Helicopter with oblique tail boom

A helicopter, comprising:

• a vertical longitudinal middle plane;
• only a single horizontal rotor including rotor blades:
• a rotor drive driving the horizontal rotor for rotation about a vertical rotor axis, the horizontal rotor having a advancing blade side on which the rotor blades run in forward direction and a retreating blade side on which the rotor blades run in backward direction in forward flight of the helicopter, the advancing blade side and the retreating blade side of the horizontal rotor meeting at the vertical longitudinal middle plane;
• and
• a boom extending backwards from the vertical rotor axis at a fixed angle selected from a range from about 20° to about 60° to the vertical longitudinal middle plane of the helicopter on the retreating blade side of the horizontal rotor;
• wherein the boom comprises a profiled body, the profiled body including a leading edge, a trailing edge and aerodynamic effective surfaces extending between the leading edge and the trailing edge, the profiled body being configured to selectively generate lift on the retreating blade side of the horizontal rotor in forward flight of the helicopter;
• and
• wherein the profiled body is swivel mounted such that at least a part of the profiled body can be swiveled about a swivel axis running parallelly to the main axis of the boom for reducing a cross-sectional area of the profiled body facing the horizontal rotor during hovering flight of the helicopter as compared to forward flight of the helicopter.