Optimal Payload Trajectory Characteristics for Winged Booster Vehicles

The prospective use of space launch vehicles equipped with one or more winged stages to permit recovery and reuse presents an interesting problem in trajectory optimization: Can the lift capability of the vehicle be used to advantage during the atmospheric phase of a boost to orbit trajectory? The results of an analysis in which optimal lifting trajectories of a hypothetical two-stage winged space launch vehicle are compared with nonlifting trajectories for the same vehicle are presented. Fixed geometry wings of various planform areas and weights were added to a basic vehicle of the Saturn V class to arrive at a winged boost-launch system. A horizontal launch take-off mode, which considered the effect of a ground-based acceleration sled, was studied in addition to the conventional vertical launch mode. Increases in weight injected into low altitude orbits of about four percent are possible for vertically launched vehicles using lifting rather than nonlifting trajectories. Ground assisted horizontally launched vehicles can inject about 40 percent more weight into orbit than vertically launched vehicles of the same weight. Increasing first-stage structural weight of the horizontally launched vehicle by one million pounds reduces this figure to 20 percent.