Definition
A type of internal combustion engine that uses a triangular rotor turning inside an oval-shaped housing to produce power, instead of pistons moving up and down in cylinders. As the rotor turns, it creates three separate chambers that go through the four stages of combustion — intake, compression, power, and exhaust — continuously and smoothly.
Plain English
An engine that makes power by spinning a three-sided rotor inside a specially shaped chamber, rather than by pushing pistons up and down. It is also called a rotary engine.
Context Anchor
Seen in powerplant and maintenance discussions for aircraft or aviation equipment that use this type of engine design.
Derivation
Named after Felix Wankel, the German engineer who developed the design in the 1950s. Knowing the name is a person's name (not a technical term) prevents confusion when reading about it.
Why Pilots Care
Wankel engines run smoothly with fewer moving parts, but they have different maintenance and operating characteristics than traditional piston engines. A technician or pilot working with one needs to understand it does not behave like a standard piston powerplant.
Analogy
Think of the rotor like a rounded triangular paddle turning inside a tight case. As it turns, the spaces around it grow and shrink, doing the work that pistons normally do in other engines.
Intuition Check
Do not assume “rotary engine” means the whole engine spins with the propeller. In a Wankel engine, the main internal rotor turns inside a fixed housing to make power.
Example Sentence 1
The light sport aircraft was powered by a Wankel engine, which gave it a noticeably smoother power delivery than a traditional piston engine.
Example Sentence 2
The light aircraft used a Wankel engine for its compact size and smooth power delivery.