Reaction Engines Announces Air Breather’s Success

Diagram of the Sabre engine (Credits: Reaction Engine Limited/BCC).

On November 28, Reaction Engines Ltd (REL) announced what it calls “the biggest breakthrough in aerospace propulsion technology since the invention of the jet engine.” Tests of the company’s SABRE air-breathing engine’s precooler have been successfully completed and validated.

“The pre-cooler test objectives have all been successfully met and ESA are satisfied that the tests demonstrate the technology required for the SABRE engine development,” the company reported the European Space Agency as saying.

The principle behind air-breathing engines is to use atmospheric oxygen as the propellant oxidizer instead of carrying the extra mass from the ground.  Accounting for the variable heat and humidity from intake air with flight-weight components has always been one of the stumbling blocks to building such an engine, and one of the reasons most organizations abandoned the idea years ago.

However, recent developments in materials have made advances in this arena possible. REL just finished a series of tests demonstrating the company’s cooling technology and frost control system. Frost control is critical as the precooler drops the incoming air from 1000°C to -150°C, and icing can severely impede engine operation. REL addressed this problem with a heat exchanger using helium at -170ºC as the exchange gas. The helium is then recovered by passing through a nitrogen boiler. 

“The REL team has been trying to solve this problem for over 30 years and we’ve finally done it,” said founder Alan Bond. “This is the proudest moment of my life.”

REL has plans for a single stage to orbit reusable spacecraft called Skylon as well as aircraft for jetting around the globe at Mach 5 – something NASA and the US Air Force have not been able to achieve, despite concerted effort. Competition in the field is likely to come from suborbital point-to-point operators, like XCor, with similar flexibility to takeoff and land from traditional airports.

 Below, an illustration of the SABRE’s operation: