I just received this Burt Rutan statement in my ‘in-basket’. It addresses the much media hyped rolls, which were in reality not a very big deal:
While observing the significant incorrect information being published about the rolls seen on the 29 Sept 04 SpaceShipOne flight, we are responding by offering a bit of discussion to help provide some clarity. This information is approved for publication — Burt Rutan
Comments On The Rolling Rumors Burt provides some preliminary information about the rolling motions seen on the First X-Prize Flight:
The complex reason on why the rolling departure occurred will be described in a report we will post at a later date. What I am intending to do here is merely address some of the incorrect rumors about the rolls that have been seen in various news stories and web discussion groups.
While the first roll occurred at a high true speed, about 2.7 Mach, the aerodynamic loads were quite low (120 KEAS) and were decreasing rapidly, so the ship never saw any significant structural stresses. The reason that there were so many rolls was because shortly after they started, Mike was approaching the extremities of the atmosphere. Nearly all of the 29 rolls that followed the initial departure were basically at near-zero-q, thus they were a continuous rolling motion without aerodynamic damping, rather than the airplane-like aerodynamic rolls seen by an aerobatic airplane. In other words, they were more like space flight than they were like airplane flight. Thus, Mike could not damp the motions with his aerodynamic flight controls.
Mike elected to wait until he feathered the boom-tail in space, before using the reaction control system thrusters (RCS) to damp the roll rate. When he finally started to damp the rates he did so successfully and promptly. The RCS damping, to a stable attitude without significant angular rates was complete well before the ship reached apogee (337,600 feet, or 103 Km). That gave mike time to relax, note his peak altitude, and then pick up a digital high-resolution camera and take some great photos out the windows. Those photos are now being considered for publication by a major magazine.
While we did not plan the rolls, we did get valuable engineering data on how well our RCS system works in space to damp high angular rates. We also got a further evaluation of our “Care-free Reentry” capability, under a challenging test condition. As seen on the videos of the flight, the ship righted itself quickly and accurately without pilot input as it fell straight into the atmosphere. No other winged, horizontal-landing spaceship (X-15, Buran, SpaceShuttle) has this capability.
Incidentally… there will be quite an all night party at Mojave Civilian Test Flight Facility (and Spaceport) the night before the second flight. Apogee Books is sponsoring an all night music fest near their tent in the public viewing area.
Sadly I will again not be there.
Addendum: For the non-pilot readers, KEAS is Knots Equivalent Airspeed. Knots are Nautical Miles per Hour in pilotese. To place this in perspective, my old Cessna 172, (N3892S circa 1981), was quite happy cruising along at 120 KIAS, or 120 Knots Indicated Airspeed. Airspeed is how fast the wind is going past your wings. If you were in a 120 Knot headwind, you could be flying 120 KIAS and sitting over someone’s head like you were the ball on top of a flagpole. Indicated means it is what you read off the dial in the cockpit; Equivalent means that the air over your wings has the equivalent effect after accounting for speed and density of the air. (You can also play with a thing called a Reynolds number which affects basic design of aircraft in various regimes, here if you are interested.)
