A cooling system for a high-speed vehicle may comprise a combustor wall at least partially enclosing a combustor and which is cooled using a coolant circulating in a Brayton cycle. The heated coolant may be expanded in a turbine, transfer heat to a fuel within a heat exchanger, and be compressed by a compressor before returning to the combustor wall. The combustor wall may be capable of withstanding high temperatures, higher than the temperature at which fuel coking may take place. Heat transfer takes place between the coolant and the combustor wall, and between the coolant and the fuel. A method of cooling an engine for a high-speed vehicle is also disclosed.