Indian Space Program: News & Discussion - Sept 2016

[Indranil]

There is one thing that ISRO has mastered well. They have figured out ways to carry multiple satellites without any significant overhead. This is not true with others. For example the difference of launch capacities of Ariane 5 for a single payload and a double payload is 500-800 kgs.

[disha]

This is a good read with nuggets http://thewire.in/68021/pslv-c35-scatsat-blacksky/

TBH., a very pathetic article. Calls student built satellites as space junk endangering ISS. The above article is actually an endangerment to the logic and rationality of space sciences.

[disha]

I am almost certain it can be. GSLV MK2 configuration is not optimum. It does not take a rocket scientist to understand so. But, there are good reasons for the same. Here are some quality posts on the internet.

Basically the posts from the internet has validated what the several posters here have been telling in several past pages. Interestingly you decided to look out rather than the quality posts within!

Now when one explains that the skew towards 'reliability' is more important than skew towards 'efficiency'., one does not have to go into a complete discussion on the complex industrial processes that go in making a rocket. The very fact that very few (less than equal to 6 agencies) world over launch bus sized objects into space demonstrates the very complexity of the process. Some countries have been restricted to launch this https://en.wikipedia.org/wiki/VS-30

Here is something you can relate to., just based on brochure JF-Thunder seems to have better statistics than LCA. Is that a right comparison?

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In previous posts., I pointed out to you that LM-4 may be using a different cryogenic engine (>150 kN) than the @75 kN assumed from wikis which is giving it better payload capacity. Did you get around to look at it? The focus is on lower stages (and unnecessary comparison between cryo/semi-cryo) on GSLV D1 when the explanation is readily somewhere else.

[Indranil]

I am almost certain it can be. GSLV MK2 configuration is not optimum. It does not take a rocket scientist to understand so. But, there are good reasons for the same. Here are some quality posts on the internet.

Basically the posts from the internet has validated what the several posters here have been telling in several past pages. Interestingly you decided to look out rather than the quality posts within!

Now when one explains that the skew towards 'reliability' is more important than skew towards 'efficiency'., one does not have to go into a complete discussion on the complex industrial processes that go in making a rocket. The very fact that very few (less than equal to 6 agencies) world over launch bus sized objects into space demonstrates the very complexity of the process. Some countries have been restricted to launch this https://en.wikipedia.org/wiki/VS-30

I did not refute you earlier on this, nor am I doing it now. I have always said that there are reasons for what ISRO is doing. I found something on the net which was a nicely articulated answer pertinent to the discussion at hand, and brought it in. I find no contradictions in suggesting that ISRO did the best with whatever they had. But those things were not enough. One is bound to come up with a suboptimal design. ISRO knowingly went down that path, because there was no other. Where is the contradiction? If one thinks that GSLV is an optimal design, (s)he is either ignorant, or in denial. The laws of physics does not change for anybody.

Here is something you can relate to., just based on brochure JF-Thunder seems to have better statistics than LCA. Is that a right comparison?

There are some aerodynamic advantages of the JF-17s layout over LCA's layout, and vice versa. That does not change whether you or I agree or not. Similarly, GSLV design is a compromise based on our national capacity at the moment. If we replace the S139 with a solid booster which burns for at least 148 seconds, we will have a launch vehicle with higher payload. If we can replace any of the stages, with another having high efficiency, the capacity will increase. This is science. It doesn't change whether you or me believe in it or not.

In previous posts., I pointed out to you that LM-4 may be using a different cryogenic engine (>150 kN) than the @75 kN assumed from wikis which is giving it better payload capacity. Did you get around to look at it? The focus is on lower stages (and unnecessary comparison between cryo/semi-cryo) on GSLV D1 when the explanation is readily somewhere else.

Actually, I did try to. The upper stage is a 157 kN cryo. But that does not change what we have been discussing. When the CE-20 comes on board, what would have happened if we replaced the CE7.5 with it. Certainly, we will not reach the payloads of the LM-3B. Reason: our first stage is not as efficient as their all-liquid stage. Fair enough, I asked, what if we replaced our S139 with a S200. It won't be as optimal as the 3B, but that should bring us close to the full potential of the GSLV Mk2 configuration. I asked these questions. I was hounded for the same.

[disha]

If one thinks that GSLV is an optimal design, (s)he is either ignorant, or in denial. The laws of physics does not change for anybody.

I did ask several times if you refer to GSLV Mk1/II or Mk III. If you are including Mk III., then the analogy equivalent is to mix LCA with Rafale in a single bucket. GSLV Mk III is altogether a different design. Not to be compared with GSLV Mk II and to even state that the air lit core L110 stage leads to a sub-optimal design because it is *air-lit* is just ridiculous. GSLV Mk III should not be even up for debate.

Nobody denies that GSLV MkII is a sub-optimal design. In fact several posts indicated that the skew was for reliability vs. efficiency. Now the quantum of "inefficiency" is debated and within that numbers from GSLV Mk1 D1 is pulled forward to claim a skew of >50% inefficiency in payload and with it a whole range of name calling and a very commie branding.

Actually, I did try to. The upper stage is a 157 kN cryo. But that does not change what we have been discussing.

Really? Particularly when the payload capacity of GSLV Mk I/II is compared with payload capacity of LM 4 to derive at "inefficiency" when the last stage (the stage which actually orbits the satellite) of LM 4 is twice (2 times) powerful than the upper stage of GSLV Mk II !! Since the last stage is 2 times powerful., it simply posits that it has higher payload capacity than that of GSLV Mk I/II with an equivalent thrust lower stages will not be able to compensate. So where is the inefficiency in payload?

My point is GSLV D1 Mk1 was compared to L4 to arrive at payload inefficiency conclusion., which itself is wrong where two completely different rocket families are compared on net payload. It is like comparing the payload capacity in Kg of Su-27 MKI with LCA and stating that LCA is a "cheetah with 3 legs" because it does not carry larger payload like Su-27 MKI. Note payload efficiency is a set of different calculations than net payload.

When the CE-20 comes on board, what would have happened if we replaced the CE7.5 with it.

In theory yes., but in practice ISRO will not (and must not) replace the CE 7.5 with CE-20 (27 tonnes propellant loading or rather 3x increase in mass) on GSLV Mk1/II. Same as why we cannot put F404 in Jaguars. Everything on the lower stages changes and needs to be redesigned. Remember while going up at 2-3 g's the lower stage itself & trusses which bear the weight of the upper stages need to be strengthened (or they will deform under pressure leading to failure) to account for now 3x increase in mass. If you think about it., you will realize why ISRO loaded only 125 tonnes of propellant in the initial test of GSLV D1 Mk1. Further the interstage & fairing - particularly between the second stage and the new CUS CE-20 has to be redesigned and it will be a going from a small diameter to a larger diameter (2m to 4m)., further with a heavier upper stage - the entire CG shifts forward and to bring it back the rocket has to be lengthened or SITVC has to be attached to compensate for the additional momentum in the pitch and yaw due to increased upper stage mass. In effect you have designed a rocket like Ares-I (you can check that out) and this is actually an entirely different new rocket calling for a different mission campaign and a whole slew of testing.

