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SpaceShipTwo Can’t Reach 100 Km Boundary of Space

By Doug Messier
Parabolic Arc
May 15, 2014
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Looking back as SpaceShipTwo's rocket engine fires during the third powered flight. (Credit: Virgin Galactic)

Looking back as SpaceShipTwo’s rocket engine fires during the third powered flight. (Credit: Virgin Galactic)

By Douglas Messier
Parabolic Arc Managing Editor

One of the more interesting revelations that came out of the London Sunday Times story I co-wrote on WhiteKnightTwo’s wing cracks was that Virgin Galactic finally acknowledged that SpaceShipTwo won’t be able to reach the internationally recognized boundary of space, which is 100 km (62 miles).

So, just how high can this first version of SpaceShipTwo go? Virgin now says the spacecraft will be able to exceed 50 miles. Other sources I know are far less confident it will be able to reach that high.

The reason is simple: the Sierra Nevada Corporation hybrid rubber-nitrous oxide engine they are using performs very poorly. The vibrations and oscillations in the version they used for the first three test flights would have torn the ship apart well if it had been fired for anywhere near full duration of about a minute.

So, remember how after the first powered flight in April 2013 when Virgin Group Founder Richard Branson declared that engineers had finally perfected the engine, and he promised to fly into space on Christmas Day dressed as Santa Claus? Utter bollocks. It had no relation to anything happening behind the scenes.

But, Virgin Galactic has a plan to fix it. Sources tell me engineers have modified SpaceShipTwo with additional tanks to hold helium that will be to dampen out the oscillations and vibrations. However, the additional weight will at least partially offset the extra engine performance. It also will reduce the number of passengers in the back from six to four, sources tell me.

Will the ship be able to reach 50 miles? In theory, yes. In practice…we’ll have to wait for flight testing to resume sometime later this year to find out.

In short, after nearly a decade of effort, Virgin Galactic has a ship that can’t even reach the same altitude as its predecessor, SpaceShipOne. This despite having advertised and sold tickets based upon a promised altitude of 100 km or more and about five minutes of weightlessness. (The actual contract with passengers says a minimum of 50 miles, but that wasn’t widely known, much less publicized.)

Further, the spaceship will carry one-third fewer passengers than originally planned. Or to put it another way, it will carry two more passengers than SpaceShipOne would have carried if it had ever been put into commercial service. Of course, SpaceShipTwo is much roomier than its predecessor, so passengers will be able to float around.

But, no matter. Virgin Galactic is pressing forward and still targeting the 100 km target at some point in the future. Meanwhile, the company expects customers to be happy with exceeding 50 miles, which in truth would still be a significant accomplishment.

Earlier this week, CEO George Whitesides said in the following statement to Gizmodo:

“NASA and the US Air Force have a long tradition of celebrating everything above 50 miles (~80km) as spaceflight, and we look forward to joining those ranks soon as we push onward and upward. We are still targeting 100km. As we have always noted, we will have to prove our numerical predictions via test flights as we continue through the latter phase of the test program. Like cars, planes, and every other type of vehicle designed by humans, we expect our vehicle design and performance to evolve and improve over time.

“When SpaceShipTwo reaches space for the first time—which we expect will happen just a few short months from now—it will become one a very small number of vehicles to have ever done so, enabling us to commence services as the world’s first commercial spaceline; our current timetable has Richard’s flight taking place around the end of the year.”

How thrilled customers will be with the change — which will likely mean less zero-g time — remains to be seen. Despite what their passenger contract says, Virgin Galactic had no trouble marketing the experience as something more than it will deliver.

This is rocket science, and it’s not surprising that something like this could happen. But, why did the customers have to find out about it from the newspaper? Astronaut relations should be more than just an endless stream of assurances that all is well and attacks on the media.