LAUSR

Optimal periodic control is an effective technique to reduce aerodynamic heating and fuel consumption of hypersonic cruise vehicles. Herein, this optimal control problem has been solved by nonlinear programming and passed the posteriori check of optimality. The results indicate that the lift coefficient and velocity in dynamical model could be recognized as constants. Accordingly, the original 3D system consists of velocity, flight path angle, and altitude, which could be decoupled into a 2D subsystem and a 1D one. The 2D subsystem could describe the correlation between the flight path angle and altitude. And the period length is mainly dependent on the maximum altitude difference. The 1D subsystem has been proved to be feasible to describe the variation of kinetic energy or velocity. On basis of the subsystems, the heating and fuel performances of periodic cruise have been studied. The heating performance is mainly dependent on the maximum altitude difference, and the fuel consumption is mainly dependent on the drag coefficient. The features concluded in this paper can support rapid trajectory planning or suboptimal feedback design of hypersonic cruise vehicles.