Certainly, we will not reach the payloads of the LM-3B. Reason: our first stage is not as efficient as their all-liquid stage. Fair enough, I asked, what if we replaced our S139 with a S200. It won't be as optimal as the 3B, but that should bring us close to the full potential of the GSLV Mk2 configuration. I asked these questions. I was hounded for the same.

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Coming to your question., this is a reverse question of the above. [paraphrasing] On GSLV Mk II (GSLV Mk I is retd.) why not put S200 as the core solid stage I booster. This is more plausible and one still needs to design and fabricate an interstage with an altogether new stage separation mechanism. In a way it will look like SLV3 only narrowing from SSI to SS2 (instead of SS2 to SS3). Of course going from 3.2 m to 2.8 m is not trivial and this will require new calculations and another new set of campaign.

Note that S200 was ready only in 2010 and it was used for LVM3 campaign in 2014., when the first successful flight with indigenous CUS on GSLV Mk II happened only in Jan 2014. Given this., it makes sense to focus more on GSLV Mk III and get it off the ground. It is not capacity but priorities.

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The question one should ask is what is the future of CUS? It went from naughty boy to adorable boy and is 10% more efficient than CE-20. However current ISRO chairman is completely for reliability., so my fear is that CE-7.5 may see a premature sunset instead of being scaled up.

It would be better if CE-7.5 (the staged combustion cycle) will be scaled up to 200-250 kN and the CE-200 to be scaled up to 2 mN (or 2000 kN). With effective throttling ., ISRO can thus have a range of engines to work with.

[vina]

GSLV Mk III should not be even up for debate

LVM3/Care flight lugged 60 tons of deadweight for 20 seconds ! Now that should NOT be debated , because it will be OT, and of course the topic should be invective laced amateur videos by a bunch of near yahoos that is presented as "Sonic Booms" . Let us hear theories (with numbers/science based justifications please) on why it is carried like this, since the "explanation" we got for GSLV MK1/2 ("industrial capacity", etc. etc.) for carrying dead weight is not applicable to GLSV MKIII. It is a clean sheet design. You are flying with well proven components.

So why did they choose to lug 60 tons of dead weight for 20 seconds ?

Nobody denies that GSLV MkII is a sub-optimal design

Now what does "EVERYBODY" (except me) say about GSLV MKIII , if "nobody" denies that the MKII is sub optimal ?

Now the quantum of "inefficiency" is debated and within that numbers from GSLV Mk1 D1 is pulled forward to claim a skew of >50% inefficiency in payload ...

On GSLV Mk II (GSLV Mk I is retd.) why not put S200 as the core solid stage I booster. This is more plausible and one still needs to design and fabricate an interstage with an altogether new stage separation mechanism.

Ah . That is why actually put in numbers and doing stuff is invaluable. Look into the "design" thread and you will be surprised.

[Indranil]

Actually, I did try to. The upper stage is a 157 kN cryo. But that does not change what we have been discussing.

Really? Particularly when the payload capacity of GSLV Mk I/II is compared with payload capacity of LM 4 to derive at "inefficiency" when the last stage (the stage which actually orbits the satellite) of LM 4 is twice (2 times) powerful than the upper stage of GSLV Mk II !! Since the last stage is 2 times powerful., it simply posits that it has higher payload capacity than that of GSLV Mk I/II with an equivalent thrust lower stages will not be able to compensate. So where is the inefficiency in payload?

My point is GSLV D1 Mk1 was compared to L4 to arrive at payload inefficiency conclusion., which itself is wrong where two completely different rocket families are compared on net payload. It is like comparing the payload capacity in Kg of Su-27 MKI with LCA and stating that LCA is a "cheetah with 3 legs" because it does not carry larger payload like Su-27 MKI. Note payload efficiency is a set of different calculations than net payload.

This does not reflect a correct understanding or analogy. If we had a CUS which had twice the thrust, it would have helped, but would not have doubled the payload. The first and second stage of the 3B are capable of lifting the twice as heavy CUS and payload to the necessary altitude and speed. The second stage of GSLV Mk2 and the 3B are almost identical. The major difference comes from the first stage. Even there the strap ons are the same engines. The only difference comes from the core. 3Bs liquid power core is obviously more efficient than our solid powered S139. Plus they discard every stage as soon as they are used up. We cannot do so for the empty S139 and lug its empty weight of 28 tons for nearly 40 seconds.

By the way their upper stage has no special magic as well. They have clustered two CE7.5 class engines. We did not have this luxury. We could not master the cryo engine fast enough, and were running out of the Russian supplied ones.

When the CE-20 comes on board, what would have happened if we replaced the CE7.5 with it.

In theory yes., but in practice ISRO will not (and must not) replace the CE 7.5 with CE-20 (27 tonnes propellant loading or rather 3x increase in mass) on GSLV Mk1/II. Same as why we cannot put F404 in Jaguars. Everything on the lower stages changes and needs to be redesigned. Remember while going up at 2-3 g's the lower stage itself & trusses which bear the weight of the upper stages need to be strengthened (or they will deform under pressure leading to failure) to account for now 3x increase in mass. If you think about it., you will realize why ISRO loaded only 125 tonnes of propellant in the initial test of GSLV D1 Mk1. Further the interstage & fairing - particularly between the second stage and the new CUS CE-20 has to be redesigned and it will be a going from a small diameter to a larger diameter (2m to 4m)., further with a heavier upper stage - the entire CG shifts forward and to bring it back the rocket has to be lengthened or SITVC has to be attached to compensate for the additional momentum in the pitch and yaw due to increased upper stage mass. In effect you have designed a rocket like Ares-I (you can check that out) and this is actually an entirely different new rocket calling for a different mission campaign and a whole slew of testing.

No sir, this is not completely true either. For example if the weight of the second + third stage is kept constant, the first stage sees no change in payload!. And changing the trusses is not that big of a deal, may be a years work.

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[\quote]
Again, it is not the right analogy.Changing the stage in a rocket is not the same as changing the engines on an aircraft. Modern rockets are designed to be modular, where stages/boosters can be added or swapped out. If what you said were true, we would not have different versions of PSLV, a potential 4th stage in GSLV, or any of our modular ULV/HLV in future. HLV for example will have payload capacity from 1 ton to 10 tons.

Well, SCE-200 take care of the 2MN class of engines.

