Pre-Cooler for Hypersonic Spaceplane Cools From 1,000°C in Less Than 0.05 Seconds

Reaction Engines has successfully tested its innovative precooler at airflow temperature conditions representing Mach 5, or five times the speed of sound, marking a significant milestone in the development of its SABRE™ engine and paving the way for a revolution in hypersonic flight and space access.

The precooler heat exchanger is a vital component of Reaction Engines’ revolutionary SABRE air-breathing rocket engine and is an enabling technology for other precooled propulsion systems and a range of commercial applications.

This ground-based test achieved the highest temperature objective of the Company’s HTX testing program and took place at its specially constructed unique facility at the Colorado Air and Space Port, United States.

During the latest series of tests, Reaction Engines’ unique precooler successfully quenched airflow temperatures in excess of 1,000°C (~1,800°F) in less than 1/20th of a second. This test shows the precooler’s can successfully cool airflow at speeds significantly in excess of the operational limit of any jet-engine powered aircraft in history. Mach 5 is more than twice as fast as the cruising speed of Concorde and over 50% faster than the SR-71 Blackbird aircraft – the world’s fastest jet-engine powered aircraft.

This most recent test builds upon the success of previous HTX hot tests undertaken in April which saw the precooler successfully operate at temperatures of 420ᵒC (~788ᵒF) – matching the thermal conditions corresponding to Mach 3.3 flight.

Commenting, Mark Thomas, Chief Executive, Reaction Engines, said:

“This is a major moment in the development of a breakthrough aerospace technology which has seen Reaction Engines’ precooler tested at Mach 5 airflow temperature conditions, smashing through previous achievements at Mach 3.3 temperatures and paving the way for hypersonic flight. In addition to its use in our SABRE class of air-breathing rocket engines, there are numerous exciting commercial applications for our precooler technology, which delivers world-leading heat transfer capabilities at low weight and compact size, and we are seeing significant interest from a range of potential customers and technology partners.”

Reaction Engines’ patented pre-cooler heat exchanger has the potential to be used in a wide range of commercial thermal management applications. These include the development of precooled systems that would significantly enhance the performance of existing jet engine technology, along with applications in automotive, aerospace, energy and industrial processes.

The major testing milestone is the culmination of 30 years of engineering innovation since Reaction Engines was founded in 1989 by three propulsion engineers from Rolls-Royce, Alan Bond, Richard Varvill and John Scott-Scott.

Pre-cooler technology

Reaction Engines pre-coolers are made from thousands of thin-walled tubes to provide high surface area to low weight. Each tube is joined to an inlet and outlet manifold, which allows coolant to be injected and removed for the cooling process. They have unique heat exchanger manufacturing experience to bond thousands of joints in a single operation and achieve zero leakage. The joints in their pre-cooler modules are hermetically sealed, meaning that the gas which escapes can be measured by the molecule.

The pre-cooler can be used with current high-performance jet engines to extend the operational envelope of the engine, allowing faster speeds to be achieved as well as assisting in the thermal management of the engine, and may also enable more efficient next-generation civil aero engines.

Richard Varvill, Reaction Engines’ co-founder and current Chief Technology Officer, said:

“This is a momentous landmark for Reaction Engines in the development of its SABRE engine, which has the potential to revolutionize both access to space and high-speed flight by powering aircraft to five times the speed of sound. The performance of our proprietary precooler technology was validated at hypersonic flight conditions and takes us closer to realizing our objective of developing the first air-breathing engine capable of accelerating from zero to Mach 5.”

The HTX hot heat exchanger testing program is a significant milestone on the roadmap to enabling transformational SABRE powered space access systems and has been keenly supported by the UK Space Agency (UKSA) and European Space Agency (ESA). In March, the two agencies reviewed and validated the preliminary design of the demonstrator engine core of SABRE, which Reaction Engines will use to undertake ground-based testing at its under-construction TF1 test facility at Westcott, Buckinghamshire, UK.

The HTX hot heat exchanger test program was supported under a contract to the Company’s US subsidiary Reaction Engines Inc. by the Defense Advanced Research Projects Agency (DARPA). The precooler test item was designed and constructed at Reaction Engines’ headquarters in the UK, before being shipped to the Company’s Colorado site for testing.

