Imagine that the two shoulders of a banana-shaped boomerang are its wings. Like the wings of an airplane, their lower surface is flat and the upper one is convex. Such a surface causes the air, which in flight flies around the boomerang, to create lift. The whole secret is that one “wing” of a boomerang is different from the other. The curvature of the curved surface of one wing looks forward, and the other - back. It is like attaching one wing backwards to the plane. You won't envy such an airplane pilot. An airplane, like a boomerang, is organically incapable of flying straight. The shape of the boomerang blades returns it after the flight to the place of throw.