Aerodynamic Design Analysis of Missiles With Strake Configurations at Supersonic Mach Numbers

Engin Usta, Kivanc Arslan and Ismail H. Tuncer

Missiles having very low aspect ratio fins are generally difficult to model by using engineering level aerodynamics tools and linear theories break due to complex nature of the flow adjacent to the mutual interference of the body and fin. For this reason fast prediction methods are not very successful in most of the cases, and there is a need for research. In this paper, computational methods are used to predict normal force and center of pressure of missiles with very low aspect ratio fin configuration. A case study is selected for comparative analysis and optimization study. Computational Fluid Dynamics (CFD) results for the case study are compared with theoretical and empirical methods at supersonic Mach numbers. In addition to total forces acting on the body-strake model, strake panel alone and body alone forces are obtained to calculate interference effects. The effects of strakes on flow field are analyzed by comparing body alone and body-strake pressure fields. The normal force and pitching moment of the strake unit is calculated by subtracting body alone values from body-strake results. The normal force and calculated center of pressure values of the strake unit (D57) are compared with data from LTV HSWT 655 Wind Tunnel Test Data [White, 1994]. The CFD results are robust and in agreement with the experimental results; however, for testing accuracy of theoretical methods, further research is required. After validating CFD tool, with the addition of fixed tail surfaces, a CFD based optimization study is performed to minimize coupling effects due to sideslip angle in the longitudinal maneuver plane and keep static margin constant.

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