The SABRE engine requires a novel design of the rocket engine’s thrust chamber and nozzle to allow operation in both air-breathing and rocket modes, as well as a smooth transition between the two. The Advanced Nozzle project is demonstrating the feasibility of this concept and represents a significant technology development effort towards the SABRE demonstrator engine.
The test engine, which has been successfully fired 15 times during its initial commissioning phase in spring 2015, incorporates several new technologies including a 3D printed, actively cooled propellant injector system. Aerodynamic data collected from the firings is being used to validate in-house computational modelling and advance the nozzle design. The test campaign is being operated by Airborne Engineering Ltd in Westcott, Buckinghamshire. Operations are planned to continue throughout 2015, including long duration burns and tests investigating the transition between air- breathing and rocket operation planned for later in the year.
Dr Helen Webber, Reaction Engines’ Project Lead for the Advanced Nozzle Programme, commented:. “This experimental engine is an important step into a new era of propulsion and space access We are using it to test the aerodynamics and performance of the advanced nozzles that the SABRE engine will use, in addition to new manufacturing technologies such as our 3D-printed injection system
Reaction Engines Ltd is an aerospace technology and propulsion company headquartered in
the UK with core capabilities in the design, manufacture and testing of ultra-lightweight heat
exchangers and aerospace propulsion technology.
Reaction Engines’ ultra-lightweight air heat exchangers cool hot air from 1,000 ° C to minus 150 ° C in 1/100th second. With proprietary frost control technology preventing the formation of ice at sub-zero temperatures, the SABRE engine’s pre-cooler is able transfer the same amount of heat generated by electricity power stations (450MW) using equipment that It weighs less than a standard car (less than 1.5 tonne).
Combined with unique thermodynamic cycles, Reaction Engines’ technology enables a new class of aerospace engine called the Synergetic Air-Breathing Rocket Engine (‘SABRE’). This breakthrough in aerospace propulsion can power aircraft from a runway start up to Mach 5.5 in the atmosphere (more than twice the speed of a conventional jet engine) and then subtly transition to a pure rocket mode which allows the engine to operate outside of the Earth’s atmosphere up to orbital velocity (Mach 25, 17,000mph, 7.5km / sec). The viability of the SABRE engine has been independently validated by the European Space Agency during a review which was undertaken at the request of the UK Space Agency.
Reaction Engines Ltd has an ongoing privately funded SABRE engine technology development programme, and in 2013 the UK Government announced a £ 60m commitment towards the development to aid preparations for the design, manufacture and testing of the first SABRE demonstrator engines.
REL’s technologies have the potential for wider application across large industrial markets to improve efficiency and create new capabilities, with applications in power generation, conventional gas turbines and desalination.
Skylon plans and projected costs
For Skylon, if no growth occurred and all operators flew equal numbers of the current approximately 100 satellites per year using 30 in-service spaceplanes from 3 spaceports, the true launch cost would be about $40 million per flight [$1200/lb to LEO].
They expect mission costs to fall to about $10 million per launch for high product value cargo (e.g. communications satellites) $2-5 million for low product value cargo (e.g. science satellites) and for costs per passenger to fall below $100k, for tourists when orbital facilities exist to accommodate them.
As high volume flights are performed the 15 ton payload to LEO orbit would be $2-10 million per launch which would be $66/lb to $330/lb.
SABRE’s heat exchanger, also known as a pre-cooler, is the engine’s key technology. Just before the engine switches to rocket mode at Mach 5, the incoming air will have to be cooled from 1,832 degrees Fahrenheit (1,000 degrees Celsius) to minus 238 degrees Fahrenheit (minus 150 degrees C), in one one-hundredth of a second, displacing 400 megawatts of heat energy using technology that weighs less than 2756 pounds (1,250 kg).
The pre-cooler technology was successfully tested in 2012, and the achievement was independently confirmed by ESA, on behalf of the UK government.
* Over 50 km of heat exchanger tubing for a weight penalty of less than 50kg
* Heat exchanger tube wall thickness less than 30 microns (less than the diameter of a human hair)
* Incoming airstream to be cooled to -150 °C in less than 20 milliseconds (faster
than the blink of an eye)
* No frost formation during low temperature operation