A potentially game-changing rocket engine has attracted significant new investment to allow it to enter development.

The Synergetic Air-Breathing Rocket Engine (Sabre) combines elements of a jet and rocket engine. It is designed to enable a “spaceplane” to take off from a conventional runway and “fly” into orbit.

Once its mission is over it would return to land like any other aeroplane. Thus it is reusable, and should make launches cheaper than a conventional rocket.

Sabre is the brainchild of British engineer Alan Bond, who founded Reaction Engines in 1989 to develop his ideas.

The viability of the engine has been validated by the European Space Agency (ESA) during a review undertaken at the request of the UK government. This has resulted in the government’s awarding £50m to aid preparations for the design, manufacture and testing of demonstration engines. The ESA is currently drawing up a contract worth $10m.

Now a private investment has also been announced. Global aerospace company BAE Systems will invest £20m in return for 20% of Reaction Engine’s share capital, and will enter into a working partnership with them. This will allow the firm to move towards the manufacture of ground-based test engines, a key milestone.

Sabre must first work as a jet engine and accelerate spaceplanes to more than five times the speed of sound. By changing the way it works, it then becomes a rocket engine, accelerating to more than 25 times the speed of sound, fast enough to put the spaceplane into orbit.