Abstract: A tilt wing VTOL aircraft has a fuselage with sides and an upper surface, an upper wing having a leading edge, a trailing edge, a chord, a lower surface and an upper surface. The wing is pivotally mounted on the fuselage for rotation from a cruise flight position in which the upper surface of the wing is flush with the upper surface of the fuselage to a hover position in which the wing is perpendicular to the upper surface of the fuselage. Aircraft engines are mounted on the wing. The aircraft has a pair of flaps at the trailing edge of the wing, each located between the fuselage and an engine and each spaced the same distance from the fuselage and each of the engines. The flaps are mounted for selective movement from colinearity with the chord of the wing to a first angle of about +30.degree. with the chord and about 30.degree. with the upper surface of the wing and to a second angle of about -30.degree. with the chord and about 30.degree. with the lower surface of the wing.