Comparison of QEG and maximum L/D trajectory generation on approach and landing for reusable launch vehicle

New generation reusable launch vehicle (RLV) programs consider vehicle safety, reliability and operational costs as their major objective. In this paper an aerodynamic model of the X-34 launch vehicle was considered. The advantages of control laws, such as constant-velocity or constant-dynamic-pressure quasi-equilibrium glide (QEG) algorithms have been tested. A control system for enforcing quasi equilibrium glide conditions by tracking the QEG flight-path angle is discussed, along with preliminary results of implementing the control system. Flight-path-angle error with CVQEG and CDPQEG control systems is discussed. The QEG is compared with Maximum range trajectory and finally arrived at a conclusion that Max L/D trajectory is much better than QEG.