ESA gives £6m to Brit spaceplane project

Passengers if you like: Pilots largely pointless

The spaceplane would initially be unmanned, but Reaction Engines say the payload bay could easily carry a pressurised module holding thirty passengers. (One or more of these could be "pilots", though there wouldn't be any genuine need for such and they certainly couldn't be provided with normal windows.)

The whole Skylon is designed with cost and commercial operation in mind. It can be moved about on the ground by a standard aircraft tractor (Skylon weighs 275 tonnes fully fuelled and loaded, as opposed to 300+ for a jumbo jet). Fuelling is intended to be easier than is normally the case with cryogenic liquid rocket juice, too:

For safety and operational simplicity the cryogenic propellants are loaded subcooled without venting of vapour. Cryogen loading is automatic through services connecting in the undercarriage wells whilst the vehicle is stood on the fuelling apron.

One snag for potential Skylon owners is that it needs a "heavily reinforced" runway. In order to lighten the undercarriage system to where a decent payload could be carried, the designers had to put more weight on each wheel than is normal. But compared to all the manifold hassles involved in vertical launch, this is no big deal.

Skylon comes down and re-enters the atmosphere in the same general fashion as the space shuttle. The airframe is a carbon-fibre and plastic structure attached to a ceramic/fibre aeroshell (just 0.5mm thick and "corrugated for stiffness") at "flexible suspension points", which let it expand under the huge heating of hypersonic ascent and re-entry. The suspension points are also "low conductivity", so as to keep the inside of the craft safe from the sizzling-hot aeroshell. Any heat which gets past the aeroshell is warded off by "layers of reflecting foil".

No need to worry about environmental issues, either - Skylon's only exhaust product is steam. The use of hydrogen fuel offers the potential for it to be a zero-carbon-burden ship, if the hydrogen were made using electricity from nuclear plants, wind farms or other such sources. (At the moment it's normally made from natural gas, emitting loads of carbon in the process.)

It's all very cool indeed, but Reaction Engines estimate the total development cost to produce a working Skylon at around US$10bn. The ESA contract announced today will yield just £6m over time, less than 1 per cent of the requirement. (Reaction Engines say that the ESA funds have been awarded as a result of UK taxpayers' money paid into ESA programmes via the British National Space Centre, an alliance of British government bodies.)

So while the Skylon "could" be flying in ten years, it seems sadly unlikely that it actually will be. ®