Effect of Cross-Shafting on Landing Reliability of V/STOL Aircraft

Abstract

Fig. 3 Axial distance and capture area vs pressure ratio. Enhancement of Facility Pumping Capability The required low backpressure, Pa, must be supplied by the facility pumping capability. This capability is usually supplied by an air or steam driven ejector. In cases where large model sizes ard to be tested, facility pumping capability can become limiting, and the requirement to enhance such capability can be imperative. When large test models with high-pressure recovery inlets are utilized, the test model flow itself can have significant pumping capability. Thus, as suggested in Fig. 4, the model exhaust flow can be utilized as the primary flow of a preliminary ejector to raise the pressure at entry to the main ejector. The preceding calculations provide the necessary mass flows in the primary and secondary streams of the preliminary ejector. Estimates of the delivery stagnation pressure from the test model should be available, and it has been found a reasonable lower estimate of the secondary stream stagnation pressure to simply take it equal to the static backpressure, Pa. With the approximations suggested above, the combined system capability can be estimated in a straight-forward fashion utilizing established theories.' When high Mach number tests are to be conducted, considerable pumping enhancement occurs when a preliminary ejector is utilized.