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Scaled Composites SpaceShipOne was dropped from the mothership at 46000 feet for its fourth glide flight on October 17th, after undergoing minor aerodynamic alterations to correct problems discovered during the third flight on September 23rd. The turn around was faster than I'd expected. As they are now testing the preliminaries to engine ignition, I expect the first in-air engine startup will happen within the next few flights.

According to Scaled Composites, the flight objectives were:

Fourth glide flight of SpaceShipOne. Primary purpose was to examine the effects of horizontal tail modifications at both forward and mid-range CG locations (obtained by dumping water from an aft ballast tank between test points). The tail modifications included a fixed strake bonded to the tail boom in front of the stabilator and a span-wise flow fence mounted on the leading edge of each stab at mid-span. (See the write up under the SPACESHIPONE GROUND TEST section that describes our Ford-250 wind tunnel which was used to help derive the current flight configuration). Other test objectives included a functional check of the rocket motor controller, ARM, FIRE and safing switches as well as the oxidizer dump valve. Additional planned maneuvers included full rudder pedal sideslips and more aggressive nose pointing while in the feathered configuration.

Launch conditions were 46,200 feet and 115 knots and produced a clean separation. The tail performance was examined by flying "longitudinal stability" points between stall and 130 knots and showed considerable improvement of the airfoil's lift coefficient as well as its post stall characteristics. No vehicle pitch up tendency was noted as the main wing now stalls first. Real time video of the tufted tails fed back down to mission control helped considerably in assessing the performance of these aerodynamic improvements. More aggressive maneuvering in the feather made it evident that the pilot could readily point the vehicle's nose where desired and all rocket motor functionality tests were satisfactory.

I expect a drop test and powered flight to occur by the Wright Brothers first flight anniversary date in mid-December. A full suborbital attempt is possible but would be pushing the envelope rather hard. How hard is impossible for anyone on the outside to estimate.

It would be a lovely Christmas present for all of us spacers though...