原著論文 Flapping for hovering, like birds and insects, is free from stalling, and works in storms. It is wonderful, but an apparatus using flapping for flight is difficult to make with artificial materials and available mechanisms, since large stress is applied to the joints. Flapping the wings up and down changes the velocity, so that unwanted inertial force is unavoidable. This difficulty is solved by introducing the rotation into the flapping. Reports on a prototype model and its theoretical analysis are presented.