Following this significant testing milestone, the Company will embark on achieving the next steps of the SABRE program while also pursuing nearer-term opportunities that will benefit from the addition of the Company’s heat exchanger technology.

Over the last four years, Reaction Engines has raised over £100m from public and private sources and has secured investment from BAE Systems, Rolls-Royce and Boeing HorizonX.

Commenting on this achievement, Science Minister Chris Skidmore said:

“The SABRE engine is one of the UK’s most exciting engineering projects which could change forever how we launch satellites into orbit and travel across the world. It’s fantastic to see Reaction Engines passing this significant milestone, which demonstrates how its precooler technology can deal with the extreme temperatures associated with traveling at five times the speed of sound. The government has invested £60 million in SABRE and is committed to taking a more strategic approach to space, developing our national capabilities to complement and expand on the UK’s leading role in the European Space Agency once we leave the EU.”

SOURCES- Reaction Engines
Written By Brian Wang,

40 thoughts on “Pre-Cooler for Hypersonic Spaceplane Cools From 1,000°C in Less Than 0.05 Seconds”

  1. I do find it amusing to read such a story. If it had been an american company the article would have had USA printed all over it and, how it was going to revolutionize flight etc etc etc.

  2. I thought they didn’t need the He precooler at normal speeds and altitude.

    I mean if it cools 1000C air to -150 it is going to do wonders on 32C air.

  3. “No, but they do have investment from Lockheed and BAE.”

    Lockheed isn’t interested in making space planes unless they are ballistic trajectory bombers.

  4. No, but they do have investment from Lockheed and BAE. The SABRE is looking more and more like the real deal with each test. It might power a commercial aviation revolution and can make space fighters and bombers a reality. Biggest benefit is its ability to potentially use commercial airports and it is not a high g ride, it will be more similar to a current aircraft when used for strictly atmospheric flight. For p2p there are some serious issues with the Starship, I am a big SpaceX fan, but the p2p use is a pipe dream.

  5. As related by someone, always remember to defrost the chicken before using a gun to launch the bird for a birdstrike test…

  6. Rockets more efficient than aircraft – unlikely. Vertical launch requires much more energy than (mostly) level flight. ICBMs use two stages to do a similar job; a single stage rocket would need that much more fuel just to carry its own weight. Rockets have to boost the oxygen as well, which jets get for nothing.
    Carbon neutral methane would make little difference compared to the effects of stratospheric water vapour, and ozone depletion.
    And if everyone could afford it, the environmental effects would be far worse.

  7. probably not, He is inert, so no explosion risk. Could create an engine freeze as the quick expansion at the leak would create icing issues, since it would temporarily increase cooling and choke the engine. Though it could always just switch to all rocket and use burst fires to control for emergency landing.

  8. Also, the precooler was tested not with LH2, but a liquid nitrogen boil, LN is -190ish only 30-40 c colder than LCH4

  9. Reaction is already irrelevant for LEO access. They were quoting $20 billion R&D costs to commercialize their space plane.

    For Mach 5 bombers though their engine is a winner.

  10. So this test cooled the air *from* 1000 °C, & a previous test operated *at* 420 °C.
    I’m curious what that 1000 °C air was cooled *to*.

  11. Run brayton cycles between the LCH4 fuel, LH2 bleed to run a LHe compressor. Also its 80 degrees not 110. Compression can make up the difference. If you look at the SABRE diagrams, only some of the LH2 fuel us used for cooling the Helium loop. That LH2 used in cooling is not closed cycle, its burned in the engine after powering a brayton from thermal expansion. The of cooling is generated by a He compressor powered by the brayton cycle that uses the heat energy exchanged.

  12. First of all, on the grander scale of things, pollution from SS P2P is largely irrelevant.
    Second, Starship would probably be more efficient than regular air planes.
    Third, Musk has proposed using the ISRU tech they develop for Mars to make the methane for Starship. So it may end up being carbon neutral.
    Fourth, prices for a P2P ride on Starship are supposed to eventually come down to levels that normal people can afford them.

