Dan Schrimpsher has a comment on Scaled’s test flight schedule for SS2:
…the test flights are going to have to start soon, perhaps later this year. At 1 flight/week, it would take two years to make 100 test flights.
I see no reason that they shouldn’t have a much higher flight rate than that. I’d think that they could probably fly every day, as long as they make the hybrid motor easy to refuel. I suspect that the only constraint on their test flight rate would be data analysis, and modifications resulting from test flight results. And I also suspect that the high number of “test” flights won’t really be test flights, but rather demonstration flights, to establish reliability confidence. Those could go every day, as long as nothing goes wrong. I doubt if flight test (or at least intrinsic flight rate ability) will be the long pole in the schedule tent–I think that just delivering the initial hardware to be tested will be have much more schedule uncertainty.
[Update in the late afternoon]
Dan follows up:
I assume that in the beginning the flights will be less often as problems will show themselves up front. I see more of an exponential cure of flights starting with one every few weeks to get the kinks out. And closer to once per day when they are close to starting service.
I think we’re now in violent a agreement.
Also, based on history, SS1 was flown months apart except for the X-Prize run, so I am trying to be conservative.
Well, I’m not sure how good a guide history is here. In the one case, they were trying to win a prize, and didn’t need a high-rate vehicle to do it (twice in two weeks, and that was it). I suspect that they’re spending more money this time, in order to hit a market, and get it to market as soon as they can within safety constraints to maximize payback. I’ll be surprised if it’s weeks before the first and second flights.
But I’ve been surprised before. After all, I didn’t think that the stand down after Columbia would be nearly as long as that after Challenger (and neither of them should have been as long as they were), so what do I know?
[Another update a few minutes later]
One other point (see, Anonymous Moron in comments isn’t completely useless–but mostly)…
The other difference (which I didn’t mention, though I also didn’t assume otherwise, contra Anonymous Moron) was that there will be a fleet of vehicles for SS2, though the initial test flights will be only for one, because they’ll want to learn a lot of lessons early to incorporate into the other vehicle builds. So the initial test flight series will be with a single version of each vehicle (White Knight and SS2), and only later, when they’re doing reliability demo flights and building flight experience, will there be multiple vehicles. And the transition from one to a fleet will be part of the exponential increase that Dan described in his follow-up post.
And in the way of disclosure, I should also add that, despite the fact that I occasionally talk to the Virgin consultant responsible for overseeing the vehicle development (who is an old friend of mine), and Alex Tai himself, this is all speculation on my part.