To enable the rapid rotational motion in the advancing direction, in the right-to-left direction and in the horizontal plane even in a stopped condition in the air by generating the aerodynamic force of a propulsion blade by the rapid air flow generated by a multiple-blade fan of an air frame.

A propulsion blade affects no force to an air frame if the parallel and angle of attack is at the zero position to an air frame. Thus, the air frame is in a stopped condition in the air if the output of a drive engine 5 is regulated so that the lift generated by multiple-blade fans 4a, 4b is balanced with the total weight of the air frame and the drag generated by the air frame due to the air flow. The air frame is designed so that the center of gravity of the whole air frame is below the center of the aerodynamic force generated by the propulsion blade. If the air frame is inclined by the aerodynamic force, the resisting rotational moment is exerted, and thus, the air frame is constantly stable. When the angle of attack is changed forward, the generated aerodynamic force is directed forward of Y-axis to form the force to advance the air frame. If the angle of attack is changed to the opposite direction, the generated aerodynamic force is naturally directed backward.