PURPOSE: To make it possible to convert a motorcycle into a light aircraft by fixing an arch-like structural body of a cage structure to a frame of a motorcycle, mounting a lowering sail at the top of the cage, the sail ends being lowable by a pedal control device, and mounting a propeller propulsion system at the rear of the motorcycle.

CONSTITUTION: An arch-like structural body (cage) similar to a cage surrounding a pilot is provided on a motorcycle frame of a motorcycle 1, a lowering sail 5 is fixed to a cross beam 7 connecting right and left posts 25, 27 of the top part of the cage to each other, and a propeller 8 is mounted at the rear. A propeller rotating shaft is connected to an output shaft of a motor or an engine 10 in such a manner as to be freely disconnected. The lowering sail 5 is formed by a blade lower face 12 and a blade upper face 14 as two parallel faces, and both faces 12, 14 are connected to each other by plural longitudinal films forming a rib. The lower ends of four suspended ropes 20-23 suspended from the longitudinal films are connected to the top of the cross beam 7 of the cage 3.