[Indranil]

LVM3/Care flight lugged 60 tons of deadweight for 20 seconds !

I don't understand this.

[disha]

LVM3/Care flight lugged 60 tons of deadweight for 20 seconds !

I don't understand this.

He is talking about the dummy upper stage. It was liquid nitrogen filled dummy stage.

I mean if that is the stick to beat ISRO/Indians with., then it proves that the said poster will even use a stump to beat ISRO/Indians with as long as the goal remains to beat with all means fair or foul (and mostly foul)

[vina]

I don't understand this.

He is talking about the dummy upper stage. It was liquid nitrogen filled dummy stage.

I mean if that is the stick to beat ISRO/Indians with., then it proves that the said poster will even use a stump to beat ISRO/Indians with as long as the goal remains to beat with all means fair or foul (and mostly foul)

Just as expected. There Indranil . They "thought" and "felt" and here , you have your answer! Brilliant!

[disha]

No sir, this is not completely true either. For example if the weight of the second + third stage is kept constant, the first stage sees no change in payload!. And changing the trusses is not that big of a deal, may be a years work.

So the propellant loading on both second and third stage has to decrease - that means a deficiency in both altitude and more importantly velocity. But to compensate that you have to increase the propellant loading (somewhere else).

Assuming X, Y and Z are your variables and X is what you put in (increasing the tonnage of CUS by 3x !!) - Basically to put in X., you now compensate with changes in Y and to compensate Y you go and change Z (see the design thread itself). Of course at the end of the day you will solve X, Y and Z and you would have produced an altogether new rocket! Congratulations!

Further posts on this in design thread.

[symontk]

LVM3/Care flight lugged 60 tons of deadweight for 20 seconds !

I don't understand this.

Vina is referring to the GSLVMK3 flight profile where the solid boosters werent separated and it was there until main liquid engines separated from the vehicle

But Vina, it was an experimental flight, ISRO was testing lot of other things and not a valid flight to comment on this. lets wait for the first dev flight this year

[SSSalvi]

Current position of satellites launched yesterday by PSLV.



First figure shows the location where SCATSAT was inserted in the Red coloured orbit. Then it released other 7 satellites after two burns of 4th stage.

After about a day we can see all those satellites spread out in two orbits.

Officially the satellites have yet to be alloted with their respective names. Currebtly these have been identified alphabetically as objects A to K. Wait! .. How many are A to K? ( There is no I to avoid confusion with 1 ) .. TEN.

But we know that in all 8 satellites were launched then how come there are 10?

The extra two are .. 1. Dual Launch Adapter ( DLA ) which was ejected after first re-burn of 4th stage .. and 2. the 4th stage itself .

Although the satellites are yet to be officially identified their positions imply to identifying at least a few :

Object H is clearly a lonely SCATSAT-1.

Objects J and A are clearly different from the other lot. One is a DLA which was independently ejected and the other one is 4th stage.

[geeth]

[quote]So why did they choose to lug 60 tons of dead weight for 20 seconds ?/quote]

Because it gives about 6% more efficiency to the vikas engines used in MKIII. In addition, the solid rocket nozzle is optimised to perform at lower altitudes.

There are other factors also like stability of the vehicle, aerodynamic load, overdesign of structural members for safety, experimental data collection payload position etc etc. In any case this is not the final configuration.

Unless a major portion of the design data is available, this kind of discussions would help massage some egos onlee...IMO ofcourse!

[prasannasimha]

Just to put it in perspective I know a student rocket program being done and guess the number of iterations analyzed for optimization (albeit algorithmic)- approaching 60000. It is not that simple as what some people think. There is a whole optimization study taken when using a particular configuration and some of these configurations are used due to some or the other constraint knwoing fully well the limitations that it may pose.

[nirav]

^ Design discussion still feels somewhat okay. Gets the gray matter running.

But making absolute conclusions and offering "fixes" out of such spreadsheet "models" is whats something outrageous and ridiculous.

The way ISRO and its design choices/configurations have bee criticized here, one feels that Scientist S is *the* authority on Rockets and that ISRO still cant rise up to his 30 minuted spreadsheet brilliance.

Yesterdays excellent launch of the PSLV and the remarkable injecting of those satellites in different orbits - "Pah" as Scientist S would say ... They should have aimed for FOUR different orbits. Why TWO only ? Very inefficient.

On a side note, if GSLV mk2 can be "fixed" for 6 tons to GTO, why not fix PSLV for 4 tons to GTO hain ?

Who needs GSLV MK3 when you have such 30 minute spreadsheet "fixes" available.

[disha]

On a side note, if GSLV mk2 can be "fixed" for 6 tons to GTO, why not fix PSLV for 4 tons to GTO hain ?

Who needs GSLV MK3 when you have such 30 minute spreadsheet "fixes" available.

Actually., Why not fix ASLV? I am really serious., here is my plan (and trust me, I did fly rockets and yes I had codes in mathematica to simulate various parameters)., and I am very certain that folks at ISRO will agree that it is a workable plan.

Instead of the two SLV boosters on it sides of ASLV., put in two S200 boosters. And put a CE-200 stage (not engine - stage with 27 tonnes propellant) on the top (also called stage 5). Get rid of the second, third & fourth stage of ASLV to save the weight and put in a core HNO4/UDMH liquid stage. Since one has to match the bigger diameter CE-200 top stage., a better deal will be to cluster the liquid engines (at least two) into a single HNO4/UDMH liquid stage. This way I do not have to create an interstage going from a smaller diameter to a larger diameter (and associated calculations of pressure/weight/CG etc)., and I also got rid of the measly 2,3 & 4 solid stages of ASLV (they were correspondingly 1,2 & 3 solid stages of SLV-3).

This one will give me based on my calculations @3-4 tonnes to GTO. I am calling this newly designed rocket as my own Augmented Super Satellite Launch Vehicle (copyrighted by Disha).

[Indranil]

Just to put it in perspective I know a student rocket program being done and guess the number of iterations analyzed for optimization (albeit algorithmic)- approaching 60000. It is not that simple as what some people think. There is a whole optimization study taken when using a particular configuration and some of these configurations are used due to some or the other constraint knwoing fully well the limitations that it may pose.

You could optimize it for 60000 more cycles, but the gain will be less than 1%. You can do a mass fraction of the payloads to GTO of 1960s circa rockets which were done using slide rules (ruling out 60,000 optimization cycles) and that of today's rocket, you will have your proof.

The problem is now people will feel I am berating the optimizations, or downplaying their role. You people are trying to convince me that ISRO is doing a fabulous job, and a lot of it. I already know it. You don't have to prove that their work is not trivial. If ISRO were to continue with the GSLV MK2 for say a decade longer, what could its payload to GTO have been "simple" modifications.

Nobody is telling ISRO what to do and how to do it. I am trying to understand why they are doing what they are doing.

So why did they choose to lug 60 tons of dead weight for 20 seconds ?

Because it gives about 6% more efficiency to the vikas engines used in MKIII.

This is very interesting. It does not make sense to me, but there are huge gaping holes in my knowledge. Could you please elaborate on the same?

In addition, the solid rocket nozzle is optimised to perform at lower altitudes.

This is true. The specific impulse of these solid motors is only slightly lesser than our liquid engines.

[Indranil]

On a side note, if GSLV mk2 can be "fixed" for 6 tons to GTO, why not fix PSLV for 4 tons to GTO hain ?

Who needs GSLV MK3 when you have such 30 minute spreadsheet "fixes" available.

Actually., Why not fix ASLV? I am really serious., here is my plan (and trust me, I did fly rockets and yes I had codes in mathematica to simulate various parameters)., and I am very certain that folks at ISRO will agree that it is a workable plan.

Instead of the two SLV boosters on it sides of ASLV., put in two S200 boosters. And put a CE-200 stage (not engine - stage with 27 tonnes propellant) on the top (also called stage 5). Get rid of the second, third & fourth stage of ASLV to save the weight and put in a core HNO4/UDMH liquid stage. Since one has to match the bigger diameter CE-200 top stage., a better deal will be to cluster the liquid engines (at least two) into a single HNO4/UDMH liquid stage. This way I do not have to create an interstage going from a smaller diameter to a larger diameter (and associated calculations of pressure/weight/CG etc)., and I also got rid of the measly 2,3 & 4 solid stages of ASLV (they were correspondingly 1,2 & 3 solid stages of SLV-3).

This one will give me based on my calculations @3-4 tonnes to GTO. I am calling this newly designed rocket as my own Augmented Super Satellite Launch Vehicle (copyrighted by Disha).

If you both don't want to enter a technical discussion on why GSLV Mk2s payload is lower than the global norms, then please stay out of it. Please stop derailing this thread and deriding other posters. And the same goes to Vina, please restrict yourself to just technical discussions and no name-calling.

By the way, you both have been reported by posters. Don't push the moderators to a point where they have no option but to act.

[nirav]

If you both don't want to enter a technical discussion on why GSLV Mk2s payload is lower than the global norms, then please stay out of it. Please stop derailing this thread and deriding other posters. And the same goes to Vina, please restrict yourself to just technical discussions and no name-calling.

By the way, you both have been reported by posters. Don't push the moderators to a point where they have no option but to act.

Indranil,

I appreciate you sharing the report on me by other posters.
I of course cant and wont tell the mods how to do their jobs but i will certainly say this and i think im well within my rights to articulate what i feel about the topic.

First up,my criticism was not directed at you.You *are* discussing whereas the other person is offering it as a "fix" for GSLV.


Just to highlight one of the glaring deficiencies of spreadsheet based 6 tons to GTO, have you guys discussed the impact of Centre of Gravity or Centre of pressure on those hypothetical models ? For all you know, the easy 30 minute fix isnt flyable at all ! But still its being brandished as a "fix" for GSLV.
This is not science nor physics .. Just a wishlist ..

Put two outside,cluster four and voila 6 tons to GTO is NOT a "technical" discussion.

Would you really appreciate this kind of technical discussions elsewhere ? LCA thread ?

I agree i have taken it a bit far with the epithets, but do understand i did that only to make a certain person realise how monikers and mockery feels when one is at the receiving end.
I'll cease and desist on that front hereon.

[disha]

Added later: One thing I learnt when I built my own model rockets that could actually carry a payload >2500 feet., was appreciation of the professionals who did the real thing! This (both appreciation and rocketry) is something that can only be learnt by experience. And that is why no serious rocketeer (and definitely not the amateur ones) will mock in any manner the rocketeers who actually do it.

As an aside: Do you know that S139 is one of the largest solid booster in continuous operation in the world and the largest in Asia? Point is why would a rocket designer ignore such a reliable, high-thrust, cheap and versatile booster while designing next evolution of the rocket?
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If ISRO were to continue with the GSLV MK2 for say a decade longer, what could its payload to GTO have been "simple" modifications.

There in lies the problem we are trying to point to. There are no "simple" modifications on the GSLV Mk2 to increase its GTO capability substantially.

Let us break it down on what we agree on.

1. Is GSLV Mk2 sub-optimal. Yes.

2. What is the quantum of "sub-optimal" (or rather what is the quantum of improvement within its current design)? There is no agreement in this number., particularly when the numbers are bandied from GSLV D1 Mk1 - which had a lower propellant loading and did not use maraging steel and the number for the inert mass of the stage was taken from spaceflight website which itself does not reveal its sources (any number outside of ISRO's own public information must be treated suspect).

So there is complete disagreement on the numbers itself. 30 tonnes of inert mass is assumed because spaceflight quoted it based on GSLV D1 Mk1. Given that egregious data as a basis., how can one come to an agreement on the number for quantum of improvement within GSLV Mk II?

Now the manner of calculations. Mistakes are piled on with several contradictions. For example the said poster completely forgot about "gravity turn" and of course his/her "spreadsheet" does not include that function. So how can one trust the numbers posted? Leave alone agree? And what is the method of arriving at staging to arrive at the numbers? Do you know that payload fairing jettisons itself is considered a staging? [Glad that the said poster discovered "gravity turn" him/herself., since if others had pointed it out - they would have been seriously beaten up.]

Yes., it is a good exercise to understand why and how they came up with GSLV Mk II design.

3. However redesigning GSLV Mk II completely is not necessarily a "simple" exercise that gives you insights into GSLV Mk II design. If you really want to make simple modifications to GSLV Mk II.,

3a. Increase the propellant loading on S139 booster without a concomitant increase in diameter so that it burns out precisely at stage separation. Increase in length will have to be adjusted by increase in mass of the strap-ons to bring back the Cg. However for ease of calculations., it can be assumed that the rocket is balanced even with increase in propellant loading.

3b. Do an early stage separation.

Those are your only two choices for simple modifications on GSLV Mk II ( in reality, your only choice is 3b)

Anything beyond is not a 'simple' modification.

Because it gives about 6% more efficiency to the vikas engines used in MKIII.

This is very interesting. It does not make sense to me, but there are huge gaping holes in my knowledge. Could you please elaborate on the same?

I would also love to know the calculations., I think that it keeps the rocket's total Cg in control hence the engines do not have to divert thrust for maintaining pitch-yaw balance.

In addition, the solid rocket nozzle is optimised to perform at lower altitudes.

This is true. The specific impulse of these solid motors is only slightly lesser than our liquid engines.

