The engines are likely to be more elaborate than the turbofan you find on a jet liner. To get to Mach 5 you need to accelerate through different speeds and nee

The engines are likely to be more elaborate than the turbofan you find on a jet liner. To get to Mach 5 you need to accelerate through different speeds and need an engine that works and is efficient enough at each speed. A turbojet works well at lower speeds but cannot go much above Mach 3 in its traditional form. A ramjet is efficient at high mach numbers but does not work at low speeds. One solution is to reconfigure the engine at different speeds, such as a variable cycle engine. Alternatively, some designs include precooling of intake air (sabre), or even a hybrid rocket/jet engine. But all these options are more complex and expensive.