PURPOSE: To obtain a foldable developing wing which allows an air frame to be contained in a launcher cylinder without restriction on the size of a main body of the air frame, by developing the wing by ant inertia force produced by conyrolling the roll of the fuselage.

CONSTITUTION: After an air frame is launched, a foldable developing wing is developed by an inertia force produced by controlling the roll of the fuselage. The foldable developing wing is folded via a hinge 6. The fuselage is rolled once after launched and then rotated in the opposite direction, so that an upper part 2 of the foldable developing wing turns on the hinge 6 by the inertia force and locked. Although the roll control to develop the developing wing is carried out for a very short period of time after the launch, there is no effect on the flight of the fuselage. This method completely eliminates the need of a power source to develop the foldable developing wing. Therefore, as a power and a developing mechanism to develop the wing can be made needless or small- sized, the size of the air frame main body can be increased. In addition, the flight performance is improved because the resistance is reduced.