This also explains why L110s are air-lit. Now somebody did say that air-lit L110 on GSLV Mk III as-well is "in-efficient".

Since you did question why they are not lit concurrently with the solid boosters on GSLV Mk III., one of the answer is simple - the air-lit L110 engines are optimized for upper atmosphere.

The question you must ask on GSLV Mk III is - why did not ISRO cluster four L110 engines? Note clustering is a challenge., but was ISRO trying to solve an engineering challenge coming with 4 engines or was it trying to solve a design challenge by going with 2 engine cluster (increased propellant loading, increased height and an altogether different aerodynamic profile). Or is the 2-engine L110 cluster a place holder for Semi-Cryo?

Regarding the assumption that GSLV Mk II will be around for a decade longer., just have to point out to ISRO history - PSLV was launched and immediately ASLV was retired. ASLV was used only to prove closed loop guidance system. So it is possible that GSLV Mk II may be retired sooner than a decade. Question than is what will ISRO do with its CE-7.5 stage?

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Saw nirav'jis post. In my post above., I purposely did not mention Cp as that would have complicated my flow of post. As it is changing the propellant loading as mentioned in 3a would mess up the Cg and then to compensate rocket will be redesigned for Cg which will mess up the Cp which will then be redesigned to accommodate both Cg and Cp. The amount of calculations that need to be run again & again will be several. This is for a rocket that has to fly!

[Indranil]

Just to highlight one of the glaring deficiencies of spreadsheet based 6 tons to GTO, have you guys discussed the impact of Centre of Gravity or Centre of pressure on those hypothetical models ? For all you know, the easy 30 minute fix isnt flyable at all ! But still its being brandished as a "fix" for GSLV.
This is not science nor physics .. Just a wishlist ..

Calculating the C.G. is high school physics. The center of pressure will not change if you do not change the frontal area of the rocket. Not of the configurations (except for the 3.2 dia rocket will have a changed C.P., and even in that case it won't move by much)

Put two outside,cluster four and voila 6 tons to GTO is NOT a "technical" discussion.

That is not what is being discussed at all. The first stage of GSLV Mk2 is not optimized, and there are proper reasons for the same. ISRO must have also considered optimizing the same. What could the options have been and what the corresponding gains be (in a ball park region)? The most likely reason ISRO did not go down that path is because, they did not have much confidence in the GSLV till 2014. Different parts of the vehicle were failing till that 2014 launch. Besides, even if they optimized the first stage, and designed a 3.0+ mtr dia GSLV, it would have topped out at 4-5 Tons. They wanted a more easily configurable system aka ULV/HLV that can launch anywhere between 1.5 - 15 tons to GTO. LVM is the first step. It can launch 4-5 Tons. But it is not really configurable. It needs the S200s. The true configurability would come with the SC160, which has enough thrust by itself so that it can be launched with smaller boosters. I suspect the L110 will be retired within 4-5 flights, and replaced with the SC160 completely. The S200s and SCE20 have much longer legs.

Would you really appreciate this kind of technical discussions elsewhere ? LCA thread ?

I am not appreciating anything wrong here either. I have questioned Vina's model and its predicted tonnage all throughout. But his model is much better than "feelings". We have lots of launch vehicles and launch data to validate his model. Although, it is not there yet, I am pretty sure that the model can be refined to within 5% of actual payload. The above statement does not mean that building rockets is easy. The capacity to build those parts is an enormous challenge. And that is why the only configurations that I have suggested contain complete stages which already have been built and flight tested by ISRO or very ones which are very similar. The ones which are not identical don't vary in weight, and therefore do not put any extra stress of the trusses. They use the same engines, but slightly wider and slightly shorter tanks. In theory, it should make them even more sturdier.

I agree i have taken it a bit far with the epithets, but do understand i did that only to make a certain person realise how monikers and mockery feels when one is at the receiving end.
I'll cease and desist on that front hereon.

Thank you.

[nirav]

Calculating the C.G. is high school physics. The center of pressure will not change if you do not change the frontal area of the rocket. Not of the configurations (except for the 3.2 dia rocket will have a changed C.P., and even in that case it won't move by much)

Calculating Cg of a stationary object could be high school physics. But calculating the impact of a S200 instead of a S139 on the Cg of the rocket in flight and its impact on the stability of the launch vehicle might not be.

If you think it is, id love to see some calcs ..

Also basic formula for Centre of Pressure involves the whole surface area of the launch vehicle, not just the frontal area.
If you change the booster from S139 to S200, thats a change in total surface area and hence a different value for Cp.

This is just a simplified version.
https://spaceflightsystems.grc.nasa.gov ... rktcp.html

For the GSLV, it would be of an order of magnitude unsolvable by a enthusiast spreadsheet.

The point is, these are just a couple of things , very basic things in theory which have a significant impact on a launch vehicle.
And need to be solved for in order to find out if its feasible or not.

Simply plugging and playing one stage from here and there makes a good rocket only on a spreadsheet.There is no way you and i can know for sure if its even flightworthy as we dont have the requisite data.

In light of this, is my criticism that there is scant attention to even such basic things. yet, its being called as an 'easy fix' for GSLV mk2 for 4-6 tons to GTO !
.

Put two outside,cluster four and voila 6 tons to GTO is NOT a "technical" discussion.

That is not what is being discussed at all. The first stage of GSLV Mk2 is not optimized, and there are proper reasons for the same. ISRO must have also considered optimizing the same. What could the options have been and what the corresponding gains be (in a ball park region)? The most likely reason ISRO did not go down that path is because, they did not have much confidence in the GSLV till 2014. Different parts of the vehicle were failing till that 2014 launch. Besides, even if they optimized the first stage, and designed a 3.0+ mtr dia GSLV, it would have topped out at 4-5 Tons. They wanted a more easily configurable system aka ULV/HLV that can launch anywhere between 1.5 - 15 tons to GTO. LVM is the first step. It can launch 4-5 Tons. But it is not really configurable. It needs the S200s. The true configurability would come with the SC160, which has enough thrust by itself so that it can be launched with smaller boosters. I suspect the L110 will be retired within 4-5 flights, and replaced with the SC160 completely. The S200s and SCE20 have much longer legs.

The sense i get after reading Vinas posts and spreadsheet is that the GSLV Mk2 is inefficient. And that if ISRO were to follow his configurations, easy fixes, GSLV could have 4-6 tons to GTO.

The thing is, L40s in, solids out, S200 instead of S139, dropping the stage together, increasing propellant loading, decreasing burn time, these things are any thing but easy !

Most recent GSLV launch had a payload hike of 100 Kgs as per one of the scientists in his speech post the launch.
I trust the competence of ISROs research team over an enthusiasts' well meaning but baseless criticism and solutions coming out of it.

