Areopagus From United States, joined Sep 2001, 1282 posts, RR: 1 Reply 1, posted (1 month 2 weeks 13 hours ago) and read 1220 times:
The caption says the engines produced 855,000 pounds of thrust, but I thought 9 Merlins were supposed to produce 1,125,000 pounds. Were they running at reduced throttle?
Nomadd22 From United States, joined Feb 2008, 367 posts, RR: 0 Reply 3, posted (1 month 1 week 6 days 16 hours ago) and read 1112 times:
Quoting Areopagus (Reply 1): The caption says the engines produced 855,000 pounds of thrust, but I thought 9 Merlins were supposed to produce 1,125,000 pounds. Were they running at reduced throttle?
The 125,000 per engine is in vacuum. They only put out 95,000 each at sea level.
I was wondering if they'd ever considered blowing an engine during a test to see if their kevlar jacket really protected the adjacent engines. It seems like that might be an important issue if they want to man rate the F9.
Thorny From United States, joined Jul 2005, 1457 posts, RR: 10 Reply 4, posted (1 month 1 week 6 days 1 hour ago) and read 1039 times:
Quoting Nomadd22 (Reply 3): It seems like that might be an important issue if they want to man rate the F9.
Probably not. Man-rating (which is very loosely defined... neither Shuttle nor Soyuz meets its strictest definitions) is mostly about preventing catastrophic failures in the first place, or failing that (since even the most reliable rockets are no more than 99% reliable), giving enough advance warning of one to allow the crew to pull the Abort Handle.
If an engine blows on a manned Falcon 9, it's going to be a bad day no matter what. Same applies to Shuttle and a potentially manned Atlas V or Delta IV.
Nomadd22 From United States, joined Feb 2008, 367 posts, RR: 0 Reply 5, posted (1 month 1 week 6 days 1 hour ago) and read 1034 times:
Quoting Thorny (Reply 4): If an engine blows on a manned Falcon 9, it's going to be a bad day no matter what. Same applies to Shuttle and a potentially manned Atlas V or Delta IV.
Not what they advertise. It's supposed to be able to complete almost any profile with an engine out and they brag about the shielding around each one to protect the others in case one of fails spectacularly. Having done an exploding engine test to see if the other engines remain unharmed might make the difference between pulling the eject handle or waiting.
I know that Spacex has missed some pretty simple things in their failures. Lacking NASAs six years, 240 million dollars and 14,000 pages of analysis for every screw and decal on the rocket, I assume they'll need to make up for it with a lot more extensive testing to cover different situations before they get their Hack license.
They advertise a lot. I have a very low opinion of their marketing department, though, after four years of Falcon 1 over-selling.
Quoting Nomadd22 (Reply 5): It's supposed to be able to complete almost any profile with an engine out
Yes, but "engine out" is not a catastrophic failure.
Quoting Nomadd22 (Reply 5): Having done an exploding engine test to see if the other engines remain unharmed might make the difference between pulling the eject handle or waiting.
There is absolutely no chance a crew is going to stay with the vehicle during a catastrophic engine failure, testing or not. Such an event is enormously unlikely anyway. "Man-rating" is supposed to mean the vehicle shuts down the malfunctioning engine before it can do (or threaten to do) catastrophic damage. If the engine went kablooey, that means the vehicle isn't doing its job right, and the Abort Handle gets a really sharp tug from a terrified flight crew, no questions asked.
The kevlar jackets are probably meant to increase the odds of making orbit for unmanned payloads, where there isn't much to lose. It's a pity SpaceX didn't show as much regard for their first three Falcon 1 payloads.
Areopagus From United States, joined Sep 2001, 1282 posts, RR: 1 Reply 7, posted (1 month 5 days 18 hours ago) and read 794 times:
How kablooey do liquid engines go? When I see the "Our rockets always blow up" footage from the early US space program, it looks to me like the big explosions must have been due to the range safety charges.
