While it still has notional plans to make its first full suborbital spaceflight launch before the end of 2014, there remains doubts amongst Virgin Galactic’s critics whether this is still possible – not least because it has been revealed that the firm going to switch its hybrid engine rocket fuel from rubber to plastic.
In his book on Virgin’s head, Richard Branson, “Branson: Behind the Mask” the author Tom Bower noted that the original engine for the SpaceShipTwo craft would not have sufficient performance to allow it reach 100km – the official start of space and about 79km further than has been reached by the rocketplane to date – and that the firm was considering a change to using a conventional bi-propellant engine instead. However, for time reasons, it seems that Virgin Galactic is going to stick with using a hybrid engine using a solid fuel and liquid oxidiser (nitrous oxide) albeit switching one of the propellants instead.
However, Parabolic Arc has revealed that during an interview with NBC News the firm has decided that instead of using rubber as the fuel, the rocket will now use plastic (polyamide grain), again burning it with nitrous oxygen. Officially this change is for performance reasons, but Parabolic Arc notes that the change has been made because the original engine also had serious vibration issues during long firings. In addition, measures to dampen out vibrations are reportedly also being considered to avoid the spacecraft and passengers being shaken to destruction.
Update on 28 May 2014: Virgin Galactic’s rival XCOR has announced that it has raised further financing worth US$14.2 million, led by its Dutch investors, to bring its suborbital launch project to fruition. The full news release is here.
Comment by David Todd: One assumes that all of Virgin Galactic’s prospective suborbital space tourists have all been informed about this engine fuel change. Regulators are not treating them as passengers in the traditional sense, but rather as spaceflight “participants” who are flying with “informed consent”. And they cannot officially consent if they have not been informed.
