The crankshaft sits at the top of the engine and the cylinder heads, valves, and spark plugs are below it.
Plain English
An engine built upside down on purpose, with the cylinders hanging beneath the crankshaft instead of standing above it.
Context Anchor
Seen in aircraft engine descriptions, maintenance discussions, and aircraft with older or specialty engine installations.
Derivation
Inverted comes from the Latin invertere, meaning to turn upside down. The name is literal: the engine is mounted in the opposite orientation from a conventional one.
Why Pilots Care
Requires modified oil and fuel systems so lubrication and fuel flow continue during inverted flight.
Intuition Check
An inverted engine does not mean an engine used only for inverted flight. It means the engine’s cylinders are positioned below the main body of the engine.
Example Sentence 1
The de Havilland Tiger Moth is powered by an inverted engine, which gives the pilot a clearer view over the cowling.
Example Sentence 2
Before flying inverted maneuvers, the pilot confirmed the inverted engine's oil system was functioning correctly.