Synergistic Numerical and Experimental Investigations of Dynamic Stability of a Lifting Capsule

Abstract

The dynamic stability of a reentry lifting capsule with a large aftbody was studied by synergistic experimental and numerical investigations. Free-to-rotate wind-tunnel tests showed that self-induced pitch oscillations depended on the Mach number, Reynolds number, and surface roughness. The experiment provided the amplitudes and frequencies of oscillations for numerical simulations in prescribed motions. Both data reduction methods for the damping coefficient are presented, and the time-series results of both methods are compared. The validated numerical simulations enabled detailed visualization of the separated flow on the side surface of the aftbody to investigate the effects of flow separation and attachment on the dynamic stability and the effect of sting interference. The dynamic characteristics observed in a postflight test with a scaled model of the recovered capsule agreed with those of the reconstructed flight in spite of deceleration effects. Wind-tunnel testing and numerical simulations as well as their mutually validated investigations provided sufficient information to fly the small lifting capsule.