A fixed-pitch coaxial contra-rotating helicopter (1) having: a rotor drive unit (2) provided with an upper rotor (7) and lower rotor (8) that rotate in opposite directions; a slide unit (3) that slides the rotor drive unit (2) in a plane orthogonal to the axis of rotation (6) of the rotors; a lower airframe (5) hung from the bottom surface of the slide unit (3) via a pivot joint (4); and a control circuit (30). So that a perpendicular that passes through the center of the thrust generated by the rotation of the rotors (7 and 8) aligns with a perpendicular that passes through the center of gravity of the lower airframe (5) when the rotor drive unit (2) tilts about the pivot joint (4) with respect to the direction of the center of gravity of the lower airframe (5), the rotor drive unit (2) slides in the direction in which said rotor drive unit (2) is tilted, thereby minimizing vibration and rocking of the airframe.
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