Flight Aborted (4GC)

The fourth flight of SpaceShipOne was scheduled to be a glide flight. Figure 7.4 shows preparations being made the day before the flight. Melvill had successfully opened more than 60 percent of the subsonic flight envelope on the previous flight. This included speeds from stall to 150 knots. Now it was planned to open up the envelope even further.

The flight envelope indicated all the ways SpaceShipOne could safely fly, which included variations and combinations of speed, altitude, attitude, and other factors. The crews flew the easiest stuff, as the pilots and engineers gained confidence and began to nail down the flying characteristics. Step by step, they pushed the boundaries as they flew the vehicle more aggressively to reveal its limitations.

However, twenty minutes prior to separation, the launch had to be aborted due to a GPS malfunction with the avionics system. Figure 7.5 shows the mated pair during the aborted test flight prior to landing. Initially designated as 4G and 31L for SpaceShipOne and White Knight, respectively, the flight numbers were modified to 4GC and 31LC as a result of the abort. But it was possible to complete some systems testing prior to landing.

Flight Test Log Excerpt for 4GC

Date: 27 August 2003

Flight Number Pilot/Flight Engineer

SpaceShipOne 4GC Mike Melvill

White Knight 31LC Brian Binnie/Cory Bird

Objective: Second glide flight of SpaceShipOne. Flying qualities and performance in the spaceship feather mode. Pilot workload and situational awareness while transitioning and handling qualities assessment when reconfigured. As a glider, deep stall investigation both at high and low altitude and envelope expansion out to 200 knots and 4 g’s. Lateral directional characteristics including adverse yaw, roll rate effectiveness and control, including aileron roll and full rudder sideslips.

(source: Mojave Aerospace Ventures LLC, provided courtesy of Scaled Composites)

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Fig. 7.4. SpaceShipOne and White Knight are poised before the fourth test flight. Planned as SpaceShipOne’s second glide flight, the flight had to be aborted midair. Mojave Aerospace Ventures LLC, photograph by David M. Moore

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Fig. 7.5. It was necessary to abort the fourth test flight because of an avionics malfunction involving the global positioning system (GPS) prior to separation. However, before returning to Mojave, test pilot Mike Melvill completed some systems testing. Mojave Aerospace Ventures LLC, photograph by David M. Moore

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