Indian Missiles and Munitions Discussion

Indranil · Post by **Indranil** » 20 Feb 2013 12:39

Also, IAF might be checking if BEL can provide good QC for 50 LGB kits.

Kartik · Post by **Kartik** » 20 Feb 2013 13:05

indranilroy wrote:
Kartik wrote:just 50 ?! What on earth is wrong with the IAF ?!
I was about to say the same thing! But Sudarshan seems to roll quite a lot. I watched the video posted by Tarmak closely. The bomb rolls quite a lot just after the tail fins deploy.

I'm not an expert in this, but wouldn't rolling help stabilise the bomb? Why would a bomb that rolls have a higher CEP than one that rolls less?

Indranil · Post by **Indranil** » 20 Feb 2013 13:31

Neither am I. Sudarshan starts rolling immediately after release. What worries me is that its longitudinal axis starts wobbling (a lot) around the line of flight as soon as the fins deploy. Most probably, at least the wobbling is dampened out by canards after the video ends.

I was seeing the videos of other LGBs. They don't roll. Anyways, one wouldn't want such long fins on something that was designed to roll. So I am assuming Surdarshan also is not supposed to roll.

pankajs · Post by **pankajs** » 20 Feb 2013 13:56

India to manufacture scaled-down model of BrahMos missile

India has started the manufacturing of a scaled-down model of the BrahMos Russian-Indian supersonic missile.

The new missile will weigh 1.5 tons; it will be some 6 metres long and will boast a range of approximately 290 kilometres.

The missile is meant for the Indian Air Force, and is due to be test-fired in a matter of 18 months to 24 months.

The joint Russian-Indian venture BrahMos Aerospace was set up in 1998, and was named after the two rivers, - Brahmaputra and Moskva.

The sea-based supersonic BrahMos missile was successfully test-fired in October last year.

The submarine-based analogue is due to be test-fired in March this year.{Seems to have moved from Feb end to March}

Sagar G · Post by **Sagar G** » 20 Feb 2013 14:16

Kartik wrote:just 50 ?! What on earth is wrong with the IAF ?!

Not a bad number since the tech is still maturing and as per the article IAF wants a CEP of 3-5m than the current CEP of less than 10m which will be incorporated in the next NG-LGB with a range of 50 Km after which massive order should be placed.

In terms of CEP we are right now here

and we need to be here

GBU-24 Paveway III

neerajb · Post by **neerajb** » 20 Feb 2013 14:17

Kartik wrote:
indranilroy wrote: I was about to say the same thing! But Sudarshan seems to roll quite a lot. I watched the video posted by Tarmak closely. The bomb rolls quite a lot just after the tail fins deploy.
I'm not an expert in this, but wouldn't rolling help stabilise the bomb? Why would a bomb that rolls have a higher CEP than one that rolls less?

Kartik, guided munitions avoid body rolling because it complicates the trajectory computation. Exception: RAM missile which uses rolling airframe to stabalize itself. Most missiles/LGBs are controlled/trajectory corrected by yaw/pitch only with roll as side effect. Exception : Meteor which uses bank to turn instead of skid to turn.

Disclaimer : I haven't seen the video yet and I am no expert even remotely

Cheers....

Kersi D · Post by **Kersi D** » 20 Feb 2013 14:58

mody wrote: As soon as news of Indigenous stuff nearing maturation start coming through, the market gets flooded with previously unavailable foreign maal.

Aditya_V · Post by **Aditya_V** » 20 Feb 2013 16:31

pankajs wrote:India to manufacture scaled-down model of BrahMos missile
India has started the manufacturing of a scaled-down model of the BrahMos Russian-Indian supersonic missile.

The new missile will weigh 1.5 tons; it will be some 6 metres long and will boast a range of approximately 290 kilometres.

The missile is meant for the Indian Air Force, and is due to be test-fired in a matter of 18 months to 24 months.

The joint Russian-Indian venture BrahMos Aerospace was set up in 1998, and was named after the two rivers, - Brahmaputra and Moskva.

