XCOR’s director of engineering and acting chief technology officer Michael Valant has announced the achievement of an important milestone in the development of the reusable 5K18 main rocket engine for the Lynx spacecraft.

XCOR engineers have successfully “closed the loop” of the thermodynamic system under test conditions. The 5K18 engine uses a novel method to drive essential engine parts using waste heat from the rocket engine, eliminating the need for large, heavy compressed-gas tanks in the vehicle. This technology is an important part of the Lynx “instant reusability,” which will allow the vehicle to fly multiple times per day without costly servicing of components.

The engine has already had hundreds of successful test firings in its basic “open-cycle” form.

“There’s still some work to do to improve the cycle efficiency before this engine is ready for flight,” Valant said, “but this is a massive step forward for us in the development of this groundbreaking technology.”