A locking mechanism for securing an articulated folding wing assembly in a fully extended position by means of a tapered locking plunger urged by a coiled compression spring to contact a complementary mating surface formed on the wing assembly. The spring urged locking plunger is released from a retracted position by rotation of the wing assembly from the folded position to the extended position. A folding mechanism for rotating the wing assembly through a compound angle from the folded position to a rigid and positively locked fully extended position is provided wherein the extended wing may be rotated about its longitudinal axis to provide directional control to the vehicle.