The sea-based supersonic BrahMos missile was successfully test-fired in October last year.

The submarine-based analogue is due to be test-fired in March this year.{Seems to have moved from Feb end to March}

Truely CHanakyian, reduce missile weight by half but manage to keep the same range.

Mukesh.Kumar · Post by **Mukesh.Kumar** » 20 Feb 2013 16:35

Aditya_V wrote:The new missile will weigh 1.5 tons; it will be some 6 metres long and will boast a range of approximately 290 kilometres.

More and more I am getting convinced that the actual range for Brahmos is far higher than 300 Km.

samverma · Post by **samverma** » 20 Feb 2013 16:40

Mukesh.Kumar wrote:
Aditya_V wrote:The new missile will weigh 1.5 tons; it will be some 6 metres long and will boast a range of approximately 290 kilometres.
More and more I am getting convinced that the actual range for Brahmos is far higher than 300 Km.

Noobie question....does this reduction with same range be adjusted with tech input to convert the brahmos into air to air?

Varoon Shekhar · Post by **Varoon Shekhar** » 20 Feb 2013 17:13

"As soon as news of Indigenous stuff nearing maturation start coming through, the market gets flooded with previously unavailable foreign maal."

Very dishonourable behaviour from the Western/rich countries. There was a major case back in the late 80's of India being refused the know-how for polysilicon. An Indian concern(Metkem??) was able to develop the technology entirely by itself. Then an American company stepped in and offered the technology at a farily low cost. The idea was to scuttle any growth by India based on its home grown ability, or that is what is looks like! Does anyone know if the Indian company continued in its efforts, or was shut down?

srin · Post by **srin** » 20 Feb 2013 17:14

I don't understand why you need to use Brahmos when you can eventually upscale a perfectly good Astra ? Why the Brahmos fetish ?

1.5t is still too much for air-to-air - check out the R-33 or R-37 - the weight around 500-600kg for comparable ranges.

The speed is also a factor - most of the AA missiles are Mach4+ to cover such a long range quickly.

And some long range AA missiles climb to very high altitudes (where air resistance is lower and hence cruising is more efficient) ... Brahmos flight profile is different.

The massive warhead of Brahmos to take out capital ships is wasted on an aerial target.

JTull · Post by **JTull** » 20 Feb 2013 17:26

As soon as news of Indigenous stuff nearing maturation start coming through, the market gets flooded with previously unavailable foreign maal.

As soon as a defense bribery news shows up on horizon, long delayed "initial" orders for desi maal start coming through. Perhaps we need a perpetual scam so desi maal can get its due.

member_22539 · Post by **member_22539** » 20 Feb 2013 17:41

+1 Every defense scam is a dark cloud with a HUGE silver lining.

Singha · Post by **Singha** » 20 Feb 2013 17:44

10m CEP can be a problem in the moutains where targets could be circled by steep slope. a small miss can mean it explodes a lot farther away.
that apart , a 3m CEP will permit smaller bombs to use the sudarshan kit like 250kg and 100kg.

not every target needs a 600kg bomb...esp the mobile targets and concentrations of vehicles...even 10kg smart weapon is enough to blast a few tanks...we should try for SFW munitions next delivered from a boxy gliding container.

JTull · Post by **JTull** » 20 Feb 2013 18:38

While an all singing and dancing desi-LGB kit is desirable, a 10m CEP but cheap Sudarshan kit will suddenly make IAF inventory of dumb bombs a very potent arsenal.

IAF could still pick a phoren LGB depending upon a particular mission.

negi · Post by **negi** » 20 Feb 2013 18:45

Rolling provides directional stability it is a desirable trait for dumb bombs as one can release it before a target and hope that it follows the parabolic trajectory to the target without swaying to either side . It might be good thing to have for a gliding munition in initial stage but for the movable fins to serve as a lifting surface the rolling needs to stop.

Singha · Post by **Singha** » 20 Feb 2013 18:47

yes it presents the chance for us to deploy PGMs fleetwide rather than only few 100 units kept for special occasions like a PA Al khalid div in outskirts of mehrauli and rohini.

