Effects of inlet airframe integration on the inlet of an upper surface blowing four-engine STOL aircraft

Inlet and nacelle static pressures were measured on a 0.55-scale model of the Quiet Short-Haul Research Airplane (QSRA) in the Ames Research Center's 40- by 80-Foot Wind Tunnel. This model is powered by four JT-15D engines located above the wing with closely spaced adjacent inlets. A fifth JT-15D engine in the fuselage provides boundary-layer control air. Each inlet was instrumented with four to eight rows of axial pressure taps located between X/R approximately plus or minus 1. The tests simulated a broad range of aircraft operating conditions, including engine-out, with lift coefficients from 0.8 to 10.0. Results indicate that the inlets perform well under most operating conditions with little interaction between inlets when the aircraft is moving. Potential problem areas identified are high sideslip angle during approach and an interaction effect between adjacent inlets with high mass flows in static conditions.