This study explores the system level design impacts of differing supersonic inlet topology. Historically, for Mach 2 flight, variable ramp angle external compression inlets have been preferred over normal shock inlets on the basis of pressure recovery. However, from a system design perspective, is inlet pressure recovery everything? We compare a variety of low-bypass ratio turbofan engines, modelled with NASA's Numerical Propulsion System Integration (NPSS), that can propel a F-16-inspired tactical fighter aircraft. We compute installed performance by applying installation limits (buzz and distortion) and losses (bleed, bypass, spillage, and total pressure recovery) as suggested by the USAF Performance of Installed Propuslion Systems (PIPSI) protocol. Our design study matrix comprises three different engines (Bypass Ratio of 0.5, 1.0, and 1.5) matched to one of three inlet topologies (normal shock, fixed ramp external compression and variable ramp external compression) scaled to any of five possible capture areas. We found that the variable ramp external compression inlet was unforgiving of higher bypass ratio engines. Compared to the robust nature of the normal shock inlet leads the authors to believe that the normal shock inlet, not the complex variable geometry ramp inlet, may be the superior choice for many supersonic propulsion design applications.
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