SABRE – Synergetic Air Breathing Rocket Engine – is a new class of engine for propelling both high speed aircraft and spacecraft. SABRE engines are unique in delivering the fuel efficiency of a jet engine with the power and high speed ability of a rocket.
Unlike jet engines, which are only capable of powering a vehicle up to Mach 3, three times the speed of sound, SABRE engines are capable of Mach 5.4 in air-breathing mode, and Mach 25 in rocket mode for space flight. They are simply going to revolutionise the way we travel around the globe, and into orbit. Like jet engines, SABRE can be scaled in size to provide difference levels of thrust for different applications which is crucial to our success – it’s going to enable a whole generation of air and space vehicles.
There are three core building blocks to the SABRE engine, the pre-cooler, the engine core and the thrust chamber. Each of these systems can be developed and validated using ground based demonstrations which saves cost and time relative to flight test, a design feature that benefitted the development of the propeller and jet engine, We plan to demonstrate each of these independently over the next four years, beginning with a high temperature test of the pre cooler in 2017.
We’re about to start building a significant new UK test site to test critical subsystems and aim to test a fully integrated engine core in 2020.
Reaction engines finalized the UK Government’s £60 million commitment in November, 2016. In November 2015, BAE Systems invested £20.6 million in Reaction Engines to acquire 20 per cent of its share capital and agreed to provide industrial, technology development and project management expertise to support Reaction Engines during its development phase.
Orbital Access Ltd announced December 7, 2016 that it has been awarded a £250,000 grant by the UK Space Agency to technically and commercially evaluate a roadmap for UK small space payload launchers. The project, coined FSPLUK, aims to define an initial commercially viable launch system able to be brought to service by 2020 leading to a fully re-usable system for services to start in 2030. The project focusses on horizontal take-off launch systems to exploit the UK’s forthcoming spaceport. The FSPLUK project team led by Orbital Access comprises BAE SYSTEMS, Reaction Engines, Fluid Gravity Engineering, the Universities of Glasgow and Strathclyde, Surrey Satellite Technologies, Clyde Space and the STFC.
The US Air Force Research lab has started working on key SABRE technologies. AFRL is working on the engine’s precooler. This device precools the air entering the engine at speeds greater than four times the speed of sound (Mach 4). SABRE’s precooler will cool such air from more than 1,832 degrees Fahrenheit (1,000 degrees Celsius) down to minus 238 F (minus 150 C) in one one-hundredth of a second. The oxygen in the chilled air will become liquid in the process.
The AFRL precooler test program, which is called Durable Pre-cooling Heat Exchangers for High Mach Flight, consists of three phases, the last of which could involve test flights. Two SABREs will power Skylon — a privately funded, single-stage-to-orbit concept vehicle that is 276 feet (84 meters) long. At takeoff, the plane will weigh about 303 tons (275,000 kilograms). AFRL views a single-stage-to-orbit Skylon space plane as “technically very risky as a first application [of SABRE],” and this is why the lab is developing two-stage-to-orbit concepts.
SABRE burns hydrogen and oxygen. It acts like a jet engine in Earth’s thick lower atmosphere, taking in oxygen to combust with onboard liquid hydrogen. When SABRE reaches an altitude of 16 miles (26 kilometers) and five times the speed of sound (Mach 5), however, it switches over to Skylon’s onboard liquid-oxygen tank to reach orbit.
Following the ground testing program, flight testing will be used to validate many key airframe and engine integration technologies while they work with their partners to finalize the design of the first operational SABRE-powered vehicle