NASA’s Langley Research Center has developed a new aircraft design with the engine nacelle over the wing, improving engine ground clearance and freeing landing gear design. While previous over-the-wing designs have produced unacceptably high drag conditions, the new NASA design reduces drag on the wing. By optimizing the nacelle design and the wing leading edge location, NASA’s design confines the shock to the leading edge of the wing. Also, placing the exhaust nozzle over the wing reduces noise to the communities below.
NASA developed the novel configuration to address the drag penalties associated with traditional over-the-wing nacelle designs. The novel features of the wing design include the unswept in board wing section between the fuselage and the nacelle with an extended chord. The chord is extended so that it is almost in line with the front face of the nacelle, promoting near two-dimensional channel flow between the nacelle and the fuselage that pulls the standing shock wave farther forward. Confining the shock naturally enhances the leading edge suction and eliminates the shock traditionally located near the trailing edge. The net effect is reduced compressibility-based interference drag.
Noise is reduced because the engine nozzle is tangential to the wing upper surface and near the middle of the wing chord to put the exhaust noise source in the best position to be shielded from the community by the wing below it.