Space Plane Tech Could Power Hypersonic Aircraft​ for US Military

This artist's illustration depicts the Skylon concept vehicle.

Credit: Adrian Mann

Engine technology being developed for a British space plane could also find its way into hypersonic aircraft built by the U.S. military.

The U.S. Air Force Research Laboratory is studying hypersonic vehicles that would use the Synergetic Air-Breathing Rocket Engine (SABRE), which the English company Reaction Engines Ltd. is working on to power the Skylon space plane, AFRL officials said.

"AFRL is formulating plans to look at advanced vehicle concepts based on Reaction Engine's heat-exchanger technology and SABRE engine concept," officials with AFRL, which is based in Ohio, told reporters.

SABRE and Skylon were invented by Alan Bond and his team of engineers at the Abingdon, England-based Reaction Engines.

SABRE burns hydrogen and oxygen. It acts like a jet engine in Earth's thick lower atmosphere, taking in oxygen to combust with onboard liquid hydrogen.

When SABRE reaches an altitude of 16 miles (26 kilometers) and five times the speed of sound (Mach 5), however, it switches over to Skylon's onboard liquid oxygen tank to reach orbit.

Two SABREs will power the Skylon space plane, a privately funded, single-stage-to-orbit concept vehicle t-hat is 276 feet (84 meters) long. At takeoff, the plane will weigh about 303 tons (275,000 kilograms).



The SABRE heat exchanger is also known as a pre-cooler. It will cool the air entering Skylon's engines from more than 1,832 degrees Fahrenheit (1,000 degrees Celsius) down to minus 238 degrees Fahrenheit (minus 150 degrees C) in one one-hundredth of a second.

The oxygen in the chilled air will become liquid in the process.

"The [pre-cooler] performance has always been pretty much what we predicted," Bond explained to reporters at the Farnborough International Airshow in England on July 16.

"We've now done over 700 actual tests. It's now done as much service as a pre-cooler would in a real engine."

Bond's team has also successfully tested the pre-cooler for a problem aviation jet engines have to deal with: foreign objects being sucked in.

"We know it [the pre-cooler] can take debris, insects, leaves," Bond said.