An analysis undertaken by the US Air Force Research Laboratory (AFRL) has confirmed the feasibility of Reaction Engines Ltd’s (REL) synergetic air-breathing rocket engine (SABRE) cycle concept.
Undertaken as part of a cooperative research and development agreement with AFRL’s Aerospace Systems Directorate (AFRL/RQ), the analysis examined the thermodynamic cycle of the SABRE concept and did not find any significant barrier to its theoretical viability, provided the engine component and integration challenges are met.
AFRL/RQ programme manager Barry Hellman said: "The activities under the CRADA have allowed AFRL to understand the SABRE engine concept, its pre-cooler heat exchanger technology, and its cycle in more detail.
"While development of the SABRE represents a substantial engineering challenge, the engine cycle is a very innovative approach and warrants further investigation.
"The question to answer next is what benefit the SABRE could bring to high-speed aerospace vehicles compared to other propulsion systems."
Reaction Engines Corporate Development director Sam Hutchison said: "The confirmation by AFRL of the feasibility of the SABRE engine cycle has further validated our team’s own assessment and conviction that the SABRE engine represents a potential breakthrough in propulsion that could lead to game-changing space access and high-speed flight capability."
SABRE is a new class of aerospace engine designed for low cost, responsive space access and high-speed atmospheric flight, and can provide efficient air-breathing thrust from standstill on the runway to speeds above Mach 5 in the atmosphere, which is twice as fast as jet engines.
The engine can then transition to a rocket mode of operation for flight at higher Mach numbers and space flight, and can potentially be adapted to efficiently power aircraft flying at high supersonic and hypersonic speeds.
Due to its ability to ‘breathe’ air from the atmosphere, SABRE significantly lowers propellant consumption compared to legacy rocket engines, thus increasing the capability of launch vehicles including options for high-performance reusable launch vehicles with increased operational flexibility, such as horizontal take-off and landing.
The company and AFRL intend to investigate vehicle concepts based on a SABRE-derived propulsion system, test the SABRE engine components and explore defence applications for the former’s heat exchanger technologies.