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#140
by
Art LeBrun
on 25 Dec, 2010 16:08
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Perhaps connectors were incorrectly attached to the intended strap on....
1 to 3 2 to 4........... several instances of such in early US space launches.
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#141
by
adithyau
on 25 Dec, 2010 16:10
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Today i was watching live ISRO launch of GSLV carrying GSAT-5P and i was really sad to see it getting wasted like that.
We are way way behind any space technology.
Today's failure was very tragic since it blew up in first stage itself.
First stage is reliable proven stage and is similar to PSLV which has a good track record.The technology that Russia, US had decades ago, we are still not able to even match that.
We still dont have our own indigenous Cryogenic Upper Stage engine;we still rely upon Russia (By the way still 1 engine of Russia is left with us and after that we need to import more )
GSLV development started during 1990's
PSLV cannot be used to launch communication satellite and heavy satellites in geo synchronous orbits
They are normally used to launch remote sensing and polar,sun synchronous satellites which i must say we have plenty and dont need any more. (However chandrayana was launched in a modified version of PSLV)
I think its time for ISRO to introduce drastic changes.
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#142
by
adithyau
on 25 Dec, 2010 16:14
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Did anyone noticed the moment of lift off ?
It was somewhat different when compared to other GSLV launches i think
It went too fast i believe while clearing the tower and it *might* have damaged launch tower ;
I am not sure about this though.
And the fumes of the rocket was also different
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#143
by
isro-watch
on 25 Dec, 2010 16:23
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It appears one of the strap ons broke apart spilling propellants during the initial loss of attitude control............
It was the second or third stage which broke first...followed by the evnt you described
The attachments are between T+50 seconds(as per voice in the video just before incident) and T+65 seconds(when the destruct command was given)
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#144
by
isro-watch
on 25 Dec, 2010 16:30
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This is the scene of self destruct command
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#145
by
Danderman
on 25 Dec, 2010 16:50
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With such a low flight rate early in the program, its not unexpected to have a relatively high failure rate for this launcher. Among other things, the bugs have not been worked out of the design, and the crew are not used to the launch procedures.
Give it 25+ launches, and we will know if its a good design.
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#146
by
seshagirib
on 25 Dec, 2010 17:06
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What is the procedure for mitigating risk when the configuration of the vehicle is changed? - simulation? -wind tunnel tesing? - anyother techniques?
I ask, because this vehicle is reported to be heavier, and taller then the previous GSLV vehicles, also with a larger payload fairing.
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#147
by
input~2
on 25 Dec, 2010 17:09
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ISRO Chairman K. Radhakrisnan said at a press conference: “The controllability of the vehicle was lost after 47 seconds because we found that the command to control it did not reach the actuator system in the first stage of the vehicle… We suspect that a connector chord, which takes the signal down, has snapped.”
Director of Vikram Sarabhai Space Centre in Thiruvanthapuram P.S. Veeraraghavan explained that the command to control the vehicle from the Equipment Bay, the electronic brain of the vehicle resident atop the rocket, did not reach the actuators in the vehicle's first stage. “So it was not basically a design problem but a problem of the connector snapping.”
http://www.thehindu.com/sci-tech/science/article979052.ece
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#148
by
Antares
on 25 Dec, 2010 17:13
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So hypotheses I see talked about here are:
1) loss of command path between flight computer and TVC
2) loss of structural integrity on a strap-on, leading to asymmetric thrust - initial loss potentially due to turbopump letting go
3) loss of connection between core and strap-ons, structural or command
I'd like to see supporting or refuting evidence for these. And, valid additional hypotheses from established NSF members.
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#149
by
input~2
on 25 Dec, 2010 17:24
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So hypotheses I see talked about here are:
1) loss of command path between flight computer and TVC
2) loss of structural integrity on a strap-on, leading to asymmetric thrust - initial loss potentially due to turbopump letting go
3) loss of connection between core and strap-ons, structural or command
I'd like to see supporting or refuting evidence for these. And, valid additional hypotheses from established NSF members.
