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#100
by
sanman
on 01 Dec, 2013 18:27
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AJA, I agree with what you've said, however I believe the flight has already been scheduled, and think it will take place anyway. The driver seems to be more political rather than engineering-driven. As you've pointed out, the Mark-III program is more than 10 years behind schedule, and the recent consecutive failures of the Mark-2 were a blow to ISRO's credibility. So they're now trying to fly this Mark-III aerodynamic test just to say "we're still making forward strides." In a way, the Chandrayaan mission has put that pressure on them, because it was that mission which suddenly put a media spotlight on ISRO and brought them a lot more attention from politicians in New Delhi.
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#101
by
antriksh
on 02 Dec, 2013 05:59
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IIRC the MkIII program when sanctioned planned on its first launch in 2004.
MK3 was sanctioned in 2005-6 with targeted first launch in 2010.
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#102
by
johnxx9
on 02 Dec, 2013 12:09
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IIRC the MkIII program when sanctioned planned on its first launch in 2004.
MK3 was sanctioned in 2005-6 with targeted first launch in 2010.
Let me rephrase my post. IIRC when the MK3 program was conceived, ISRO planned on its first launch in 2004.
But you are wrong. The program was approved in 2002. At that time ISRO said it would have its first launch in 2007-2008.
Development of GSLV-Mk III approvedPTI Aug 17, 2002, 08.04pm IST
BANGALORE: The government has given its approval for developing an advanced version of ISRO's Geo-synchronous Satellite Launch Vehicle, known as GSLV-Mk III, which will have the capability to launch four tonne satellites into Geo-synchronous Transfer Orbit.
According to ISRO, the development will take about six years.
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#103
by
antriksh
on 02 Dec, 2013 12:22
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IIRC the MkIII program when sanctioned planned on its first launch in 2004.
MK3 was sanctioned in 2005-6 with targeted first launch in 2010.
Let me rephrase my post. IIRC when the MK3 program was conceived, ISRO planned on its first launch in 2004.
But you are wrong. The program was approved in 2002. At that time ISRO said it would have its first launch in 2007-2008.
Development of GSLV-Mk III approved
PTI Aug 17, 2002, 08.04pm IST
BANGALORE: The government has given its approval for developing an advanced version of ISRO's Geo-synchronous Satellite Launch Vehicle, known as GSLV-Mk III, which will have the capability to launch four tonne satellites into Geo-synchronous Transfer Orbit.
According to ISRO, the development will take about six years.
Again, 2004 was never a target date because ISRO required new facilities for 200t solid motor, and a new cryogenic engine development.
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#104
by
johnxx9
on 02 Dec, 2013 17:10
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Again, 2004 was never a target date because ISRO required new facilities for 200t solid motor, and a new cryogenic engine development.
When the project was sanctioned in 2002 the target launch date was 2007. But when the project was conceived, as ISRO was ready to launch the original GSLV, the end of 1990s, was when the date of 2004 was mentioned. I remember having read it from one ArunS's articles and will try to look for it. But the GSLV itself had its first launch only in 2001 therefore the sanctioning for MkIII had to wait. And the other thing, ISRO knew it had to work on indigenous cryogenic engine for the GSLV soon after Russia signed the MTCR in early 1990s.
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#105
by
antriksh
on 22 Dec, 2013 07:16
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#106
by
sanman
on 05 Jan, 2014 11:12
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I'm curious - with the initial atmospheric test flight of GSLV-Mk3 only 4 months away, would it be conceivable to delay that launch date a little, in order to upgrade it to a full developmental test flight using an actual functioning cryogenic upper stage engine instead of a dummy load?
My understanding was that originally the first launch of GSLV-Mk3 was in fact intended to be a full developmental test flight with an actual cryogenic engine being part of that test. It seems to me that this was downgraded to an atmospheric test flight only because of the failure of the indigenous cryogenic engine on the preceding GSLV-Mk2 test flights.
With the cryogenic upper stage engine now having performed reasonably well according to predictions, it might be useful to return to the original plan of a full developmental flight including a working cryogenic upper stage engine, rather than just a mere atmospheric aerodynamic test flight with the dummy engine.
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#107
by
antriksh
on 05 Jan, 2014 11:18
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I'm curious - with the initial atmospheric test flight of GSLV-Mk3 only 4 months away, would it be conceivable to delay that launch date a little, in order to upgrade it to a full developmental test flight using an actual functioning cryogenic upper stage engine instead of a dummy load?
For a full developmental flight, ISRO will require the CE20 engine that is still under development. Only component level tests have been completed and engine level tests will take place this year. The cryo engines used on GSLV mk2 and LVM3 are totally different. GSLV mk2 uses CE7.5 which is a staged combustion cycle engine. LVM3 uses gas generator cycle engine.
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#108
by
sanman
on 05 Jan, 2014 11:23
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Hmm, I thought gas generator is easier, and staged combustion is the hardest.
Oh well, I didn't know that CE20 was a different animal than CE7.5, instead of being a scaled-up model.
Why did they choose gas generator for CE20, instead of going with staged combustion?
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#109
by
antriksh
on 05 Jan, 2014 11:28
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Hmm, I thought gas generator is easier, and staged combustion is the hardest.
Oh well, I didn't know that CE20 was a different animal than CE7.5, instead of being a scaled-up model.
Why did they choose gas generator for CE20, instead of going with staged combustion?
Less complexity and components can be tested separately without being part of engine. GSLV mk2 failure delayed the CE20 development because then both CE7.5 and CE20 shared the same engine test facility. Now ISRO has built one for CE20.
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#110
by
AJA
on 05 Jan, 2014 17:23
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...
