Author Topic: GSLV-Mk III - General Discussion  (Read 47342 times)

Offline Kosmos2001

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Re: GSLV-Mk III - General Discussion
« Reply #120 on: 06/22/2017 05:11 PM »
A nice shot of the CE-20 engine (an exhibit) with all the 'messy' plumbings visible..  :D

Source

Why it is so messy? Is it because the propellant?

Offline russianhalo117

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Re: GSLV-Mk III - General Discussion
« Reply #121 on: 06/22/2017 05:18 PM »
A nice shot of the CE-20 engine (an exhibit) with all the 'messy' plumbings visible..  :D

Source

Why it is so messy? Is it because the propellant?
Because its a gas generator cycle rather than expander or staged combustion cycle but most are this way.

Offline Kosmos2001

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Re: GSLV-Mk III - General Discussion
« Reply #122 on: 06/22/2017 06:04 PM »
Because its a gas generator cycle rather than expander or staged combustion cycle but most are this way.

Ah, thanks. I know some gas generators engines much more simplified than this one. At first I thought it was a prototype and therefore it needed to have more outputs for sensors and that stuff.

Online Lars-J

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Re: GSLV-Mk III - General Discussion
« Reply #123 on: 06/22/2017 09:25 PM »
On the lower PMF of GSLV-III compared to other rockets of its class and ISRO's plans to address it
...
The solid-vs-liquid debate
Quote
"We use solid fuel in the lower stages as it is cheaper than cryogenic fuel. Even other space agencies are looking to use solid fuel to cut costs," ISRO`s Liquid Propulsion Systems Centre Director S. Somanath told IANS.

"But other space agencies are looking at solid fuel to reduce cost only after their rockets carry far much heavier satellites than Indian rockets," the space industry expert pointed out.

That's an interesting claim to make... Solids being cheaper. It is not one that seems to have much real life support, with the possible exception of small boosters, perhaps. But the industry as a whole is moving away from them. All who use them in new designs (Ariane 6 and H-III) do so because they have the existing capability, so why not use it? Or because they have an existing military need for solids where they are trying to share costs somehow.

And as far as only being able to choose between solids and cryogenic (HydroLox). That's a false dilemma. What about KeroLox and MethaLox? Both are likely cheaper than either extreme option, and can outperform HydroLox upper stages. (the all-kerolox F9 is lighter than the GSLV-MK-III and yet lifts more)

My big issue with the GLSV-Mk III is how ISRO seems to be behind the curve. There is clearly so much technical capability, so why do they keep trying to re-create vehicles that are 20-30 years old (GSLV-Mk III being the child of Titan IV and Ariane 5) instead seeing where current industry trends, or even better - chart their own course completely?

(Doing reusability through fly-back boosters seems to be another example of this... People have talked about them for over 40 years, yet none have surfaced. But despite the recent successes of vertical landing boosters, ISRO appears to have made up their minds that fly-back boosters are the way forward)
« Last Edit: 06/22/2017 09:29 PM by Lars-J »

Offline vineethgk

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Re: GSLV-Mk III - General Discussion
« Reply #124 on: 06/23/2017 01:00 AM »
On the lower PMF of GSLV-III compared to other rockets of its class and ISRO's plans to address it
...
The solid-vs-liquid debate
Quote
"We use solid fuel in the lower stages as it is cheaper than cryogenic fuel. Even other space agencies are looking to use solid fuel to cut costs," ISRO`s Liquid Propulsion Systems Centre Director S. Somanath told IANS.

"But other space agencies are looking at solid fuel to reduce cost only after their rockets carry far much heavier satellites than Indian rockets," the space industry expert pointed out.

That's an interesting claim to make... Solids being cheaper. It is not one that seems to have much real life support, with the possible exception of small boosters, perhaps. But the industry as a whole is moving away from them. All who use them in new designs (Ariane 6 and H-III) do so because they have the existing capability, so why not use it? Or because they have an existing military need for solids where they are trying to share costs somehow.

And as far as only being able to choose between solids and cryogenic (HydroLox). That's a false dilemma. What about KeroLox and MethaLox? Both are likely cheaper than either extreme option, and can outperform HydroLox upper stages. (the all-kerolox F9 is lighter than the GSLV-MK-III and yet lifts more)

My big issue with the GLSV-Mk III is how ISRO seems to be behind the curve. There is clearly so much technical capability, so why do they keep trying to re-create vehicles that are 20-30 years old (GSLV-Mk III being the child of Titan IV and Ariane 5) instead seeing where current industry trends, or even better - chart their own course completely?

