Impact of Missile Cross-Sectional Shape on Aerodynamic Performance at Supersonic Speeds

Recent developments in missile technology have demonstrated both the feasibility and desirability of changing the outer mold line of the missile during flight. In order to better understand how varying the body shape of a missile would impact aerodynamic performance, two series of experiments were conducted in the United States Air Force Academy’s trisonic wind tunnel at a variety of Mach numbers. The first series of experiments focused on missiles with a consistent cross-sectional shape along their length, and the second series of experiments examined missiles that had smooth variation of cross-sectional shape and size along their length. Both series of experiments highlighted how the maximum width (or planform area) is directly related to aerodynamic efficiency, with wider bodies having higher lift-to-drag ratios than narrower bodies. An examination of the pitching moment showed significant differences between bodies with a consistent cross-section and bodies with a varying cross-section. The oval shape was the least stable of the constant-cross-section bodies, while the bodies with flat windward surfaces were the least stable of the varying-cross-section bodies. Computational fluid dynamics simulation results indicate that the changes in vehicle stability are heavily dependent on the details of the shape change.