Indian Space Programme Discussion

Austin · Post by **Austin** » 03 Sep 2015 14:42

The GSLV design is good though Mark 3 is yet to be flight proven but they can later opt of LOX/Kerosine engine that would be efficient and environmental friendly.

From ISRO pov what proven and works is good

KrishG · Post by **KrishG** » 03 Sep 2015 15:31

Singha wrote:So is the falcon9 config most efficient and tfta or the ariane4 the proven industry workhorse?

Efficiency of a config can be very vague and can be achieved in many ways. What the Falcon 9 has is a very efficient cluster of engines (Merlin). AFAIK it has the highest T/W ratio among modern engines. And design is simple, just 2 stages ( ie no need to worry about booster seperation etc). Ariane 4 is considered an old design just like the GSLV. Too many stages, too many different propellants. The approach now is to have as few stages as possible (2,3 or rarely 4)

vina · Post by **vina** » 03 Sep 2015 18:00

One thing is clear. The zero stage and 1st stages of the GSLV MKII and the core stage of the GSLV MKIII are inefficient Pakistans. We need the semi cryo stage to be tested and qualified at the earliest and an entire new set of stacks built.

1) 2MN semicryo core + CE 7.5 --> replaces PSLV and with a couple of SRBs, GSLV MKII
2) S200+ 2MN Semi cryogenic core +CE 20 --> replaces GSLV MK3

arshyam · Post by **arshyam** » 03 Sep 2015 18:42

Nothing new from the launch itself, but documenting some regional media coverage of the GSLV launch. Especially since the 'national' media was more interested in someone killing someone and ignored this.

A few news reports by a Tamil channel:

Nice close visuals of the assembly in HD:

ISRO's GSLV D-6 puts GSAT-6 satellite in orbit successfully | India | News7 Tamil - Youtube

PM Modi greets ISRO scientists for GSAT-6 mission success | India | News7 Tamil - Youtube

ISRO Scientists after GSAT-6 mission's success | India | News7 Tamil - Youtube

Culminating in this:

vasu raya · Post by **vasu raya** » 03 Sep 2015 19:16

India to launch multi-spectral remote sensing Indonesian satellite

India will launch a second multi-spectral remote sensing Indonesian satellite that will help the country to monitor land-use, natural resource and in disaster mitigation.

The indigenously-made LAPAN A2/Orari satellite is a successor to LAPAN A1/Tubsat, which was also launched in India in 2007.

nachiket · Post by **nachiket** » 03 Sep 2015 20:49

symontk, thanks a lot for the explanation.

A follow up question. Suppose we have a hypothetical GSLV Mk4 with an S139 motor as first stage sitting below the L110. Say the S139 and the 2 S200's burn together and fall off as one unit after which the L110 ignites.

Now from what I gleaned from your post, this will have two problems.

1. First, the L110 cannot ignite when the thrust from the first stage is tapering off. It has to fire after the separation. Which introduces a gap when there is very little or no thrust. This is inefficient.

2. Even though we have much higher total first stage thrust at liftoff, the velocity increase that can be achieved is limited by aerodynamic design of the rocket, since it is flying in dense air at low altitudes. So the final improvement in throw weight may not be as much as we would expect. It can also be dangerous for the rocket and it would need design changes.

Did I get that right?

symontk · Post by **symontk** » 03 Sep 2015 21:07

nachiket wrote:symontk, thanks a lot for the explanation.

A follow up question. Suppose we have a hypothetical GSLV Mk4 with an S139 motor as first stage sitting below the L110. Say the S139 and the 2 S200's burn together and fall off as one unit after which the L110 ignites.

Now from what I gleaned from your post, this will have two problems.

1. First, the L110 cannot ignite when the thrust from the first stage is tapering off. It has to fire after the separation. Which introduces a gap when there is very little or no thrust. This is inefficient.

2. Even though we have much higher total first stage thrust at liftoff, the velocity increase that can be achieved is limited by aerodynamic design of the rocket, since it is flying in dense air at low altitudes. So the final improvement in throw weight may not be as much as we would expect. It can also be dangerous for the rocket and it would need design changes.

Did I get that right?

