Space Shuttle Orbiter Static Stability and Control Derivatives Obtained from Wind-Tunnel and Flight Tests

Abstract

T HIS Synoptic presents a comparison of the results of tests conducted in the Langley 8 ft transonic pressure tunnel with the static stability and control parameters extracted from the Space Shuttle Orbiter approach and landing flight tests (ALT). To obtain the wind-tunnel values of the static longitudinal and lateral directional stability and control derivatives, an 0.02 scale model of the prbiter with remotely driven elevens, ailerons, and body flap was tested at flight values of angle of attack, Mach number, trimmed eleven deflection, bodyflap deflection, and speed-brake position. Utilizing these data, a comparison has been made of stability and control parameters determined from the wind tunnel, ALT flight tests, and the Space Shuttle Orbiter Design Data Book. limited portion of the subsonic speed regime. Because of the nature of the ALT flight program, all data obtained are subsonic over a Mach number range of 0.41-0.56 and over an angle-of-attack range of approximately 2-10 deg. The complete comparison of wind-tunnel and ALT flight values of the static stability and control derivatives is presented in Ref. 1 and a comparison of the dynamic derivatives is presented in Ref. 2. A comparison of the stability and control derivatives measured in the Langley 8 ft transonic pressure tunnel with those extracted by both the Air Force and NASA from ALT flights 4 and 53'4 and those presented in the aerodynamic design data book5 are presented in Figs. 1-3 (e.g. at 0.65 Q. The values from Ref. 5 were determined from a large volume of wind-tunnel data obtained prior to the ALT flights. Each of the data points represents a different flight condition (Mach number and angle of attack). An uncertainty band (variations), defined in Ref. 5, is presented on the comparison figures. The variations were determined using wind-tunnel and flight data for aircraft similar to the Orbiter.4 Longitudinal Stability and Control The comparisons show that the longitudinal stability derivatives Cma determined from the wind-tunnel tests are in good agreement with the flight data. The data book values indicate a lower level of stability over the test angle-of-attack range than for either the flight or wind-tunnel results. In all cases, both the wind-tunnel and flight values of Cma fall within the variations band. There are three sets of flight values of CNa presented in Fig. 1. Reference 3 provided CNa data from both a primary and a backup accelerometer, but only one set of data is presented in