Dynamic derivatives are fundamental parameters for aerodynamic modeling and crucial for assessing vehicle dynamic characteristics. For hypersonic lifting-body vehicles, aerodynamic coupling among pitch, yaw, and roll directions is significant due to aerodynamic layout and unsteady aerodynamic effects, leading to marked increases in cross dynamic derivatives that characterize yaw-roll coupling. In this paper, the forced oscillation method was employed to calculate and identify the dynamic derivatives based on the National Numerical Windtunnel hypersonic software, named NNW-HyFLOW. First, the method is validated using the OV-102 space shuttle standard model. Then, the effects of parameters (e.g., angle of attack and Mach number) on dynamic derivatives were analyzed. Results indicate significant yaw-roll aerodynamic coupling in the quasi-HyTRV (high-speed transition research vehicle) lifting body. The results show that the aerodynamic coupling effect between the yaw and roll directions of the quasi-HyTRV lifting-body is significant. The rolling-moment derivative due to yaw rate exceeds the roll damping derivative when the angle of attack is greater than 2° or the Mach number is less than 5. As the angle of attack increases, the pitching static stability decreases, while the dynamic stability first slightly drops to a minimum at the equilibrium angle of attack then increases significantly. The yaw static and dynamic stability both decrease, while the roll static and dynamic stability enhance simultaneously. With increasing Mach number, the static stability in the pitch, yaw, and roll directions improves, while the damping and cross-dynamic derivatives gradually decrease, and the dynamic stability declines. This study can provide a theoretical basis and data support for the dynamic stability assessment and aerodynamic modeling of lateral-symmetric hypersonic vehicles.

When a high-speed reentry vehicle enters the near space, the boundary layer undergoes the transition process as the Reynolds number increases. The boundary layer transition modifies the surface pressure and skin friction distributions on high-speed vehicles, thus affecting the aerodynamic and stability characteristics. The asymmetric transition fronts on inclined axisymmetric vehicles induce extra force and moment, thereby affecting the vehicle's static and dynamic stability. Consequently, an investigation into the effects of boundary layer transition on aircraft's stability is critical for the design and control of high-speed vehicles. This paper analyzed the influence of boundary layer transition on the static and dynamic stability of a sharp cone using a high-speed numerical simulation software. This was accomplished by numerical simulations of forced transition with different types of transition fronts by integrating RANS models and the forced pitching oscillation method. For this dynamic numerical simulation, a transition control surface was essential, constructed by extending the transition front from the cone surface in the wall-normal direction. Results showed that as the transition front moves backward, the static stability decreased while the dynamic stability increased. The boundary layer transition introduced additional pressure and skin friction, with the former being the primary contributor to the overall induced pitching moment dynamic derivative.