Definition
The imaginary circular plane traced by the tips of a helicopter's main rotor blades as they rotate. The orientation and tilt of this plane determines the direction the rotor system pulls the helicopter through the air.
Plain English
If you watched the very tips of a spinning helicopter rotor, they would draw a flat circle in the air. That circle is the tip-path plane. When the pilot tilts it forward, the helicopter moves forward; when tilted sideways, it moves sideways.
Context Anchor
Seen in helicopter aerodynamics, especially when discussing rotor control, cyclic input, and the direction of rotor thrust.
Derivation
Literally the plane (flat surface) traced by the path of the blade tips. The name describes exactly what it is — a geometric description rather than a technical coined term.
Why Pilots Care
Recognizing the tip-path plane lets a pilot understand how cyclic inputs tilt the rotor disc to change direction and attitude.
Analogy
Think of the spinning rotor as making an invisible plate in the air. Tilt that plate, and the helicopter’s lift is tilted too.
Grounding Statement
Picture a spinning ceiling fan. If you could tilt the whole fan slightly forward, the air would be pushed down and slightly back, and anything attached underneath would be pulled forward. That tilt is what the tip-path plane does for a helicopter.
Intuition Check
“Plane” here does not mean an airplane. It means an imaginary flat surface formed by the path of the rotor blade tips.
Example Sentence 1
When the pilot moved the cyclic forward, the tip-path plane tilted forward and the helicopter began to accelerate.
Example Sentence 2
During a stable hover the tip-path plane stays level with the rotor mast.