Mojave Launch Successful, Far From Perfect

328,491 Feet, 2.9 Mach, and Awaiting Confirmation …

Sixty-three-year-old Mike Melville’s flight Monday in Burt Rutan’s design, funded privately to the tune of roughly $20 million by Paul G. Allen, and built mainly by a group of no more than 30 individuals (though all of Scaled Composites’ 120 or so employees had a hand in it) was a success – rocketing at “about” 2.9 Mach to “about” 328,491 feet. That mark (reported by “inertial nav data”) is just 491 feet above the target altitude required for “space” flight, but 31,509 feet shy of the planned 360,000-foot apogee. It was enough to earn Melville astronaut wings from the government, and a handshake plus a “You’ve joined the club” from Buzz Aldrin (Melville said later of the encounter, “That was serious stuff, man.”). However, the altitude deficit was similarly attributable to some serious stuff – including a control-system failure. The system that failed was described by Rutan in this way: “I can’t think of anything more important on the vehicle itself.” [See AVweb‘s pre-launch and launch day image galleries.]

One problem, failure (buckling) of a carbon-fiber fairing that covered the lower half of the rocket’s new bell nozzle, was perhaps more obvious, but less critical; Rutan said, “It could have fallen off, and not been a problem.” The nozzle itself was in no way compromised. But shortly after the rocket gave Melville 3 G’s of forward acceleration plus the 4 G’s of vertical acceleration as he guided the craft into its near-vertical climb (this is normal), the craft also rolled 90 degrees left (this is not normal) and experienced failure of a trim actuator. Fortunately, Melville recovered the craft – actually he “stomped the rudder” and it rolled back 90 degrees right. But he also immediately went to the backup trim system, later telling reporters, “It’s never done that before.” He continued, “That’s what drove me about 20 miles away [from the intended flight path] in about five seconds … it was amazing.” After all, the actuators control the craft’s direction of flight. The backup system worked as designed and “saved the day,” said Melville. From the ground, a deviation (slight curve) of the rocket’s otherwise-vertical-appearing contrail was visible early in the burn, but there is no confirmation that such a physical manifestation was representative of the actuator failure. Rutan would later say the trajectory error plus the fairing failure, which could have added some percent increase in drag (depending on exactly when it happened), could have contributed to the lower-than-expected reported altitude.

In a post-flight press conference Monday, Melville said he couldn’t say he didn’t do it (command the roll), but also noted that a trim actuator used to control the craft’s pitch while supersonic had failed. Of the roll problem, Rutan said that upon review of the data, “we will know exactly what caused that.” For now, there are two actuators, one left and one right, Rutan explained. If the actuators do not act in unison, they would not command pitch, but roll. Fortunately, Rutan’s design incorporates backup systems, one of which (we understand) was used by Melville to trim the craft for landing while near the apogee phase of the flight. At that altitude, two bottles of compressed gas are used for control – Melville sad that system worked extremely well, and he only used half of one bottle. Melville noted that he had no intent of touching the primary system after the failure or troubleshooting while flying the flight profile, but had control response not been regained almost immediately, would have shut down the rocket and attempted to return home early.