An integrated and modular high-speed aircraft (200) and method of design and manufacture. The aircraft (200) can have a supersonic or near-sonic cruise Mach number. In one embodiment, the aircraft (200) can include an aft body integrated with a delta wing (204) and a rearwardly-tapering fuselage (202) to define a smooth forward-to-rear area distribution. A propulsion system (206), including an engine (216), inlet (220), and exhaust nozzle (222) can be integrated into the aft body to be at least partially hidden behind the wing (204). In one embodiment, the entrance of the inlet can be positioned beneath the wing (204), and the exit of the nozzle (222) can be positioned at or above the wing (204). An S-shaped inlet duct (221) can deliver air to the aft-mounted integrated engine.