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Sabre – Synergetic Air Breathing Rocket Engine – is a new class of engine for propelling both high-speed aircraft and spacecraft, delivering the fuel efficiency of a jet engine with the power of a rocket.
The engine is designed to operate in two modes. Within atmosphere it acts like a conventional jet engine to propel an aircraft from take-off to Mach 5. Outside atmosphere it switches to conventional rocket operation using stored liquid oxygen to reach 25 times the speed of sound.
“The innovative and disruptive nature of Sabre technology unlocks new ways of accessing space, furthering growth and sustainment of the future space economy,” said Mark Thomas, chief executive at Reaction Engines. The technology that Reaction Engines is developing for Sabre could also be used in the transport industry, for example, to help drive towards the government’s net-zero target.
Science minister Amanda Solloway said: “Backed by government, UK firms are leading the way in developing space technology that can reduce costs, improve sustainability and make space more accessible as we pursue our ambitious plans to grow the sector.”
This latest investment of £3.9m builds on £50m of previous government funding since 2015. Reaction Engines’ Sabre technology is expected to bring new developments not just in space, but also potentially in other spin-out areas including sustainable aviation fuels, unlocking atmospheric high-speed flight and extending electric vehicle battery life through pioneering thermal management technology.
Technology validation
Transport minister Rachel Maclean said: “We will continue to invest in, and support, companies like Reaction Engines, as we look to a greener, cleaner future – including as we embark on sustainable space exploration.”
This new funding comes after successful validation of Sabre technology in February 2021, where Reaction Engines completed tests of two important sub-systems, the HX3 heat exchanger and the advanced hydrogen pre-burner.
Together, these sub-systems deliver heat to the engine’s core. As the aircraft accelerates, heat energy is converted in the engine intake and extracted through the pre-cooler, progressively taking over the energy provided by the pre-burner extracted through the HX3 heat exchanger.
The objectives of both test campaigns were to produce full-size test rigs to validate performance modelling and de-risk high-temperature operation in advance of further integration. The pre-burner test campaign also intended to show that the fuel-injection system would function at full scale, that it was able to control the heat output precisely and provide even temperature to the HX3.
The HX3 test was conducted at Airborne Engineering’s Buckinghamshire test facility where the company built a custom hot-gas source, which was capable of providing partially combusted air with variable mass flow and temperatures controlled from 428°C to well in excess of 928°C. The rig also required closed-loop feedback control of the mass flow of hydrogen and air for combustion, the mass flow of helium coolant and the pressure of the hot coolant exhausted from the heat exchanger.
The latest round of government funding will secure further near-term technology demonstrations in hydrogen combustion, thermal management, and engine control technologies, which are all critical to the air-breathing core of future Sabre systems.
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