Yes. absolutely correct. For LVM4, ISRO diagrams showed 4 S200's. I would have loved 2 L110's added instead of 2 more S200's to the LVM3

Singha · Post by **Singha** » 03 Sep 2015 21:08

the ariane5 also seems to have gone the 2-stage way. does it have this "semi cryogenic engine" thing?

https://upload.wikimedia.org/wikipedia/ ... EN.svg.png

Singha · Post by **Singha** » 03 Sep 2015 21:10

looks like restartable upper stage cryogenic engine is also a big play:

The Ariane 5 ME uses a new upper stage, with increased propellant volume, powered by the new Vinci engine. Unlike the HM-7B engine, it can restart several times, allowing for complex orbital maneuvers such as insertion of two satellites into different orbits, direct insertion into geosynchronous orbit, planetary exploration missions, and guaranteed upper stage deorbiting or insertion into graveyard orbit.

Amber G. · Post by **Amber G.** » 03 Sep 2015 21:18

symontk wrote: There are 2 problems for a rocket lift off and both of them work against each other

1. You need get the rocket off the atmosphere ASAP as both air gives the friction and as you climb you have less gravity
2. Your rocket cannot go into a high acceleration while in atmosphere since it will affect the overall aero design
<snip>

Let me add something to this excellent explanation ..Even just using the most basic physics, one calculate that one can not send an object (made out of known materials) in the space from ground alone, no matter how efficient the engine. For example, Jules Verne's story about using a large cannon to fire the rocket to moon is not possible -- which btw Jules Verne knew and was bothered by the inaccuracy but he could not think of multistage rockets then.. Even using best rail guns, one can fire a missile quite far almost reaching an orbit, but it can not reach an orbit let alone escape and go to moon etc..

Point is, with atmosphere it will just burn up, even if one uses best known heat shields.. one needs multistage rockets on earth.

If one is designing for moon (no/little atmosphere) .. the story/design may be slightly different.

KrishG · Post by **KrishG** » 04 Sep 2015 01:48

Singha wrote:the ariane5 also seems to have gone the 2-stage way. does it have this "semi cryogenic engine" thing?

https://upload.wikimedia.org/wikipedia/ ... EN.svg.png

Nope.

First definitions -
Semi cryo - Burns LOX and Kerosene
Cryo - Burns LOX and LH
Solids - most common is HTPB

Currently (and for short term future), there are 2 broad design philosophies for heavy rockets among the major space faring nations.

1) Western designs - USA, Europe, Japan
2) Eastern designs - Russia, China

The Western designs use cryogenic stages and solid propellants. Usually you do not find many semi cryogenic stages among these rockets. Examples are Delta, Space Shuttle, upcoming SLS for USA, Ariane 5 for Europe and H-II family for Japan. All these use cryogenic core stages/upper stages with solid boosters. Obviously you exceptions like Falcon 9 (privately developed) and Atlas V (uses Russian semicryo core stage engines). But this is how their design philosophy broadly works (Cryogenics, Solids, No Semi cryo)

The Eastern designs hate solids in their heavy lift vehicles as opposed to the western designers who simple love it. These eastern designs typically make use of semi cryogenic boosters, cryogenic/semicryogenic core stages and cryogenic upper stages. Examples are upcoming Angara of Russia, and Long March 5,6,7 of China.

You would have noticed that you didnt find India in the above list. Yes..India has peculiar policy which cannot be categorized as eastern or western. We want solids on our HLVs (ISRO is VERY serious about having solid boosters on its HLV). They will also use semi cryogenic engines for the core stage. And the upper stage will be cryogenic. So as you see, ISRO isn't averse to solids like Russia or China and has built up very build expertise in this area (better than the 2 nations mentioned). Nor does ISRO want to stay away from semi cryogenic engines like the US or Europe or Japan by favouring cryogenics more. So you have a mix of both the sides.

NOTE: This analysis is valid for current and near future designs. For the long term future, Methox or LNG/LOX engines seem to be new the craze among US, Russia (and will be promptly followed by Europe, Japan and China)

hnair · Post by **hnair** » 04 Sep 2015 08:31

Nice writeup KrishG

Cheen has some medium-dia SRB programs for Long March, though not as elaborate or pivotal as khan, oirope or ISRO's. The next-gen Araine6's previous configuration (current one is full-cryo, IIRC) and Ares' sole sub-orbital flight used or planned to use solid first stages. Both program's senior afsars used the rationale of "reliability and ease of manufacture". So solids are not going anywhere and rightly so.

