The walls of combustion chambers used for air-breathing hypersonic vehicles are subject to substantial thermo-mechanical loads, and require active cooling by the fuel in conjunction with advanced material systems. Solutions based on metallics are preferable to ceramic matrix composites due to their lower cost and greater structural robustness. Previous work suggested that a number of metallic materials (e.g. Nickel, Copper and Niobium alloys) could be used to fabricate actively cooled sandwich structures that withstand the thermo-mechanical loads for a Mach 7, hydrocarbon-powered vehicle (albeit with different weight efficiencies). However, this conclusion changes when the Mach number is increased. This work explores the feasibility of the Nickel superalloy MARM246 for a wide range of Mach numbers (7–12). Since hydrocarbon fuels are limited to Mach 7–8, Hydrogen is used as the coolant of choice. A previously derived analytical model (appropriately modified for gaseous coolant) is used to explore the design space. The relative importance of each design constraint is assessed, resulting in the distillation of essential guidelines for optimal design.