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#60
by
jcm
on 16 Apr, 2010 07:01
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A rough estimate suggests that GSLV-D3 reached a -4400 x 137 km x 19.4 deg orbit
and reentered over the Andaman Sea at around 95E 9N +/- a few deg.
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#61
by
osiossim
on 16 Apr, 2010 07:27
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#62
by
input~2
on 16 Apr, 2010 09:18
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In watching the velocity numbers from the video, I didn't see the expected velocity increase that should have occurred following cryo engine ignition. So in my own humble opinion, I don't think that the cryo engine ignited.
I tend to agree, as supported by these telemetry data (extracted from various live broadcasts):
Time (s) velocity (km/s) altitude (km) event
262.8 4.113 127.5
263.8 4.138 127.8
290.4 GS2 Shutoff
293.0 GS2 Separation
297.0 4.898 134.7
298.0 4.898 134.9
299.0 4.898 135.1
300.0 4.898 135.3
301.0 4.897 135.5
304.9 CUS Ignition
308.0 4.895 136.5
309.0 4.895 136.7
310.0 4.895 136.8
316.0 4.893 137.5
317.0 4.893 137.6
318.0 4.893 137.7
319.0 4.893 137.8
320.0 4.893 137.8
321.0 4.893 137.9
322.0 4.893 138.0
323.0 4.893 138.0
324.0 4.892 138.1
325.0 4.892 138.2
326.0 4.892 138.2
327.0 4.892 138.3
328.0 4.892 138.3
329.0 4.892 138.3
373.0 4.899 134.9
379.0 4.901 133.7
446.5 4.951 107.4
505.0 5.023 65.9
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#63
by
kanaka
on 16 Apr, 2010 10:43
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We should have real time simulated flight - testing system instead of direct test flight. Atlest we should have some dummy payloads or components. This would help in minimizing cost as well as risks.
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#64
by
just-nick
on 16 Apr, 2010 14:33
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In watching the velocity numbers from the video, I didn't see the expected velocity increase that should have occurred following cryo engine ignition. So in my own humble opinion, I don't think that the cryo engine ignited.
Anyway, just my personal opinion.
Makes sense. Why would a failure of two verniers cause anything but a roll issue? I assume the engine gimbals in pitch and yaw. Anyway a shocking development for modern spaceflight.
I wouldn't assume that the verniers were for roll only. Zenit and Soyuz both, I believe, use fixed engines with verniers (Zenit 2nd stage) for pitch, roll, and yaw.
--N
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#65
by
jcm
on 16 Apr, 2010 18:38
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In watching the velocity numbers from the video, I didn't see the expected velocity increase that should have occurred following cryo engine ignition. So in my own humble opinion, I don't think that the cryo engine ignited.
Anyway, just my personal opinion.
Makes sense. Why would a failure of two verniers cause anything but a roll issue? I assume the engine gimbals in pitch and yaw. Anyway a shocking development for modern spaceflight.
I wouldn't assume that the verniers were for roll only. Zenit and Soyuz both, I believe, use fixed engines with verniers (Zenit 2nd stage) for pitch, roll, and yaw.
--N
If it tumbled right away, the cryo engine could have ignited but not yielded a net velocity change. However I tend to suspect that there was no ignitiion. Condolences to my friends on the ISRO team - I have confidence that they will fix this and make this engine work in the future.
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#66
by
Art LeBrun
on 16 Apr, 2010 18:46
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In watching the velocity numbers from the video, I didn't see the expected velocity increase that should have occurred following cryo engine ignition. So in my own humble opinion, I don't think that the cryo engine ignited.
Anyway, just my personal opinion.
Makes sense. Why would a failure of two verniers cause anything but a roll issue? I assume the engine gimbals in pitch and yaw. Anyway a shocking development for modern spaceflight.
I wouldn't assume that the verniers were for roll only. Zenit and Soyuz both, I believe, use fixed engines with verniers (Zenit 2nd stage) for pitch, roll, and yaw.
--N
Good point - I must have thought more than 2 would be required for pitch and yaw. Perhaps one vernier ignited to cause the tumbling....
if tumbling is the correct term?
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#67
by
sanman
on 17 Apr, 2010 00:38
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#68
by
input~2
on 17 Apr, 2010 15:45
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From the Hindu front page (17April 2010)
Why didn't the cryogenic engine ignite? The cryogenic engine has not ignited, that is for sure.
It is very clear that the cryogenic engine did not ignite when you look at the curve [of the vehicle's trajectory], everything was normal up to the GS2 [second stage] shutdown. Then you can see clearly that there is no increment in the vehicle's velocity. The velocity is the same. It started losing its altitude also.
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#69
by
Art LeBrun
on 17 Apr, 2010 15:54
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Interesting - where is the data for engine chamber pressure, pump speeds, propellant flow and pressures and other information? New vehicle would have lots of detailed telemetry? Maybe the information will come out later.
