Aircraft

SABRE hypersonic jet/rocket hybrid engine passes key precooler test

The precooler is an essential element of the SABRE hypersonic engine
The precooler is an essential element of the SABRE hypersonic engine
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The precooler is an essential element of the SABRE hypersonic engine
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The precooler is an essential element of the SABRE hypersonic engine
The SABRE precooler being tested in Colorado
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The SABRE precooler being tested in Colorado
The Reaction Engines team conducting precooler tests
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The Reaction Engines team conducting precooler tests

Reaction Engines' hypersonic SABRE air-breathing rocket engine has taken a major step towards flight after a key component passed the first phase of high-temperature testing. Under conditions simulating supersonic flight, the engine's precooler unit quenched a 420° C (788° F) intake airflow in less than 1/20th of a second.

The Synergetic Air-Breathing Rocket Engine (SABRE) engine is a hypersonic hybrid design that draws in air like a conventional jet while accelerating to speeds of up to Mach 5 (3,704 mph, 5,961 km/h), then converts to a pure rocket engine burning hydrogen and liquid oxygen, making speeds of up to Mach 25 (17,521 mph, 29,808 km/h) possible.

The idea is that by breathing air during low-speed acceleration, SABRE can drastically reduce the amount of oxidizer needed to feed the engine, reserving liquid oxygen for only the hypersonic, high-altitude phase when it acts like a pure rocket. In this way, SABRE can power hypersonic aircraft or even orbiters like the Skylon spaceplane.

The SABRE precooler being tested in Colorado
The SABRE precooler being tested in Colorado

The problem is that when the air is coming in at supersonic speeds, it has a force 25 times that of a category 5 hurricane, generating temperatures that would melt any material that the engine might be made of. It's for this reason that the precooler unit is so vital to the SABRE engine's operation as it will one day use recirculated cryogenic hydrogen fuel to cool incoming air down from 1,000° C (1,832° F) to -150° C (-302° F) in 1/100th of a second.

The current tests that began in early March were nowhere near that range. According to Reaction Engines, the test at the company's TF2 test facility at the Colorado Air and Space Port in Aurora, Colorado used a General Electric J79 turbojet engine originally built to power the McDonnell Douglas F-4 Phantom to feed air into the precooler at the equivalent to Mach 3.3 (2,127 knots, 2,448 mph, 3,939 km/h) or the speed of the SR-71 Blackbird aircraft.

Reaction Engines says the compact precooler worked as expected and managed a heat transfer of 1.5 MW, or equivalent to the energy demands of 1,000 homes. Later tests will simulate Mach 5 flight. It has also been extensively tested at the TF1 test facility at Westcott, Buckinghamshire, UK, where it operated under ambient air temperatures. It's at TF1 that the engine core is being tested.

The Reaction Engines team conducting precooler tests
The Reaction Engines team conducting precooler tests

"This is a hugely significant milestone which has seen Reaction Engines' proprietary precooler technology achieve unparalleled heat transfer performance," says Mark Thomas, Chief Executive, Reaction Engines. "The HTX test article met all test objectives and the successful initial tests highlight how our precooler delivers world-leading heat transfer capabilities at low weight and compact size. This provides an important validation of our heat exchanger and thermal management technology portfolio which has application across emerging areas such as very high-speed flight, hybrid electric aviation and integrated vehicle thermal management."

Source: Reaction Engines

5 comments
paul314
Talk about a critical part. If it performs below spec for even a few milliseconds...
Koolski2
I am so hyped about this technology; I am anxiously awaiting each step in the process. I think this will be game changing when it is applied to a real world vehicle. No doubt, many standard air frame designs will radically change with the introduction of an engine that can achieve such speeds.
Koolski2
I am so hyped about this technology; I am anxiously awaiting each step in the process. I think this will be game changing when it is applied to a real world vehicle. No doubt, many standard air frame designs will radically change with the introduction of an engine that can achieve such speeds.
JagtygerII
Just think in a few years the SR-71 could be back with a new engine and become a t4ue space plane capable of reaching orbit. If so that would allow the first stage to be refueled for the rocket phase, sweet
ljaques
I'm hyped over it, too. But only if we get it. If another country perfects it, we's in a heap o' trouble. Then again, how long will it take for the Russians, Chinese, and Iranians to bribe one of our people for all the docs and tech? Yeah, Paul, wondering if this cooler will be farmed out to the lowest bidder. <g>