Indian Missile Technology Discussion

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Aditya_V
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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Aditya_V » 23 Sep 2008 15:32

Rahul M wrote
Quote:
liquid fuel has shelf life of few months once the fuel is stored inside rocket

don't think that's quite correct.



I read the report and thats what it says. Regarding Liquid fuel, I am no expert but if I am right the First generation liquid fuel was heavily corrosive and could not be stored for more than a few hours, however, liquid fuels became more storable as time went by...

I think the 80-90's tech liquid fuel in the Prithvi's could be stored for a few months within the missiles.

I hope experts like Arun_S can throw more light on this

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Singha » 23 Sep 2008 15:45

not all liquid fuels may be dangerous. isnt the brahmos fueled by kerosene?

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Austin » 23 Sep 2008 16:20

Well from a stastical POV you still need a 3 perfect test to get that V Gama Graph as ramana had suggested , most likely as Arun pointed out the 3rd test will be done along with the Army , generally such test by the army was done on missile of production batch , DRDO seems pretty confident about A-3 now with two text book launch as they call it :)

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby ramdas » 23 Sep 2008 18:10

While this may clear Agni III for induction, Agni III should be repeatedly tested after induction by the army. Maybe even multiple Agni III and Agni II launches within a short time period as part of a military excersise - likewhat iran did with Shahab-3's a while ago.

Has Agni III gone into serial production , then ? Even 20 odd inducted Agni-III's will raise the threshold that China has to cross to repeat 1962 a lot. So, if the rate of production is good, by 2010, it will be very difficult for China to do a 1962 provided the political leadership is not made of napumsakas. Hopefully they have arrangements for building 20 such missiles per year.

I find it disturbing that yearly tests of batch produced BM's aent carried out. How then can they maintain quality control ?

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby rakall » 23 Sep 2008 18:17

Austin wrote:Well from a stastical POV you still need a 3 perfect test to get that V Gama Graph as ramana had suggested , most likely as Arun pointed out the 3rd test will be done along with the Army , generally such test by the army was done on missile of production batch , DRDO seems pretty confident about A-3 now with two text book launch as they call it :)



Actually we should not worry too much about it -- Because most probably Agni3 wont be the workhorse of our missile arsenal.. at best a intermediate step between Agni2 to true-ICBM and might probably see a LSP at best..

Agni3's value lies in it being a vehicle for testing the efficacy of a host of new systems like the Indigenous RLG based INS (or INGPS), new Composite rocket motor casing etc... Avinash Chander repeatedly pointed out that we were validating the building blocks for longer range missiles..

So instead of diverting the efforts for a third developmental trial (if the DRDO is confident enough, which seems they are) - we can morph the D3 into the first user trial and concentrate efforts on Agni5 of 5000km range with MIRV's..

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby asbchakri » 23 Sep 2008 18:19

ramdas wrote:While this may clear Agni III for induction, Agni III should be repeatedly tested after induction by the army. Maybe even multiple Agni III and Agni II launches within a short time period as part of a military excersise - likewhat iran did with Shahab-3's a while ago.

Has Agni III gone into serial production , then ? Even 20 odd inducted Agni-III's will raise the threshold that China has to cross to repeat 1962 a lot. So, if the rate of production is good, by 2010, it will be very difficult for China to do a 1962 provided the political leadership is not made of napumsakas. Hopefully they have arrangements for building 20 such missiles per year.

I find it disturbing that yearly tests of batch produced BM's aent carried out. How then can they maintain quality control ?


So what is the number of Warheads that AGNI 3 production version will carry. Building 20 misiles per year is not a problem. If A3 is to carry multiple warheads are we sure that the 2 successfull tests conducted are enough.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Austin » 23 Sep 2008 18:35

rakall wrote:Actually we should not worry too much about it -- Because most probably Agni3 wont be the workhorse of our missile arsenal.. at best a intermediate step between Agni2 to true-ICBM and might probably see a LSP at best..


