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#120 by sanman on 06 Jan, 2014 03:40
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The dimensions of CUS12 and CUS25 are different, so its not feasible to switch the stages.
Are you sure that swapping in the engine really amounts to swapping the entire stage? It seems to me that it's more feasible to swap in the smaller CE7.5 engine into the larger CUS of the Mark-3. Then do vibrational testing, etc. Anyway, just a thought. It really seems to be a shame that they're doing the initial Mark-3 flight without testing the full launch stack, because it's not a true test of the vehicle. Instead, it looks like this aerodynamic test is being done to save face, in spite of the CE20 not being ready. Oh well, I guess it's more baby steps - Gradatim Ferociter and so on. -
#121 by johnxx9 on 06 Jan, 2014 09:37
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The dimensions of CUS12 and CUS25 are different, so its not feasible to switch the stages.
Are you sure that swapping in the engine really amounts to swapping the entire stage? It seems to me that it's more feasible to swap in the smaller CE7.5 engine into the larger CUS of the Mark-3. Then do vibrational testing, etc. Anyway, just a thought. It really seems to be a shame that they're doing the initial Mark-3 flight without testing the full launch stack, because it's not a true test of the vehicle. Instead, it looks like this aerodynamic test is being done to save face, in spite of the CE20 not being ready. Oh well, I guess it's more baby steps - Gradatim Ferociter and so on.
That is way too complex for a single flight. The stage and the whole LV is built around the laid out specs. So, if I were to change the engine (or a stage) a lot of other stuff need to be changed and changes/effects needs to studied. ISRO has already invested significantly into the upperstage although they are still some distance from completion. -
#122 by AJA on 06 Jan, 2014 11:15
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Both GG & SC cycles have gas generator.
I'm aware of that. I used the term gas-generator in the conventional sense, and wasn't referring either to the gas generated by LH2 boiling, through regenerative heat exchange between fuel-exhaust in the nozzle cooling jacket (for the expander cycle) or to the gas generated in the fuel-rich, lower temperature pre-burner combustion (the staged-combustion cycle).
The quote you mention is from this paper titled "Turbomachines for Cryogenic Engines", presented by N K Gupta of LPSC at the Proceedings of the 37th National & 4th International Conference on Fluid Mechanics and Fluid Power, held at IIT-Madras between Dec 16-18, 2010; and not from the GSLV-D5 brochure (which doesn't specify the cycle used).
I did find an ISRO Press release about a hot-fire acceptance test of a cryogenic engine from 2008 that talks about a 42,000 rpm integrated turbopump driven 73 kN (Vacuum) engine (with an Isp of 454 seconds, 2 x 2kN steering engines, and a 13% uprated thrust mode) -- that I assume is the CE-7.5 (not explicitly stated in the release)-- and says that this uses the staged combustion cycle.
Anyway, back to the paper you took the quote from. In the very next paragraph after the quoted text, the paper says that ISRO's planning to build an engine with a gas generator cycleQuoteISRO has embarked on a plan for realizing a gas generator cycle based cryogenic engine in the 12 to 20 tonne thrust range.
The graphs, diagrams and the data are for the CE-20 and the C25.
Interestingly, the gas-generator does burn LOX/LH2...QuoteHot gas at 853 K received from LOX/LH2 gas generator runs the turbine
But they then dump the exhaust instead of sending it into the main combustion chamber to realise staged combustion!!
And this is in 2010... TWO YEARS AFTER the acceptance test of the staged combustion engine. I don't understand why they went with staged combustion for the smaller engine, but are proceeding without it for a subsequent, larger engine. Surely the Isp and performance gains are more pronounced here? I know scaling introduces complexities... but it's still surprising.
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#123 by pippin on 06 Jan, 2014 11:27
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Probably a booster engine where cost and T/W are more important than ISP?
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#124 by antriksh on 06 Jan, 2014 11:28
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The dimensions of CUS12 and CUS25 are different, so its not feasible to switch the stages.
Are you sure that swapping in the engine really amounts to swapping the entire stage? It seems to me that it's more feasible to swap in the smaller CE7.5 engine into the larger CUS of the Mark-3. Then do vibrational testing, etc. Anyway, just a thought. It really seems to be a shame that they're doing the initial Mark-3 flight without testing the full launch stack, because it's not a true test of the vehicle. Instead, it looks like this aerodynamic test is being done to save face, in spite of the CE20 not being ready. Oh well, I guess it's more baby steps - Gradatim Ferociter and so on.
In launch vehicle design certification, the most challenging part is LV's journey through the atmosphere where its subjected to maximum pressure, load and stress. Now, ISRO can wait for 3 more years and then conduct the same launch with an operational cryo stage just to find out that something is wrong in the LVM3 design or it can do that testing now and certify the design. They have the first two stages ready, so its better to sort out any aerodynamic challenges now rather than discovering them after 3 yrs. -
#125 by antriksh on 06 Jan, 2014 14:26
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And this is in 2010... TWO YEARS AFTER the acceptance test of the staged combustion engine. I don't understand why they went with staged combustion for the smaller engine, but are proceeding without it for a subsequent, larger engine. Surely the Isp and performance gains are more pronounced here? I know scaling introduces complexities... but it's still surprising.
ISRO started with russian cryo engine as a reference design, which was staged combustion. During the development process, they realised the complexities involved in testing the subsystems (in sc engine, subsystem level tests are not possible). It seems after mastering the SC tech, for the CE20 engine, they chose cost and development complexity over efficiency or payload gain (200 kg).
