Quote from: CorvusCorax on 12/18/2018 05:14 pmthese new boosters are always so finicky on their first launch...[...]I think we might begin to witness the positive effect of "flight proven" being turned around against all these "untested" boosters there's ever only so much you can test in component tests, dress rehearsal or even a hold down hot fire.Not true. [...]c. Can't say that the grid fin failure was due to infant mortality, poor workmanship (which still applies to a refurb booster), effects from second stage engine.
these new boosters are always so finicky on their first launch...[...]I think we might begin to witness the positive effect of "flight proven" being turned around against all these "untested" boosters there's ever only so much you can test in component tests, dress rehearsal or even a hold down hot fire.
Are the second and later launches of the same booster more or less likely to proceed through the countdown without encountering technical bugs causing a scrub? There are reasons each direction might be possible - infant mortality vs wear-and-tear, for example:Quote from: Jim on 12/19/2018 01:14 amQuote from: CorvusCorax on 12/18/2018 05:14 pmthese new boosters are always so finicky on their first launch...[...]I think we might begin to witness the positive effect of "flight proven" being turned around against all these "untested" boosters there's ever only so much you can test in component tests, dress rehearsal or even a hold down hot fire.Not true. [...]c. Can't say that the grid fin failure was due to infant mortality, poor workmanship (which still applies to a refurb booster), effects from second stage engine.But now we are emerging from the wilderness of opinions to the department of data, though we are not there yet. There have been (or will be after GPS) 10 launches of Block 5. The number of technical scrubs after the countdown has started are:Booster scrubs mission1046.1 1 Bangabandhu1047.1 0 Telstar 191048.1 0 Iridium/Grace1046.2 0 Merah Putih1049.1 0 Telstar 181048.2 0 SAOCOM1047.2 0 Es'hail1046.3 0 SSO-A1050.1 0 CRS-161054.1 1 GPS-III So there have been 6 new and 4 used launches, and overall 2 of 10 (20%) had a technical scrub during countdown. If two scrubs were evenly distributed among the 10 launches, we would naturally expect both on new boosters 15/45 (33%) of the time, both on used boosters 6/45 (13%) of the time, and one each 24/45 (53%) of the time.Clearly the numbers are small, and not statistically significant, but the evidence points slightly in the direction of used boosters having fewer scrubs. By the end of next year we may have better data on this. (On the other hand, SpaceX is presumably trying to reduce the number of scrubs in general. If they succeed, then the number of scrubs will remain low and the statistical power will be limited).
The Bangabandhu scrub is listed in the log as being a ground system fault. Seems like dubious reasoning to chalk that up to SpaceX using a new booster for that mission. Should we also evaluate whether the likelihood of weather scrubs is higher/lower when using pre-flown boosters?
If it's GSE, then it will statistically effect new and used booster in the same manner, and factor out. However if some unforeseen effect causes there to be a difference, it'll show up in the data as well.
Quote from: meekGee on 12/25/2018 06:40 pmIf it's GSE, then it will statistically effect new and used booster in the same manner, and factor out. However if some unforeseen effect causes there to be a difference, it'll show up in the data as well.Not entirely true. Every time they have introduced a new "block", they have made changes to the GSE, and have had to work through new problems as a result. These problems faded with more launches, and so the first launches were disproportionately affected.
[...] 1035.1 actually had no scrubs on its "unproven" flight, but the same booster did scrub on its re-use attempt.
Quote from: meekGee on 05/09/2019 02:42 amQuote from: scr00chy on 05/08/2019 02:04 pmI wrote an article about the recent Starlink-1 news and I'm also speculating that SpaceX might soon stop doing static fires before Starlink launches.https://www.elonx.net/falcon-9-will-launch-dozens-of-starlink-satellites-and-there-could-be-up-to-7-such-launches-this-year/That would be interesting.My view on this from a few years back was that static fires could be eliminated for reused boosters once SpaceX feels comfortable that data collected through ascent and descent is understood well enough to be used in lieu of static fire data for the following flight.Maybe we have arrived...Several years ago ULA stopped doing WDRs for the Atlas V (unless for military, NASA, or customer request) because they got to the point where they almost never uncovered an issue before launch.
Quote from: scr00chy on 05/08/2019 02:04 pmI wrote an article about the recent Starlink-1 news and I'm also speculating that SpaceX might soon stop doing static fires before Starlink launches.https://www.elonx.net/falcon-9-will-launch-dozens-of-starlink-satellites-and-there-could-be-up-to-7-such-launches-this-year/That would be interesting.My view on this from a few years back was that static fires could be eliminated for reused boosters once SpaceX feels comfortable that data collected through ascent and descent is understood well enough to be used in lieu of static fire data for the following flight.Maybe we have arrived...
I wrote an article about the recent Starlink-1 news and I'm also speculating that SpaceX might soon stop doing static fires before Starlink launches.https://www.elonx.net/falcon-9-will-launch-dozens-of-starlink-satellites-and-there-could-be-up-to-7-such-launches-this-year/
Cross threading at Gongora's suggestion.Quote from: whitelancer64 on 05/09/2019 03:21 pmQuote from: meekGee on 05/09/2019 02:42 amQuote from: scr00chy on 05/08/2019 02:04 pmI wrote an article about the recent Starlink-1 news and I'm also speculating that SpaceX might soon stop doing static fires before Starlink launches.https://www.elonx.net/falcon-9-will-launch-dozens-of-starlink-satellites-and-there-could-be-up-to-7-such-launches-this-year/That would be interesting.My view on this from a few years back was that static fires could be eliminated for reused boosters once SpaceX feels comfortable that data collected through ascent and descent is understood well enough to be used in lieu of static fire data for the following flight.Maybe we have arrived...Several years ago ULA stopped doing WDRs for the Atlas V (unless for military, NASA, or customer request) because they got to the point where they almost never uncovered an issue before launch.True. And I like how you still use "almost" in there.The thing is, a static fire still suffers from the risk of "but what if the static fire broke something".That, plus that ability to do real time analysis during the regular hold-down, plus the fact the a major risk factor is solid motors that can't be tested anyway - all added up to a "why bother".With F9, it's different. The vehicle is designed for a very large number of flights, there are no solids, and so why not?The path to removing static fires for SpaceX is different. Once a vehicle already flew, the chance of there being a pad-detectable fault that's not already detectable in the post flight data analysis is really low, basically limited to landing damage.
