Indian Space Programme Discussion

Raveen · Post by **Raveen** » 12 Dec 2014 03:13

HKumar wrote:
Shalav wrote:
Perhaps instead of asking questions which may have already been answered up-thread or in previous iterations of the thread, you should read up the archives.

Try a search on BRF. Why demand answers from others which you can find for yourself.

Whats wrong with people? Is it so hard to be polite?

The original responder prasannasimha politely answered the question the second time. I don't see YOU participating in the recent conversations, so what gives you the right to barge in and be a d1.ck about it?

If you read my post correctly - I only say that I didn't know what it was. I never ask or 'demand' (whatever that means)!

If you had just politely pointed that the question was already answered, I would replied - 'sorry dude. I was in middle of another conversation and this just came up' . Instead you go about lecturing me. My advise to you - please make yourself useful by participating instead of policing others posts.

Asking the same questions disrupts the ongoing conversation and leads to page after page of the same thing - read before you post is the best policy.

HKumar · Post by **HKumar** » 12 Dec 2014 03:42

Raveen wrote:
Asking the same questions disrupts the ongoing conversation and leads to page after page of the same thing - read before you post is the best policy.

And repeating the same point doesn't ?

Varoon Shekhar · Post by **Varoon Shekhar** » 12 Dec 2014 04:15

[quote="prasannasimha"]I find it funny when armchair warriors denigrate the efforts put by ISRO engineers.

Even I

know that the Vikas engine they have today is not exactly the same one they used in 1993-94. They have increased the chamber pressure of the engine from 52 to 58 units, and the propellant has been UH-25 from all launches after 2003. Not UDMH. So they have made adjustments, modifications. And there have certainly been others.

There was an awful message in the comments section of a recent issue of "The Hindu", deriding even this upcoming GSLV Mark 3! Because it can only lift 4 tonnes, as opposed to 10 or 15, the capability of the most advanced countries. If ISRO can in a few years can launch all the Insats and GSats, and on top of that send a manned capsule into space( first an unmanned), that is something to be respected and applauded.

vina · Post by **vina** » 12 Dec 2014 05:35

BTW, how do the Russians build their rockets? If I am not mistaken that determines how it is transported. ?????

Horizontally, and integrated horizontally. It is rolled out horizontally on a train and then jacked up vertically and launched ?

Waaa! How is that possible ? Well, because their rockets are all liquid and the empty weight of the rocket without the propellants is a very small fraction. So, you can integrated horizontally (far easlier to do), cheaper as well, and then after you raise it vertical, fill it with propellants. You cant do that with the GSLV for eg, becuase of the solid stages which are full loaded with propellants.

Also, their launching system is unique and very innovative. None of the launch pad rubbish like the rest of the world. Some folks I know ,told me back in the mid 80s on how that entire thing worked. Entire launcher sits on pins on the supports , which simulate flight conditions, and when the rocket engine fires and lifts off, the supports swivel away as the weight of the launcher is off them. The swiveling is done by mama gravity, because there are weights on the other end of the lever.

Think of it as if the rocket is a fat kid sitting on the end of a see-saw, with another lighter kid on the other end. The fat kid jumps up like our neighboring Packee Raakit Mard and takes off, the see saw swivels away because the lighter kid on the other end of the lever.

The Soyuz vehicle basically sits on three see-saws arranged so that each of one of their ends support the vehicle.

vina · Post by **vina** » 12 Dec 2014 05:41

symontk wrote:To mature a SC engine and keep the cost down would be a tough exercise. For all issues it has, Vikas has performed excellently well apart from two accidents it had during launch (both GSLV launches). With a SC engine, costs would be prohibitive. US and USSR can afford those since they used to launch 100's per year

Well, you've got to start sometime. And rather than trying to replicate a 1960s style RP1-Lox, we should put our efforts on the cutting edge to get an LCH4-LOX one into service. That is what everyone else is trying to do and frankly that is the way to go.

We need to make the right investments if we want to be competitive. We are getting there, and with the propulsion experience from the cryogenic stages, getting a 220 ton LCH4-LOX engine wont be a stretch capability wise. We should put our money and efforts there rather than this manned space flight distraction , which frankly is useless and reeks of a me-too and a d*ck measuring contest with the Chinese.

Vayutuvan · Post by **Vayutuvan** » 12 Dec 2014 05:54

What is this obsession with "manned" space flights?
I am not in favour of it (not that it matters).
More can be achieved with less with unmanned flights. In other blas'e words "more bang for the buck".
(Ducking for cover for an indefinite interval

).

