Farnborough Reaction Engines, the British firm aiming to build an enhanced "Skylon" space shuttle which would take off from a runway without external tank or boosters, says it expects to test its revolutionary "SABRE" rocket/jet engine within "three to four years".
Here's the basic Skylon movie, for those few Reg readers who may not have seen it already:
A team from Reaction Engines, like everyone else in the aerospace world, is at the Farnborough Airshow this week and the Reg spaceplane desk got the chance to have a chat with the firm's technical director Richard Varvill.
According to Varvill, Reaction Engines is gradually closing in on the goal of building and testing a SABRE engine at last. The SABRE burns hydrogen fuel, from takeoff up to Mach 5 using the surrounding air to provide oxygen. It isn't a ram or scram jet, however: the incoming air is compressed and almost instantly chilled to the point where it is about to liquefy, using a turbocompressor and tremendously powerful freezer kit running on a closed liquid-helium loop. Then the supercold air is fed into the combustion chamber and used to burn hydrogen. The heat arising from the super air chilling process is dumped into the liquid hydrogen fuel.
As a Skylon accelerates through Mach 5.5, it will have climbed to such heights that the air is no longer worth scooping. The intakes are shut off and liquid oxygen from the ship's tanks used instead, as the SABREs become relatively normal liquid fuelled rocket engines.
The SABRE is very much the key to Skylon's success, then, so it will be difficult for the spaceplane design to be much further refined until the radical space motor can be tested.
According to Varvill, that's now on the horizon. A test project to show the validity of the pre-cooler technology is under way for tests by Reaction Engines, while the German space agency DLR (Deutsches Zentrum für Luft- und Raumfahrt) is to try out the novel air- or oxygen-cooled combustion chamber.
With those tests set to complete in 2011, assuming no unpleasant surprises, Varvill expects that "the powers that be will ask us to build a complete test engine". He said this could be in tests within "three to four years".
Reaction Engines' work is funded partly by the European Space Agency - to which the UK government contributes - and partly by private investors. Varvill says that as the technology progresses, mainstream commercial backers are becoming more and more interested: full-blown orbital space is a huge market (unlike the suborbital sector targeted by most "new space" firms), so a realistic prospect of lower cost launch is a big draw.
"Merchant banks are showing interest now," he says, though declining to name any specific firms.
"The usual suspects," he says.
To offer some perspective, Reaction Engines' latest estimates indicate that fully developing the Skylon would cost around $12bn - about what it cost to get the Airbus A380 or the Ariane 5 rocket working.