This paper details the development, validation and use of a thermal model created for the UK Ministry of Defence funded Sustained Hypersonic Flight Experiment (SHyFE). This compact ramjet will operate at Mach 4 to 6 leading to very high air flow stagnation temperatures. The thermal management system must be designed to maintain the avionics and fuel system at acceptable temperatures throughout the flight. The heat exchange mechanisms were predicted throughout the acceleration section of the f...