High-Speed Supersonic and Hypersonic Engines

The present passenger or cargo aircraft fly at high subsonic speeds (maximum Mach number of 0.84–0.86). However, passengers become bored by long trips, such as across the Atlantic, or by flights lasting 5–7 h or more. Extensive efforts are underway today to meet passengers’ needs and develop supersonic commercial aircraft. The most promising projects are the civilian Lockheed Martin X-59 Quesst (flight-tested in October 2025) and the military Hermeus aircraft, which conducted its first flight in May 2025 (Quarterhorse Mk 1). Supersonic and hypersonic flights necessitate new engine designs, namely Turboramjet and scramjet engines. The two types of Turboramjet engines (wraparound and over/under layouts) are analyzed. Scramjet engines are supersonic ramjet engines that operate at Mach numbers greater than 4. Thermodynamics and aerodynamics of both engines, along with case studies, are described in detail. Exergy analysis is used to examine the availability of both engines under different flight conditions. Artificial Intelligence (AI) is reviewed for the design, operation, and control of both turboramjet and scramjet engines. Representative programs using AI in the turbo-ramjet context are listed. Moreover, an example architecture for an AI-enhanced scramjet system is discussed.