  13. Thus the importance of ISRU, to use the launches wisely, so that global heating can be CURED with lunar derived or positioned Space Solar. Mars direct is not the way to go.

  14. Please remember, SABRE is a rocket engine, so just as noisy. It can get its O2 from 2 sources, a LOX tank or the atmosphere. P2P it would be better than Starship for the passenger, but the noise makes it worse than Concord.

  15. Can’t land anywhere close to a city, too noisy. Airport already have problem getting built with that constraint.

  16. I’m not sure its idiotic but I do think its inherently quite risky, relative to planes or potential SABRE rocket/jet planes.

  17. maybe a dual fuel LCH4 -161c as primary fuel and a LH2 secondary used as mostly as a bleed for cooling and burned off at the bell edge. That way it needs a small LH2 tank. LCH4 can keep the LH2 chilled.

  18. The SABRE is a vastly superior design to a Starship for p2p and all forms of atmospheric flight. It’s a hybrid, it is not as effective for orbital as the Starship, but more suitable for dual purpose and military application. Mach 5 strike fighters that can access LEO is a big plus. Can’t do that with the Starship tech. For p2p travel, it makes more sense as well, a high g rocket ride does not suit all, if over 55 you might be asking for an aneurysm or heart attack. This engine has the ability to replace jet turbines and should dominate business travel initially if they can build a commercial 50-100 seat version with it to start. Powered off of hydrogen is also a plus, it satisfies the green agenda.

    However, for orbital it’s inferior.

  19. Musk is pushing his electric car and solar roof businesses supposedly to counter global warming, but now he’s proposing thousands of rocket launches a year, to cater for a tiny, wealthy minority, which would blast millions of tons of water vapour and CO2 into the stratosphere. Jet aircraft already have three or four times as much impact on the climate as just their fuel use would suggest, because what determines the overall warming effect is the altitude from which the earth radiates infra red to space. Pumping water into the stratosphere, which is normally dry, thickens our blanket, and also interferes with the ozone layer.

  20. I fail to see how the Reaction Engines helium-loop exchanger Precooler can be applied to a regular aircraft. You can’t use Jet-A as a heatsink with that precooler– At high mach airspeeds, the Jet-A will not be able to accommodate all of the heat accumulating in the helium loop from the superhot air coming through the turbine inlet. Jet-A’s freezing point is -40C. At its freezing point, Jet-A is positively HOT compared to Liquid Hydrogen (-252C).

    The only cryogenic fuel cold enough to re-cool that heated helium in the exchanger loop fast enough is liquid hydrogen.

  21. avoid a pebble or bug from being sucked in near the runway and crashing through those sub .001″ wall thickness tubes? If any single tube breaks, are they ‘royally screwed’?

  22. They are good with other cooling sources besides cryogens apparently, though the amount of cooling becomes limited. For aircraft it would be conventional fuel cooling, Jet-A and friends. F-35 already uses fuel for cooling purposes, though not with a heat exchanger in direct line with the engine.

  23. The precooler is called a precooler for a reason, not an “aftercooler” LOL..

    It’s to precool the air intake of an air-breathing engine to allow faster speeds in atmospheric flight.

    Rocket engines don’t care about inlet air temperature because they carry their own oxygen. Indeed, the precooler in the SABRE engine shuts down after it transitions from air-breathing to rocket mode, when it starts using onboard LOX rather than atmospheric oxygen through the intakes.

  24. “The pre-cooler can be used with current high-performance jet engines to extend the operational envelope of the engine, allowing faster speeds to be achieved as well as assisting in the thermal management of the engine, and may also enable more efficient next-generation civil aero engines.”

    I wonder how true is the above statement. Apparently the only cryogenic fuel cold enough to make this helium-loop heat-exchanger precooler work is Liquid Hydrogen. Putting LH2 tanks aboard a conventional aircraft will require lots of volume and mass, since LH2 has such low density that it needs huge tanks with heavy insulation to keep it cold. Wonder what kind of drag and performance penalty will that incur on an aircraft.

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