Hypersonic Rocket Engine Passes Testing Milestone

Most aircraft are limited to subsonic cruising speeds, but an experimental hypersonic engine from a UK-based firm is one step closer to reality today. Reaction Engines says it successfully tested an integral component of its Synergetic Air Breathing Rocket Engine (SABRE). This could clear the way to build rocket engines that push commercial aircraft to several times the speed of sound.
Supersonic flight has been limited to military and governments ever since the retirement of the Concorde in 2003. That aircraft was capable of flying at Mach 2.04 (1,354 mph or 2,180 kph), but it was costly to maintain. There is an appetite to bring back supersonic flight and possibly even push into hypersonic speeds. That’s the future Reaction Engines is planning for with the SABRE engine.
One of the most vexing issue when flying at high speeds is how you handle airflow. In supersonic and hypersonic flight, air reaching the engine intake gets extremely hot, and an engine that can’t manage that heat is going to fail in spectacular fashion. The SABRE design includes a pre-cooler that quenches heat from incoming air. Reaction Engines says it successfully tested its precooler test article (HTX) with air at 788 degrees Fahrenheit (420 degrees Celsius). That corresponds to Mach 3.3 flight, the maximum speed of the now-retired SR-71 Blackbird. Engineers believe the final engine could hit Mach 5 or higher.
All just got a little hotter round here! The first phase of test results for our precooler heat exchanger replicate supersonic flight conditions at Mach 3.3. Further #HotHTX tests to #hypersonic coming soon @SpaceportCO #futureflight #thermalmanagement https://t.co/4fMgeTgEvD pic.twitter.com/JWUOhpsuLr
— Reaction Engines Ltd (@ReactionEngines) April 8, 2019
The HTX test took place on the ground at the company’s Colorado test facility with the aid of a repurposed General Electric J79 turbojet engine. These engines, designed more than 50 years ago, powered aircraft like the McDonnell Douglas F-4 Phantom II and the Lockheed F-104 Starfighter. Reaction Engines simply pointed the exhaust from the J79 at the precooler and tested its performance.

Reaction Engines says the HTX cooled the high-temperature air in less than 1/20th of a second. That’s 1.5MW of heat transfer, the energy equivalent of 1,000 average American homes. In its next test, Reaction Engines plans to subject the HTX to air at 1,800 degrees Fahrenheit (1,000 degrees Celsius). That corresponds to Mach 5 hypersonic flight.
This is a significant milestone, but the SABRE engine is still just a concept. It could be years before you can hop a hypersonic flight to another continent.
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