Well military planners dont work and plan according to what they may get , but according to what they have , Agni-5 will come when it comes , for now Agni-3 will be our workhouse against china and those who matter with a light warhead.

What I would be keen to look at or know if they have tested lighter composite 2nd stage.

Some time between now and Agni-5 , tesse aunty will also launch the A-2AT that will be one of our workhorse against Chinki/Paki

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US Missile defence Shild: NPR.org

Postby Uttam » 23 Sep 2008 18:39

which part of "Indian" missile technology discussion is confusing ?
please post these in the international discussion threads.
Last edited by Rahul M on 23 Sep 2008 19:13, edited 1 time in total.
Reason: OT post edited.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Katare » 23 Sep 2008 20:32

Arun_S wrote:
Katare wrote:It's a upgraded derivative of an already proven platform so it may be OK.

Please help me understand which already proven platform is Agni-III an upgraded derivative of? and if there is any basis for such assertions w.r.t any similar missile anywhere in the world?


?? Agni1, 2 & 3

But I think DRDO works on shoe-string budgets and tries to do as little testing as possible,


Arun_S wrote:I do not think DRDO will embark on a missile program with a budget not enough for minimum number of test required for credible weapon.
IIRC after last test Saraswat said A-3 is ready for induction. Also that one more test by Army may be conducted before induction. The accuracy of the last 2 tests was gratifying, and the crucial first stage was basically sound on the first launch.


May be but to me the budgets that DRDO works on apprear shoe-string budgets.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby pkudva » 23 Sep 2008 20:52

The A-3 has still not gone for production, it will atleast take one year before the production starts. The clearnence has been given now and hence the various procedures before formal induction will start.

We should remember the a-3 was developed primarly to fit into the ATV. the range of the A-3 as known i.e 3,500km can easily be covered by A-2.

The Range of every missile is very confidential and no way it will be made public.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby neerajb » 23 Sep 2008 21:14

Singha wrote:not all liquid fuels may be dangerous. isnt the brahmos fueled by kerosene?


I don't have much idea about it but just guestimating. IMHO the oxidiser like red fuming nitric acid and not the fuel (which is toxic at best) makes the shelf life shorter for liquid fueled rockets. After all an oxidiser is an oxidiser.

Cheers....

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby ramana » 23 Sep 2008 22:36

Austin wrote:


I remember to my question ramana had stated that a bare minimum 3 test is needed for the system to be technically proven and to draw the V gama graph , why are we satisfied with just two test ?


The difference is between the qualifying the RV and the vehicle. The former is already qualified by the numerous Agony (as my MS Word calls it) tests. Need to look at big picture. Army induction is now very much needed as part of the nuke power status acceptance from the NSG waiver. So there are other drivers than just technology. So a quick induction is in order.

ramdas, this stuff is not like OFB product that needs regular proofing. And Iran is hardly a marker to match.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Arun_S » 24 Sep 2008 00:09

Aditya_V wrote:
Rahul M wrote
Quote:
liquid fuel has shelf life of few months once the fuel is stored inside rocket

don't think that's quite correct.



I read the report and thats what it says. Regarding Liquid fuel, I am no expert but if I am right the First generation liquid fuel was heavily corrosive and could not be stored for more than a few hours, however, liquid fuels became more storable as time went by...

I think the 80-90's tech liquid fuel in the Prithvi's could be stored for a few months within the missiles.

I hope experts like Arun_S can throw more light on this

neerajbhandari wrote:
Singha wrote:not all liquid fuels may be dangerous. isnt the brahmos fueled by kerosene?


I don't have much idea about it but just guestimating. IMHO the oxidiser like red fuming nitric acid and not the fuel (which is toxic at best) makes the shelf life shorter for liquid fueled rockets. After all an oxidiser is an oxidiser.

Cheers....

