Virgin Galactic's VSS Unity completes sixth glide test

The composites-intensive VSS Unity is nearing rocket-powered flight testing as the craft prepares to enter service, taking passengers into low-Earth orbit.

Commercial space flight services firm Virgin Galactic (Mojave, CA, US) reported on Aug. 4 that its composites-intensive VSS Unity space craft has completed its sixth glide test — this one with propulsion systems installed but not operating — in preparation for rocket-powered test flights.

VSS Unity was carried to its launch point by VMS Eve, which was piloted by Nicola Pecile and Mike Masucci with flight test engineer Dustin Mosher. Pilots Dave Mackay and CJ Sturckow were at VSS Unity’s controls with a test card which kept them fully occupied as we expanded the speed and load envelope, put the vehicle into the feathered reentry configuration, and evaluated flying with an increased weight and rearward shift in the center-of-gravity for landing.

The craft flew with all the spaceship’s principle propulsion components on-board and live.  This meant that Unity took off with her forward pressurant tank loaded with helium and for the first time, her centrally positioned Main Oxidizer Tank fully charged with nitrous oxide. In a repeat of the last flight, Unity also carried a ballast tank in the rear fuselage filled with 1000 lb of water to simulate the weight and positioning of the CTN (case-throat-nozzle).

The pilots tested the venting of the nitrous tank while still mounted on the carrier aircraft. The procedure proceeded smoothly, as Eve and Unity climbed past 40,000 ft and approached the drop point. After a clean separation from Eve and an approach-to-stall test, Unity’s tail-booms were raised into their re-entry position for the second time in flight. Once back into the normal glide configuration, the pilots used the descent to execute the remaining test points, including a high-g pull-up maneuver and bank-to-bank rolls. Unlike the previous glide test, the water ballast in the rear tank was not jettisoned, allowing the company to test the spaceship’s  performance with a heavier landing weight and a center-of-gravity towards the back of the vehicle.

Mackay says, “We are really pleased with what we saw today. We collected hundreds of gigabytes of data for us to review, and from the pilots’ point of view, it felt really wonderful. All of you here at Virgin Galactic and The Spaceship Company should be very proud: VSS Unity is a great spaceship!”

VSS Unity is the first craft build by Virgin Galactic since its predecessor, SpaceShipTwo, broke apart during flight testing on Oct. 31, 2014. One test pilot was killed and the second survived. Subsequent investigation revealed that the craft’s feathering system was prematurely deployed, causing SpaceShipTwo to break apart. The ultimate goal and mission of VSS Unity is to deliver paying passengers to low-Earth orbit for short-duration flights in a weightless environment miles above the planet.

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