Neat. Apparently it's called coning. https://en.wikipedia.org/wiki/Coning https://en.wikipedia.org/wiki/Coning > The tips of the rotor blades move faster throu

Neat. Apparently it's called coning. https://en.wikipedia.org/wiki/Coning https://en.wikipedia.org/wiki/Coning > The tips of the rotor blades move faster through the air than the parts of the blades near the hub, so they generate more lift, which pushes the tips of the blades upwards, resulting in a slight cone shape to the rotor disc. This is balanced by centrifugal force. If rotor RPM drops too low, the rotor blades fold up with no chance of recovery. > Rotors are typically designed with washout (twist) so that lift is relatively uniform along the blades. However, because lift increases quadratically with airspeed, coning still occurs at higher RPMs. > Some helicopters such as the Bell UH-1 Iroquois are designed with "pre-coned" blades, which are curved downwards but lay more flat in flight.