Virgin Galactic's suborbital rocket glider SpaceShipTwo (SS2) could have a low wing and its carrier aircraft, White Knight II (WK2), a 43m (140ft) wingspan and four engines, chief designer Burt Rutan has said.

Rutan, chief executive of Scaled Composites and a director of the Virgin Group-Scaled WK2/SS2 intellectual rights joint venture The Spaceship Company, revealed the possible design changes at the Responsibility for the Future Exploration and Development of Space Symposium, held at the University of Alabama in Tuscaloosa on 25 August.


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 © Virgin Galactic/Tim Bicheno-Brown

In Virgin Galactic's conceptual images, SS2 has a mid-wing, unlike its predecessor SpaceShipOne (SS1), and WK2 has two engines, like SS1's carrier aircraft White Knight.

The low wing is a possible solution to SS1's dihedral effect-induced spin on its ascent.Rutan declined to elaborate but did not deny he made the comments, while Virgin Galactic president Will Whitehorn told Flight International,'s sister publication: "We will unveil the design of WK2 and SS2 next January in New York and work progresses at Scaled. Both vehicles are well progressed but you will have to wait for the surprises. We have never confirmed a definitive schedule but are still hopeful of achieving our 2008/9 testing.

"Rutan's comments were reported by US blog site The Space Review on 27 August. It also reported that Rutan said there would be a "significant delay" to the start of rocket-powered SS2 flight tests because of the recent fatal injector test accident.

Previously Virgin Galactic's leadership has indicated a WK2/SS2 flight testing period from May 2008 to the third quarter of 2009, with SS2 altitude release and rocket firings in the latter half of next year.

Source: Flight International