HKumar · Post by **HKumar** » 12 Dec 2014 06:23

prasannasimha wrote:When I see those rockets stand on the transporter crawler I always wonder how they just don't tip over during transport !!

I thought it was the size and CG that kept the rocket stable. But I got curious and looked around. This is specific to the crawlers at KSC but I think other transporters might be similar

The crawlers have a leveling system designed to keep the top of a space shuttle vehicle vertical within plus or minus 10 minutes of one degree of arc having the dimensions of a basketball. This system also provides the leveling operations required to negotiate the 5-percent ramp leading to the launch pads and to keep the load level when it is raised and lowered on pedestals at the pad and in the VAB

This is an screenshot of the leveling control system in the crawlers - http://i.imgur.com/ASr5du2.jpg

HKumar · Post by **HKumar** » 12 Dec 2014 07:00

vina wrote: Waaa! How is that possible ? Well, because their rockets are all liquid and the empty weight of the rocket without the propellants is a very small fraction. So, you can integrated horizontally (far easlier to do), cheaper as well, and then after you raise it vertical, fill it with propellants. You cant do that with the GSLV for eg, becuase of the solid stages which are full loaded with propellants.

The Chinese use vertical assembly/transport http://www.spaceflightnow.com/news/n1109/25lm2fphotos/

Soyuz in transport for launch.
http://en.wikipedia.org/wiki/Soyuz-FG#m ... to_pad.jpg

symontk · Post by **symontk** » 12 Dec 2014 08:20

Varoon Shekhar wrote:
prasannasimha wrote:I find it funny when armchair warriors denigrate the efforts put by ISRO engineers.

Even I know that the Vikas engine they have today is not exactly the same one they used in 1993-94. They have increased the chamber pressure of the engine from 52 to 58 units, and the propellant has been UH-25 from all launches after 2003. Not UDMH. So they have made adjustments, modifications. And there have certainly been others.

There was an awful message in the comments section of a recent issue of "The Hindu", deriding even this upcoming GSLV Mark 3! Because it can only lift 4 tonnes, as opposed to 10 or 15, the capability of the most advanced countries. If ISRO can in a few years can launch all the Insats and GSats, and on top of that send a manned capsule into space( first an unmanned), that is something to be respected and applauded.

If my reading of tea leaves are correct, the GSLVMk3 should give 5-6 tonnes to GTO once fully developed in 2-3 years. Adding two more solid strapons would give it 6-7 tonnes to GTO. That is the weight of the biggest satellite we are going to have in near future. Why worry about 10-15 tonnes to GTO when we don't have satellites like that? Are we going to start our space station in few years?

Even if we need 10 tonnes to GTO, and as I mentioned in the past, add two more L110 to the GSLVMk3, it should comfortably do it. But lets wait until SC engine comes and it will be all cool

member_28911 · Post by **member_28911** » 12 Dec 2014 16:36

member_28108 · Post by **member_28108** » 12 Dec 2014 17:16

This is the proposed upgradation of the GSLV

member_28911 · Post by **member_28911** » 12 Dec 2014 17:47

^ So this means GSLV MkIII has capability to lift 6.5t to GTO.

member_28108 · Post by **member_28108** » 12 Dec 2014 18:43

Ankar wrote:^ So this means GSLV MkIII has capability to lift 6.5t to GTO.

Not the present configuration which can lifet upto 5 tons.With additional 2 boosters they may reach 6.5 tons but if the semi cryogenic stage is launchworthy then the pciture awill change.

SaiK · Post by **SaiK** » 12 Dec 2014 22:09

matrimc, there would be significant common components between advanced fighter jet and space based RVs for man-machine interface and environment. i wish, we had no gravity!

KrishG · Post by **KrishG** » 12 Dec 2014 23:18

prasannasimha wrote:This is the proposed upgradation of the GSLV

Mk-IV is an old concept. There is no official ISRO source for this version. I doubt it will ever fly. And I would be happy if it doesn't.

IMO The current ISRO approach of upgrading the core stage with semi cryogenic CLC (ULV) is the better way.

The S200 boosters don't come cheap. Using 4 of them will cost a LOT. In addition to that will be costs associated with the current core (earth storable propellants used by them also don't come cheap). And we don't know if the current core is structurally strong enough to take 4 big solid boosters. The combination will cost lots of money and moreover will be a developmental dead end.

The ULV on the other hand is the logical way of upgrading our capabilities even if it takes more time. Both in terms of eventual launch costs and for developing Heavy/Super heavy launchers if the need arises.

