SABRE development update: advanced hydrogen preburner testing complete

September 28, 2021
advanced hydrogen preburner testing complete

Reaction Engines is pleased to be able to provide an update on the development of SABRE. In partnership with S&C Thermofluids, we have tested the engine’s advanced hydrogen preburner at energy delivery levels in excess of two megawatts and proved output temperature uniformity under pressurised conditions. The preburner will now be combined with the HX3 heat exchanger to provide heat to the SABRE cycle at take-off and early flight.


Building on the success of the preburner prototype testing in 2020 followed by the initial demonstrator test phase of the preburner at the beginning of the Spring, this campaign sought to test improvements to the system and prove temperature uniformity at the back of the preburner so that it can be effectively combined with the HX3 heat exchanger.

The preburner and HX3 provide the heat source to SABRE’s core engine to enable flight from sea level. As the aircraft accelerates, the heat energy converted in the engine intake and extracted through the precooler gradually takes over the energy provided by the preburner extracted through the HX3 heat exchanger.

Test Campaign

During this test campaign, the preburner was tested at delivery energy levels of more than 2 Megawatts, something which had not been done before. Proving the temperature uniformity at this level is a vital step in the development of SABRE as the team can now move to the next phase of the mission – to demonstrate how the preburner and HX3 work together.

Nathan Gosney, Engineering Project Lead at Reaction Engines added the following:

“We are really pleased with the results of this campaign. Now, armed with test data on what conditions the HX3 will experience when combined with the preburner, the team can better plan for scenarios that might otherwise have delayed further development of the engine”


This campaign has been conducted in partnership with S&C Thermofluids based at their facility at Cotswold Airport in Gloucestershire. Utilising their innovative gas turbine air delivery system, we were able to simulate temperature and mass flows that the preburner will experience in flight on SABRE.
Tony Smith, S&C Thermofluids Company Director had this to say about the campaign:

“During this campaign, the S & C control systems were combined with the REL Engine Control System for the first time and to great effect. The new N-site facility at Cotswold Airport proved to be a very suitable location for operating this and other future aerospace engine technologies using hydrogen.”

Next steps

The completion of this test campaign marks an important step on the road to a full engine demonstrator. The next phase of development will take place imminently and will involve testing the preburner and HX3 together to establish a full early flight heat control system for the engine core.

Reaction Engines CEO Mark Thomas had this to say:

“The completion of this test campaign marks an important milestone in the realisation of SABRE. The hydrogen preburner is a vital element of the engine cycle and I am thrilled at the progress the team is making.”