The aerodynamic characteristics and its estimation method of finned missile experiencing spin-deformation coupling motion

The coupling of rolling motion and bending deformation of a finned missile can significantly affect its lateral force and yawing moment, thus threatening flight stability and maneuverability. By solving the unsteady Reynolds-averaged Navier-Stokes (URANS) equations with a dual-time stepping method and a previously proposed coupling motion mode, flow over the Air Force Modified Basic Finner Missile (AFF) experiencing spin and spin-deformation coupling motion were simulated, and the aerodynamic characteristics were obtained. The relationship between the variation tendency of aerodynamic characteristics and different motion modes was analyzed. On this basis, an aerodynamic model previously proposed by Murphy was revised and a modified model suitable for the aerodynamic prediction of spin-deformation coupling missiles was developed and verified. The results indicate that as angle of attack (AoA) increases, the total time-averaged lateral force induced by spin-deformation coupling motion alters direction and increases by an order of magnitude compared with that induced by spin, and the time-averaged body lateral force becomes dominant. Combining the three aerodynamic components, including that of rigid spinning missile at non-zero AoA, that produced by bending deformation and spin-deformation coupling effect at zero AoA, and that account for the aerodynamic interference effect at non-zero AoA, the accuracy of the modified aerodynamic model can be greatly improved. At forebody cross sections, the results of the modified aerodynamic model and the computational fluid dynamic (CFD) method match well. While at aftbody cross sections, the transient results have certain deviation, while the relative differences for the time-averaged normal force and lateral force are within 10% and 20%, respectively.