PURPOSE: To obtain high flight speed by disposing a vertical tail turnable on a vertical shaft and a tail rotor rotatable on a rotary shaft and also turnable around the vertical shaft and so using the tail rotor as ordinary tail rotor at time of hovering and utilizing it for forward thrust at time of forward flight.

CONSTITUTION: A tail rotor 5a is disposed in which a vertical tail 4a turnable on a vertical rotary shaft 9 is fixed and the tail rotor rotates on a rotary shaft 10 and also turnable around the vertical rotary shaft 9. At time of hovering when there occurs no forward flight resistance, the vertical tail 4a is turned on the vertical shaft and laterally to helicopter axis, and the tail rotor 5a is horizontally turned around the vertical shaft. And thus, thrust of the tail rotor 5a is utilized as forward thrust, so that speed of the helicopter is increased at time of forward flight.