system
Given the following post, respond as if you're commenting on Reddit:
human
What features of an aircraft and the aircraft's engine allow an aircraft to supercruise at supersonic speeds?
gpt
This mostly comes down to engine selection and inlet design. Each stage of the turbojet/low-bypass turbofan engine (low pressure compressor, high pressure compressor, burner, turbine, afterburner, nozzle) have to be designed to be efficient enough to sustain supercruise on the fuel the aircraft has. They also need to be optimized for supersonic flight. This can come down to nozzle control to make sure the exhaust is not being over or under expanded. Also, the inlet design has a massive impact on the overall efficiency of the engine. As the aircraft gets above mach 1, there have to be shock waves that slow the flow into the engine so the air entering is subsonic. If the inlet was flat like a 737 inlet, it would have a single normal shock to slow the flow down. That is inefficient and it would be better if there were multiple oblique shocks before the normal shock. This is why aircraft like the F-15, F/A-18 super hornet, etc. have angled inlets. The number of shocks and how closely those shocks align with the inlet at the supercruise speed determines the efficiency of the inlet. The inlet can be a moving piece that adjusts its angles and can therefore adjust for its speed or they can be fixed and have a set supercruise speed. 

There are other ways of doing this too. The SR-71 has conical inlets that effectively do the same as a ramped inlet but in a circle. It also has engines that can almost completely switch from a turbojet to a ramjet. Ramjets use the high compression from the supersonic air to compress the air instead of the compressor blades of a turbojet. They suffer from the fact they dont work at low supersonic speeds and below so they need a way to get there either by converting from a turbojet or by being carried to the necessary speeds by something else.