seconds of weightlessness before the suborbital event. It is intended to have a service ceiling of about 60,000 ft (18 km), offering a dark blue sky to passengers. This will allow tourists to practice before the real flight. White Knight Two is of twin fuselage design with four jet engines mounted two on each wing. One fuselage is an exact replica of that of SpaceShipTwo (to allow tourist training), and the other will offer 'cut-rate' trips to the stratosphere. The design is quite different from the White Knight, both in size, use of tail, engine configuration and placement of cockpit(s). The White Knight uses two T-tails, but the White Knight Two uses two cruciform tails. Engine configuration is also very different. White Knight Two has four engines hung underneath the wings on pylons while White Knight's pair of engines are on either side of its single fuselage. Timeline of introduction Virgin Galactic contracted aerospace designer Burt Rutan to build the mothership and spacecraft. On January 23, 2008 the White Knight Two design was revealed. On July 28, 2008 the completion and rollout of the first aircraft, Eve, (Tail Number: N348MS) occurred at Scaled's Mojave headquarters. Branson predicted that the maiden space voyage would take place in 18 months: "It represents... the chance for our ever-growing group of future astronauts and other scientists to see our world in a completely new light." On March 22, 2010 the VMS Eve completed its 25th flight, the first occasion it carried the SpaceShipTwo, VSS Enterprise. In a flight of 2 hours 54 minutes, it ascended to an altitude of . The launch customer of White Knight Two is Virgin Galactic, which will have the first two units, and exclusive rights to the craft for the first few years. Flight test program An extensive flight test program of VMS Eve, with nearly twenty flights between December 2008 and August 2009, was undertaken to validate the design and gradually expand the aircraft operating envelope. The flight tests were complete by September 2009, and testing with SpaceShipTwo began in early 2010. Aircraft specifications See also Scaled Composites Proteus, predecessor to WhiteKnightOne Scaled Composites Stratolaunch Roc, derivative of WhiteKnightTwo SpaceShipTwo, payload for WhiteKnightTwo WhiteKnightOne, predecessor to WhiteKnightTwo References External links BBC - In pictures: Space tourism jet Video of White Knight Two being unveiled Photos of Virgin Galactic’s White Knight Two unveiling Photos of cockpit and interior of