Analysis of Aerodynamic Performances of Experimental Flying Test Bed in High-Altitude Flight

Abstract

An aerodynamic, computational study has been performed on the 3.9.2_FW50 configuration of the winged experimental flying test bed (FTB-X) of an experimental unmanned space vehicle in the altitude interval 90—110 km, where the vehicle is in transitional regime. The range of the angle of attack was 0—40° and the side slip angle was 15°. The flow field has been solved by the three-dimensional (3D) direct simulation Monte Carlo (DSMC) code: DS3V. The results showed better aerodynamic behaviour both in symmetric and in side-slip flights, but worst longitudinal stability in symmetric flight with respect to the previous version of FTB-X (1.1.2). In fact, both the aerodynamic efficiency and the derivative of pitching moment coefficient in symmetric flight increased. Furthermore, a preliminary analysis about the possibility of an aerodynamic control of the vehicle by deflection of a trailing edge flap has been fulfilled. This analysis has been carried out in terms of the lift and drag forces and pitching moment at the altitude of 70 km in the range of the angle of attack 0—30° and flap deflection 0—30°. The flow field has been solved by a 2D DSMC code (DS2V) and computational fluid dynamic code (H3NS). A thermal analysis has been also carried out for evaluating the heat flux on the flap. This heat flux is comparable with that at the nose stagnation point, and therefore a thermal protection system should be necessary also on the flap. The effect of the flap deflection on the flow separation has been also evaluated. In particular, at high flap deflection angle, the shock wave boundary layer interaction produces a decrease of the airfoil aerodynamic efficiency. Therefore, the increases of lift and drag of the aerodynamic force, as functions of the flap deflection angle, encourage performing similar tests considering the whole vehicle.