Longitudinal static stability analysis of hypersonic waveriders

The study of hypersonic glider design has great application value. Its longitudinal design has great difference with the airplane design. Because of its high flying altitude, hypersonic velocity and lack of horizontal tail, The traditional flight mechanics do not have specific design rule for such flight condition. Based on osculating cone waverider method, this paper has established an infinitesimal computational model for the analysis of its longitudinal stability, both the first and second derivative are taken into consideration. By combining Newtonian Theory, Piston Theory and Tangent Cone/Wedge Theory, the typical 2D profiles are used to investigate its longitudinal stability under hypersonic and wide angle of attack conditions. The result shows that the "convex" case could improve its longitudinal stability while the "concave" case has the contrary effect. This conclusion is verified by both 2D and 3D computational examples. On the basis of the theory above, the physical reason why conical derived waverider do not satisfy longitudinal static stability, and the influence of pitch trim rudder are also illustrated. Further analysis shows that this conclusion could also be applied to a broad Mach number and altitude, and the viciousity has little influence on such law. The conclusions of this paper could be used in the preliminary aerodynamic design of hypersonic vehicles.