GSLV mk2 uses CE7.5 which is a staged combustion cycle engine. LVM3 uses gas generator cycle engine.
The ISRO - DECU video clip detailing the cryogenic stage shown during today's launch coverage shows a stage with a gas-generator (2:06). I don't think they're talking about a generic cryo-stage either, given that the clip is talking specifically about the GSLV Mk-II, and therefore CES-7.5...
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#111
by
sanman
on 05 Jan, 2014 22:27
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For a full developmental flight, ISRO will require the CE20 engine that is still under development. Only component level tests have been completed and engine level tests will take place this year. The cryo engines used on GSLV mk2 and LVM3 are totally different. GSLV mk2 uses CE7.5 which is a staged combustion cycle engine. LVM3 uses gas generator cycle engine.
Could they substitute in the existing CES7.5 cryogenic engine stage from GSLV-Mk-2 into the GSLV-Mk-3 on this initial flight, just to fly something better than a dummy payload? Fine, it won't be the desired CE20 gas-generator engine, but at least it would provide more useful data than a dummy payload, which to me seems the least useful of all. Then at least that flight could loft some useful payload into orbit - like the prototype manned capsule, for instance.
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#112
by
hop
on 05 Jan, 2014 22:48
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Could they substitute in the existing CES7.5 cryogenic engine stage from GSLV-Mk-2 into the GSLV-Mk-3 on this initial flight, just to fly something better than a dummy payload?
Even if they could, it's not at all clear they should.
Dummy payloads are cheap. High performance cryogenic stages are not. There are good reasons to fly the least expensive option on an initial test flight. Especially when the alternative is creating a one-off configuration you are never going to use again.
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#113
by
chota
on 05 Jan, 2014 23:00
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The next test will be a civilian version of a ballistic missile test albeit the "war-head" will probably be a crew capsule with a parachute
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#114
by
sanman
on 05 Jan, 2014 23:08
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Even if they could, it's not at all clear they should.
Dummy payloads are cheap. High performance cryogenic stages are not. There are good reasons to fly the least expensive option on an initial test flight. Especially when the alternative is creating a one-off configuration you are never going to use again.
Well, it wouldn't have to be a one-off -- it could be used specifically for lunar/mars flights, while leaving the upcoming gas-generator for more routine nearby destinations. If you're going all the way to the Moon or Mars, then that extra little bit of performance from the staged-combustion might be more worth it. It seems like the farther you go, the more every tiny bit of Isp counts. Call it an "Earth Departure Stage" if you like.
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#115
by
chota
on 05 Jan, 2014 23:49
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A fully assembled GSLV-MK3 way back in 2012!
Photo Credit : ISRO
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#116
by
antriksh
on 06 Jan, 2014 01:54
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For a full developmental flight, ISRO will require the CE20 engine that is still under development. Only component level tests have been completed and engine level tests will take place this year. The cryo engines used on GSLV mk2 and LVM3 are totally different. GSLV mk2 uses CE7.5 which is a staged combustion cycle engine. LVM3 uses gas generator cycle engine.
Could they substitute in the existing CES7.5 cryogenic engine stage from GSLV-Mk-2 into the GSLV-Mk-3 on this initial flight, just to fly something better than a dummy payload? Fine, it won't be the desired CE20 gas-generator engine, but at least it would provide more useful data than a dummy payload, which to me seems the least useful of all. Then at least that flight could loft some useful payload into orbit - like the prototype manned capsule, for instance.
the production rate of CUS is very low and no flight worthy CUS is available.
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#117
by
antriksh
on 06 Jan, 2014 02:05
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...
GSLV mk2 uses CE7.5 which is a staged combustion cycle engine. LVM3 uses gas generator cycle engine.
The ISRO - DECU video clip detailing the cryogenic stage shown during today's launch coverage shows a stage with a gas-generator (2:06). I don't think they're talking about a generic cryo-stage either, given that the clip is talking specifically about the GSLV Mk-II, and therefore CES-7.5...
Both GG & SC cycles have gas generator.
In staged combustion cycle (SCC) the gas generator uses full LH2 flow rate and small quantity of LOX to generate
the hot gas at temperature acceptable to turbines. The hot gas expands in the turbines to develop the power required
for LOX/LH2 pumps and then it enters the combustion chamber where it burns with remaining LOX to develop
necessary thrust. Since combustion take place in staged manner in this cycle, hence it is called staged combustion cycle. In this cycle since gas generator gas enters the main combustion chamber there is no loss of ISP. Only draw back is that sub system level development is complicated and also pump/turbine power ratings are higher compared to GG Cycle for the
same chamber pressure.
In GSLV D5 brochure you can read about CUS.
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#118
by
sanman
on 06 Jan, 2014 02:39
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the production rate of CUS is very low and no flight worthy CUS is available.
Yeah, I'd read they can only produce 1 CUS every 6 months. So if they delayed the Mark-3 maiden flight by say, 4 months, would that be enough time? At least it would allow for the test flight to test the whole launch stack, rather than a half-test ("aerodynamic flight"). It would also count as an additional qualification flight for the CUS.
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#119
by
antriksh
on 06 Jan, 2014 03:24
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the production rate of CUS is very low and no flight worthy CUS is available.
Yeah, I'd read they can only produce 1 CUS every 6 months. So if they delayed the Mark-3 maiden flight by say, 4 months, would that be enough time? At least it would allow for the test flight to test the whole launch stack, rather than a half-test ("aerodynamic flight"). It would also count as an additional qualification flight for the CUS.
The dimensions of CUS12 and CUS25 are different, so its not feasible to switch the stages.