(Doing reusability through fly-back boosters seems to be another example of this... People have talked about them for over 40 years, yet none have surfaced. But despite the recent successes of vertical landing boosters, ISRO appears to have made up their minds that fly-back boosters are the way forward)
Perhaps ISRO's design choices for GSLV-III might make a bit more sense when we take into account the times they made them. The GSLV-III project was conceived back in the late 90s, with the full-fledged development starting by 2002. They were struggling to build a cryo engine for GSLV-II back then, and lacked the tech for bigger engines or clustering them. Ariane-5 was probably the success story that they counted on in those times. The rocket was supposed to start flying before the year 2010, but got delayed due to various reasons - the primary reason being the CE-20 development being held up by issues with CE-7.5. It is only now, with the success of GSLV-II, GSLV-III and the Mars missions (all incidentally happened within the last 3-4 years) that the agency has gained confidence to dip their toes into 'uncharted' (for them) waters of larger kerolox engines, their clusters and propulsive recovery.

But yes, it would seem that ISRO had a habit of missing the bus on many occasions. They conceived a GSLV-I/GSLV-II (based on PSLV design template) in the late 1980s confident that it would meet the country's requirement for carrying communication satellites, but when it started flying they found that those very satellites had become much heavier and beyond the capacity of the GSLV. A similar jinx would have happened for GSLV-III too if not for the promise of electric propulsion.

But it would seem now that they have finally decided to catch up with the rest of the world if one were to look at the new LV studies they are making. Other than their immediate plan to use the under-development SCE-200 kerolox engine to enhance the capability of GSLV-III to 6T, they are looking to cluster the engines in numbers of 4-5 to make a new, more powerful core which they then plan to couple with a hydrolox upper stage to create an all-liquid launcher for their future needs. That 5-engine version in particular appears to be conceived with the possibility of future propulsive recovery in mind, F9 style. In parallel they have also started works on a smaller methalox engine as a tech demo, and might proceed to the development of a much larger one after SCE-200 is realized (by the year 2020 or so going by their planned timelines).
« Last Edit: 06/23/2017 01:11 AM by vineethgk »

Offline vyoma

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Re: GSLV-Mk III - General Discussion
« Reply #125 on: 06/23/2017 06:04 PM »
As mentioned in PSLV-C38 post-launch briefing - ISRO is working on increasing the thrust of L110 stage Vikas engines in order to improve GSLV Mk III efficiency.

Offline vineethgk

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Re: GSLV-Mk III - General Discussion
« Reply #126 on: 06/24/2017 12:10 AM »
As mentioned in PSLV-C38 post-launch briefing - ISRO is working on increasing the thrust of L110 stage Vikas engines in order to improve GSLV Mk III efficiency.
To add to that, they mentioned increasing the performance of CE-20 as well towards the same objective.

Offline russianhalo117

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Re: GSLV-Mk III - General Discussion
« Reply #127 on: 06/24/2017 12:50 AM »
As mentioned in PSLV-C38 post-launch briefing - ISRO is working on increasing the thrust of L110 stage Vikas engines in order to improve GSLV Mk III efficiency.
To add to that, they mentioned increasing the performance of CE-20 as well towards the same objective.
C-25 stage to be upgraded to C-27 with uprated engine

Online sanman

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Re: GSLV-Mk III - General Discussion
« Reply #128 on: 06/26/2017 10:02 PM »
On the lower PMF of GSLV-III compared to other rockets of its class and ISRO's plans to address it
...
The solid-vs-liquid debate
Quote
"We use solid fuel in the lower stages as it is cheaper than cryogenic fuel. Even other space agencies are looking to use solid fuel to cut costs," ISRO`s Liquid Propulsion Systems Centre Director S. Somanath told IANS.

"But other space agencies are looking at solid fuel to reduce cost only after their rockets carry far much heavier satellites than Indian rockets," the space industry expert pointed out.

That's an interesting claim to make... Solids being cheaper. It is not one that seems to have much real life support, with the possible exception of small boosters, perhaps. But the industry as a whole is moving away from them. All who use them in new designs (Ariane 6 and H-III) do so because they have the existing capability, so why not use it? Or because they have an existing military need for solids where they are trying to share costs somehow.

And as far as only being able to choose between solids and cryogenic (HydroLox). That's a false dilemma. What about KeroLox and MethaLox? Both are likely cheaper than either extreme option, and can outperform HydroLox upper stages. (the all-kerolox F9 is lighter than the GSLV-MK-III and yet lifts more)

My big issue with the GLSV-Mk III is how ISRO seems to be behind the curve. There is clearly so much technical capability, so why do they keep trying to re-create vehicles that are 20-30 years old (GSLV-Mk III being the child of Titan IV and Ariane 5) instead seeing where current industry trends, or even better - chart their own course completely?