Few observations:
    1. Brahmos missile does not use rocket engine, so IMHO not applicable. Rocket engine by definition is one that does not need air to operate.
    2. Earth sortable liquid oxidizers are by its very nature very corrosive thus a serious fire and health hazard.
    3. Rocket fuel tank need to be lightweight, robust and cheap, and that competes with chemical characteristics needed for earth sortable liquid oxidizers as well as energetic liquid fuel. So will always be issue with keeping the fuel loaded in rocket fuel tank, as against loading it just before flight. Again depending on fuel tank's bells and whistles, it may be possible to de-fuel the rocket fuel tanks (of fuel and oxidizer) few times only.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Katare » 24 Sep 2008 00:59

DRDO scientists have stated several times over the years that liquid fuel technology has matured to the point where the shelf life (of a fueled Prithvi) is comparable to solid fuels or 10 years.

They also stated that world moved away from liquid fuels because of those early limitations but India being late entrant has enjoyed the benefits of later technology improvements in liquid fuels with obvious advantage of liquid propulsion technology like better precision etc.

Link

From Dr V.K. Saraswat....

"Pirthvi missile can be fuelled anywhere though it is generally done in depots. But once this missile is fuelled, it has a life of 10 years," he said.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby sam_kamath » 24 Sep 2008 04:47

Arun_S wrote:
Aditya_V wrote:
Rahul M wrote
Quote:
liquid fuel has shelf life of few months once the fuel is stored inside rocket

don't think that's quite correct.



I read the report and thats what it says. Regarding Liquid fuel, I am no expert but if I am right the First generation liquid fuel was heavily corrosive and could not be stored for more than a few hours, however, liquid fuels became more storable as time went by...

I think the 80-90's tech liquid fuel in the Prithvi's could be stored for a few months within the missiles.

I hope experts like Arun_S can throw more light on this

neerajbhandari wrote:
Singha wrote:not all liquid fuels may be dangerous. isnt the brahmos fueled by kerosene?


I don't have much idea about it but just guestimating. IMHO the oxidiser like red fuming nitric acid and not the fuel (which is toxic at best) makes the shelf life shorter for liquid fueled rockets. After all an oxidiser is an oxidiser.

Cheers....

Few observations:
    1. Brahmos missile does not use rocket engine, so IMHO not applicable. Rocket engine by definition is one that does not need air to operate.
    2. Earth sortable liquid oxidizers are by its very nature very corrosive thus a serious fire and health hazard.
    3. Rocket fuel tank need to be lightweight, robust and cheap, and that competes with chemical characteristics needed for earth sortable liquid oxidizers as well as energetic liquid fuel. So will always be issue with keeping the fuel loaded in rocket fuel tank, as against loading it just before flight. Again depending on fuel tank's bells and whistles, it may be possible to de-fuel the rocket fuel tanks (of fuel and oxidizer) few times only.



Arun,
I need to calculate sheer stress on a composite cylender object at different speeds at different g's at different altitudes and ambient temperatures.. Do you know something like rockism which might help me model this ...

thanks

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Gerard » 25 Sep 2008 02:06

DRDO to make missiles lighter, cost-effective
With an intention to make the country’s missiles lighter, cost-effective and possess greater hit power, the Defence Research & Development Organisation (DRDO) is augmenting its composite materials facilities and capabilities.
“In 6-7 years, we want to make all the stages of the Agni missile composite structured,” said Mr Avinash Chander
“At present, the payload and a small portion (nose tip) of Agni is made of composites, while the rest is metallic. Progressively, we will make the airframe, the upper stages and payload completely composite,” he told Business Line.
On Agni-V, he said the development is progressing. “We can test it in two to two and half years. Two out of three stages will be composite, which will reduce its weight and increase range,” he added.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby asbchakri » 25 Sep 2008 14:59

Gerard wrote:DRDO to make missiles lighter, cost-effective
With an intention to make the country’s missiles lighter, cost-effective and possess greater hit power, the Defence Research & Development Organisation (DRDO) is augmenting its composite materials facilities and capabilities.
“In 6-7 years, we want to make all the stages of the Agni missile composite structured,” said Mr Avinash Chander
“At present, the payload and a small portion (nose tip) of Agni is made of composites, while the rest is metallic. Progressively, we will make the airframe, the upper stages and payload completely composite,” he told Business Line.
On Agni-V, he said the development is progressing. “We can test it in two to two and half years. Two out of three stages will be composite, which will reduce its weight and increase range,” he added.