KrishG wrote: NOTE: This analysis is valid for current and near future designs. For the long term future, Methox or LNG/LOX engines seem to be new the craze among US, Russia (and will be promptly followed by Europe, Japan and China)

vina would be grossly unhappy to be in august company, since he is the foremost proponent of methox here

I think the current ISRO LV roadmap is pretty decent and within cost. Can't waste billions on large diameter rockets, whose missions are not yet even envisaged and probably can be funded by ISRO for maybe, maximum of two times a decade. Even khan, with all their influential "super-science community of scientists", is frugal and canned Saturn V (without going ahead with the Nova). Going by their vibrant space community's deep, deep thoughts on the Flagship class missions, the meager numbers of expensive New Frontiers missions and the earlier Discovery missions, ISRO will be even more thoughtful.

Singha · Post by **Singha** » 04 Sep 2015 08:38

the falcon9 @ 78m has to be one of the tallest rockets in the current era. its a good fraction of the enormous SaturnV 110m length. most of the heavy lifters today and tomorrow are in the range 50m...pretty fat ofcourse and with enormous payload fairings.

JE Menon · Post by **JE Menon** » 04 Sep 2015 09:50

Thanks for that simple and very clear write up KrishG.

member_28108 · Post by **member_28108** » 04 Sep 2015 22:20

Methane LOX engines while tantalizing have not really met with great success so far.Russsia experimented a lot with it but was unable to maintain astable ingition and the fuel density is also less compared to RP1 which offsets the 10 second or so Isp advantage though it does not have issues like caking/coking which would be an advantage in multiple restartable engines but even RP1 engines can be restarted 10-12 times

Gagan · Post by **Gagan** » 05 Sep 2015 06:42

symontk wrote:
disha wrote:Vina - you are making several false statements.

1. Solid boosters are *never* going to go away.
True, solids will stay

Wrong
Everybody's wrong.

Wait till the semi cryos start coming out of mahendragiri in various sizes.

Ultimately there will be a pure semi-cryo or a Semi-Cryo + Cryo upper stage launch vehicle

gakakkad · Post by **gakakkad** » 05 Sep 2015 07:46

Te reason why Russians used onlee cryo /semicryo for space launches is historical and probably not technical..

The father of Russian space program Sergei Korolev is much less well known than von Braun (WVB)..

https://en.wikipedia.org/wiki/Sergei_Korolev

Around 1940 , he had acheived a rocket similar to those made by WVB...

http://www.jyi.org/issue/50th-anniversa ... e-program/

But his career was not going to be one great streak of achievement. In 1938, during one of Stalin's purges, Korolev was thrown into a concentration camp in Siberia for apparently working on liquid rocket fuel instead of solid rocket fuel. In 1940 he was sent to the infamous Butyrskaya, known for brutal treatment of its prisoners for several centuries. After several months, Russia decided to use Korolev's genius and sent him to TsKB-29, a work camp for scientists under the direction of Andrei Tupolev, one of Russia's most known aircraft designers and the namesake of the current aviation company.

But Commie politics sent him to a brutal prison camp , where he was made to work as a mine worker.(the exposure to heavy metals lead to his kidney damage)..One of the persons who testified against him was Valentin Glusko...

https://en.wikipedia.org/wiki/Valentin_Glushko

Glushko was a proponent of the hypergolic fuels while Korolev preferred cryo...

When WVB , surrendered to the Americans , Ruskies were damn pissed ... Both US and Russia competed with each other for WVB...

They removed Korolev from the prison camp and made him the head of the space program after they successfully tested a weaponized 8000 km range missile...

He obviously never got along well with glusko...glushko worked with hypergolic fuels ... we know that they can be toxic and korolev was against having toxic fuels for a manned space program... As a result glushko mainly worked for military and korolev for space...

Proton probably has the descendant of Gluskos design engine..

it is a shame that korolev died because of a botched piles operation (the renal failure due to heavy metal exposure in prison camp contributed to it)....one of the reasons why they were never able to send a man to the moon...

Rupesh · Post by **Rupesh** » 05 Sep 2015 15:37

^^

There is a BBC documentary(space race) on Korolev and WVB. Worth watching all 4 parts.

member_22539 · Post by **member_22539** » 05 Sep 2015 16:13

^Excellent series, would recommend watching all 4.

member_23694 · Post by **member_23694** » 05 Sep 2015 16:39

Varoon Shekhar wrote:
dhiraj wrote:http://www.thehindu.com/news/isro-to-bo ... 594838.ece

[

Between D5 and D6 :
Strapons moves from 680 to 760 KN
First stage from 4800 to 4815
Second stage from 720 to 799
Further if i heard correctly CUS weight reduced by around 70 Kg."

