Inspired by a comment to this question "How does the Sabre engine's pre-cooler achieve such high performance?": the comment was that Reaction Engines have demonstrated that the pre-cooler works on a test stand.

Question: In what way was the test representative of the intended altitude and vehicle velocity conditions and what shortfalls, if any, are unavoidable?


1 Answer 1


In 2012, the precooler was tested at ambient temperature/pressure (there have been lots more test runs, but this one was well-publicized and there's video).

In the summer of 2018, the precooler will be tested at 1000 ºC inlet conditions (comparable to the conditions at Mach 5), using a J79 engine from an F-4 as a hot air source.

The HTX test programme is a manufacturing and performance ground level demonstration of a pre-cooler type heat exchanger in a high enthalpy (temperature) environment, similar to that expected to be seen by the SABRE engine during its air-breathing flight regime – up to ~1000°C air inlet temperature.

The pre-cooler is designed to absorb over 5 megawatts of heat energy from the incoming hot air passing through it so that the outlet air temperature is just above ambient.

  • 1
    $\begingroup$ Reaction Engines have tested have tested lab-scale precoolers (a few inches) across high temperature ranges, but the full size ones have only been tested at ambient temperatures using liquid nitrogen as a heat sink. The purpose of the 2012 tests was primarily to demonstrate the frost control. $\endgroup$
    – user20636
    Jul 29, 2018 at 1:10

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