Agni -3 is a 2 stage missile with a range of 3,500KM. Agni 5 is a 3 stage missile with a range of 5,000KM. As per official reports, the 3rd stage is sufficient to carry it to 5,000 with metal stages. So as per the above report where it says 2 out of 3 stages will be composites to increase range, does he mean that it will be more than 5,000KM. Can any gurus, Arun_S comment :D

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Austin » 25 Sep 2008 15:11

Hven't you seen the range vs payload graph of Agni 3 , what is surprising is that they claim except of RV they dont use carbon composites(CC) , but AFAIK we do use CC for the first stage of A-3 and even the 2nd stage was supposed to receive that in the 3rd test of A-3

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Arun_S » 25 Sep 2008 15:22

Katare wrote:DRDO scientists have stated several times over the years that liquid fuel technology has matured to the point where the shelf life (of a fueled Prithvi) is comparable to solid fuels or 10 years.

They also stated that world moved away from liquid fuels because of those early limitations but India being late entrant has enjoyed the benefits of later technology improvements in liquid fuels with obvious advantage of liquid propulsion technology like better precision etc.

Link

From Dr V.K. Saraswat....

"Pirthvi missile can be fuelled anywhere though it is generally done in depots. But once this missile is fuelled, it has a life of 10 years," he said.


That is an apple and orange argument. Once fuelled Prithvi becomes a 8 months pregnent women and cant be transported unless defuelled. Thus essentially a sitting duck fit for living in a deep sialo. So it very different from mobile solid fuel missile types.

sam_kamath: Not that I know.
asbchakri: Not much to add, except that to get a sense of A3 range with current 2 stage confign or a future 3 stage confign the BR's Agni pages is the only place that will give realistic picture. Of course unless if you want to hear Brahma satya from GoI press release, GoI have many other considerations that will prevent release of range that can be construed provocative by unkill, auntie, unkill's nanny and 2 cent Swaziland, switzerland, and other types of WASP underwear.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby asbchakri » 25 Sep 2008 15:25

Austin wrote:Hven't you seen the range vs payload graph of Agni 3 , what is surprising is that they claim except of RV they dont use carbon composites(CC) , but AFAIK we do use CC for the first stage of A-3 and even the 2nd stage was supposed to receive that in the 3rd test of A-3


If you mean in Br's Agni page, yeah i have seen that. What i meant was about the official statement from Mr Avinash Chander. :D

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby asbchakri » 25 Sep 2008 15:29

Arun_S wrote:[asbchakri: Not much to add, except that to get a sense of A3 range with current 2 stage confign or a future 3 stage confign the BR's Agni pages is the only place that will give realistic picture. Of course unless if you want to hear Brahma satya from GoI press release, GoI have many other considerations that will prevent release of range that can be construed provocative by unkill, auntie, unkill's nanny and 2 cent Swaziland, switzerland, and other types of WASP underwear.


Ha ha :rotfl:

I have seen and always check on Br Agni pages. U r right what i said was from Mr Avinash Chander statements i feel that they are slipping some small bits of Brahma satya knowingly or ..u know :wink:

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby neerajb » 25 Sep 2008 15:40

Arun_S wrote:Once fuelled Prithvi becomes a 8 months pregnent women and cant be transported unless defuelled.


But why it is non transportable once fuelled? If it can tolerate corrosive fuels for 8 months then corrosion must not be the issue with transportation.

