Forced motions design for aerodynamic identification and modeling of a generic missile configuration

Abstract

This article is focused on the design of forced motions and developing models that can accurately and rapidly predict the aerodynamic stability derivatives of air vehicles over a wide range of air speeds using time-accurate computational fluid dynamic (CFD) simulations. The test case is a generic missile configuration known as the Army–Navy (basic) Finner (ANF) missile. Longitudinal stability coefficients are available from a combination of free-flight and wind tunnel tests for Mach numbers in range of 0.5–4.5. Estimating stability derivatives of this vehicle requires a large number of static and dynamic CFD simulations using a brute-force approach. The present study instead uses a single forced motion to estimate vehicle's stability derivatives over a wide range of speed regimes. The results of this study show that identification of aerodynamic coefficients from time-accurate simulation of the forced motions requires significantly less computational time. A new aerodynamic model is also proposed that captures the aerodynamic coefficients' dependence on the angle of attack, pitch rate, time rate of change of angle of attack, and Mach number including the transonic region. The results presented show that the model predictions agree well with experimental data and those calculated from a brute-force approach. The methods of this work could reduce the computational cost of estimating stability derivatives up to 90%.