ISRO's current plans for the future (10-15 years ahead) is something like this.
Lower end - Fully solid launch vehicle
Mid tier - ULV
Heavy - RLV / ULV Heavy

And it's a good plan. So I don't think there will every be a GSLV Mk IV, at least like the one above.

member_28911 · Post by **member_28911** » 12 Dec 2014 23:38

member_28108 · Post by **member_28108** » 13 Dec 2014 06:54

See how the axis of the GSLV is maintained to ensure the Center of gravity stays within the structure during travel

Whatever one says about center of gravity etc etc making a tall thin structure move gives one the jitters

member_28108 · Post by **member_28108** » 13 Dec 2014 06:54

The double post bootha strikes again.

Varoon Shekhar · Post by **Varoon Shekhar** » 13 Dec 2014 07:07

Ankur, what is the large building with the blue 'doors' in the immediate background? Not the first VAB, is it? Would they have 2 assembly buildings so close together

NRao · Post by **NRao** » 13 Dec 2014 07:08

On double posts, the last post will always have a little box with a small x inside it. As long as no one has posted after, you can click on that and that post will be deleted.

On CG and jitters while moving, all one needs is a set of bolts that counter the max force expected to tip it over. I would imagine that is the least of their worries. A good CE should be able to resolve that issue.

And to ensure greater stability the rocket, in this case, is aligned towards the path of traverse.

vina · Post by **vina** » 13 Dec 2014 07:26

ISRO seriously needs to look at the GSLV Mk2 config. The present config is underwhelming. It has the spare capacity to take in a much larger payload to GTO.

If you look at the booster stages and the zero stage, the 4 WeakAss (Vikas) engine, burn for 160 secs, while the zero stage the S139 with a piddly specific impluse of 166s (seems an error. I picked it up from wiki) burns for only 100 secs and the 4 WeakAss engines lug that dead weight of the spent zero stage for a full minute.

The easy way out would be to S-200 booster stage from the MKIII (which puts out 5150KN) and Three improved Vikas from the L110 of the GSLV , which put out 700 KN each(or rather Not So WeakAss),all burning for approx same time of 150 secs , the S200 might need some extra propellant loading to burn for the 150s or so.

I think if that is done, and the CE-7.5 is brought upto full performance , the GSLV Mk2 would go to it's full potential of close to 3 tons or more to GTO .That improvement will come from the higher efficiency of the S200 and improve Vikas engines (they seem to have higher iSp than what the current ones have) , and also from not carrying dead weight for a full minute.

In addition, it would cost less, as you would have 1 WeakAss engine less than current and also be more reliable (one engine less to fail). I think it would be a more competitive and credible offering than the current GSLV Mk2 config.

member_28108 · Post by **member_28108** » 13 Dec 2014 07:38

vina wrote:ISRO seriously needs to look at the GSLV Mk2 config. The present config is underwhelming. It has the spare capacity to take in a much larger payload to GTO.

If you look at the booster stages and the zero stage, the 4 WeakAss (Vikas) engine, burn for 160 secs, while the zero stage the S139 with a piddly specific impluse of 166s (seems an error. I picked it up from wiki) burns for only 100 secs and the 4 WeakAss engines lug that dead weight of the spent zero stage for a full minute.

The easy way out would be to S-200 booster stage from the MKIII (which puts out 5150KN) and Three improved Vikas from the L110 of the GSLV , which put out 700 KN each(or rather Not So WeakAss),all burning for approx same time of 150 secs , the S200 might need some extra propellant loading to burn for the 150s or so.

I think if that is done, and the CE-7.5 is brought upto full performance , the GSLV Mk2 would go to it's full potential of close to 3 tons or more to GTO .That improvement will come from the higher efficiency of the S200 and improve Vikas engines (they seem to have higher iSp than what the current ones have) , and also from not carrying dead weight for a full minute.

In addition, it would cost less, as you would have 1 WeakAss engine less than current and also be more reliable (one engine less to fail). I think it would be a more competitive and credible offering than the current GSLV Mk2 config.

Vina - how conversant are you about strap on booster separation dynamics ? Also are you aware that the boosters are still attached to minimize fuel unsettling when igniting in the coast phase and is an intentional design despite recognizing that it will decrease performance and performance and has been factored in and found to compensate for that ? Do you really think that you can easily just mix and match these stages so easily.Why did you not join ISRO if you have all the information ?

