Installed Performance of Vectoring/Reversing Nonaxisymmetric Nozzles

An experimental program was conducted to determine the internal and installed performance characteristics of five different thrust vectoring and reversing nonaxisymmetric nozzle concepts for tactical fighter aircraft. As part of this program, the nonaxisymmetric nozzles and an advanced axisymmetric baseline nozzle were tested in the AEDC 16-ft transonic Propulsion Wind Tunnel at Mach numbers from 0.4 through 1.5. The twin-nozzle models were mounted to a partially metric jet-effects model, with nozzle exits located at the trailing edge of a fighter wing plan form. Tests were conducted at three unvectored power settings, thrust vector angles up to 30 deg and dry power reverse thrust. Nozzle pressure ratios were varied about nominal values for an advanced turbofan engine cycle at each test Mach number. At unvectored conditions, the nonaxisymmetric nozzles with external expansion surfaces exhibited the highest thrust-minus-drag at both cruise and maneuver conditions. Performance was equal to or better than that of the axisymmetric baseline nozzle. Vectoring was found to improve the lift-to-drag ratio for all nonaxisymmetric nozzles at all positive thrust vector angles. The lift, drag, and pitching moment increments associated with vectoring were shown to correlate well with modified trailing edge flap theory. Reverse thrust levels equalled 50% of forward, dry power thrust at static conditions, with a reversing effectiveness nearly twice this value demonstrated at Mach 0.9.