Where does your #2 come from?
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#150
by
FinalFrontier
on 25 Dec, 2010 17:24
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ISRO Chairman K. Radhakrisnan said at a press conference: “The controllability of the vehicle was lost after 47 seconds because we found that the command to control it did not reach the actuator system in the first stage of the vehicle… We suspect that a connector chord, which takes the signal down, has snapped.”
Director of Vikram Sarabhai Space Centre in Thiruvanthapuram P.S. Veeraraghavan explained that the command to control the vehicle from the Equipment Bay, the electronic brain of the vehicle resident atop the rocket, did not reach the actuators in the vehicle's first stage. “So it was not basically a design problem but a problem of the connector snapping.”
http://www.thehindu.com/sci-tech/science/article979052.ece
Seems to me that that IS a design problem. I highly doubt a sensitive control cable is "designed to snap" prior to the intended time leading to a vehicle breakup. Also seems like the thing started breaking up on its own before an authorized destruct was issued, usually RSO destructs look cleaner than that.
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#151
by
FinalFrontier
on 25 Dec, 2010 17:27
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Look we don't know much right now, my current thinking is a critical cable (as they said) broke either during or was broken before launch (and was not caught in that case) which led to the rocket going off course in a high stress part of the flight, leading to breakup. At some point they issued a destruct command but my thinking is it had already mostly destroyed itself by then.
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#152
by
input~2
on 25 Dec, 2010 17:29
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Also seems like the thing started breaking up on its own before an authorized destruct was issued, usually RSO destructs look cleaner than that.
Yes, this has been acknowledged by ISRO and is visible on the video
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#153
by
FinalFrontier
on 25 Dec, 2010 17:29
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In the video if you look closely at the frames right before the initial explosion, you can see the rocket veering upwards somewhat and then breakup begins. Seem to me to be an obvious guidance failure (probably resulting from that broken cable they mentioned). The failure happened at a high stress point in the flight so when the vehicle went off course (by veering upwards) it simply broke into pieces. Destruct command came later.
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#154
by
FinalFrontier
on 25 Dec, 2010 17:30
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Also seems like the thing started breaking up on its own before an authorized destruct was issued, usually RSO destructs look cleaner than that.
Yes, this has been acknowledged by ISRO and is visible on the video
agreed sorry for redundant posts. Seems pretty obvious what happened here, ashame that it happened though. They just can't get away from these failures :\
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#155
by
FinalFrontier
on 25 Dec, 2010 17:32
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And no there is no chance of sat recovery (even if it had survived the breakup) because it appears in the video the payload is the first thing to disintegrate :|
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#156
by
Antares
on 25 Dec, 2010 18:27
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So hypotheses I see talked about here are:
1) loss of command path between flight computer and TVC
2) loss of structural integrity on a strap-on, leading to asymmetric thrust - initial loss potentially due to turbopump letting go
3) loss of connection between core and strap-ons, structural or command
I'd like to see supporting or refuting evidence for these. And, valid additional hypotheses from established NSF members.
Where does your #2 come from?
Reply #137. Speculation about turbopump contribution comes from discussions among colleagues this morning.
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#157
by
Antares
on 25 Dec, 2010 18:30
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FinalFrontier, the observed attitude error could have as easily been caused by loss of thrust in one of the strap-ons as from a control anomaly in the avionics.
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#158
by
isro-watch
on 25 Dec, 2010 18:37
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Did anyone noticed the moment of lift off ?
It was somewhat different when compared to other GSLV launches i think
It went too fast i believe while clearing the tower and it *might* have damaged launch tower ;
I am not sure about this though.
And the fumes of the rocket was also different
I can confirm that there was NO damage to tower...
In what way are the fumes different
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#159
by
Danderman
on 25 Dec, 2010 18:41
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Perhaps this is too obvious, but with the LH2 experiencing a leak prior to launch, I would not rule out the possibility of some drops of very cold liquid somehow contacting a control cable.
