The Scaled Composites Model 348 White Knight Two (WK2) is a quadjet cargo aircraft that was used to lift the SpaceShipTwo (SS2) spacecraft to release altitude.

With an "open architecture" [citation needed] design and explicit plans for multi-purpose use, the aircraft could also operate as a zero-g aircraft for passenger training or microgravity science flights, handle missions in high-altitude testing more generally, or be used to launch payloads other than SpaceShipTwo.

[7] During 2012–2014, Virgin Galactic was also considering use of the WhiteKnightTwo as the air-launch platform for a new two-stage liquid-fueled rocket small satellite launcher called LauncherOne.

[10] White Knight Two is a very modern aircraft, as even the flight control cables are constructed of carbon fiber, using a new patented design.

[16] On July 28, 2008 the completion and rollout of the first aircraft, Eve, (Tail Number: N348MS[17]) 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."

[18] The launch customer of White Knight Two was Virgin Galactic, which was planned to have the first two units, and exclusive rights to the craft for the first few years.