Assertion: helicopter's speed | /r/DefinedAs | the turn speed of the rotor
Facets:
value: in a helicopter
type: OTHER
Source sentences:
text: In a helicopter the maximum forward speed is defined by the turn speed of the rotor; at some point the helicopter will be moving forward at the same speed as the spinning of the backwards-moving side of the rotor, so that side of the rotor sees zero or negative airspeed, and begins to stall.