An investigation of wing elasticity effects on store separation based on computational fluid dynamics

The study explores wing elasticity effects on the store separation process, based on computational fluid dynamics simulations. The nominal test case is that of an unmanned aerial vehicle that carries two identical stores, without fins or control surfaces, on two wing stations in a symmetric configuration. The stores are ejected during straight and level flight at 0.35M, 2500m. Simultaneous, time-accurate analysis of the dynamic aeroelastic wing response and the store’s trajectory reveals that the most significant aeroelastic effect is a roll motion developed by the store. This roll motion is due to misalignment of the ejection force vector and the store’s center of gravity, due to the wing’s static and dynamic elastic deformations. The second part of the paper presents a parametric study of the effects of various structural and configurational parameters on the wing’s response, and consequently on the store’s rolling motion. A more flexible wing, a heavier store, a larger ejection force, or a shorter ejection period, all result in increased store rolling. Ejection of a store from an asymmetric configuration (of a single store) resulted in a very similar store roll compared to the symmetric ejection. The dynamic wing response plays a significant role in generating the store roll, in different conditions of friction between the store body and ejection piston. Hence the store roll is also dependent on the relation between the ejection period and the structural frequencies of the wing.