(Doing reusability through fly-back boosters seems to be another example of this... People have talked about them for over 40 years, yet none have surfaced. But despite the recent successes of vertical landing boosters, ISRO appears to have made up their minds that fly-back boosters are the way forward)


Hi, let me please quote from the following:

http://www.frontline.in/science-and-technology/in-the-big-league/article9731133.ece?homepage=true#test

Quote
Locational constraint

An area of major concern was the launch constraint imposed by the location of Sriharikota, India’s space port. The launch had to take place eastward from the island to put a communication satellite into the GTO. This did not offer “full freedom” because after the vehicle cleared the Bay of Bengal, the Indonesian land mass appeared on the scene. The launch vehicle debris—from the jettisoned stages—should not be allowed to fall over Indonesia.

Sivan said: “We had seen that when the vehicle reached a velocity of more than 5 km a second, the Indonesian land mass came in. So we had a requirement of designing a launch vehicle that will have a capacity of reaching [a velocity of] 5 km a second. But it is the lower stages that should produce that velocity of 5 km a second. We then needed one more stage which will produce another 5 km a second of velocity. There cannot, however, be an intermediary stage. [A total of 10.2 km a second velocity is required to put a four-tonne satellite into the GTO.] After the vehicle crosses the land mass, its stages should not come down. They should continuously burn and go into orbit. That means we should have a stage that should give another 5 km a second after the vehicle crosses the land mass. So we had to necessarily go in for a cryogenic stage that will give 5 km a second at a stretch and carry the four-tonne satellite into orbit. To put a 2.2-tonne satellite into orbit, we had a cryo stage with 12 tonnes of liquid oxygen and liquid hydrogen. But to put a four-tonne satellite into orbit, we needed a cryogenic stage which will use 25 tonnes of propellants. That is how the C-25 stage came into the picture.”


Launch site geography was a key constraint here.

Online Lars-J

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Re: GSLV-Mk III - General Discussion
« Reply #129 on: 06/26/2017 10:39 PM »
Hi, let me please quote from the following:

http://www.frontline.in/science-and-technology/in-the-big-league/article9731133.ece?homepage=true#test

Quote
Locational constraint

An area of major concern was the launch constraint imposed by the location of Sriharikota, India’s space port. The launch had to take place eastward from the island to put a communication satellite into the GTO. This did not offer “full freedom” because after the vehicle cleared the Bay of Bengal, the Indonesian land mass appeared on the scene. The launch vehicle debris—from the jettisoned stages—should not be allowed to fall over Indonesia.

Sivan said: “We had seen that when the vehicle reached a velocity of more than 5 km a second, the Indonesian land mass came in. So we had a requirement of designing a launch vehicle that will have a capacity of reaching [a velocity of] 5 km a second. But it is the lower stages that should produce that velocity of 5 km a second. We then needed one more stage which will produce another 5 km a second of velocity. There cannot, however, be an intermediary stage. [A total of 10.2 km a second velocity is required to put a four-tonne satellite into the GTO.] After the vehicle crosses the land mass, its stages should not come down. They should continuously burn and go into orbit. That means we should have a stage that should give another 5 km a second after the vehicle crosses the land mass. So we had to necessarily go in for a cryogenic stage that will give 5 km a second at a stretch and carry the four-tonne satellite into orbit. To put a 2.2-tonne satellite into orbit, we had a cryo stage with 12 tonnes of liquid oxygen and liquid hydrogen. But to put a four-tonne satellite into orbit, we needed a cryogenic stage which will use 25 tonnes of propellants. That is how the C-25 stage came into the picture.”


Launch site geography was a key constraint here.

Yes, it is a constraint, but an not as important as it might seem. An upper stage with 5km/s delta-v is not that unusual and does not require hydrogen. For example, the F9 upper stage (again KeroLox) provides 7.5-8 km/s of delta-V.

It does bug me when the Sriharikota location is used an excuse like that. Most countries would LOVE to have that location. It may be the 2nd best located launch complex on earth after French Guyana, and many two-stage launch vehicles could operate out of there without making any changes.
« Last Edit: 06/26/2017 10:39 PM by Lars-J »

Online sanman

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Re: GSLV-Mk III - General Discussion
« Reply #130 on: 06/27/2017 05:15 PM »
Yes, it is a constraint, but an not as important as it might seem. An upper stage with 5km/s delta-v is not that unusual and does not require hydrogen. For example, the F9 upper stage (again KeroLox) provides 7.5-8 km/s of delta-V.

It does bug me when the Sriharikota location is used an excuse like that. Most countries would LOVE to have that location. It may be the 2nd best located launch complex on earth after French Guyana, and many two-stage launch vehicles could operate out of there without making any changes.

Well, I'd prefer a precedent from a pre-Falcon rocket, because GSLV was conceived long before it. Besides, ISRO was looking to scale past what individual expendable Falcon9 can do.

But I'd agree that Sriharikota is a pretty decent launch site, overall - other than the fact that nearby Sri Lanka forces ISRO rockets to do a dog-leg maneuver for some launches. Once ISRO develops a reusable booster, I'd imagine that it could have more latitude in turning around rather than traveling ballistically.
« Last Edit: 06/27/2017 05:18 PM by sanman »

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