To solve handling and stability problems Virgin Galactic has made structural modifications to the vertical stabiliser fins of its WhiteKnight Two carrier aircraft prototype Virgin MotherShip (VMS) Eve. has obtained photographic evidence that VMS Eve's two booms' vertical stabilisers have been reshaped by prime contractor Scaled Composites for a larger lower rudder hinge and a more pronounced horn that may contain a heavier counterweight. The image also shows two new vortex generators added just forward of the lower hinge point and the right boom's fin has a new antenna bulb attached to its top.

The two pictures in the composite image below were taken before and after the second test flight that took place on 5 February. The left hand side of the composite image was taken before that second flight and it is the port boom.

The right hand side of the composite image shows the starboard boom since the second test, now altered in preparation for the 25 March third flight. Before the 25 March test the left boom fin was altered in the same way as the right hand stabiliser.

The spaceline's president Will Whitehorn had described the 5 February second flight as "flawless".

WK2 Tail Compare
                                                                                                                                       © Alan Radecki
This composite image shows VMS Eve's starboard boom on the right side and its port boom on the left 
The structural modifications to the fins would explain the seven week gap between the second and third flights. Virgin Galactic declines to comment on any aspect of the test flight programme in detail including technical matters regarding the flight test prototype VMS Eve.

Flight first reported a possible rudder issue for VMS Eve on 7 January this year and published a photo on 6 February showing the prototype with vortex generators added to the vertical stabilisers.

Official Virgin Galactic video of flight testing, released on 27 March, can be found here while earlier test footage including taxi runs obtained by Hyperbola can be seen in this blog post.

Images of the spaceline's air and spacecraft can be found here at's Virgin Galactic gallery.

Source: Flight International