Trajectory optimization study of a lifting body re-entry vehicle for medium to intermediate range applications

Abstract

Investigation on aerodynamic characteristics of baseline-II E-2 blended wing-body aircraft with canard via computational simulation AIP Conf. Abstract.A numerical optimization study of lifting body re-entry vehicles is presented for nominal as well as shallow entry conditions for Medium and Intermediate Range applications. Due to the stringent requirement of a high degree of accuracy for conventional vehicles, lifting re-entry can be used to attain the impact at the desired terminal flight path angle and speed and thus can potentially improve accuracy of the re-entry vehicle. The re-entry of a medium range and intermediate range vehicles is characterized by very high negative flight path angle and low re-entry speed as compared to a maneuverable re-entry vehicle or a common aero vehicle intended for an intercontinental range. Highly negative flight path angles at the re-entry impose high dynamic pressure as well as heat loads on the vehicle. The trajectory studies are carried out to maximize the cross range of the re-entry vehicle while imposing a maximum dynamic pressure constraint of 350 KPa with a 3 MW/m 2 heat rate limit. The maximum normal acceleration and the total heat load experienced by the vehicle at the stagnation point during the maneuver have been computed for the vehicle for possible future conceptual design studies. It has been found that cross range capability of up to 35 km can be achieved with a lifting-body design within the heat rate and the dynamic pressure boundary at normal entry conditions. For shallow entry angle of -20 degree and intermediate ranges a cross range capability of up to 250 km can be attained for a lifting body design with less than 10 percent loss in overall range. The normal acceleration also remains within limits. The lifting-body results have also been compared with wing-body results at shallow entry condition. An hp-adaptive pseudo-spectral method has been used for constrained trajectory optimization.

Numerical Performance Study of Small Size Lifting-Body Reentry Vehicle

“…The aerodynamic model of the glide vehicle used is same as in ref. [2]. The maximum lift-to-drag ratio of a lifting-body vehicle is approx.…”

“…[1] that burn-out angle is a single important parameter on which depends the overall performance, max g-load as well as the integrated heat load. Previous study performed on lifting-body vehicle has shown that for nominal shallow re-entry angle of 20 degree a cross range capability of 240-260 km can be obtained in the intermediate range [2] at re-entry speed of approximately 5 km/s. The re-entry angle was not optimal in that particular case.…”

“…The present study is an extension of the trajectory study carried out in ref [2] and is aimed at computing best burn-out angle, which would result in optimal performance of lifting-body vehicle for the launch vehicle under consideration. The lifting-body design has a trim lift-to-drag ratio of close to 1.0 and are capable of limited cross-range capability [2].The trajectory optimization problem of a lifting-body vehicle using a boost vehicle is modeled as a four phase optimal control problem with the objective to compute the best burn-out conditions and the control deflections that would maximize the cross-range of the lifting-body glide vehicle under study. The nonlinear optimal control problem is solved using hp-adaptive Pseudospectral method implemented in Gauss Pseudospectral Optimization Software, GPOPS [3].…”