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#126 by sanman on 10 Jan, 2014 03:22
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Just another article reiterating that the planned April 2014 flight of the GSLV-Mk3 will carry the crew module on a suborbital flight:
http://timesofindia.indiatimes.com/india/Isro-inches-closer-to-manned-mission/articleshow/28609291.cms -
#127 by vyoma on 10 Jan, 2014 03:31
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Just another article reiterating that the planned April 2014 flight of the GSLV-Mk3 will carry the crew module on a suborbital flight:
http://timesofindia.indiatimes.com/india/Isro-inches-closer-to-manned-mission/articleshow/28609291.cms
This is cool
I'm eagerly waiting for crew module tests. By the way, what's the difference between the module used in SRE and this crew module - in terms of technology used?
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#128 by sanman on 10 Jan, 2014 03:42
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I've no idea, but I'm imagining that testing the full crew module would sort of make SRE-2 redundant. SRE-2 is supposed to test communication blackout handling, as well as aerothermal structures and materials, and also carry some simple biological payload, I think.
http://en.wikipedia.org/wiki/Space_Capsule_Recovery_Experiment_II
If the crew module is being launched on Mk3, then I don't see why they couldn't do all the same tests on that flight. Anyway, just speculation.
Heh, I kind of like this rejiggering of the schedule along the way - it kind of keeps you on the edge of your seat, since nothing is totally set in stone. -
#129 by antriksh on 10 Jan, 2014 14:13
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Just another article reiterating that the planned April 2014 flight of the GSLV-Mk3 will carry the crew module on a suborbital flight:
http://timesofindia.indiatimes.com/india/Isro-inches-closer-to-manned-mission/articleshow/28609291.cms
Isro, as an additional feature, has also built in a separate escape module within the crew capsule. Sources said this module will in itself be a miniature space vehicle that can safely bring home its passengers.
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#130 by vyoma on 10 Jan, 2014 14:32
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Just another article reiterating that the planned April 2014 flight of the GSLV-Mk3 will carry the crew module on a suborbital flight:
http://timesofindia.indiatimes.com/india/Isro-inches-closer-to-manned-mission/articleshow/28609291.cms
Isro, as an additional feature, has also built in a separate escape module within the crew capsule. Sources said this module will in itself be a miniature space vehicle that can safely bring home its passengers.
Well, that's confusing!! It sounds like a crew module within a crew module
May be they're referring to "Launch Escape System" or even ejection seats, which separates the crew module from rocket in case of emergency during launch or first/second stage separation.
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#131 by sanman on 10 Jan, 2014 15:53
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ISRO's going for a traditional Launch Escape System, so I think the reporter's just muddled up on their understanding.
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#132 by vyoma on 11 Jan, 2014 02:39
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ISRO aims to fly GSLV Mk3 X1 up to 120km altitude, at which point crew module will also be tested:Quote
A manned space flight to a low-earth orbit (upwards of 160 km to a few hundred km) is on Isro's radar. Except the US' Apollo missions to the moon, all other human space flights took place in these zones.
QuoteThe experimental flight, however, will not carry a functional cryogenic engine. The heavy-duty rocket will fly up to an altitude of 120 km, after which it will take a parabolic path and dive in the Bay of Bengal.
http://www.deccanherald.com/content/379799/big-leap-indias-efforts-manned.htmlQuoteWhen GSLV Mk-III will be tested in three months' time, the heavy-duty rocket will fly the module to an altitude of about 120 km to see if it is safe for human flight. “GSLV Mk-III will carry the crew module to study re-entry and thermal behaviour,” said Isro chairman K Radhakrishnan here on Friday.
http://www.deccanherald.com/content/379831/india-test-human-crew-space.html -
#133 by antriksh on 11 Jan, 2014 04:43
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C25 stage & L110 Vikas engines!!!
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#134 by antriksh on 11 Jan, 2014 04:46
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Looking forward to LVM3-x!!
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#135 by antriksh on 11 Jan, 2014 08:46
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#136 by vyoma on 11 Jan, 2014 09:06
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Thanks for posting pics and video, antriksh. I had seen that video earlier. That opening song, which is from movie "Border", gives me goosebumps every time I hear it
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#137 by antriksh on 11 Jan, 2014 09:54
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Thanks for posting pics and video, antriksh. I had seen that video earlier. That opening song, which is from movie "Border", gives me goosebumps every time I hear it
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#138 by spaceash2 on 11 Jan, 2014 11:28
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It looks like Reentry module will be tested with GSLV III
Is this same as SRE?
http://www.deccanherald.com/content/379799/big-leap-indias-efforts-manned.html -
#139 by vyoma on 11 Jan, 2014 11:57
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It looks like Reentry module will be tested with GSLV III
Is this same as SRE?
http://www.deccanherald.com/content/379799/big-leap-indias-efforts-manned.html
No. Crew module and SRE are different, although they may share some common bits of technology (just speculating here).
GSLV Mk3 will carry this 3 people capacity crew module: http://en.wikipedia.org/wiki/ISRO_Orbital_Vehicle
SRE-2, which is a smaller sized capsule compared to crew module, will be carried by a PSLV in near future: http://en.wikipedia.org/wiki/Space_Capsule_Recovery_Experiment_II
Check these earlier posts as well:By the way, what's the difference between the module used in SRE and this crew module - in terms of technology used?
I've no idea, but I'm imagining that testing the full crew module would sort of make SRE-2 redundant. SRE-2 is supposed to test communication blackout handling, as well as aerothermal structures and materials, and also carry some simple biological payload, I think.
http://en.wikipedia.org/wiki/Space_Capsule_Recovery_Experiment_II
If the crew module is being launched on Mk3, then I don't see why they couldn't do all the same tests on that flight. Anyway, just speculation.
I'm eagerly waiting for crew module tests. By the way, what's the difference between the module used in SRE and this crew module - in terms of technology used?
May be they're referring to "Launch Escape System" or even ejection seats, which separates the crew module from rocket in case of emergency during launch or first/second stage separation.