Hybrid Air-Breathing Engines for Orbital Launch Vehicles: Performance and Challenges
Anirudh S
31/08/2026
Access to space still depends on traditional rocket propulsion that involves carrying the propellant consisting of fuel and oxidizer. This leads to relatively heavy launch mass and inefficiency. The use of air-breathing engines during the initial ascent phase and then switching into the rocket propulsion at higher altitudes is an alternative to this problem. This work describes a literature comparison of hybrid air-breathing rocket propulsion systems and their performance relative to traditional rocket engines and air-breathing engines.
The literature comparison covers various ideas on propulsion technologies like SABRE, HOTOL, LAPCAT Scimitar, and NASA GTX using journal articles, technical reports, and other official sources for each program. Comparison of performance parameters includes specific impulse, thrust, thrust-to-weight ratio, propulsive efficiency, Mach number, fuel consumption, integration into launch vehicle, reliability, and reusability.
Hybrid air-breathing engines have been found to have higher atmospheric specific impulses and lower on-board oxidizer requirements and therefore qualify to be considered for the design of reusable rockets and future single-stage-to-orbit designs. The complexity of the systems, difficulty in thermal management, and the absence of in-flight demonstration of the systems pose major challenges.