GSLV mk2 , you guys call it 'inefficient', i choose to call it 'optimized' solution based on the limited choices we had when it was designed.

Radically altering mk2 at this point in time makes no sense, as ISRO has an ambitious program with the semi cryos and the solids in mind and the growth path is charted out.

IMO, they will keep using the GSLV like how they are currently using the PSLV, all the time making incremental upgrades.

[Indranil]

Added later: One thing I learnt when I built my own model rockets that could actually carry a payload >2500 feet., was appreciation of the professionals who did the real thing! This (both appreciation and rocketry) is something that can only be learnt by experience. And that is why no serious rocketeer (and definitely not the amateur ones) will mock in any manner the rocketeers who actually do it.

This, I completely agree.

As an aside: Do you know that S139 is one of the largest solid booster in continuous operation in the world and the largest in Asia? Point is why would a rocket designer ignore such a reliable, high-thrust, cheap and versatile booster while designing next evolution of the rocket?

Because, ISRO can do better. No scratch that, because ISRO has done better, in S200.

So there is complete disagreement on the numbers itself. 30 tonnes of inert mass is assumed because spaceflight quoted it based on GSLV D1 Mk1. Given that egregious data as a basis., how can one come to an agreement on the number for quantum of improvement within GSLV Mk II?

Now the manner of calculations. Mistakes are piled on with several contradictions. For example the said poster completely forgot about "gravity turn" and of course his/her "spreadsheet" does not include that function. So how can one trust the numbers posted? Leave alone agree? And what is the method of arriving at staging to arrive at the numbers? Do you know that payload fairing jettisons itself is considered a staging? [Glad that the said poster discovered "gravity turn" him/herself., since if others had pointed it out - they would have been seriously beaten up.]

Yes, spaceflight 101 has the take off mass of S139 wrong at 166 Tons. Various GSLV brochures place the take off mass of S139 at 161 Tons, putting the inert mass of S139 at 23 Tons, and not 28 Tons.

Yes., it is a good exercise to understand why and how they came up with GSLV Mk II design.

3. However redesigning GSLV Mk II completely is not necessarily a "simple" exercise that gives you insights into GSLV Mk II design. If you really want to make simple modifications to GSLV Mk II.,

3a. Increase the propellant loading on S139 booster without a concomitant increase in diameter so that it burns out precisely at stage separation. Increase in length will have to be adjusted by increase in mass of the strap-ons to bring back the Cg. However for ease of calculations., it can be assumed that the rocket is balanced even with increase in propellant loading.

3b. Do an early stage separation.

Those are your only two choices for simple modifications on GSLV Mk II ( in reality, your only choice is 3b)

Anything beyond is not a 'simple' modification.

Now we are talking. I think 3a is not possible, because the length of the vehicle will increase by 9-10 mtrs. That is why I went with the fatter S200. We can use a conical interstage to connect to the 2.8 m second stage. Alternatively, I changed the diameter of the second and third stage to 3.2 mtrs, but kept their weights exactly as they are now.

This also explains why L110s are air-lit. Now somebody did say that air-lit L110 on GSLV Mk III as-well is "in-efficient".

I don't know why it is air-lit. I am sure if ISRO had strong enough liquid engines or a way to cluster the smaller ones, then I would have gone down that route. That's what they are trying to get to. They will only be able to get there with the SC500. The heaviest configuration of HLV uses the two other SC500 stages as boosters. Getting back to today, going from S139 to the S200 was a much less riskier route, and that is likely why they went down this path. They really did a fabulous job with the S200. S200 and S230 are definitely crown jewels of solid rocket technology anywhere in the world.

Since you did question why they are not lit concurrently with the solid boosters on GSLV Mk III., one of the answer is simple - the air-lit L110 engines are optimized for upper atmosphere.

That is an interesting part of the puzzle. They have designed an uprated version of the Vikas for this stage called Vikas-X. It has higher specific impulse higher than both Vikas 2 and Vikas 4B, but I am trying to find the area-ratio of the engine.

The question you must ask on GSLV Mk III is - why did not ISRO cluster four L110 engines? Note clustering is a challenge., but was ISRO trying to solve an engineering challenge coming with 4 engines or was it trying to solve a design challenge by going with 2 engine cluster (increased propellant loading, increased height and an altogether different aerodynamic profile). Or is the 2-engine L110 cluster a place holder for Semi-Cryo?

I am not sure of many things. However, I am sure that L110 don't have any life after the SC160 come on board.

Regarding the assumption that GSLV Mk II will be around for a decade longer., just have to point out to ISRO history - PSLV was launched and immediately ASLV was retired. ASLV was used only to prove closed loop guidance system. So it is possible that GSLV Mk II may be retired sooner than a decade. Question than is what will ISRO do with its CE-7.5 stage?

You are probably right. CE20 is almost ready. Once the SC160 comes on board, ULV development will be complete. There will be no need for continuing PSLV/GSLV. The lives of PSLV/GSLV is likely to be 2-3 years beyond the arrival of SC160 and 2-3 successful flights. CE 7.5 will likely be retired with GSLV Mk2. That day is at least 5 years away. How much can it extend? I don't know. We took 14 years from first flight to get a reliable GSLV. Mk3 was supposed to be operational in 2010.

[Indranil]

Calculating the C.G. is high school physics. The center of pressure will not change if you do not change the frontal area of the rocket. Not of the configurations (except for the 3.2 dia rocket will have a changed C.P., and even in that case it won't move by much)

Calculating Cg of a stationary object could be high school physics. But calculating the impact of a S200 instead of a S139 on the Cg of the rocket in flight and its impact on the stability of the launch vehicle might not be.

If you think it is, id love to see some calcs ..

You have caught me off guard here. You are right, the CG would be moving as the fuel gets burnt up. But, if that is so, then what you are arguing becomes even less valid. The CG of the vehicle travels much more than what would be brought about by the slight change in one of the stages that we are considering.

Also basic formula for Centre of Pressure involves the whole surface area of the launch vehicle, not just the frontal area.
If you change the booster from S139 to S200, thats a change in total surface area and hence a different value for Cp.

This is just a simplified version.
https://spaceflightsystems.grc.nasa.gov ... rktcp.html

At zero AoA, diameter of the rocket would not matter, as long as it is smaller than the shroud.

[bharats]

Mega launchers for ISRO soon- Apart from powering rockets to lift heavier satellites, it will also lower the cost per kilo. -MADHUMATHI D. S. THE HINDU September 28, 2016 02:31 IST

An advanced Indian mega space launcher that can deliver ten-tonne and heavier communication satellites to space and using a semi-cryogenic engine is likely to to power ISRO’s launchers by around 2018....
This would readily boost Mk-III's maximum lifting capability from 4,000 kg to 6,000 kg,” Dr K. Sivan, Director of Vikram Sarabhai Space Centre at Thiruvanthapuram, the lead centre for launch vehicle development, said.
Two years thereafter, around 2020, this will be enhanced to 15,000 kg by putting strap-ons in clusters — the stage where major European and U.S. launch providers already are...

