Supersonic Inlet Shaping for Dramatic Reductions in Drag and Sonic Boom Strength

An alternate approach has been identified for defining supersonic inlet compression surface geometry, the use of which increases the design latitude for lofting the inlet cowling region while permitting control over other key inlet design variables. Through this approach, a novel inlet design space is analytically shown to significantly improve supersonic aircraft performance and reduce sonic boom overpressure compared to high-speed inlets designed using traditional methods and constraints. Installed specific fuel consumption improvements of up to 11 percent and sonic boom overpressure reductions of 16 percent were observed for a podded axisymmetric external compression inlet designed for Mach 1.8 cruise. A theoretical discussion and physical description of the alternate inlet design concept is provided along with a summary of the analysis methodology used to judge the concept’s merit against conventional configurations. Inlet performance metrics, presented as a function of key design variables, are compared; and CFD solutions of the compression and diffusion flow environment are included. Drag characteristics at off-design Mach number are also presented. An extended range, low sonic boom vehicle concept is used as an aircraft study platform for which installed CFD-based drag and sonic boom comparisons are made.