Surya · Post by **Surya** » 13 Dec 2014 07:40

prassana - oh come on - if you ask questions like that - BRF will have to shutdown

Vayutuvan · Post by **Vayutuvan** » 13 Dec 2014 07:44

SaiK: Just do advanced fighter jets, I say, if that's what is needed immediately plus (of course) unmanned space flights. Space is very large and escaping solar system is a tremendous task. Even if one is able to establish colonies on other planets in the solar system, the environment is so hostile that it would be impossible to set up any kind of permanent colony. FTL is impossible from known physics. Reaching even a fraction (say 1/10 C) of speed of light for any reasonable (rest) mass is out of reach for 20-30 year technology (I would even go so far to say 50 year technology).

sanjaykumar linked some pages here when the discussion was focused on Methane. I understood the point he was making at that time but went on a involuntary vacation from BRF and lost track of my thoughts. But the dots (in no particular order) are

1. Abolition of equal but separate principle (after Rosa Parks and Dr. MLK)
2. Competition between FSU and the US
3. Public (read tax payers) support for funding the space race due to insecurity created by incessant marketing of "godless communists are going to take the world over".

member_28108 · Post by **member_28108** » 13 Dec 2014 09:05

http://www.star.ucl.ac.uk/~iac/spaceflight.html

http://www.theatlantic.com/technology/a ... ns/255341/

http://freakonomics.com/2008/01/11/is-s ... cs-quorum/

vina · Post by **vina** » 13 Dec 2014 09:43

prasannasimha wrote:Vina - how conversant are you about strap on booster separation dynamics ? Also are you aware that the boosters are still attached to minimize fuel unsettling when igniting in the coast phase and is an intentional design despite recognizing that it will decrease performance and performance and has been factored in and found to compensate for that ?

. Unfortunately for you, actually yes.

The trouble is, before mouthing off such high faultin' stuff like "separation dynamics" and throwing in "fuel unsettling" when igniting in"coast phase" hence calling it "intentional" etc , you should have considered if you what you said actually made sense or just so much gibberish dusted with some nice phrases.

For eg. slosh (the correct technical term) is a problem with liquid engines only ? Why because liquids have a free surface and transverse moment of inertia lowers stability. The problem doesn't apply to solid engines (in rockets).. Why ? Because the solids are cast solid and can't move (if they are in powder form/granular form like say grains or granules, then there is a slosh problem and you have to analyse them like liquids.. for e.g., a plane or a ship or a truck carrying liquids, grain, coal etc will have stability problems due to free surface).

Specifically for GSLV MK1&2, the core solid is spent at 100s and the liquid boosters keep firing until 160s. You cannot drop the dead mass from the core stage, because it is in the middle and the boosters are attached to it! Sure it is intentional, for a different reason and I will tell you in the next part.

Do you really think that you can easily just mix and match these stages so easily.

And pray why can't you ? The entire GSLV Mk1/2 and it's sub optimum config is due to mix and match.. See, the GSLV was realised "cheaply" by reusing the PSLV stuff. The core stage of the GSLV is the core stage of PSLV, the boosters are the 2nd stage of PSLV. The reason why the GSLV carries the spent core for 60s, is precisely because they didn't engineer a separate core stage for the GSLV MK1/2.

The MKIII is a clean sheet. That is why the config is cleaner. The thing now, is you have better /more suitable components to come up with a cleaner MK2 from the MKIII, rather than from the suboptimal ones from the PSLV, so why not do it ?

Actually, the MKIII and the MK2 give components that can replace the PSLV (which is a complex vehicle 4 engines in all, though very reliable) with a more compact, efficient and reliable version..

member_23694 · Post by **member_23694** » 13 Dec 2014 09:58

prasannasimha wrote:Do you really think that you can easily just mix and match these stages so easily.

Sir, I believe that if ISRO in early 1990's was aware that the first indigenous cryo will be coming up only in 2014 then the GSLV MK.2 config would have been quite different , probably with solid straps and liquid core just like MK.3.
With INSAT's around 1.5-2 tonne that time , it was probably assumed to quickly move to required GTO capability with mix and match lower PSLV stages and a cryo upper stage with Russian help even at the expense of all the stuffs that are being discussed.
But unfortunately things did not go according to plan. But all these learning now seem to have gone in MK.3 which will be in a better position
to absorb Semi-cryo etc in the future.

arun · Post by **arun** » 13 Dec 2014 10:06

Smash returned with overhead lob to the line.

I make it Vina 15, Prasannasimha 0. Let the game continue and the best person win.