Dhiraj, it's great news, but where did you get this information? The Hindu article is talking about future launches.

For these improvements in GSLV-D6, was it mainly a question of increasing the propellant load? Or were there increases in the thrust chambers of the respective stages? ( not for the first stage, where it would be increased fuel)
All the details available in the brochure itself in the "at a Glance" table

http://www.isro.gov.in/sites/default/fi ... slv-d5.pdf
http://www.isro.gov.in/sites/default/fi ... ission.pdf

Further wiki mentions
https://en.wikipedia.org/wiki/Vikas_(rocket_engine)
The engine uses up about 40 metric tons of UDMH as fuel and Nitrogen tetroxide (N2O4) as oxidizer with a maximum thrust of 725 kN. An up-graded version of the engine has a chamber pressure of 58.5 bar as compared to 52.5 bar in the older version and produces a thrust of 800 kN.

member_28108 · Post by **member_28108** » 05 Sep 2015 19:05

^ if you look carefully they are mostly the specs for the individual launch as per design for the launch

symontk · Post by **symontk** » 05 Sep 2015 20:51

Gagan wrote: Wrong
Everybody's wrong.

Wait till the semi cryos start coming out of mahendragiri in various sizes.

Ultimately there will be a pure semi-cryo or a Semi-Cryo + Cryo upper stage launch vehicle

Not with current planned SCE from ISRO. It cant lift itself out of ground with just 2MN. Just for thrust comparison browse and see Saturn's famed engine. Once SCE is improved to give a thrust of 4MN, things will look good for your scenario, not now

member_28108 · Post by **member_28108** » 05 Sep 2015 21:31

As far as cost effectiveness goes solid rocket boosters still are efficent so even with a semicryo there will be some solid rocket booster mostly to keep costs down.

member_23694 · Post by **member_23694** » 05 Sep 2015 22:30

As per ISRO

A Heavy lift Launch Vehicle capable of placing up to 10 ton class of spacecrafts into Geosynchronous Transfer Orbit is currently under study by a project team. This new generation launch vehicle will derive its propulsion modules from LVM3 as well as from new developments, which include semi cryogenic booster stage, larger solid strap on boosters as compared to S200 strap on motors used in LVM3 and a larger cryogenic upper stage. The Heavy Lift Launch Vehicle will have an optimal and robust design incorporating the latest technologies.

KrishG · Post by **KrishG** » 05 Sep 2015 23:13

prasannasimha wrote:Methane LOX engines while tantalizing have not really met with great success so far.Russsia experimented a lot with it but was unable to maintain astable ingition and the fuel density is also less compared to RP1 which offsets the 10 second or so Isp advantage though it does not have issues like caking/coking which would be an advantage in multiple restartable engines but even RP1 engines can be restarted 10-12 times

There has been some sucess with low thrust methox test beds built by Blue Origin and the also the Russians. ULA seem to be so convinced with their potential that they have already decided that they will be using Blue Origins 4 kN Methox engine (BE-4) on the successor of Atlas. The Russians are as always playing a wait and watch game. They have their Methox program ready and the successor of Soyuz (Soyuz 5 family) are supposed to use it. But they are waiting to see if the Americans really succeed and when they do (I think the question is when they succeed not if), they will fund their own production Methox engines and rockets in some form.

gakakkad wrote:Te reason why Russians used onlee cryo /semicryo for space launches is historical and probably not technical...

True. But, historical reasons usually manifest into technical shortcomings over a period of time due that very fact. The Russians even had a some trouble when they moved away from liquid ballistic missiles to solid ones. But, yes Korolev would have done a lot more if not for hs premature death.

KrishG · Post by **KrishG** » 05 Sep 2015 23:14

member_23694 · Post by **member_23694** » 05 Sep 2015 23:22

Good Video.
Godrej Engine In Every ISRO Space Launch Vehicle

gakakkad · Post by **gakakkad** » 06 Sep 2015 07:17

excellent video dhiraj ...

member_28108 · Post by **member_28108** » 06 Sep 2015 15:13

GSAT-6 UPDATE:
GSAT 6 has been successfully positioned in its orbital slot of 83 Deg E and colocated with INSAT 4A, GSAT 12, GSAT 10 and IRNSS1C today (Sept. 06 2015) morning, after carrying out four drift arresting manoeuvers

vina · Post by **vina** » 07 Sep 2015 09:09

There has been some sucess with low thrust methox test beds built by Blue Origin and the also the Russians. ULA seem to be so convinced with their potential that they have already decided that they will be using Blue Origins 4 kN Methox engine (BE-4) on the successor of Atlas. The Russians are as always playing a wait and watch game. They have their Methox program ready and the successor of Soyuz (Soyuz 5 family) are supposed to use it. But they are waiting to see if the Americans really succeed and when they do (I think the question is when they succeed not if), they will fund their own production Methox engines and rockets in some form.

