Effect of Wing Geometry on Volume and Weight

prompted the consideration of other techniques. One alternate or perhaps interim approach presently being considered is that of establishing the average values of inlet performance in such an environment by means of force-balance measurements of the internal drag of these inlets. Such performance data can be used to determine where (for families of arbitrary inlet con­ figurations) a particular inlet's operating point will be on para­ metric inlet-performance curves similar to those in Fig. 1. Such experimental data also afford a relatively simple means of evalu­ ating the end effects of hypersonic shock, boundary-layer inter­ action, and inlet boundary-layer separation phenomena on the performance levels of such inlets. In addition, these average values of inlet performance can be used as a basis for supporting combustor and nozzle performance calculations, thus permitting estimation of the complete propulsion-system performance. This note presents the results of a preliminary investigation of the accuracy to be expected from computed values of inlet performance based on force-balance measurements of inlet drag. For purposes of discussion here, the two basic parameters neces­ sary to specify the performance of supersonic/hy personic com­ bustion inlets—i.e., diffusion efficiency and degree of diffusion— are considered to be the familiar inlet total-pressure recovery and the inlet static-pressure ratio, respectively. Inlet total-pressure recovery, among other things, is indicative of inlet-area dis­ tribution, and aside from combustion considerations, inlet static-pressure rise is an index of viscous problems associated with the diffusion process. Assuming that the internal drag of the model can be ade­ quately isolated from other model drag values, and assuming that