Abstract: A rotorcraft having four symmetrically disposed intermeshing rotors coupled to a common drive unit, each rotor having a single blade which is formed with a lifting surface and an oppositely projecting balance arm. The four rotors are coupled to the drive unit by respective rotor shafts and the shafts are inclined with respect to one another such that the path surface traced by each blade is inclined with respect to the path surface traced by each other blade. Each rotor is connected to its associated rotor shaft by way of a universal joint which provides for torque transmission and which permits blade flapping and blade pitch adjustment, and actuators are provided for applying differential collective pitch to the rotors by way of pitch control shafts.