Heat transfer characteristics of hypersonic waveriders with an emphasis on the leading edge effects

The heat transfer characteristics in surface radiative equilibrium and the aerodynamic performance of blunted hypersonic waveriders are studied along two constant dynamic pressure trajectories for four different Mach numbers. The inviscid leading edge drag was found to be a small (4 to 8 percent) but not negligible fraction of the inviscid drag of the vehicle. Although the viscous drag at the leading edge can be neglected, the presence of the leading edge will influence the transition pattern of the upper and the lower surfaces and therefore affect the viscous drag of the entire vehicle. For an application similar to the National Aerospace Plane (NASP), the present study demonstrates that the waverider remains a valuable concept at high Mach numbers if a state-of-the-art active cooling device is used along the leading edge. At low Mach number (less than 5), the study shows the surface radiative cooling might be sufficient. In all cases, radiative cooling is sufficient for the upper and lower surfaces of the vehicle if ceramic composites are used as thermal protection

Application of a new economic analysis tool to a two-stage-to-orbit RBCC launch vehicle design

6th AIAA/USAF/NASA/ISSMO Symposium on Multidisciplinary Analysis and Optimization, Bellevue, WA, September 1996.As aerospace industries are forced to compete in an environment of declining federal budgets and increased competition, 'design for performance' is quickly giving way to 'design for cost.' Many modern launch vehicle programs are initiated with the goal of lowering the cost of delivering payloads to orbit while limiting investment costs and yielding a reasonable rate of return. Designers of new vehicles will need tools to quickly evaluate not only the costs, but also the revenue potential of various design options. To provide information that can be used to drive design decisions or an optimization process, these economic analysis tools must be fully integrated into the design environment. This paper reports the status of research to create a design-oriented economic analysis tool for conceptual launch vehicle design (called CAM). An overview of each CAM component is presented -- program definition, non-recurring costs, recurring costs, market evaluation, and revenue. As a demonstration, CAM is used to optimize the end-customer launch prices to four individual launch markets for a multi-market capable two-stage-to-orbit launch system. The vehicle utilizes rocket-based combined-cycle engines on the booster state and has two interchangeable rocket upper stages (one for GTO missions and one for LEO missions). Business-oriented results such as rate of return, and sensitivities to government investment, airframe life, and operations costs are presented