The first Falcon 1 launch attempt at Omelek on November 25, 2005 was scrubbed after a ground-supply LOX vent valve allowed the small LOX supply to boil off.
I think it would be fairer to compare them to something earlier in the Delta family, or the Titan II
I'll add another comment. While we are seeing plenty of problem getting past the static hot fires and only getting caught in real count-downs, we're not seeing problems getting past the count-down and causing LOVs.That's significant, since the record for a new rocket, both for F9 1.0 and F9 1.1 is for all intents and purposes pristine. (yes we can argue about F9 1.0 flight 4)A possible explanation to this discrepancy is that they abort on a hair trigger. Perhaps (speculating) the level of instrumentation is higher, and the number of abort conditions is higher, and the thresholds for the abort conditions are tight, and they do all this because in these transformative years, they're rather take a hit on their launch rate than on their track record.Because honestly - I'm a amazing people, I think SpaceX is highly competent, and so I am looking for a rational explanation not to why there are aborts (I expect that), but to why there are post-hot-fire aborts (which is odd).
Quote from: meekGee on 01/07/2015 04:25 amI'll add another comment. While we are seeing plenty of problem getting past the static hot fires and only getting caught in real count-downs, we're not seeing problems getting past the count-down and causing LOVs.That's significant, since the record for a new rocket, both for F9 1.0 and F9 1.1 is for all intents and purposes pristine. (yes we can argue about F9 1.0 flight 4)A possible explanation to this discrepancy is that they abort on a hair trigger. Perhaps (speculating) the level of instrumentation is higher, and the number of abort conditions is higher, and the thresholds for the abort conditions are tight, and they do all this because in these transformative years, they're rather take a hit on their launch rate than on their track record.Because honestly - I'm a amazing people, I think SpaceX is highly competent, and so I am looking for a rational explanation not to why there are aborts (I expect that), but to why there are post-hot-fire aborts (which is odd).It seems that static test firing does not involve the second stage.
I get no specified infornation regarding this, but there is a simple reason, engines optimized for vacuum have problems with firing at sra level.And how the thrust vectoring problem was detected for this attempt is a mystery.
Quote from: nadreck on 01/07/2015 12:44 amI think it would be fairer to compare them to something earlier in the Delta family, or the Titan III wouldn't disagree except for one key thing. SpaceX is trying to pitch the Falcon9 and eventually Falcon Heavy against the Atlas-V and Delta-IV for US govt launch contracts. For lack of a better phrase, "If you want to run with the big dogs, you got to learn to pee in the tall grass."
This thread is not without merit.... But when I start seeing scrubs of hot fires, then I think it has gone too far.The same goes for delays months in advance which shifts the launch date.How about limiting it to scrubs/delays of actual launch attempts, only within a few days of the first launch attempt? In other words, any delay or scrub AFTER the hot fire.
Quote from: brovane on 01/07/2015 03:00 amQuote from: nadreck on 01/07/2015 12:44 amI think it would be fairer to compare them to something earlier in the Delta family, or the Titan III wouldn't disagree except for one key thing. SpaceX is trying to pitch the Falcon9 and eventually Falcon Heavy against the Atlas-V and Delta-IV for US govt launch contracts. For lack of a better phrase, "If you want to run with the big dogs, you got to learn to pee in the tall grass." Of course, the F9/FH are intended to compete with these older rockets, and will need to match their reliability, but you are comparing the wrong things i.e. a relatively new rocket with an older heavily tested rocket. To make the 'comparison statistics' valid, you need to compare them at similar points in their development schedule. I would expect that Spx will get to the same level of reliability/launch cadence more quickly than Atlas and Delta did, simply because of advances in technology. But they still need to be careful.
Personally for me I would like to know how SpaceX compares to historical scrub rates with the early launches of Atlas-V/Delta-IV.
I get no specific infornation, but there is a simple reason, engines optimized for vacuum have problems with firing at sea level.And how the thrust vectoring problem was detected for this attempt is a mystery.
Why is there a discrepancy for the CRS-5 launch this week in the abort time? I know SpaceX officially reported the abort time for 1:21, but very clearly the "hold hold hold" was called at 1:29, according to the display on the tv.