Definition
The upward bending of a helicopter's rotor blades into a shallow cone shape during flight, caused by the combined action of lift pulling the blade tips up and centrifugal force pulling them outward. The angle of the cone depends on the balance between these two forces — heavier loading or lower rotor RPM increases coning, while higher RPM flattens it.
Plain English
When a helicopter is flying, its spinning rotor blades don't stay perfectly flat. Lift pulls the tips upward and the spin pulls them outward, so the blades flex into a slight cone shape, like an upside-down shallow bowl.
Context Anchor
Seen in helicopter aerodynamics, especially when discussing rotor blade forces, rotor speed, aircraft weight, and high-load maneuvers.
Derivation
From the word 'cone' — the shape the rotor disc takes when the blades bend upward in flight. The blades, viewed from the side, no longer lie in a flat plane; together they form the surface of a cone.
Why Pilots Care
Recognizing coning helps pilots assess rotor loading and avoid excessive blade stress in high-power or heavy conditions.
Analogy
Think of a child swinging a weighted string in a circle. As they spin faster, the string flattens out; as they slow down, it droops. A rotor blade behaves the same way — the faster it spins, the flatter the cone.
Intuition Check
Coning does not mean the helicopter is flying in a cone-shaped path. It means the rotor blades themselves angle upward and form a cone-like shape as they spin.
Example Sentence 1
The instructor explained that coning increases when the helicopter is heavily loaded, because the blades must produce more lift to support the weight.
Example Sentence 2
High gross weight increased blade coning and required careful power management.