Advances in hypersonic vehicle synthesis with application to studies of advanced thermal protection system

AbstractA methodology for determining the near-optimal operation of the propulsion system ofhybrid air-breathing launch vehicles is derived. The method is based on selecting propulsionsystem modes and parameters that maximize a certain performance function. This function isderived from consideration of the energy-state model of the aircraft equations of motion.The vehicle model reflects the many interactions and complexities of the multi-mode air-breathing and rocket engine systems proposed for launch vehicle use. The method is used toinvestigate the optimal throttle switching of air-breathing and rocket engine modes, and toinvestigate the desirability of using liquid oxygen augmentation in air-breathing enginecycles, the oxygen either carried from take-off or collected in flight.IntroductionStudies are underway to select thenext generation of space launch vehicles.The main incentive is to dramatically reducethe cost of access to space. The key toachieving this goal is thought to be use ofvehicle systems that are completely reusableand operationally more like current aircraftthan current launch vehicles.One launch vehicle candidate is asingle-stage-to orbit (SSTO) airplane thataccelerates within the atmosphere with air-breathing engines for a substantial portion ofits flight. This concept has been developedunder the National Aerospace Planeprogram. Such an airplane is considerablydifferent than any aircraft ever built andflown, and its development presents manychallenges, most notably the design andoperation of the propulsion system."Professor and Chairman, Dept. of Mechanical Engineering, Associate Fellow AIAA"'Aerospace Engineer"'"Programmer/Analyst