The Influence of High Angle of Attack Flow Phenomena on the Dynamic Stability of Slender Missiles.

The purpose of this study was to gain a better understanding of the influence of the separated wake flows on vehicle dynamic stability. This was accomplished by mapping out the body vortex wake flow around several slender missile configurations using flow visualization techniques. Two techniques were employed, one using a laser-produced sheet of light illuminating smoke passing around the model, and the other using neutrally buoyant helium-filled soap bubbles as flow tracers. The models were tested at angles of attack from 15 to 55 degrees, at subcritical Reynolds numbers and for freestream turbulence levels of 0.1 to 0.8 percent. The body vortices were observed to assume positions relative to the models that were either steady and symmetric, steady and asymmetric, or unsteady and asymmetric. The wake structure was found too sensitive to model surface roughness and freestream turbulence.