By Glenn Pew, Newswriter, Editor
The Sky Shook, The Earth Shook ... The Aircraft Rolled...
The Paul Allen funded, Burt Rutan designed Ansari X Prize inspired SpaceShipOne burned rubber (quite literally -- as a major component of its fuel) and scrolled through mach numbers most of the way toward an apogee of roughly 337,500 feet over Mojave, CA -- the altitude yesterday quoted by on-location X Prize judge Gregg Maryniak. As with June's public launch, the flight might not be described by anyone as passenger-soothing smooth, and again, both pilot and craft returned safely and with questions to answer. Mike Melvill (plus ballast equivalent to two passengers) piloted yesterday's flight and set the clock running on the launch window for a second -- to be flown no later than Wednesday, October 13, at 8:34:04 a.m. in order to win the X Prize payoff of $10 million. Yesterday's privately funded jaunt into space wasn't without drama. While flying straight up and reaching the end of the rocket's burn, Melvill (and craft) entered a series of oscillating rolls that peaked near 180-degrees per second (and had nothing to do with the earthquake felt on the ground during the flight). The motion itself may have seemed to many incongruous with Melvill's post-landing comment, "I was very pleased with how the vehicle behaved." Rutan indicated that his team would provide notification of intent regarding a subsequent flight by afternoon, today (Thursday).
Shortly after witnessing the rolls via video feed, AVweb asked Dick Rutan (Burt's brother) for his thoughts. "Well, his trajectory was 'up' so he made the altitude," Rutan said. Then he paused, looked away, looked back, said, "OK," and left. As he did, another member of the press offered, "it looked like a missile out of control." And while that perception may or may not prove positive among potential patrons of space tourism, SpaceShipOne is a technology demonstrator, not a production prototype. The cause of the roll anomaly was not readily apparent to Scaled Composite's crew upon inspection of the aircraft, but "when we know what it is we'll tell everyone," said designer, Burt Rutan. Structurally, the aircraft itself was said to be an engine change short of ready to fly, which is "normal."
...Does The Craft Have A Design Flaw?...
Note: AVweb's coverage includes an image gallery.
Without an early explanation for the roll during yesterday's flight, the general message offered by the team was that Melvill felt he had the control authority necessary to counter the movement. Data showed the roll had dampened itself from 180 to 140-degrees per second prior to Melvill's application of corrective control inputs. Tonight the team will look at wind shear, thrust, pilot inputs and other factors in search of a causal factor or chain. A roll suffered during the team's very public June flight was traced to wind shear and pilot induced oscilations. But Rutan yesterday told media that the roll phenomenon has been consistent in the simulator, too. He also said the aircraft's performance has revealed at least one trait worthy of correction -- too much dihedral effect. Side loads, Rutan said, (such as those imposed by wind shear) cause the aircraft to roll. The problem may be built out of future craft, but has proven difficult to correct in the already-built SpaceShipOne.
Still, Rutan stated that preliminary inspection of the data from yesterday's flight did not suggest wind shear components would have induced loads likely to produce the aircraft's observed behavior during Wednesday's flight. Melvill was quick to suggest that an errant foot to rudder could have been the cause, but was similarly not convinced he was the culprit. "Probably, I stepped on something ... I don't think so, but I've been wrong before." Whatever the cause, the roll did provoke mission control to recommend that Melvill shut down the rocket, which he did seconds later. "I could have gone to 360,000 feet today," said Melvill. Burt Rutan added, "We had performance to beat the X-15's altitude record today, but we recommended Mike shut down due to the excessive roll rates."