Cheers....

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby ramdas » 25 Sep 2008 17:49

Arunji,

Did'nt you assume for the A-3 range-payload graph that the first stage has composite motor casing ? Shri. Avinash Chander clearly says that as of now, both A-3 casings are metallic. As for A-5 , 2 stages will be metallic though by around 2015 they are moving to all stages composite.

So, is'nt that likely to mean A-3 range is less than what your range payload graph says, maybe 4500-5000 km @1500kg rather than 5500km @ 1500kg ?

However, reports of testing large composite motor casings have been circulating for a while- the PS-3 PSLV 3rd stage has such a casing. So I do not know why they stuck to maraging steel. Is it that right now they do not have manufacturing scale with composites as of now ? Or is it this great "separating strategic from civilian" business that has landed us up in this ?

As for the life time of liquid fuelled missiles. Many Soviet SLBMs were liquid fuelled. they were fuelled in the manufacturing plant itself . Special care was taken to see to it that no leaks occurred. The main engines were largely submerged in the fuel tanks. The fuel used was NTO/UDMH. Still, they had lifetimes of at least 15 years. Maybe even more than 20 years.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Avid » 25 Sep 2008 18:02

Actually - parse the statement with a little more nuance.

He said - in future all stages will be composite.

That does not mean - at present none of the are stages are composite :)

His statement can be see exactly as it is, and the converse of it means:
at least one stage of Agni-3 is not composite. That can mean what one interprets - depending on whether they are realists, optimists, or skeptics.

A-3 combined with the other party's intelligence in interpretation is a weapon, not just A-3 by itself.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby ramdas » 25 Sep 2008 19:36

"At present, the payload and a small portion (nose tip) of Agni is made of composites, while the rest is metallic. Progressively, we will make the airframe, the upper stages and payload completely composite,”


So , A-3 is right now, maraging steel casing...

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby sam_kamath » 25 Sep 2008 22:15

Arun_S wrote:
That is an apple and orange argument. Once fuelled Prithvi becomes a 8 months pregnent women and cant be transported unless defuelled. Thus essentially a sitting duck fit for living in a deep sialo. So it very different from mobile solid fuel missile types.



So are the Brahmos missiles solid fuled? I am assuming here that you are referring to the problem of Liquid sloshing. Physical properties of liquids staying same, sloshing should happen in both these missiles, not to mention a Brahmos carrier carries 3 missiles.
From what I have read (so i can be mistaken here) canisterising of a missile involves fuel stabilization too, read (gasoline to napalm)

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Katare » 25 Sep 2008 22:26

Arun_S wrote:
Katare wrote:DRDO scientists have stated several times over the years that liquid fuel technology has matured to the point where the shelf life (of a fueled Prithvi) is comparable to solid fuels or 10 years.

They also stated that world moved away from liquid fuels because of those early limitations but India being late entrant has enjoyed the benefits of later technology improvements in liquid fuels with obvious advantage of liquid propulsion technology like better precision etc.

Link

From Dr V.K. Saraswat....

"Pirthvi missile can be fuelled anywhere though it is generally done in depots. But once this missile is fuelled, it has a life of 10 years," he said.


That is an apple and orange argument. Once fuelled Prithvi becomes a 8 months pregnent women and cant be transported unless defuelled. Thus essentially a sitting duck fit for living in a deep sialo. So it very different from mobile solid fuel missile types.

sam_kamath: Not that I know.
asbchakri: Not much to add, except that to get a sense of A3 range with current 2 stage confign or a future 3 stage confign the BR's Agni pages is the only place that will give realistic picture. Of course unless if you want to hear Brahma satya from GoI press release, GoI have many other considerations that will prevent release of range that can be construed provocative by unkill, auntie, unkill's nanny and 2 cent Swaziland, switzerland, and other types of WASP underwear.