Vayutuvan · Post by **Vayutuvan** » 13 Dec 2014 12:25

Criticism
Freakonomics has been criticised for, in fact, being a work of sociology and/or criminology, rather than economics. Israeli economist Ariel Rubinstein criticised the book for making use of dubious statistics and complained that "economists like Levitt ... have swaggered off into other fields", saying that the "connection to economics ... [is] none" and that the book is an example of "academic imperialism".[6] Arnold Kling has suggested the book is an example of "amateur sociology".[7]
Thomas Ferguson, author of Golden Rule: The Investment Theory of Party Competition was asked in 2009 to respond to the following claim in Freakonomics:
"A winning candidate can cut his spending in half and lose only 1 percent of the vote. Meanwhile, a losing candidate who doubles his spending can expect to shift the vote in his favor by only that same 1 percent."
His response was:
"Where on earth do such figures come from? You would need a fully specified regression equation to do this, that incorporated a lot of variables. Unless you hold constant everything else, including issues -- not easy even to imagine -- such claims are nonsense. Think of a couple of cases. Obviously, an incumbent Congressman or woman with a big margin could spend a bit less and probably do almost as well. By contrast, candidates in close elections surely cannot do this. The real issue is the dependence of money on taking conservative issue positions. Claims about existing candidates typically reflect censored data. That is, there's no one able to run that can run very far to the left."
Economist Robert P. Murphy takes exception to the way the book describes economists and their field, saying the authors end up actually describing econometrics. He also contends the book's ambiguous style makes it very difficult to determine exactly what the authors are claiming in various chapters.

I do understand game theory reasonably well.

KrishG · Post by **KrishG** » 13 Dec 2014 14:11

When designing GSLV, ISRO wanted to make it as an extension of the PSLV. That's why, they took almost the same solid core of the PSLV and put in on the GSLV. Instead of the solid boosters of the PSLV, liquid boosters were added. Even the second stage of the PSLV and GSLV were decided to remain same. The 3rd and 4th stages of PSLV were replaced with the cryogenic stage. This is how ISRO arrived at the GSLV.

So, GSLV is very much based on the PSLV. And rightly so. At that point ISRO really did the best with what technology they had. It's a commom misconception that GSLV was based on the Ariane 4. No, GSLV was based on the PSLV. If ISRO wanted, they could have gone to Ariane 4 route and decided to cluster the Vikas engines for core stage of GSLV. But, Liquid engine tech was still not mature at that time.

vina wrote:ISRO seriously needs to look at the GSLV Mk2 config. The present config is underwhelming. It has the spare capacity to take in a much larger payload to GTO.

IMHO What we might see are small improvements in GSLV but not any major redesign. Replacing the core takes a lot of effort. I am not certain ISRO will be wanting to spend that kind of effort on a serious upgrade of the GSLV. Once LVM3 is fully operational, it and the PSLV will be the ones that will be logging in the maximum number of flights. If we assume a total of 6 launches every year, it will something similar to 3 PSLV, 2 LVM3 and 1 GSLV.

symontk · Post by **symontk** » 13 Dec 2014 14:26

A lighter GSLV would also do good, like a TSTO option of a single S-140 and CS15(CE7.5) would be lobbing a 1.5 - 2 tonne satellite to GTO. It would be in the same lines of PSLV-3S which ISRO was planning, replace the two upper stages with cryo and you would get this

A S200 and CS25(CE20) would also do good

member_28108 · Post by **member_28108** » 13 Dec 2014 21:28

Vina sorry whatever you may say it indeed is ISRO's justification and not just mine.
Please read-

The four boosters ignite 4.6 seconds prior to the first stage to allow the Vikas engines to reach operational conditions before the Core Stage is ignited and the rocket blasts off. In flight, the four boosters continue to burn after first stage shutdown and are separated from the vehicle with the first stage. The advantage of this simpler design is that a Booster Separation event is avoided, but it comes at the cost of performance because the four boosters have to propel the first stage once it has burned out which represents nearly 30 tonnes of dead weight.

The stage separates with the four boosters once they are reaching depletion. Staging between S139 and GS2 (Stage 2) is accomplished in hot-staging mode - the second stage ignites 1.6 seconds ahead of Booster Shutdown. When the boosters have shut down, the two stages are separated by flexible linear shaped charges that pyrotechnically separate the two stages allowing the spent first stage and boosters to be pushed away by the second stage. This maneuver comes at the cost of propellant and performance but minimizes propellant unsettling that occurs when igniting in coast mode.

