CHINE-SHAPED FOREBODY EFFECTS ON DIRECTIONAL STABILITY AT HIGH-ALPHA

Computational fluid dynamics has been used to study the flowfields ove r chine-shaped forebodies at low-speed high angle-of-attack conditions with sideslip. The purpose is to define forebody geometries that prov ide good directional stability characteristics under these conditions. An analytically defined generic forebody model is described, and a pa rametric study of various forebody shapes was then conducted to determ ine which shapes promote a positive contribution to directional stabil ity at high angle of attack. An unconventional way of presenting the r esults is used to illustrate how the positive contribution arises. The effect of cross-sectional shape on directional stability was found to be very significant. Broad chine-shaped cross sections were found to promote directional stability. Also, directional stability is improved if the chine is placed closer to the top of the cross section. Planfo rm shapes also played an important role in determining the forebody di rectional stability characteristics. Based on the results of this init ial parametric study, some guidelines for aerodynamic design to promot e positive directional stability are presented.