Reverse Thrust Performance of the QCSEE Variable Pitch Turbofan Engine

Results of steady-state reverse and forward-to-reverse thrust transient performance tests are presented. The original QCSEE 4-segment variable fan nozzle was retested in reverse and compared with a continuous, 30° half-angle conical exlet. Data indicated that the significantly more stable, higher pressure recovery flow with the fixed 30° exlet resulted in lower engine vibrations, lower fan blade stress and approximately a 20% improvement in reverse thrust. Objective reverse thrust of 35% of takeoff thrust was reached. Thrust response of less than 1.5 sec was achieved for the approach and the takeoff-to-reverse thrust transients.