Please also note that propellant slosh and propellant unsettling are both technical terms used. Sorry if you are unfamiliar with it. And yes slosh does occur in liquid motors and who said no ?
for eg see the article
Microgravity Propellant Gauging Using Modal Analysis PI: Kevin Crosby, Carthage College and see the term that you claim is not used/correct - NASA used that term.
See also the ISRO statement .just because you are unfamiliar with the term doesn't mean that it doesn't exist. So also for strap on booster separation dynamics. There are whole theses and research projects on that.

And is it simple to just mix and match engines just like that - sorry if it appears as a piece of cake but do you think that it is so easy- so why aren't you doing it ? Also do not forget that the whole point of GSLV was to use existing infrastructure as much as possible whereas GSLV mark3 was an attempt to do something differentin graded stages.How do you expect them to put s200 when it was not even vaildated at the time GSLV was designed ?

it is easy to comment with hindsight but difficult to do it when you had nothing at hand.
Oh and while I am no space scientist and dont remotely claim to be well why aren't you out there helping our country instead of commenting from the armchair ? If you have the insight and the ability - why are you not solving ISRO's problems? since you obviously have the solution at hand ? We would indeed be grateful and appreciative if you did.

vina · Post by **vina** » 13 Dec 2014 21:50

prasannasimha wrote:Please also note that propellant slosh and propellant unsettling are both technical terms used. Sorry if you are unfamiliar with it. And yes slosh does occur in liquid motors and who said no ?
for eg see the article ..

Oh and while I am no space scientist .....

Dude. Give it a rest. Frankly you have no idea of what you are talking about here. The first basics of anything related to aviation and rocketry is, if there is any dead weight you drop it / leave it behind.. In fact, that is the genesis of staging and that is the reason why a single stage to orbit is out of reach of current chemical rockets. Some ISRO spin doctor or you putting on a play a words and brochure quoting doesn't change the basic laws of physics.

And slosh doesn't exist in this case because the core stage is solid. That is a stark fact whichever way you look at it, and as for the 4 boosters, the tank dis will be so small in each case, that the slosh effects will be negligible (in case you wonder, a single large tank of dia X , will have much higher free surface effects than 4 tanks of X/4 dia put together, in fact that is the way you control slosh, by putting in baffles /subdividing a large areas).

Suffice to say that the GSLV MK2 and MKIII are very inefficient vehicles, despite the use of the cryo stages, because 1) the GSLV MKI/II config is such that it uses lower Isp engines in the lower stages and also because of not having a dedicated core stage, it lugs a big dead weight for a full minute and 2) GSLV MKIII because of the low ISP of the two giant 500t thrust S200s and the L110 with twin Vikas engines.

member_28108 · Post by **member_28108** » 13 Dec 2014 22:13

vina wrote:
prasannasimha wrote:Please also note that propellant slosh and propellant unsettling are both technical terms used. Sorry if you are unfamiliar with it. And yes slosh does occur in liquid motors and who said no ?
for eg see the article ..

Oh and while I am no space scientist .....
Dude. Give it a rest. Frankly you have no idea of what you are talking about here. The first basics of anything related to aviation and rocketry is, if there is any dead weight you drop it / leave it behind.. In fact, that is the genesis of staging and that is the reason why a single stage to orbit is out of reach of current chemical rockets. Some ISRO spin doctor or you putting on a play a words and brochure quoting doesn't change the basic laws of physics.

And slosh doesn't exist in this case because the core stage is solid. That is a stark fact whichever way you look at it, and as for the 4 boosters, the tank dis will be so small in each case, that the slosh effects will be negligible (in case you wonder, a single large tank of dia X , will have much higher free surface effects than 4 tanks of X/4 dia put together, in fact that is the way you control slosh, by putting in baffles /subdividing a large areas).

Suffice to say that the GSLV MK2 and MKIII are very inefficient vehicles, despite the use of the cryo stages, because 1) the GSLV MKI/II config is such that it uses lower Isp engines in the lower stages and also because of not having a dedicated core stage, it lugs a big dead weight for a full minute and 2) GSLV MKIII because of the low ISP of the two giant 500t thrust S200s and the L110 with twin Vikas engines.