Read the entire arcticle at http://www.thehindu.com/news/national/m ... 155342.ece

[arshyam]

Mega launchers for ISRO soon- Apart from powering rockets to lift heavier satellites, it will also lower the cost per kilo. -MADHUMATHI D. S. THE HINDU September 28, 2016 02:31 IST

An advanced Indian mega space launcher that can deliver ten-tonne and heavier communication satellites to space and using a semi-cryogenic engine is likely to to power ISRO’s launchers by around 2018....
This would readily boost Mk-III's maximum lifting capability from 4,000 kg to 6,000 kg,” Dr K. Sivan, Director of Vikram Sarabhai Space Centre at Thiruvanthapuram, the lead centre for launch vehicle development, said.
Two years thereafter, around 2020, this will be enhanced to 15,000 kg by putting strap-ons in clusters — the stage where major European and U.S. launch providers already are...

Read the entire arcticle at http://www.thehindu.com/news/national/m ... 155342.ece

It's worth posting the full article. Many nuggests for the aam junta like myself who are trying to keep up with the excellent discussions on this thread . Perhaps the gurus might add more details based on this article.

An advanced Indian mega space launcher that can deliver ten-tonne and heavier communication satellites to space and using a semi-cryogenic engine is likely to to power ISRO’s launchers by around 2018.

That is the space agency’s next big space vehicle, having just achieved the GSLV for lifting 2,000-kg payloads. The agency is gearing up for first test flight of the GSLV Mark-III vehicle in December with a 4,000-kg payload.

Currently, the government has approved the development of the semi-cryogenic stage alone.

When fitted suitably into a launch vehicle, it will see India putting satellites of the class of 6,000 to 10,000 kilos — or with some variations, lift even 15,000-kg payloads — to geostationary transfer orbits at 36,000 km. The engine is expected to triple or quadruple ISRO's transportation ability.

Massive payloads

Pre-project work on what is called the SCE-200 began about four years back. "We plan to have an [semi-cryogenic] engine and stage capable of flight by the end of 2018 and try it on the GSLV-MkIII.

This would readily boost Mk-III's maximum lifting capability from 4,000 kg to 6,000 kg,” Dr K. Sivan, Director of Vikram Sarabhai Space Centre at Thiruvanthapuram, the lead centre for launch vehicle development, said.

Two years thereafter, around 2020, this will be enhanced to 15,000 kg by putting strap-ons in clusters — the stage where major European and U.S. launch providers already are.

The engine will use space-grade kerosene as fuel and liquid oxygen as oxidiser. The development is going on at the Liquid Propulsion Systems Centre and the ISRO Propulsion Complex at Mahendragiri in Tamil Nadu.

“The semi-cryogenic engine is getting fabricated. Testing of its pump and components has been going on. An engine testing facility is also getting set up at Mahendragiri,” Dr. Sivan said.

Apart from powering rockets to lift heavier satellites, it will also effectively lower the cost per kilogram to reach orbits, which is the goal of all space-faring nations, he said.

Liquid fuel

The high-power local capability is needed as Indian communication satellites move towards 5,000-plus kg and more from 2017. By then, ISRO plans to build and launch its heaviest 5,700-kg GSAT-11 spacecraft, although on a European Ariane rocket for a big fee. Its present rockets can lift only up to 2,000 kg to this orbit.

Dr. Sivan said, “The GSLV-MkIII that we plan to test in December has a core liquid fuel stage. When the semi-cryogenic engine gets ready, our plan is to replace the liquid stage with the SCE. We straightaway get six-tonne payload capability, two tonnes over what Mark III can give.”

Subsequently the plan is to have a modular vehicle (earlier called the unifield launch vehicle) which allows variations suited to different payloads; this being done with the PSLV with its three versions.

For example, Dr. Sivan said: “We can have a bigger semicryogenic stage with clustered engines, similar to what SpawceX did using nine Merlin engines. We can then get a payload of 15 tonnes in the GTO.”

[nirav]

Calculating Cg of a stationary object could be high school physics. But calculating the impact of a S200 instead of a S139 on the Cg of the rocket in flight and its impact on the stability of the launch vehicle might not be.

If you think it is, id love to see some calcs ..

You have caught me off guard here. You are right, the CG would be moving as the fuel gets burnt up. But, if that is so, then what you are arguing becomes even less valid. The CG of the vehicle travels much more than what would be brought about by the slight change in one of the stages that we are considering.

Also basic formula for Centre of Pressure involves the whole surface area of the launch vehicle, not just the frontal area.
If you change the booster from S139 to S200, thats a change in total surface area and hence a different value for Cp.

This is just a simplified version.
https://spaceflightsystems.grc.nasa.gov ... rktcp.html

At zero AoA, diameter of the rocket would not matter, as long as it is smaller than the shroud.

Im amazed at how lightly you are taking the Cg/Cp issue.. These are not constants for a multi staged rocket.

Considering the size/weight of the whole rocket and proposed changes + the rapid rate at which it changes post the launch + the velocities involved and the need to keep Cp to ensure a stable flight necessitate an indepth study into the Cg/Cp


you cant just wish it away.
for someone offering an "easy" fix for GSLV, and who has been criticising ISRO from years now, the onus is on him to quantify change in Cg/Cp and show graphs that actually validate his radical proposals for "fixing" GSLV.

Just saying "It is so because im saying so" doesnt cut it.

[bharats]

Why India's commercial space programme is thriving- A good view point from BBC (non bashing)
By Yogita Limaye, BBC News, Mumbai, 26 September 2016, From the section India

On Monday, India sent a rocket into space which successfully launched eight satellites in one go.
The main purpose of the launch which took place at the Sriharikota space centre off India's eastern coast, was to put into orbit SCATSAT-1, a satellite that will help weather forecasting. Five of the other satellites that were on board are foreign, from the US, Canada and Algeria.

Read full article at http://www.bbc.com/news/world-asia-india-37448629

[Varoon Shekhar]

Good BBC article, but made a major omission, by not mentioning the two different orbits the satellites were placed into- after all, that's what makes this launch different than the other multi-satellite missions

[Indranil]

You have caught me off guard here. You are right, the CG would be moving as the fuel gets burnt up. But, if that is so, then what you are arguing becomes even less valid. The CG of the vehicle travels much more than what would be brought about by the slight change in one of the stages that we are considering.


At zero AoA, diameter of the rocket would not matter, as long as it is smaller than the shroud.

