Virgin Galactic nears next phase of SpaceShipTwo test program

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WASHINGTON — Virgin Galactic performed another glide flight of SpaceShipTwo June 1 as the company suggested it was nearing a new phase in the test program of the suborbital spaceplane.

The flight, in the skies above the Mojave Air and Space Port in California, was the fifth free flight of the second SpaceShipTwo, named VSS Unity, and the first in a month. The vehicle was released from its WhiteKnightTwo carrier aircraft and glided to a safe landing back at the airport.

The company said they used this flight to test the handling characteristics of the vehicle in conditions closer to that of a typical flight. A ballast tank, loaded with about 450 kilograms of water, was placed in the rear of the fuselage to simulate a fuel tank. That water was jettisoned during the course of the glide flight, allowing pilots to study how the spaceplane flew as its center of gravity changed.

In a statement, the company suggested that it was nearing the end of an initial phase of glide flights that tested the SpaceShipTwo’s aerodynamic performance, including the use of its feathering system that raises the vehicle’s twin tail booms during reentry.

“Today’s events represent another important milestone as we move towards the end of the initial glide test portion of the program and turn our attention to the spaceship’s propulsion system,” the company said in a June 1 statement. “To that end, as we analyze the data from today’s flight, we will be moving into a period of ground-based activity focused on preparation for fuelled and then powered flights.”

The company has not set a specific number of glide flights that it expects to perform with SpaceShipTwo before moving on to powered test flights. In an October interview, company president Mike Moses said there were “10 glide flights’ worth of targets” the company had planned, referring to the number of test objectives the company had for the glide test program.

However, he said it may take more, or less, flights to achieve all those test objectives. “We could do those in 8 flights, or it might take 15, but we’re not going into the next phase before we clear those,” he said then.