Carefully look at what ISRO is saying (not me) and take the sequence they are referring to.You have still missed that and are talking of the ist stage whereas the seperation that is being referred to is the second stage with hypergolic propllants and you are conveniently deviationg the discussion to the ist stage. You dont seem to be paying attention to that.
Agree that they may not be the most efficent a system but then-

So why aren't you out there solving the problems of ISRO since you have all the solutions ? Your expertise that you have should be used to solve their problems isn't it since yu indeed have all the solutions. we can use it.

vina · Post by **vina** » 13 Dec 2014 22:15

KrishG wrote:When designing GSLV, ISRO wanted to make it as an extension of the PSLV. That's why, they took almost the same solid core of the PSLV and put in on the GSLV. Instead of the solid boosters of the PSLV, liquid boosters were added. Even the second stage of the PSLV and GSLV were decided to remain same. The 3rd and 4th stages of PSLV were replaced with the cryogenic stage. This is how ISRO arrived at the GSLV.

So, GSLV is very much based on the PSLV. And rightly so. At that point ISRO really did the best with what technology they had. It's a commom misconception that GSLV was based on the Ariane 4. No, GSLV was based on the PSLV. If ISRO wanted, they could have gone to Ariane 4 route and decided to cluster the Vikas engines for core stage of GSLV. But, Liquid engine tech was still not mature at that time.

Indeed. If you look at the basic take off thrust of the PSLV and the GSLV Mk1/2, they are remarkably the same. The PSLV S139 + 4 * 50KN + 2* 50KN boosters (air lit), i.e S139 + 300 KN, is very similar to GSLV Mk1/2 with S139+ 4*70 KN (i.e. S139 + 280 KN) . So basically what saves the day for GSLV is the higher Isp due to the Cryo stage and longer duration use of higher Isp than solid Vikas engines.

Symontk wrote:A lighter GSLV would also do good, like a TSTO option of a single S-140 and CS15(CE7.5) would be lobbing a 1.5 - 2 tonne satellite to GTO. It would be in the same lines of PSLV-3S which ISRO was planning, replace the two upper stages with cryo and you would get this

A S200 and CS25(CE20) would also do good

Yes of course. That as a stop gap would be the way to go. Those kind of combos would be more efficient than the GSLV Mk1/2 and PSLV. The PSLV I think, frankly due for retirement and the GSLV Mk1/2 is too inefficient to see any large scale service. However, I do hope that these come about with a LOX/Hydrocarbon core.

KrishG wrote: Once LVM3 is fully operational, it and the PSLV will be the ones that will be logging in the maximum number of flights. If we assume a total of 6 launches every year, it will something similar to 3 PSLV, 2 LVM3 and 1 GSLV.

I do think your split up in numbers will be correct with the current inward focused ISRO model. However, there is a whole wide world of commercial launches waiting for a competitive entry and for you to conquer . ISRO should not get into the export pessimism promoted by the sclerotic Govt/ISI/Planning Commission/DSE/ISI ding dong cabal. At least the planning commission is now history, and with SHAR now in CB Naidu's Seemandhra, I do hope that some of his pirate like instincts and no prisoners taken attitude/ approach in business rubs off on ISRO.

For that you need highly efficient (both capital and operational cost wise) proven launchers . We have the cryo stages needed for that in place and the missing link in that is a good LOX/Hydrocarbon stage . Have that last link in place and we are globally competitive and can give the global launch and satellite market hell.

For eg.. The base GSLV MKIII for a 4 ton to 5 ton GTO has a lift off mass of 660 tons (a mass fraction of 0.7% or so), and it is a 3 stage vehicle to boot. A base Atlas V with a similar 4 to 5 ton GTO has a lift off mass of around half of that at just 330 tons (a mass fraction of 1.5% or so, double that of GSLV MKIII) and the Atlas V is a 2 stage vehicle ! The Atlas burns kerosene (dirt cheap, okay special grades albeit) from refineries, while the GSLV burns up gargantuan amount of solid propellants and carcinogenic UDMH and N2O4 which needs special plants to produce it and require special hazmat handling.

ISRO desperately needs the LOX/Hydrocarbon stage ASAP. All efforts and funds should go into that. This manned space flight thingy is just a whole load of baloney and a distraction. Hand it to NASA and the Chinese and focus on what you need to get.

Like I said earlier, if the science "fundamentalists" like Bade Mian whine, do a moon shot or mars shot or something once a while to quite them. But otherwise, follow the money, and rake it in. You can never go much wrong with that.

KrishG · Post by **KrishG** » 13 Dec 2014 23:05

vina wrote:For that you need highly efficient (both capital and operational cost wise) proven launchers . We have the cryo stages needed for that in place and the missing link in that is a good LOX/Hydrocarbon stage . Have that last link in place and we are globally competitive and can give the global launch and satellite market hell.

