LONDON — BAE Systems has taken a 20 percent stake in a British company developing an air-breathing rocket engine capable of powering aircraft at speeds in excess of 4,500 miles per hour.

Europe's largest defense contractor announced Nov. 2 it was investing £20.6 million (US $31.8 million) in the Abingdon, England-based company Reaction Engines.

The synergetic air-breathing rocket engine, or SABRE for short, uses ground-breaking technology able to propel an air vehicle at more than Mach 5 in the atmosphere before transitioning into a rocket mode giving spaceflight at speeds up to orbital velocity, equivalent to 25twenty five times the speed of sound.

The technology would allow an aircraft to take off from a conventional runway, accelerate to Mach 5 and then convert to rocket mode taking the vehicle up to orbital velocity.

Reaction Engines said SABRE'sS ability to breath air offered a significant reduction in propellant consumption and weight compared to conventional rockets, which have to carry their own oxygen.

Nigel Whitehead, BAE's group managing director of programs and support, said the collaboration gives the company "a strategic interest in a breakthrough air and space technology with significant future potential."

The British government is expected to confirm a £60 million grant later this year to help develop the engine for ground-based testing and investigate potential applications for a space access vehicle.

Mark Thomas, Reaction Engines' managing director, said negotiations with the government are almost complete and he was confident the grant would be approved by the end of the year. Thomas said the company was in the transition phase between research and development, and the target was to run a ground test engine by the end of the decade and a flight demonstration for the first time over the following five years.

"My expectation is we will go with a scale engine for the tests as it's a more manageable undertaking," he said.

Thomas said the engine architecture is highly scalable: "I can envisage the engine being applicable across quite a large thrust range, enabling multiple applications."

A key element of the engine is the development of ultra-lightweight heat exchangers that allow the cooling of very hot airstreams from more than 1,000 degrees Celsius to minus 150 degrees Celsius in less than 1/100th of a second while preventing the formation of ice at sub-zero temperatures.

Earlier this year a US Air Force Research Laboratory (AFRL) analysis confirmed the feasibility of the thermodynamic cycle of the SABRE concept and said that in theory the approach was viable, provided engine component and integration challenges are met.

Thomas said they are looking at formulating plans for continuation of the relationship with AFRL.

"They clearly have a strong interest in this key new propulsion technology," he said.

Chris Allam, the engineering and program management director at BAE Military Aircraft and Information business, said buying a stake in the company wasn't a signal BAE was were about to enter the space access market.

"What we are looking at here is an opportunity to use the kind of skills we have with our aerospace background in a different sector. It enables the company to invest in what we think will be the next great breakthrough in terms of aerospace propulsion," Allam said. "We will look at the opportunities that come out of this. The focus is to get the propulsion technology working in a demonstration engine. At the moment space access is where the technology has its sweet spot but there are other things you could do. The guys that invented the jet engine didn't really know what it would lead to and we are kind of in the same place here." said the BAE executive.

"For us it looks like a big step into an engine. In reality it is a complex piece of engineering in the air sector and needs the kind of skills we have rather than more traditional [engine] skills which may be useful as we go forward and as we build the partnerships." he said.

"Integration is a thing we are good at. This is about the propulsion integration side of it and more general engineering. It does operate like an engine at times but it also acts like a thermo-dynamic system which is the kind of thing we are used to and wrapped around it is the test side we also know well." said Allam.


Andrew Chuter is the United Kingdom correspondent for Defense News.

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