And, despite this ISRO goes back to 1960 and reinvents the kerosene-LOX engine (with special grades of rare to find blends of Kerosene etc rolled out as ISROrene).

The BE-4 is 4MN I think. It the replacement for RD-180. The Russians couldn't be bothered. They have excellent RP1-LOX engines . But for folks who don't have it, like the Americans and us, it makes sense to go the Liquid Methane-LOX way and leapfrog. ISRO desperately needs a 4MN LCH4-LOX engine. That engine size, with the ISP of Kerosene/LOX or LCH4/LOX , topped with a cryogenic 2nd stage is absolutely the most efficient configuration to get to GTO with a 5 ton payload (the GSLV MKIII class) as the core offering with just 2 stages. The solid boosters are for heavier lift configurations which are not the normal bread and butter situations but rather one off special stuff like "scientific payloads" or an opportunistic launch with multiple satellites etc.

The rest of the stuff is simply outdated. ISRO is going to go through all the pain in developing testing and qualifying a 2MN class engine Kerosene-LOX engine! Atleast, they should look to cluster that immediately as a parallel program and look to get a 4MN engine (though the Russian way of having common turbo machinery is probably more reliable , with less stuff to fail), the best way to salvage something from a suboptimal solution. The ULV should have two core stages. The 2MN for a PSLV class and 4MN cluster for a GSLV class.

hnair · Post by **hnair** » 07 Sep 2015 10:28

gakakkad, the soviet elves who IMO, worked silently to achieve soviet survival (for a few decades) are glushko, khariton and for H&D, korolev. Without whingeing about nobel like that sakharov et al, these silent types ensured that their country stayed relevant in cold war, particularly since khan's industrial and research prowess being fully intact, despite WWII.

And this despite the torture and imprisonment by the NKVD lowelife Beria! What ever the demerits of the system they served, these are some hardcore patriots, who, if they so wished, would have been whisked off in a jiffy.

Despite having a relatively less oppressive system like NKVD, there is nothing even remotely pioneering (like what these guys did) from the cheenland stables. My only guess is that cheen has finally improved upon something, better than the original it copied : The NKVD.

Anyways, OT.

Vina, CH4 is too risky a path for a risk averse ISRO. There might be a pilot running somewhere. But that is it. Until then, the K2 fueled binge it is

Singha · Post by **Singha** » 07 Sep 2015 10:39

of the original team of the 3-stage tsar bomba mega weapon, very little is known about some of them
he components were designed by a team of physicists headed by Academician Yulii Borisovich Khariton and including Andrei Sakharov, Victor Adamsky, Yuri Babayev, Yuri Smirnov, and Yuri Trutnev

yuri babayev - http://www.nytimes.com/1986/10/29/obitu ... icist.html
yuri smirnov - nothing
yuri trutnev - seems to be around still . again no real info on what he did. I read he had just passed out of college when he was put in as the youngest member of the tsar bomba team so must have been identified as a outlier talent to work with such heavyweights. https://en.wikipedia.org/wiki/Yuri_Trutnev_(scientist)

Neela · Post by **Neela** » 07 Sep 2015 13:25

Loaded statements above needed some digging to understand whats happening. Really tough choices it seems.

In the RP1 vs CH4 game, it appears ( I think ) it boils down to which of these is easier to overcome
- Coking of RP1 - affecting long term reusability/restart + higher Isp of CH4.
- Extra hardware to store CH4 cryogenically.

The energy density between the two is close enough.
RP1: 43.34 MJ/kg
CH4: 50 MJ/kg
->Isp is in favour of CH4.

But the LOX:Fuel ratio is higher for CH4.Meaning you lose additional hardware, weight to store CH4 cryogenically.
RP1 OTOH, seems to be "easier" to handle with no fancy temperature equipment needed

But considering "true" re-usability, long term, CH4 wins due to coking of RP1.

