Abstract:Analyzes the factors that influence the helicopter speed - overload envelope - overload helicopter velocity was proposed flight envelope expansion method, presents a stable hover, symmetric rod and push rod flight method, and in view of the various methods are compared, and analyzed the speed of a certain type of machine is given - overload envelope expansion flight test results, has been clear about the speed-overload envelope expansion flight safety precautions, help to follow-up with the helicopter flying speed-overload envelope test.