The folks at Scaled Composites took full advantage of yesterday's break between winter storms to bring out WhiteKnightTwo for two sets of taxi tests on Runway 12/30. The emphasis of these appeared to be braking and spoiler operations. Since WK2 will be used as a training platform for SpaceShipTwo, the ability to descend rapidly (essentially duplicating SS2's low lift/drag ratio) is important, so designer Burt Rutan included a spoiler/air brake system that could easily double as barn doors. For the majority of yesterday's tests, the runway runs would start out with the inboard air brakes deployed, and the outboard ones would then be actuated near the end of the run. Since the ability to stop grants the privilege to go, mastering these systems is a major step toward the upcoming first flight of the VirginMotherShip.