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#260
by
edkyle99
on 05 Jan, 2011 19:52
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#261
by
robertross
on 05 Jan, 2011 22:47
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http://ibnlive.in.com/news/gslv-failed-as-germanmade-connectors-snapped/139522-11.html
The "snapped" connectors were German-made, for whatever that is worth.
Note that this report says that even the "backup" connectors "snapped".
I'm an electrical engineer, but I am still completely baffled as to what the term "snapped" means when used to describe connectors. 
- Ed Kyle
Yeah, it's more likely the improper use of the term. Perhaps a 'case fracture', or 'premature separation event' (since these would likely be break-away connectors designed to separate at a specific pulling force).
If I were to put money on it, without even knowing the full depth of the issue, I'd say connectors were not properly spec'd (or applied) for the vehicle, given the cryo conditions & vehicle's acceleration environment.
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#262
by
edkyle99
on 05 Jan, 2011 23:48
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http://ibnlive.in.com/news/gslv-failed-as-germanmade-connectors-snapped/139522-11.html
The "snapped" connectors were German-made, for whatever that is worth.
Note that this report says that even the "backup" connectors "snapped".
I'm an electrical engineer, but I am still completely baffled as to what the term "snapped" means when used to describe connectors.
- Ed Kyle
Yeah, it's more likely the improper use of the term. Perhaps a 'case fracture', or 'premature separation event' (since these would likely be break-away connectors designed to separate at a specific pulling force).
If I were to put money on it, without even knowing the full depth of the issue, I'd say connectors were not properly spec'd (or applied) for the vehicle, given the cryo conditions & vehicle's acceleration environment.
My guess would be premature "separation", although I don't know how anyone could say for certain that the cables separated *at* the connectors (unless there was on-board video). I suppose it might be a good conjecture to make if the symptoms indicated that *all* electrical connections suddenly opened at the same instant.
Aren't "cable cutters" often used for separating electrical connections during staging? Not always though. I've recently read about a failed Atlas booster package electrical separation event where a connector was supposed to be pulled apart by a lanyard as the booster fell away (the lanyard failed on that one, causing a bad separation that must have messed up the booster separation event signal, leading to loss of flight control).
- Ed Kyle
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#263
by
Art LeBrun
on 06 Jan, 2011 02:41
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A story needing more details: AC-33 suffered an electrical event at staging that, of all things, lead to Centaur ignition while under sustainer flight. I would like to find the accident report and any films (night shot but I don't know the cloud conditions).
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#264
by
pradeep
on 06 Jan, 2011 06:28
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http://ibnlive.in.com/news/gslv-failed-as-germanmade-connectors-snapped/139522-11.html
The "snapped" connectors were German-made, for whatever that is worth.
Note that this report says that even the "backup" connectors "snapped".
I'm an electrical engineer, but I am still completely baffled as to what the term "snapped" means when used to describe connectors.
- Ed Kyle
Yeah, it's more likely the improper use of the term. Perhaps a 'case fracture', or 'premature separation event' (since these would likely be break-away connectors designed to separate at a specific pulling force).
If I were to put money on it, without even knowing the full depth of the issue, I'd say connectors were not properly spec'd (or applied) for the vehicle, given the cryo conditions & vehicle's acceleration environment.
My guess would be premature "separation", although I don't know how anyone could say for certain that the cables separated *at* the connectors (unless there was on-board video). I suppose it might be a good conjecture to make if the symptoms indicated that *all* electrical connections suddenly opened at the same instant.
Aren't "cable cutters" often used for separating electrical connections during staging? Not always though. I've recently read about a failed Atlas booster package electrical separation event where a connector was supposed to be pulled apart by a lanyard as the booster fell away (the lanyard failed on that one, causing a bad separation that must have messed up the booster separation event signal, leading to loss of flight control).
- Ed Kyle
I think they mean "disconnect" here when they say snapped. That is generally the way a lay Indian person in Mumbai would describe it when we have electrical complaints. I am not so sure of other places in India. I guess ISRO scientists wanted to use local layman terms while saying this to ensure people here understood.
I also hope they're not trying to blame foreign components here because whatever the source of the component - Indian or foreign - it was their duty to check whether the system worked. Quality check and assurance is the purchaser's responsibility. I think it is more the media waiting for every tid bit of information and bloating the quote out of all context.
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#265
by
Jim
on 06 Jan, 2011 11:46
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#266
by
asdert
on 06 Jan, 2011 12:57
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#267
by
robertross
on 06 Jan, 2011 15:28
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#268
by
sanman
on 06 Jan, 2011 15:40
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I think they mean "disconnect" here when they say snapped. That is generally the way a lay Indian person in Mumbai would describe it when we have electrical complaints. I am not so sure of other places in India. I guess ISRO scientists wanted to use local layman terms while saying this to ensure people here understood.
I also hope they're not trying to blame foreign components here because whatever the source of the component - Indian or foreign - it was their duty to check whether the system worked. Quality check and assurance is the purchaser's responsibility. I think it is more the media waiting for every tid bit of information and bloating the quote out of all context.
Well, first of all, I think he was just casually responding to a query on who made the connectors, and not actually assigning blame to them. After all, for 10 connectors to fail simultaneously sounds like there was some underlying cause (eg. premature state separation)
The thing here is that the media are hungry for even the slightest new tidbit of news on this failed launch, and so even the smallest innocent remark seems to get magnified through headlines.
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#269
by
seshagirib
on 07 Jan, 2011 05:47
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It is not clear (to me) if the connectors get separated because of the stage moving away (stage separation ) - that is pulled apart as the stages move away from each other OR there is some other explicit mechanism for de-mating the connector pairs, prior to the stages moving away.
Could anyone in the know clarify?
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#270
by
Jim
on 07 Jan, 2011 12:01
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It is not clear (to me) if the connectors get separated because of the stage moving away (stage separation ) - that is pulled apart as the stages move away from each other OR there is some other explicit mechanism for de-mating the connector pairs, prior to the stages moving away.
Could anyone in the know clarify?
the first method.
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#271
by
seshagirib
on 23 Jan, 2011 08:16
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Don't see how they can launch anything - PSLV or GSLV without sorting out this failure completely.
Same/Similar connectors and separation mechanisms may be shared across the family of launch vehicles(?).
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#272
by
input~2
on 29 Jan, 2011 16:55
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#273
by
seshagirib
on 02 Feb, 2011 03:32
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New information from ISRO on why, potentially, the connectors snapped:
The German made connectors are fixed on a metal plate. The plate, in turn, is fixed to a shroud or cylindrical cover that comes between the cryogenic engine and the lower stage (engine).
According to Nair, the shroud made of composites is part of the Russian cryogenic engine and it got deformed due to the flight load. The committee is yet to conclude why the shroud was not able to bear the load.
from: http://www.sify.com/news/rocket-failure-isro-awaits-data-from-russia-news-national-lb2qugdhiab.html
How did they come to the conclusion that the shroud deformed?
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#274
by
isro-watch
on 02 Feb, 2011 04:19
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#275
by
input~2
on 08 Feb, 2011 15:07
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#276
by
Shams
on 22 Feb, 2011 14:47
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#277
by
sanman
on 19 Apr, 2011 23:56
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#278
by
Danderman
on 20 Apr, 2011 00:26
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"A successful flight of the GSLV is not an impossibility."
Truly inspiring.
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#279
by
Salo
on 20 Apr, 2011 20:08
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