Im amazed at how lightly you are taking the Cg/Cp issue.. These are not constants for a multi staged rocket.


Considering the size/weight of the whole rocket and proposed changes + the rapid rate at which it changes post the launch + the velocities involved and the need to keep Cp to ensure a stable flight necessitate an indepth study into the Cg/Cp


you cant just wish it away.
for someone offering an "easy" fix for GSLV, and who has been criticising ISRO from years now, the onus is on him to quantify change in Cg/Cp and show graphs that actually validate his radical proposals for "fixing" GSLV.

Just saying "It is so because im saying so" doesnt cut it.

I am not trivializing it. I am saying the Cg management is not an issue. if you just changed a S139 to S200. The movement of Cg by virtue of that change is much more trivial than how much it naturally travels when the stage is being used. For e.g. the C.G. of a solid stage moves up steadily as the fuel is used up and then the propellant mass goes below the inert mass of the stage, it starts to quickly travels down. In a liquid stage, the same thing happens in reverse.

Regarding Cp, I think you are simply wrong. If both vehicles have near equal length and same frontal area, then it will have near identical Cp. When flying at 0 AoA, the side of the spacecraft doesn't present any frontal area.

[Bheeshma]

So ULV is back now? All these presentations by ISRO guys are seriously confusing now. So ULV itself with strap on and variants can cover 4-15 tonne by 2024 then we really don't need PSLV/ GSLV. Hoping they have many more successful launches of these till then.

[prasannasimha]

There will not always have a 0 angle of attack- for eg when there is a pitch or yaw.

[prasannasimha]

^ ULV or the heavy launch vehicle is the goal in a series of modifications in the multistage nonrecoverable rocket path. I doubt they will totally ditch the PSLV as it is a very cost effective rocket till they get a reusable rocket system in place which is cheaper than the PSLV.

[enaiel]

IMVHO onlee...

ULV as a replacement for PSLV and GSLV 1/2/3 seems to be on the backburner. ULV as the building blocks to build HLV seems to be what's being focussed on. PSLV and GSLV Mk 3 will continue to be used for many many more years. PSLV generally taking the commercial LEO/SSO market while GSLV Mk 3 will take on the huge backlog of India's GTO needs, and will not have any bandwidth for commercial launches.

I wonder if this means that HSP has taken precedence over commercial launch capability in ISRO.

Again, it's my 2c onlee...

[Indranil]

There will not always have a 0 angle of attack- for eg when there is a pitch or yaw.

Read here.

[abhik]

There is one thing that ISRO has mastered well. They have figured out ways to carry multiple satellites without any significant overhead. This is not true with others. For example the difference of launch capacities of Ariane 5 for a single payload and a double payload is 500-800 kgs.

Has the numbers for PSLV been released? Sorry if I have missed it.

[Indranil]

Read the entire arcticle at http://www.thehindu.com/news/national/m ... 155342.ece

This is actually a validation of what we have been discussing so far. ISRO is on a great path.

1. The first step is LVM which allows us to get 4 Tons to GTO. It does not give us much flexibility though because the core is not powerful enough.

2. THE ULV : When the SCE200 powered SC160 stage comes on board, the limitations on the flexibility of LVM3 will be set aside. The core stage itself will be generating enough thrust, so that it can be boosted by a variety of the solid boosters to cater to a variety of payloads from 1.5 Tons to 6 Tons. Additionally, by virtue of the higher efficiency of the Semi-cryo engine, ULV will be much more efficient then LVM/GSLV/PSLV. For example, when combined with two S200 boosters (same as LVM3), it will be able to lift 6T to GTO (50% increase over LVM3) with an increase of just 50 Tons (7.5% over LVM) to the launch mass.

3. The TSTO: The next step is to cluster 5 SCE200 engines to power the core stage called SC500. This core is powerful enough, that it does not need any boosters at all. The second stage will be two CE20 engines clustered together with 60 tons of fuel. This vehicle will be even more efficient than the ULV as there are no solid stages involved. This launch vehicle will be lighter than LVM, and will be able to lift more the 6-7 tons to GTO. Also, it will be our first vehicle for manned missions.

4. THE HLVs[\b]: However, one can add boosters to the TSTO to get higher payloads. With 2 S230 stages (slightly larger solid boosters than what you see on LVM3), one would be able to lift 10 Tons to GTO. If the boosters are 2 other SC500 stages, one can lift 15 Tons to GTO. When the SC500s are used as boosters, once again one has one of the most efficient vehicles built by man.

What is not covered in the article but has been presented elsewhere is:
1. SC800: a semicryo stage with 800 Tons of propellant load.
2. SC460: A semicryo stage with 460 Tons of propellant (likely morphed into SC500)
3. Humongous rocket configurations for manned mission to moon.

[nirav]

Read the entire arcticle at http://www.thehindu.com/news/national/m ... 155342.ece

This is actually a validation of what we have been discussing so far. ISRO is on a great path.

Disagree and agree.

ISRO certainly is on a great path.

But what was being discussed is the "inefficient" GSLV mk2 and the easy solutions to "fix it". And also how "inefficient" the GSLV Mk3 is.

The configurations discussed by ISRO are the ones which after their indepth analysis have been deemed feasible.
It doesnt give any one of the spreadsheet configurations any validation whatsoever.
The spreadsheet configurations for all you know are simply unflyable.

To repeatedly offer it as an "easy fix" without even being aware of its Cg/Cp issues is extremely unfortunate and fanboyish.

I think its gotten to a point that an argument is being made just for the sake of it. I do expect technical and scientific explanations for a configuration so confidently being offered as an "easy fix" for 4-6 tons to GTO.

Not having a clue about the 'slap this and that' into GSLV configurations' Cg&Cp is being made a reason to dispute the impact of Cg/Cp itself on the rockets stability and flightworthiness..

This is exactly the reason why id said that such exercises are nothing but flights of fancy. And that theres wayyy too much science that goes into a space launch vehicle. You are only kidding yourself and those who think its a "scientific discussion" that spreadsheet rocketry can solve for and "fix" a space launch vehicle by jugaadu mix and match.

[JTull]

I've been following this thread for a while with all the pow-wow happening.

I just wonder that with GSLV-MkIII/ULV/HLV/human-rated vehicle/etc, ISRO seems to be getting ahead of itself. Perhaps ISRO should update the public with the progress made on the SC engine. From what I can google, only parts are being fabricated at the moment along with some test facilities. This timeline and launch date of 2018 is meaningless, when we know that it took ISRO two years for converting a fully working cryo engine to a stage with tests of various duration. With SCE, we are nowhere near a hot test of a SCE even, leave alone a stage.

I'll distribute the mithai equal to the weight of the stage if there's a hot test for even 1 sec by end of 2018.