Reaction Engines Scimitar

{{Short description|Jet engine}}

The Reaction Engines Scimitar is a derivative of the SABRE engine technology, but intended for jet airliners (the Reaction Engines LAPCAT A2 concept), rather than space launch applications. Consequently, most of the Scimitar engine technology is similar to SABRE but designed for much longer life.{{cite web |url=http://www.reactionengines.co.uk/lapcat_scim.html |title=Reaction Engines Limited :: LAPCAT - Scimitar Engine |accessdate=2009-07-03 |url-status=dead |archiveurl=https://web.archive.org/web/20090706032941/http://www.reactionengines.co.uk/lapcat_scim.html |archivedate=2009-07-06 }} Both engines are designed around existing ramjet technology, but the Scimitar engine lacks the rocket features and has high bypass features for greater efficiency. The engines burn liquid hydrogen as fuel.[http://eprints.imperial.ac.uk/handle/10044/1/1456 The Reaction Engines Limited: Scimitar Pre-cooled Mach 5 Engine]

The incorporation of lightweight heat exchangers in the main thermodynamic cycles of these engines is a new feature to aerospace propulsion.{{cn|reason= There have been attempts dating back to the 1960s to solve this problem by using a pre-cooler heat exchanger in front of the air compressor face to reduce the temperature of the incoming air. from http://www.acq.osd.mil/osbp/sbir/solicitations/sbir20161/af161.html claims. The key differences to earlier attempts being the "lightweight" and use of the energy in the "thermodynamic cycle" - to the point that this solicitation was used to fund the high temperature testing of Reaction's heat exchanger|date=December 2012}} Similar studies of intercoolers used on jet engines show significant improvement of efficiency.{{cite web|last=Boggia|first=S|title=INTERCOOLED RECUPERATED AERO ENGINE|url=https://www.yumpu.com/en/document/read/11154596/intercooled-recuperated-aero-engine-mtu-aero-engines|publisher=MTU Aero Engines|accessdate=19 April 2021|author2=K Rüd}}