[See update below]
SPACE.com and Flight International both reported that WhiteKnightTwo, the carrier aircraft for SpaceShipTwo, made its fourth and longest test flight on Mon day, a four-hour flight that reached an altitude of 6,100 meters and speed of nearly 260 km/h. However, both reported on an incident during a touch-and-go approach at Mojave Air and Space Port: as the aircraft pulled up from the runway the tail boom on the port fuselage struck the runway, apparently as a result of crosswinds. There was no visible damage to the aircraft, and the flight continued. Flight International also reported that WK2 appeared to have some steering problems when taxiing after landing, needing to power up the engines on one side of the aircraft while holding the brakes on the other to straighten out the aircraft.
So is this evidence of serious design problems with the aircraft? Flight International’s Hyperbola blog suggests that Scaled Composites didn’t realize that an aircraft like this would need larger vertical fins to deal with stability issues. That is, though, part of any test flight program: put the plane through its paces to see what was overlooked and can be improved. However, as noted, it doesn’t appear likely that we’ll see WK2 carrying SS2 for even captive carry flight any time soon, regardless of the status of SS2.
Update 1 pm EDT: Scaled Composites took the rather unusual (for them) step of issuing a press release to set the record straight about Monday’s test flight and the tail-scraping incident during it. According to Scaled, “an asymmetric idle thrust setting”, and not crosswinds, caused the plan to yaw during the touch-and-go maneuver, causing the tails to scrape the runway. “Only procedural changes are required to ensure we do not experience it again,” the company stated. Scaled added that the plane’s stability is “strongly positive” in all three axes, and this summer they plan to start flying to 50,000 feet (15,000 meters), the approximate altitude SpaceShipTwo would be deployed from.
Scaled also took a swing at the media reports of the incident and the speculation that followed, calling them “sufficiently inaccurate and negative” that they warranted the press release, which Scaled issued with the permission of its customer, Virgin Galactic. “In the mean time, do be cautious of what you read if it does not come from either our flight test team or our customer,” the release concludes. “Also, to state the obvious, you should question the motivations of a publication that reports design or flight test information that is based only on speculation.”