My understanding is little different. I do not beleive that 150KM range prithvi was ever designed to sit in a silo neither it makes any sense to put an SRBM in a silo. The missiles are fueled and kept in the depot redy to be deployed fueld as needed. There are no issues with transporting modern liquid fueled SRBMs.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby vivek_ahuja » 25 Sep 2008 22:48

sam_kamath wrote:So are the Brahmos missiles solid fuled?


Yes and no. Yes because you do have a short burn-length solid fuel grain sitting in the combustion chamber prior to launch and no because the burn time for that thing is small enough and used only for the launch phase after which the kerosene fuel stored further up front of the combustion chamber is let in. The valves at the front of the combustor are allowed to open to let air in and you have the standard combustion based ramjet engine working. In essence, the solid fuel burns itself out and clears the combustion chamber for kerosene and air to use later. All remaining solid fuel slivers are burned off by the latter.

-Vivek

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby p_saggu » 25 Sep 2008 23:29

Only the launch booster is solid fuelled. It drives the missiles out of the launcher and gives it a certain speed before the ramjet takes over. it seems that the ramjet needs a certain speed before it fires.
Vivek the solid fuel sits "inside" the combustion chamber of the liquid fuel engine? This is ingenious tech by the russians!
I thought that the solid fuelled part was attached to the rear end of the missile and was jettisoned when it burned off like all the numerous missiles.

Image

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby sam_kamath » 25 Sep 2008 23:39

vivek_ahuja wrote:
sam_kamath wrote:So are the Brahmos missiles solid fuled?


Yes and no. Yes because you do have a short burn-length solid fuel grain sitting in the combustion chamber prior to launch and no because the burn time for that thing is small enough and used only for the launch phase after which the kerosene fuel stored further up front of the combustion chamber is let in. The valves at the front of the combustor are allowed to open to let air in and you have the standard combustion based ramjet engine working. In essence, the solid fuel burns itself out and clears the combustion chamber for kerosene and air to use later. All remaining solid fuel slivers are burned off by the latter.

-Vivek

your point being? ..how is this related to Sloshing ...which is a transportation issue...kindly read the entire post before going off on a tangent...

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby vivek_ahuja » 25 Sep 2008 23:46

p_saggu wrote:Vivek the solid fuel sits "inside" the combustion chamber of the liquid fuel engine?


Well, that's not exactly a liquid engine per se, just like the turbojet engine combustor is not a liquid engine. Its just a mixer for fuel and air like a car engine, albiet at different conditions. If you want to save space, you can fix the solid fuel in the chamber and let it clean itself off. For Ramjets you have a combustor section that's like a hollow cylinder, perfect for use with a solid fuel. Its perfectly possible as long as you adjust the space and the flame holders and injectors for the fuel are sealed off from the rocket gases. I know that's something the Russians looked at, but going back and looking at the image you posted, and some terminal scenes of the missile just before impact it would seem that the Brahmos jettisons off the latter section somewhere along the way. So you could be right: the solid fuel sits in the jettison-able canister at the end.

And yes, the Ramjet needs to reach just near Mach 1 to before the inlet air and kerosene combustion can take over.

-Vivek
Last edited by vivek_ahuja on 25 Sep 2008 23:49, edited 1 time in total.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby vivek_ahuja » 25 Sep 2008 23:47

sam_kamath wrote:your point being? ..how is this related to Sloshing ...which is a transportation issue...kindly read the entire post before going off on a tangent...


It was in reference to your question about the Brahmos being a solid fueled missile etc. Nothing to do with liquid sloshing. Don't compare apples to oranges!

-Vivek

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby sam_kamath » 25 Sep 2008 23:57

edited.
Last edited by Rahul M on 25 Sep 2008 23:59, edited 1 time in total.
Reason: idiotic post edited.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby vivek_ahuja » 26 Sep 2008 00:03

You know, by default I am a pretty mild mannered person, and one thing I try to do is be civil on threads such as BR, so my first instinct is to see what the Moderators do about this direct provocation since the last thing I want is to get a warning for vulgar language trying to respond to your comments. So I will wait.

