Virgin Galactic Flight Test Program Update: SpaceShipTwo Preparing For Fourth Powered Test Flight

Press Release From: Virgin Galactic
Posted: Wednesday, December 12, 2018

Our SpaceShipTwo, VSS Unity, is entering the next stage of testing. During this phase of the flight program we will be expanding the envelope for altitude, air speed, loads, and thermal heating. We also plan to burn the rocket motor for durations which will see our pilots and spaceship reach a space altitude for the first time. Although this could happen as soon as the next flight, the nature of flight test means that it may take us a little longer to get to that milestone. It has taken years of design and manufacturing work by The Spaceship Company to get to this exciting stage and has required testing of all the parts and subsystems that make up SpaceShipTwo.
Only once we had completed all vehicle ground testing did we take Unity airborne; first mated to her carrier aircraft and mobile “wind tunnel” VMS Eve, then through a series of glide tests and finally to the three successful rocket powered supersonic flights we completed this year.
Incremental flight test programs are by definition open-ended and, to a great extent, each test depends on the data from the test that precedes it. There is no guarantee that everything will work perfectly first time and, like all programs seeking to take bold steps, we will inevitably have times when things don’t go as planned. Our team’s biggest priority is to use meticulous planning and preparation to ensure that stages are dealt with safely, and that every outcome informs and improves future performance.

In any human spaceflight program there is a high level of attention paid to crew safety—including not only what happens when everything is going as planned, but also when something unexpected occurs at any stage of flight. At Virgin Galactic, this approach is brought sharply into focus by the fact that SpaceShipTwo is crewed by two pilots. This means that circumstances may require the team to cancel or change plans either before take-off or in-flight in order to bring our pilots and the spaceship home safely. None of this though, takes away the excitement, anticipation and great pride of being at the vanguard of a new space age and of history in the making.
Fourth Rocket Powered Test Flight Goals

So, what are the plans for the next flight? Our window for our fourth powered test flight opens on December 13, 2018. At a basic level, this flight will aim to fly higher and faster! We plan to burn the rocket motor for longer than we ever have in flight before, but not to its full duration. At the end stages of the rocket burn in the thin air of the mesosphere and with the speeds that we expect to achieve, additional altitude is added rapidly. That results in new and important data points, particularly relating to supersonic handling qualities and thermal dynamics, both of which we will be watching closely in the cockpit and on the ground in Mission Control. These observations will largely determine at what stage we decide to shut the rocket motor down. If all goes to plan our pilots will experience an extended period of micro-gravity as SpaceShipTwo coasts to apogee, although they will remain securely strapped in throughout. They should also have some pretty spectacular views which we look forward to sharing as soon as possible post flight. 

We are at a stage now in our testing program where we want to start simulating the commercial weight distribution in the spaceship represented by our future passengers. Excitingly, we are partly achieving that on the next flight by carrying four research payloads that are part of the NASA Flight Opportunities Program.

Whether we complete all our objectives during the next flight or need to wait a little longer, we remain committed to completing the final stages of this extraordinary flight test program as quickly, but more importantly as safely, as possible.


Virgin Galactic is the world’s first commercial spaceline. Founded by Sir Richard Branson and owned by the Virgin Group and Mubadala Investment Company, Virgin Galactic will transform access to space for the benefit of life on Earth. To date, over 600 men and women from over 50 countries—greater than the total number of humans who have ever been to space—have reserved places to fly on Virgin Galactic’s reusable space launch system, consisting of carrier aircraft WhiteKnightTwo and spacecraft SpaceShipTwo. SpaceShipTwo and WhiteKnightTwo are manufactured and tested in Mojave, California by its manufacturing partner, The Spaceship Company (TSC). Spaceflight operations will be based at Spaceport America in New Mexico, the world’s first purpose-built commercial spaceport.

The Spaceship Company (TSC) is Virgin Galactic’s space-system manufacturing organization. Headquartered at Mojave Air and Space Port in Mojave, California, it is building and testing a fleet of WhiteKnightTwo carrier aircraft and SpaceShipTwo reusable spaceships that, together, form Virgin Galactic’s human spaceflight system. Its team of talented and dedicated engineers, technicians and professionals are drawn together by a willingness to disrupt and challenge the status quo and deliver innovative aerospace solutions to our customers’ needs. TSC’s extensive capabilities encompass preliminary vehicle design and analysis, manufacturing, ground testing, flight testing and post-delivery support.

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