Lifeboat Foundation

Reaction Engines of the UK has scaled back its design for the Sabre engine to bring about a demonstrator that is more affordable and better suited to early applications, including a potential X-plane.

The Oxfordshire-based firm has been developing a turbine that combines both jet and rocket technologies to achieve rates five times the speed of sound, to fly anywhere in the world in just four hours.

Rather than aiming for a demonstrator that can achieve more than 150,000 lb thrust, the firm will instead now target an engine size capable of roughly 44,000 lb thrust, according to Aviation Week Network.