Existing plans of ISRO rely on the RP1 semicryo engine. Which means limited reuse of RP1 is seens as acceptable. I did read somewhere that ~15 times reuse is foreseen from ISRO.
Plus with RD-180 as the golden standard, its seen as "Known" devil vs Unknown angel. ( read "risk-averse" satement in one of the posts above)

But at 111K to store CH4, it is close enough to LOX meaning hardware can be shared.

Then again, CH4 and is associated paraphernalia all needs to be analysed after multiple uses , must undergo qualification cycles before being cleared. Costs time and money for ISRO.
With RP1 you know you have a problem ( coking, soot in the preburner(?) , combustion chamber(?) )

Added later: hnair's statement "risk averse" is a very heavily loaded statement.

symontk · Post by **symontk** » 07 Sep 2015 14:33

Neela wrote:Existing plans of ISRO rely on the RP1 semicryo engine. Which means limited reuse of RP1 is seens as acceptable. I did read somewhere that ~15 times reuse is foreseen from ISRO.
<snip>
With RP1 you know you have a problem ( coking, soot in the preburner(?) , combustion chamber(?) )

There is an ISV program planned by ISRO (saw some drawings 18 years back), where in which at first a reusable solid first stage is developed and then semicryo secind stage is also developed. Those reusable stages then fly back for reuse and will reused 10 times

Soot in semicryo is good for heat insulation but will create other issues, but needs to be managed

Singha · Post by **Singha** » 07 Sep 2015 16:10

how will they fly back? parachute into the sea like shuttle solid boosters ? spaceX has been lurching from failure to failure on the "proper" flyback part of landing by itself. https://www.youtube.com/watch?v=vmJK_v5wRZw
expensive failures as the falcon9 contains a bunch of engines in 1st stage....maybe releasing some anti corrosion gel to blanket the engines and then parachuting into sea would be cheaper albeit reloading and cleaning them will be much more work than a clean-drop self landing.

if there could be 6 folding spider legs from middle of 1st stage that splay wide out to 5 meters each to support the landing it would be relatively better. the current minimal 3 short legs are not going to hack it.

Singha · Post by **Singha** » 07 Sep 2015 16:11

dumb question. these rockets have a very high L:d ratio yet they remain standing on the launchpad when all support structures at various levels are withdrawn......how do they balance so perfectly until launch and not fall?

vina · Post by **vina** » 07 Sep 2015 16:33

support structures at various levels are withdrawn......how do they balance so perfectly until launch and not fall?

The rockets are firmly secured to the launch pad (like clamped at the base) and not free standing . I would think that the the restraints are let go once the steering engines are fired and build up sufficient thrust, and then the clamps are released and the main engines ignite.

symontk · Post by **symontk** » 07 Sep 2015 17:05

Singha wrote:how will they fly back? parachute into the sea like shuttle solid boosters ? spaceX has been lurching from failure to failure on the "proper" flyback part of landing by itself. https://www.youtube.com/watch?v=vmJK_v5wRZw
expensive failures as the falcon9 contains a bunch of engines in 1st stage....maybe releasing some anti corrosion gel to blanket the engines and then parachuting into sea would be cheaper albeit reloading and cleaning them will be much more work than a clean-drop self landing.

if there could be 6 folding spider legs from middle of 1st stage that splay wide out to 5 meters each to support the landing it would be relatively better. the current minimal 3 short legs are not going to hack it.

Will glide to the nearest airport, usually these stages will expend in minutes and so will not be quite far from main land

hnair · Post by **hnair** » 07 Sep 2015 17:26

The pyro fasteners firing (faint whiff of smoke) as the giant SRBs liftoff slowly at full power

https://vimeo.com/21414718

member_28108 · Post by **member_28108** » 07 Sep 2015 19:49

Two things keep a rocket erect - one the center of gravity that stays within the body of the craft (If you see a rocket being transported it does not tip over) and it is held to the launch pedestal by pyrofasteners or explosive bolts. These bolts are cut through once the liquid/solid engines develop enough thrust so at the time of firing the rocket is being pinned down to the launch pedestal and the rocket is then cut free and takes off.
Check out the GSLV launches - the umbilical tower is more of a delivery system that has various pipes /hoses that deliver the fuel etc to thetanks, communication cables etc etc which are detatched at the time of launch. See the GSLV CUS stage separation video and you can see some of the cords(interstage ) ripping off and flying off after separation.