Quote from: renclod on 05/19/2012 04:47 pmQuote from: Robotbeat on 05/19/2012 04:05 pmEach stage has undergone multiple firings in Texas. Also,it's not terribly uncommon to have the same engine give you grief both times. Assuming you have a random engine problem to different launches, the probability of it being the same engine position both times is still one ninth (~11%).Combinations of 18 taken 2 at a time = 18! / (2! x 16!) =18 x 17 / 2 =1531 in 153 = 0.0065 = 0.65%Exactly. It's not the engines or the turbopumps or the valves, it's the engine location relative to the fuel feed.
Quote from: Robotbeat on 05/19/2012 04:05 pmEach stage has undergone multiple firings in Texas. Also,it's not terribly uncommon to have the same engine give you grief both times. Assuming you have a random engine problem to different launches, the probability of it being the same engine position both times is still one ninth (~11%).Combinations of 18 taken 2 at a time = 18! / (2! x 16!) =18 x 17 / 2 =1531 in 153 = 0.0065 = 0.65%
Each stage has undergone multiple firings in Texas. Also,it's not terribly uncommon to have the same engine give you grief both times. Assuming you have a random engine problem to different launches, the probability of it being the same engine position both times is still one ninth (~11%).
Can outside pressure propogate back through the shock at the throat to affect chamber pressure? I don't think so.
You method allows for two engines failing on one flight.
Quote from: renclod on 05/19/2012 05:12 pmQuote from: ugordan on 05/19/2012 05:02 pm... If your starting point is that you have two launches with an engine problem,Per Robotbeat' s post, the starting point is (correctly IMO):two launch attemptstwo engine problemsrandom engine failurequestion to the stats folks, is it significant that a similar problem seems to be happening to as engine is position 5, i.e. is position 5 a bad palace for an engine ? is the sample size too small? and if so how many more firings until its significant?
Quote from: ugordan on 05/19/2012 05:02 pm... If your starting point is that you have two launches with an engine problem,Per Robotbeat' s post, the starting point is (correctly IMO):two launch attemptstwo engine problemsrandom engine failure
... If your starting point is that you have two launches with an engine problem,
If all the fuel constraints were on Dragon because of the demo, why were we thinking that the launch window was only one second wide because of fuel constraints? Does Dragon do the "cross range" burns and not the boosters?
One article in AW&ST that was addressing all the ISS scheduling constraints saw this flight pushing out to September if it had a significant delay in May, and that was before the delay caused by software validation.
That's correct, in supersonic flow anything that happens downstream of the choke point cannot communicate upstream.
Also, can you guys who are arguing about the statistics just agree to disagree and stop cluttering this update thread, especially as many of us are checking this thread (and L2) frequently throughout the weekend to see what SpaceX finds out and decides?
Taken by Andre Kuipers as ISS passed overhead a few minutes before the T-0http://www.flickr.com/photos/astro_andre/
Quote from: brihath on 05/19/2012 05:13 pmOne article in AW&ST that was addressing all the ISS scheduling constraints saw this flight pushing out to September if it had a significant delay in May, and that was before the delay caused by software validation.Correct - there are some windows in May and June, after which the ISS schedules and beta angles likely push the flight into September.Are you sure it was AW&ST? I never saw that. Here's the one I wrote from two weeks ago:http://www.nasaspaceflight.com/2012/05/iss-schedule-dragon-launch-19-may-future-manifest-outlook/
My apologies! I thought it was in the commercial space articles from an April issue, but I reviewed them and it wasn't. That information was presented in your article, and it was excellent. That is why I come here FIRST for authoritative spaceflight reporting!
