Damn

I have been following the story of this technology for over 40 years, and it looks like the liquidation of Reaction Engines has put a steak in the heart of pre-cooled hypersonic engines.

The short version is that there is an heat generated when supersonic flow is slowed down to subsonic speeds in an engine inlet, and at around Mach 5, the air becomes too hot to burn.

One solution is supersonic combustion, but another, first pursued as HOTOL in the 1980s, the idea was to use the cryogenic temperatures in the fuel to cool down the intake air to manageable temperatures.

At higher altitudes, it would transition to a conventional rocket motor.

Given the higher fuel efficiency of the air breathing engines, on the order of a factor of at least 10, this could promise better performance and potentially a single stage to orbit platform.

Well, I thought that it was cool, but it's gone now:

Aerospace specialist Reaction Engines has gone into administration, potentially taking with it the dreams of hypersonic aircraft powered by its hybrid air-breathing rocket engine tech.

The company is a privately owned engineering research biz that operated for more than 30 years. Its major focus was the development of SABRE (Synergetic Air Breathing Rocket Engine), said to combine the fuel efficiency of a jet engine with the power and high speed offered by rockets.

It had been hoped that SABRE would lead to a new generation of hypersonic spaceplanes, but on October 31, PricewaterhouseCoopers (PwC) was appointed as administrator after the company was unable to secure further funding.

………

SABRE is an exotic design, described as an air-breathing rocket engine. It allows an aircraft to take off from a runway as normal, then travel at velocities of about five times the speed of sound in the atmosphere. Switching over to liquid oxygen, a spaceplane using SABRE engines was envisioned as accelerating to Mach 25 to go beyond the atmosphere and into orbit.

The innovative precooler technology, one of the three core building blocks of SABRE, was tested in 2019. This is necessary because the air entering the engine would otherwise be hot enough to melt steel, thanks to the effects of friction and compression. Testing of the core engine components and preburner took place during 2020 and 2021.

Visitors to the Reaction Engines website will find the home page redirects to PwC, but the rest of the site still appears to be up, including pages on the SABRE engine technology.