Though SABRE engines utilise many existing rocket and jet engine technologies, two key areas new to aerospace had to be addressed: ultra-lightweight heat exchangers and frost control. REL has focused primarily on developing these new technologies and the advanced manufacturing techniques required for their commercialisation.
These cool the incoming airstream very quickly and effectively, from over 1,000 °C to minus 150 °C in less than 1/100th of a second (six times faster than the blink of an eye). They are extremely lightweight — approximately 100 times lighter than current technology — allowing them to be used for aerospace applications for the first time.
The impact that these miniaturised heat exchangers will have on aerospace propulsion systems is comparable to the impact of the silicon chip on computing: new products, new markets, new capabilities.
The moisture content in air turns to frost when it passes over REL’s very cold heat exchangers. This frost blocks the heat exchangers and stops them working. REL has therefore developed technology to prevent frost formation.
An independent review undertaken by ESA on behalf of the UK government has confirmed the viability of the frost control system that REL has developed:
"[REL’s] successful demonstration of the frost control mechanism at laboratory scale (a major milestone that has so far eluded other international developments)."