Definition
An airfoil that produces lift or thrust by spinning around a central axis rather than by moving forward through the air as a fixed wing does. Propeller blades and helicopter rotor blades are rotating airfoils — each blade has a curved cross-section like a wing, and as it rotates it generates an aerodynamic force perpendicular to its path of motion.
Plain English
A wing-shaped blade that creates lift or pull by spinning. A propeller is the most common example: each blade is shaped like a small wing, and spinning it forward pulls the airplane through the air.
Context Anchor
Seen in propeller and powerplant discussions, where each propeller blade is treated like a small wing moving in a circle.
Derivation
From 'rotating' (turning around an axis) and 'airfoil' (a shape designed to produce a useful aerodynamic force as air flows over it). The phrase simply names what it is: an airfoil that does its job by rotating instead of by being pushed through the air on a fixed wing.
Why Pilots Care
The rotating airfoils are the actual surfaces that turn engine power into usable thrust for takeoff, climb, and cruise.
Grounding Statement
Picture one propeller blade circling in front of the airplane: at each point in the circle, it meets the air like a small wing and creates a force that helps pull the airplane ahead.
Intuition Check
A rotating airfoil is not the airplane’s main wing spinning around. In this context, it usually means a propeller blade acting like a small wing as it turns.
Example Sentence 1
The propeller is a rotating airfoil that converts engine power into thrust by pulling air rearward as it spins.
Example Sentence 2
Inspect the rotating airfoils for nicks before flight because even small damage reduces thrust and creates vibration.