For eg.. The base GSLV MKIII for a 4 ton to 5 ton GTO has a lift off mass of 660 tons (a mass fraction of 0.7% or so), and it is a 3 stage vehicle to boot. A base Atlas V with a similar 4 to 5 ton GTO has a lift off mass of around half of that at just 330 tons (a mass fraction of 1.5% or so, double that of GSLV MKIII) and the Atlas V is a 2 stage vehicle ! The Atlas burns kerosene (dirt cheap, okay special grades albeit) from refineries, while the GSLV burns up gargantuan amount of solid propellants and carcinogenic UDMH and N2O4 which needs special plants to produce it and require special hazmat handling.

ISRO desperately needs the LOX/Hydrocarbon stage ASAP. All efforts and funds should go into that. This manned space flight thingy is just a whole load of baloney and a distraction. Hand it to NASA and the Chinese and focus on what you need to get.

Beginning in the 2000s ISRO realized that semi cryogenic tech is the way ahead (90s were wasted in this respect but that's a different story). It is getting a lot of attention and funding but ISRO is threading cautiously here. It will optimistically take another 5 years to be ready. When it arrives, ISRO can further decrease launch costs.

And about the solids. ISRO will not let go of it anytime soon. They have built such expertise in this field that in many respects we are ahead of the Russians and the Chinese in solid booster technology. There is no denying this fact. We will see it even on the next generation ULV. Solids are cheap (not as cheap as they are made to look but still cheap). One suggestion is that ISRO should standardize the boosters like on Atlas, instead of having S12,S6,S138,S200 and what not. Different combinations of relatively cheap SRBs are a good way to diversify the range of payloads a vehicle can carry. (Angara for example doesn't have this advantage where as ULV with a similar core will)

geeth · Post by **geeth** » 14 Dec 2014 10:53

The GSLV MK 1/2 were not designed for commercial exploitation as such, but as test beds for Cryo Engines. Obviously these rockets were assembled using available material and technology. One can say ISRO failed in is vision/ and/or were over cautious to think big and design bigger rockets from scratch early enough. But the counter point is, what is the point in developing gigantic booster rockets without mastering the cryo tech? Now that they have mastered the cryo tech, sky is the limit. A helping Govt at the centre will boost their confidence further.

kit · Post by **kit** » 14 Dec 2014 11:14

No offense but if india is so advanced in solid propellants won't it be using the newer generation polymer propellants ? I think China also has started using it..higher specific impulse and ? Eco friendly ?

Sridhar · Post by **Sridhar** » 14 Dec 2014 13:39

Varoon Shekhar wrote:Ankur, what is the large building with the blue 'doors' in the immediate background? Not the first VAB, is it? Would they have 2 assembly buildings so close together

The building in the back is the solid stage assembly building. The S200 stages are assembled there,before being wheeled out to the Vehicle Assembly Building in thr foreground.

vina · Post by **vina** » 14 Dec 2014 17:24

kit wrote:No offense but if india is so advanced in solid propellants won't it be using the newer generation polymer propellants ? I think China also has started using it..higher specific impulse and ? Eco friendly ?

India is streets ahead of China in solid rockets. No two questions about it. China does not have a solid propelled space vehicle. Let the Chinese first put up something even the size of an SLV3 core stage first (50KN thrust) and then let us talk about it.

In fact, if the Chinese launch vehicles can be summed in one sentence,

it is a HUUUGE number of WeakAss Engines (700 KN thrust class UDMH/N2O4) engines used in stages.

For eg, the Long March 3B series (4 WeakAss in Boosters, 4 More clustered in the core /1st stage, 1 more in the 2nd stage, topped by 2 75KN thrust class cryogenic engines, of gas generator cycle). A total of 9 WeakAsses. All in all,nothing spectacular technologically, and stuff that goes back to 60s/70s .

Fact is China for it's next gen Long March 5 is finally going to LOX/Hydrocarbon way. And oh, do expect that fair share of initial launches like the Long Marc 2/3 series and the villagers close to the launch site better get some serious catastrophe insurance, as the Chines rockets have a propensity of flying into their homes. It will be a while before the LOX/Hydrocarbon stage becomes reliable for the Chinese.

As for schlong measuring contest, the twin S200 solid boosters give a take off thrust of 10.5MN for the GSLV MKIII, while the take off thrust for the Long March 5 series, even in the best case is 8MN! The GSLV MKIII has far higher growth potential and flexibility and the cryogenic stage of the GSLV MKIII is a arguably a far better config than the 2* YF-75 of the LM-5!

ANd to top it all off, the GSLV MKIII flies earlier than the LM-V!