(REL) Reaction Engines Limited is British Company which developed an engine which could be used in the future on space planes, that space plane they called it Skylon. The engine will be completed in 2020 and the hybrid jet rocket engine allows an engine which can work on Earth atmosphere and outside in space. This project is worth over $92 million and it is an investment from the U.K. Government.
In the Earth atmosphere that engine will be work in an air breathing jet mode with burning oxygen with liquid hydrogen fuel in its combustion chamber. This investment reflects the strength of British engineering technology and their ambitions to be a leading space nation and they hope so than this SABRE engine will be reality very soon.
SABRE is the first engine by operating in two rocket modes. They are initially in air-breathing mode and subsequently in conventional rocket mode. At air breathing mode, the rocket engine sucks in atmospheric air as a source of oxygen. After that burn with its liquid hydrogen fuel in the rocket combustion chamber. The second conventional rocket mode. Is when the engine is above the atmosphere and transitions to using conventional liquid oxygen. In both modes the thrust is generated using the rocket combustion chamber and nozzles. This is made possible through a synthesis of elements from rocket and gas turbine technology.
Saturn V Propellants of skylon
This approach enables SABRE powered vehicles to save carrying over 250 tons. Of on board oxidant on their way to orbit. And after that removes the necessity for massive throw away first stages that are jettisoned once the oxidant they contain has been used up. And also allowing the development of the first fully re usable space access vehicles such as SKYLON.
Maybe this sounds simple. But the problem is that in air-breathing mode. The air must be compressed to around 140 atmospheres before injection into the combustion chambers. Which raises its temperature so high that it would melt any known material. SABRE avoids this by first cooling the air using a Pre-cooler heat exchanger. Then a relatively conventional turbo compressor using jet engine technology. It can be used to compress the air to the required pressure.
Skylon SABRE Airflow
This means when SABRE is in the Earth’s atmosphere. And the engine can use air to burn with the hydrogen fuel rather than the liquid oxygen used when in rocket mode. Which gives an 8 fold improvement in propellant consumption. The air breathing mode can be used until the engine has reached over 5 times the speed of sound. And an altitude of 25 km. Which is 20 % of the speed and 20 % of the altitude needed to reach orbit. The remaining 80 % can be achieved using the SABRE engines in rocket mode.
For space access, the thrust during air breathing ascent is variable but around 200 tonnes per engine. During rocket ascent this rises to 300 tonnes. But then throttled down towards the end of the ascent to limit the longitudinal acceleration to 3.0g.