The European Space Agency (ESA) has chipped in €1m to study the viability of the Skylon spaceplane concept - a radical single stage to orbit (SSTO) vehicle whose motors use "a synthesis of elements from rocket and gas turbine technology".
According to the BBC, the ESA cash will allow a consortium of companies – led by Skylon designer Reaction Engines Ltd – to establish whether or not the substantial investment required to make the spaceplane a reality has a sound business basis.
On paper, Skylon can lift 15 tonnes from a conventional runway to 300km, whereupon it releases a secondary propulsion module to propel satellites into the required final orbit - at a 36,000km altitude for a telecoms satellite, the BBC notes.
To get into its initial Low Earth Orbit, Skylon packs two Synergistic Air-Breathing Rocket Engine (SABRE) powerplants, which use LH2 mixed with atmospheric air in a jet phase up to Mach 5.5, at which point they go into LH2/LOX rocket mode, shoving the aircraft into space at Mach 25.
By burning atmospheric oxygen during the jet phase of the flight, the engines "save carrying over 250 tons of on-board oxidant on their way to orbit, and removes the necessity for massive throw-away first stages that are jettisoned once the oxidant they contain has been used up".
Simple as that, although there is one slight problem. Reaction Engines explains: "In air-breathing mode, the air must be compressed to around 140 atmospheres before injection into the combustion chambers which raises its temperature so high that it would melt any known material.
"SABRE avoids this by first cooling the air using a precooler heat exchanger until it is almost a liquid. Then a relatively conventional turbo compressor using jet engine technology can be used to compress the air to the required pressure."
While the SABRE engine transitions from the drawing board to the test bench, Reaction Engines and its partners - including QinetiQ Space in Belgium and the UK's 42 Technology Limited - must make the business case for Skylon, including identifying a prospective operator and suitable launch site for operations to commence by 2020.
Reaction Engines' future programmes director, Mark Hempsell, told the BBC: "At the end of the study we would like to have demonstrated the full business case for an operator, whoever that might be.
"It would be an operator who has bought two Skylons, some upper stages, some other equipment and flies out of Kourou in French Guiana. We have a market that is defined in the [study] requirements and our aim is to determine how much money this operator could make."
The ultimate aim is to make the Skylon system truly 100 per cent reusable. Italy's Thales Alenia Space (TAS) is mulling the secondary propulsion unit, and the hope is that this will, after delivering its satellite, make its way back to the spaceplane for return to base. ®
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