A few notes on the big SpaceShipTwo roll out (in?) on Friday.
Virgin Galactic has switched back to the rubber/nitrous oxide hybrid engine it had abandoned in May 2014 in favor of a supposedly superior nylon/nitrous oxide hybrid.
It looks as if they have improved the performance of the rubber motor so that it could actually go all the way to space (100 km/62 miles) with a full complement of six passengers. That will not be known, however, until after test flights begin.
The engine improvements include reducing the oscillations and vibrations that kept the first three powered flights to no more than 20 seconds of burn time. Virgin officials have not said how they achieved this improvement.
However, sources have told Parabolic Arc that Sierra Nevada Corporation — which developed the rubber hybrid before the company was dumped after the switch to nylon — had achieved this breakthrough in December 2013 by adding helium. It is apparently an effective, if expensive, solution.
The New & Improved Almost Carbon Copy
Virgin has added a pin to prevent the recurrence of the premature deployment of SpaceShipTwo’s during powered flight that destroyed the first vehicle. The company also has added larger horizontal stabilizers to the vehicle’s twin tail booms and made a series of other unspecified changes to the spacecraft.
SpaceShipTwo will be on the ground for some months as it undergoes a series of tests. Those will be followed by captive carry, glide and powered flights as was done for the original vehicle. Officials gave no timetable for the flights, but they indicated that testing would move faster due to the experience with the first vehicle.
Virgin officials said they were no longer making predictions because the media took them seriously and held them to account. That’s a lot easier than getting fired for telling the truth: that your publicity hound boss had spent the previous 11 years making absurd schedule claims.
The Unshape of Things to Come
The planned length of the flight test program was not revealed. The original ship had 32 glide flights in which it was released from the WhiteKnightTwo mother ship at about 50,000 feet.
The spacecraft had only four powered flights using two different types of engines, the last of which ended in a crash after 13 seconds. SpaceShipTwo never reached above 71,000 feet and its engines never burned for more than 20 seconds.
Thus, large portions of the flight envelope remain unexplored. And Virgin is starting with a brand new ship — the first it has ever built, the first one was constructed by Scaled Composites — that has a more powerful engine, larger horizontal stabilizers on the tails, a new safety system for the feather, and a host of other unspecified changes.
The situation might call for treating SpaceShipTwo as a brand new vehicle that would have to repeat many of the tests of its predecessor. However, this does not appear to be the path that Virgin Galactic is following.
A source said that during a private Q&A session with ticket holders in Mojave, company officials stressed the similarities between the first and second SpaceShipTwos. They indicated that a shortened flight test program would be possible given the experience they gained with the first vehicle.
Virgin Galactic had originally planned to conduct at least 30 powered flights during the flight test program. That number had been cut down prior to the accident. Only a handful of additional tests — including only one to maximum altitude — were planned before the flight test program would have been declared complete and the ship would be turned over to Virgin Galactic to begin commercial service at Spaceport America in New Mexico.
The plan had a lot of people in Mojave on edge in the months prior to the October 2014 crash. There was a fear that the ship would not be fully tested before Virgin began flying passengers. Or that it would suffer an accident either in Mojave or in New Mexico. There were also concerns about the new nylon engine, which had only four complete ground tests before the flight.
Scaled Composites had built the original SpaceShipTwo as a proof of concept vehicle only. The company had never intended it for commercial service; it was to serve as a testbed for the production model. Scaled officials were not pleased with the decision.
SpaceShipTwo was destroyed before it got anywhere near space, preventing engineers from obtaining much needed data required to modify and build the second vehicle that Virgin Galactic has built.
Safety Safety Safety
Virgin Galactic officials said all the right things about doing the flight test program properly, not flying until they were ready, with safety being the North Star of the operation. They said the same things before the crash when they were pursuing an aggressive schedule.
There are two factors that could shape the upcoming flight test program. One is the high cost of each flight; one estimate puts them at close to $1 million. The high cost is due, in part, to the fact that SpaceShipTwo isn’t fully reusable. The hybrid engine must be replaced after each flight.
The second factor involves competition. Word has it that Richard Branson was none-too-pleased when Jeff Bezos’ Blue Origin beat Virgin Galactic to space last year with its New Shepard system, a fully reusable rocket and capsule designed to fly tourists into suborbital space.
Virgin Galactic’s approximately 700 customers have waited patiently — some for as long as a decade — through multiple delays. An unspecified number of ticket holders canceled their reservations after the SpaceShipTwo crash. Any further delays could cause defections to Blue Origin.
Bezos’ company appears to be in no great hurry. It hasn’t even started taking reservations yet. The company has flown three flight tests thus far; officials have said they plan to fly dozens more before putting anyone on board. The company has not announced a schedule.
For his part, Bezos has ignored Branson and Virgin Galactic, preferring to spar with SpaceX Founder Elon Musk on social media. SpaceX is also making its rocket and crewed spacecraft reusable.