Sideslip Behavior of Elliptic Cross-Sectional Forebodies at High Angle of Attack

This paper reports on the results of tests conducted on two elliptical cross-sectional forebodies with major/minor axis ratios of 1:0.8 and 1:0.6, respectively. The experiments were performed in a Reynolds number range between 8 3 10 4 and 3.1 3 10 5 (based on major axis of the ellipse ). These elliptical forebodies were found to have unique sideslip behavior in contrast to the multiple solutions that have been found for circular cross-sectional forebodies. When the major axis of the elliptic forebody is in line with the aircraft y-body axis (termed e at ellipse ) the forebody is directionally stable. When the major axis of the ellipse is in line with the aircraft z-body axis (termed vertical ellipse ) the forebody is directionally unstable. The effect of turbulent reattachment on one side of the body is described. It was found that reattachment increases the directional instability of vertical ellipses.