Determination of tailless aircraft tumbling and stability characteristics through computational fluid dynamics

Tailless aircraft configurations such as flying wings are susceptible to tumbling. Tumbling involves an autorotative pitching motion primarily about an axis parallel to the aircraft's lateral axis combined with planar translation. Tumbling is the suspected cause of a tailless aircraft (Northrop YB-49) crash in the late 1940s and is a potential problem for future flying wing and blended wing body aircraft. It may be difficult if not impossible for a tailless aircraft to escape the tumbling motion once it begins. It is therefore important for aircraft designers to know the causes of tumbling in order to prevent its onset. Tumbling has been demonstrated in qualitative free-flight wind tunnel experiments, but few have attempted to quantify the motion using computational fluid dynamics. The purpose of this research is to use computational fluid dynamics to study the tumbling characteristics of a tailless aircraft and then determine dynamic stability information from the simulations. Specifically, the effects of initial conditions, degrees-of-freedom, Reynolds number, and aircraft static margin will be investigated. Lumped pitch damping derivatives will be determined from the simulations.