The structural breakups of Challenger, the first Ariane V, and the first Delta III look pretty bad, but I suppose that steering anomalies and oscillations should give indications that such an event is threatening.
Thorny From United States, joined Jul 2005, 1457 posts, RR: 10 Reply 8, posted (1 month 4 days 22 hours ago) and read 709 times:
Quoting Areopagus (Reply 7): How kablooey do liquid engines go? When I see the "Our rockets always blow up" footage from the early US space program, it looks to me like the big explosions must have been due to the range safety charges.
Its rare, but they do go kablooey. The last one to do so was probably the SeaLaunch explosion in Jan 2007. Foreign object ingesion into one of the turbopumps, if memory serves.
Challenger didn't go kablooey, it broke apart at Mach 2 and the spilled prop from the External Tank was rapidly burned off, but there wasn't an actual explosion. Not much difference to the crew's family and friends, but a big technical difference.
The Ariane V (1996), Delta II (1997), Titan IV (1998) and Delta III (1998) explosions were all control system failures or solid motor failure.
Areopagus From United States, joined Sep 2001, 1282 posts, RR: 1 Reply 9, posted (1 month 4 days 18 hours ago) and read 672 times:
Quoting Thorny (Reply 8): Challenger didn't go kablooey,
I agree with your commentary, but note that I said structural breakup, not kablooey, in those cases. I would think that such events were sudden enough that they would pose considerable danger to an Orion crew if the launch escape system wasn't activated before the hard-over or breakup started. But even then, in a parachute-equipped small structural unit like the Orion command module, it's conceivable that the crew could survive a Challenger-type event, considering that (some of) the Challenger crew survived the initial breakup.
The Delta II and Titan IV solid-motor explosions you referenced are indeed quite another matter.
Thorny From United States, joined Jul 2005, 1457 posts, RR: 10 Reply 10, posted (1 month 4 days 16 hours ago) and read 655 times:
Quoting Areopagus (Reply 9): I agree with your commentary, but note that I said structural breakup, not kablooey, i
So you did, sorry!
Quoting Areopagus (Reply 9): The Delta II and Titan IV solid-motor explosions you referenced are indeed quite another matter.
The Titan IV failure in 1998 was also a control system failure. It was blown by Range Safety when a cable harness failed. That one gave enough warning that a hypothetical crew would have been able to abort. (There was a Titan IV failure in 1993 due to the SRM, but I don't have the details handy. The other 1998-ish Titan IV failure was an upper stage failure.)
The spectacular Delta II 'kablooey' in 1997 looks totally unsurvivable, but then again the GPS satellite was later found in surprisingly good shape (aside from hitting the ground very hard...) so it isn't clear that sort of explosion would be unsurvivable.
Areopagus From United States, joined Sep 2001, 1282 posts, RR: 1 Reply 11, posted (1 month 3 days 18 hours ago) and read 581 times:
Quoting Thorny (Reply 10): The Titan IV failure in 1998 was also a control system failure. It was blown by Range Safety when a cable harness failed.
Really? I must have mixed that with another launch. I'm thinking of a Titan failure where the SRM went so suddenly that the rocket appeared normal in one frame, and totally gone in the next. Was that the 1986 failure?
Do you know of any videos available online of one of the really bad liquid failures you mentioned?
Nomadd22 From United States, joined Feb 2008, 367 posts, RR: 0 Reply 12, posted (1 month 3 days 17 hours ago) and read 575 times:
Quoting Areopagus (Reply 11): Really? I must have mixed that with another launch. I'm thinking of a Titan failure where the SRM went so suddenly that the rocket appeared normal in one frame, and totally gone in the next. Was that the 1986 failure?
I think that was a Titan 34D in 86. Caused by insulation in the SRB failing. A guy who worked there told me that it was from out of date epoxy combined with project managers who got the job by flunking out of Walmart greeter school.
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