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#70
by
sanman
on 17 Apr, 2010 17:07
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I wonder if India's going to have to build a dedicated vacuum test facility now, or if they can rent someone else's.
As I mused in another thread, I wonder if it's possible to just float an engine test rig up on a balloon to some high altitude, in order to test-fire it. Otherwise, there would seem to be a huge amount of engineering involved in building a ground-based vacuum test facility.
Or else perhaps India could have used its older, cheaper ASLV rocket to loft the new engine upto 50 miles altitude for suborbital flight-testing.
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#71
by
Damon Hill
on 17 Apr, 2010 22:31
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I wonder if India's going to have to build a dedicated vacuum test facility now, or if they can rent someone else's.
As I mused in another thread, I wonder if it's possible to just float an engine test rig up on a balloon to some high altitude, in order to test-fire it. Otherwise, there would seem to be a huge amount of engineering involved in building a ground-based vacuum test facility.
How big will the balloon need to be to support the weight of the engine, propellant supply and instrumentation, and support structure?
How will this flying arrangement compensate for thousands of pounds of thrust, in whatever direction?
I suspect the real problem with the Indian engine will be something other than the vacuum condition. If ISRO doesn't have a altitude compensating test chamber, it's time they build one. Do you know how it works? It's surprisingly simple in principle.
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#72
by
sanman
on 17 Apr, 2010 23:16
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How big will the balloon need to be to support the weight of the engine, propellant supply and instrumentation, and support structure?
How will this flying arrangement compensate for thousands of pounds of thrust, in whatever direction?
Hmm, I suppose that it would be a very giant balloon, but that this would be much cheaper than an actual rocket test flight. Plus, the balloon could be tethered to compensate for the engine thrust. Yes, this would be a very long tether.
I suspect the real problem with the Indian engine will be something other than the vacuum condition. If ISRO doesn't have a altitude compensating test chamber, it's time they build one. Do you know how it works? It's surprisingly simple in principle.
India does not have a macro-scale vacuum test chamber, and vacuum conditions were not simulated in ground testing of the engine. I think they may have tried to simulate this merely through numerical methods, and not through an actual test-firing under these conditions.
From what I've read, these vacuum chambers work through "steam ejectors" which not only have to produce a vacuum, but have to maintain it in the face of the huge exhaust put out by the engine being tested.
Perhaps it would be easier just to rent somebody else's in the near term, and consider building one for the long haul.
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#73
by
Damon Hill
on 18 Apr, 2010 02:10
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I suspect the real problem with the Indian engine will be something other than the vacuum condition. If ISRO doesn't have a altitude compensating test chamber, it's time they build one. Do you know how it works? It's surprisingly simple in principle.
India does not have a macro-scale vacuum test chamber, and vacuum conditions were not simulated in ground testing of the engine. I think they may have tried to simulate this merely through numerical methods, and not through an actual test-firing under these conditions.
From what I've read, these vacuum chambers work through "steam ejectors" which not only have to produce a vacuum, but have to maintain it in the face of the huge exhaust put out by the engine being tested.
Perhaps it would be easier just to rent somebody else's in the near term, and consider building one for the long haul.
The steam ejector works initially to pump down the chamber; the high speed exhaust of the engine being tested does the rest of the work.
Russia has a couple of dandy facilities, and India has traditionally worked closely with them.
But let's wait for a failure analysis to point to the real problem. Quite a number of things could have caused this. Liquid hydrogen has an annoying tendency to freeze anything that's not helium, for example.
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#74
by
WHAP
on 18 Apr, 2010 02:30
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Interesting - where is the data for engine chamber pressure, pump speeds, propellant flow and pressures and other information? New vehicle would have lots of detailed telemetry? Maybe the information will come out later.
It's likely with ISRO, and won't be released unless and until they feel it's necessary. I suspect that would be never.
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#75
by
tonthomas
on 18 Apr, 2010 15:38
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#76
by
tonthomas
on 18 Apr, 2010 15:50
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So may be the verniers have had to work as ullage motors for fuel settling but failed. The main motor made a short burp and starved without fuel.
Thomas
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#77
by
Art LeBrun
on 18 Apr, 2010 15:57
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Since this was still a high velocity flight why do you need to settle fully loaded cryogenic propellants with ullage pressures in place?
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#78
by
tonthomas
on 18 Apr, 2010 16:14
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Donīt think velocity is the factor. But interesting to know should be if there was driven flight of the third stage, and, concerning stage pressurisation, in which way it was realised. Besides the pressure, the aggregate phase matters, and i think, the motors turbomachinery is not designed to pump gaseous O2 oder H2.
Thomas
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#79
by
sanman
on 18 Apr, 2010 19:04
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