Upper Surface Blowing Technology as Applied to the YC-14 Airplane

The exhaust from a high bypass ratio turbofan engine, passing over the upper surface of a wing and trailing edge flap system, can be deflected by the Coanda effect to create both deflected thrust and supercirculation. This technique, known as “upper surface blowing,” has been applied to the U.S. Air Force/Boeing YC-14 advanced medium STOL transport airplane. Laboratory and wind tunnel tests have shown very efficient turning of the jet flow, large values of supercirculation, and excellent boundary layer control of the external flow on the upper surface of the wing. This combination creates a powered lift system having unusual efficiency and versatility.