<h2>AAS 99-129</h2>
<h2>Optimization of Ascent Trajectory and Related Design Issues for an Aerial Propellant Transfer Rocketplane                                        </h2>
<h4>K.  Gallagher                                                                                                                                                                       </h4>
Pioneer Rocketplane, Vandenberg AFB, CA                                                                                                                                   
<h2> Abstract </h2>
Pioneer Rocketplane is designing and building a new reusable launch vehicle, to begin commercial operations in 2001. The "Pathfinder" rocketplane used the technique of "aerial propellant transfer" to enable lower costs for reaching orbit without using unproven technologies. The optimum trajectory and design trade-offs for this concept are very different from pure rocket vehicles or others using highly advanced propulsion technology. Design trades showed that a lower altitude for beginning rocket powered-flight produced higher performance. Staging conditions were constrained by payload environmental requirements, first state reentry limits, and second stage trajectory optimization, limiting staging to a narrow range of conditions.