Added later: Thanks Rahul.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby p_saggu » 26 Sep 2008 00:25

Why would the fuel slosh about if it were completely filled into the tank with a pump ensuring that there is no air bubble inside. An air bubble might be fatal to the functioning of the missile, might it not cause an air lock??? (An air embolus in medical parlance :-))

The weight of the missile goes up a lot after it is fuelled, and requires much more care, any damage / leak / stress fracture to the tank could be fatal.

Are the Prithvi's fuelled after being erected by the TEL? I know some of the ICBM's deployed by the US, Soviet Union, and China were lugged around empty to increase mobility and for safety, were refuelled immediately before launch and after erected.

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby sam_kamath » 26 Sep 2008 02:32

p_saggu wrote:Why would the fuel slosh about if it were completely filled into the tank with a pump ensuring that there is no air bubble inside. An air bubble might be fatal to the functioning of the missile, might it not cause an air lock??? (An air embolus in medical parlance :-))

The weight of the missile goes up a lot after it is fuelled, and requires much more care, any damage / leak / stress fracture to the tank could be fatal.

Are the Prithvi's fuelled after being erected by the TEL? I know some of the ICBM's deployed by the US, Soviet Union, and China were lugged around empty to increase mobility and for safety, were refuelled immediately before launch and after erected.


OK .. i see where you are going with it.. so you want to tell me that a completely full jar of water if tightly sealed (lets say vacume sealed ) will not slosh... hmm no..it will sloshing is a property of the liquid.. you can control dynamic sloshing in a variety of ways (baffels, air suspensions, adaptive control, viscosity etc).. but in this case i have seen stabilizers being added.. Napalm is gasoline with stabilizers...cant comment on this much propitiatory issues...

do you get what i am saying? ask me if you still have doubts i can may be give you a better example..

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby sunilUpa » 26 Sep 2008 02:44

^^^Are you refering to Thixotropic gelled fuels?

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby sam_kamath » 26 Sep 2008 02:50

sunilUpa wrote:^^^Are you refering to Thixotropic gelled fuels?

yes .. the buffer polymers though is where the magic lies... loads of parameters to take care of not to mention near smokeless burns..

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Raj Malhotra » 26 Sep 2008 03:18

IIRC there was a report from a DRDO publication about development of gelled liquid rocket fuel. I hav'nt saved the link but it was a page that also referred to RLG INS credits

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Re: Indian Missile Technology Discussion - 27 March 2008

Postby Arun_S » 26 Sep 2008 03:44

sam_kamath wrote:So are the Brahmos missiles solid fuled? I am assuming here that you are referring to the problem of Liquid sloshing. Physical properties of liquids staying same, sloshing should happen in both these missiles, not to mention a Brahmos carrier carries 3 missiles.
From what I have read (so i can be mistaken here) canisterising of a missile involves fuel stabilization too, read (gasoline to napalm)

No, I am not pointing to sloshing issue but structural stresses when the lady is pregnant with loaded fuel.

Again comparison with jet engine powered missile like Brahmos with rocket powered Prithvi is inappropriate, the former has significantly higher ISP and is not a flying fuel tank, OTOH ISP of rocket engine Prithvi is much lower thus carriers a large fuel weight, and is more of a flying fuel tank going up and an empty light weight fuel tank coming down (when its light skin can afford some aerodynamic maneuver).
ramdas wrote:Arunji,

Did'nt you assume for the A-3 range-payload graph that the first stage has composite motor casing ? Shri. Avinash Chander clearly says that as of now, both A-3 casings are metallic. As for A-5 , 2 stages will be metallic though by around 2015 they are moving to all stages composite.

So, is'nt that likely to mean A-3 range is less than what your range payload graph says, maybe 4500-5000 km @1500kg rather than 5500km @ 1500kg ?

