LIVE: GSLV Mk-3 1st test launch (X1) December 18, 2014 (0400UTC)

[johnxx9]

 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.

[antriksh]

 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.

[johnxx9]

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.   

[antriksh]

A prototype of the crew capsule that will be used for ISRO’s future manned space flight will be tested aboard the GSLV Mk-III

http://www.newindianexpress.com/states/kerala/VSSC-Chief-Hints-at-Second-Mars-Mission-Using-GSLV/2013/12/21/article1957410.ece

[sanman]

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.

[antriksh]

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.

[sanman]

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?

[antriksh]

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.

[AJA]

...
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...

[sanman]

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.

[hop]

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.

[chota]

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

[sanman]

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.

[chota]

A fully assembled GSLV-MK3 way back in 2012!

Photo Credit : ISRO

[antriksh]

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.

[antriksh]

...
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.

[sanman]

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.

[antriksh]

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.

[sanman]

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.

[johnxx9]

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.