However, reports of testing large composite motor casings have been circulating for a while- the PS-3 PSLV 3rd stage has such a casing. So I do not know why they stuck to maraging steel. Is it that right now they do not have manufacturing scale with composites as of now ? Or is it this great "separating strategic from civilian" business that has landed us up in this ?

As for the life time of liquid fuelled missiles. Many Soviet SLBMs were liquid fuelled. they were fuelled in the manufacturing plant itself . Special care was taken to see to it that no leaks occurred. The main engines were largely submerged in the fuel tanks. The fuel used was NTO/UDMH. Still, they had lifetimes of at least 15 years. Maybe even more than 20 years.

Suggest to read the Agni news report again: http://www.thehindubusinessline.com/200 ... 721200.htm
The first half of the article quoted below generally talks about DRDO missiles and Agni (and not Agni-3) meaning older versions of Agni (A1, A2, A2AT).
M. Somasekhar
Hyderabad, Sept. 24 With an intention to make the country’s missiles lighter, cost-effective and possess greater hit power, the Defence Research & Development Organisation (DRDO) is augmenting its composite materials facilities and capabilities.

An independent centre for composite testing and evaluation is being set up at the Hyderabad-based Advanced Systems Laboratory (ASL), the premier lab guiding the long range missile — Agni programme and providing key technology inputs to other missiles.

ASL already has composites production centre (Comproc), which fabricates the lightweight material for Agni and other missiles. “In 6-7 years, we want to make all the stages of the Agni missile composite structured,” said Mr Avinash Chander, Director of the Laboratory under DRDO.

At present, the payload and a small portion (nose tip) of Agni is made of composites, while the rest is metallic. Progressively, we will make the airframe, the upper stages and payload completely composite,” {Arun: He is alluding to the Agni-2AT that is now headed by Ms Thomas. A2AT second stage will be composite while the booster will stay metallic albeit much stronger and lighter maraging steel. The composite nose tip again refers to A1,A2 RV, because A3 RV is all carbon composite body with no metal backing}he told Business Line. There is lot of interest from the private sector in the composites arena and no dearth of raw materials, he added. Composite material, which can withstand very high temperatures and are robust, finds application in aerospace, the light combat aircraft and satellites.

The ASL provides composites and solid propulsion systems to most missiles such as Prithvi, Akash, Nag and Astra, Mr Chander said. Another initiative taken up by ASL is in the area of non-destructive evaluation of materials. This would help in assessing the health of the missile systems and components.


The second half of the article then transitions to Agni-3 discussion, quoted below:
Cost-effective

Since we cannot bring these back from the field, the testing done through NDE tools and methods on site would make it cost-effective, he added.

These techniques are useful in detecting degradation of materials, cracks or other minor defects, which can reduce the life of the missile or make it ineffective.

Typically, ultrasound and nuclear magnetic resonance techniques are used. Asked about Agni-3, the long-range, surface to surface missile, Mr Chander said it has been cleared for induction into the Defence forces.

“We will do user trials when required, but it is ready for manufacture and induction,” he said. The missile was tested thrice between July 2006 to May 2008, with the first being a failure.

On Agni-V, he said the development is progressing.

“We can test it in two to two and half years. Two out of three stages will be composite, which will reduce its weight and increase range,” he added.


ramdas wrote:
"At present, the payload and a small portion (nose tip) of Agni is made of composites, while the rest is metallic. Progressively, we will make the airframe, the upper stages and payload completely composite,”


So , A-3 is right now, maraging steel casing...
Wrong context. See above response.

The 3 A3s that were tested all had Composite booster motor and second stage casing was maraging steel. 3'rd or 4'th A3 test was expected to use composite case for second and/or 3rd stage motoralso (it is still intriguing why the choice was made, to fly the initial missions with upper stage made of maraging case).

JMT.


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