SaiK · Post by **SaiK** » 20 Feb 2013 20:23

Aditya_V wrote:The new missile will weigh 1.5 tons; it will be some 6 metres long and will boast a range of approximately 290 kilometres.

It can go straight into the external fuel pylon carriage of strengthened LCA-mk2 then.

ramana · Post by **ramana** » 20 Feb 2013 20:42

Where is the video of the rolling Sudarshan please?

pankajs · Post by **pankajs** » 20 Feb 2013 21:01

tarmak

http://tarmak007.blogspot.in/2013/02/blog-post.html

member_20067 · Post by **member_20067** » 20 Feb 2013 21:14

pankajs wrote:tarmak

http://tarmak007.blogspot.in/2013/02/blog-post.html

Holy Crap... !! that almost hit the chasing plane.... is that normal... the release seemed very bouncy and unstable...

jamwal · Post by **jamwal** » 20 Feb 2013 21:24

Aditya_V wrote: Truely CHanakyian, reduce missile weight by half but manage to keep the same range.

Not an expert but it's not that special.
Air launched Brahmos can be lighter because it doesn't have to start from a stationary point on ground with inertia and gravity acting against it. When launched from an aircraft traveling at near supersonic speed, it will not need to burn so much fuel just to get off ground and attain a certain velocity.
Only point bothering me is the long time it's been taking. It's too long for a supposedly mature missile system.Designers may have optimised it's center of gravity and some other characteristics so that before ignition it'll fall longitudinally instead of nose first; in case it was not like that earlier.
Unavailability of launch platforms can be another factor which brings me to my pet

of lack of heavy bombers in Indian inventory.

TL;DR: It's true range is unlikely to be more than 300km, with or without Chanakiyan theories.

Baikul · Post by **Baikul** » 20 Feb 2013 21:31

Varoon Shekhar wrote:"As soon as news of Indigenous stuff nearing maturation start coming through, the market gets flooded with previously unavailable foreign maal."

Very dishonourable behaviour from the Western/rich countries.

It's just business; I'd warrant every entity in the world will do likewise.

Varoon Shekhar wrote:There was a major case back in the late 80's of India being refused the know-how for polysilicon. An Indian concern(Metkem??) was able to develop the technology entirely by itself. Then an American company stepped in and offered the technology at a farily low cost. The idea was to scuttle any growth by India based on its home grown ability, or that is what is looks like! Does anyone know if the Indian company continued in its efforts, or was shut down?

This link http://www.sanmargroup.com/metkem-silicon.php suggests that it is still around and producing "hyper pure polysilicon since 1982".

ramana · Post by **ramana** » 20 Feb 2013 22:16

The test article rolls because of roll torque due to assymetric fin areas and the roll rate is dependent on the roll moment of inertia.

Is the CG forward enough? The way it drops tail first shows some other problems for the control system to overcome.

The target circle painted is the CG of the assembly.

Do we have any videos of plain dumb bombs being released from IAF planes?

I think the roll and other irregularities are what reduce the energy of the test article guidance and result in higher CEPs.

One can calculate the roll moment of Inertia for the assy and calculate the roll torque due to the fins. It might be the fins are sized for larger test article and thus spin it.

Would mount the kit on a heavier test article(the FSU versions) and see how it behaves.

---------------------

Going back to previous page and reading the link:

IAF wants 50 LGBs

Confirms the roll problem is noted and needs to fix it.

By Anantha Krishnan M
Express News Service
Bangalore: After series of flight trials, the Indian Air Force (IAF) has asked the Aeronautical Development Establishment (ADE), to make 50 laser-guided bombs (LGBs) -- Sudarshan. These dumb bombs (Mark 11 N bombs), hitherto part of IAF’s vintage ammunition, is getting a life-extension with ADE’s help, with an improvised range and strike capabilities.
The ADE won the project for developing an LGB seven years back and subsequently successfully demonstrated the capabilities to the IAF during differed flight trials in 2010. It was also dropped from a Jaguar as part of the user trial in Pokhran, the same year. “Our mission was to develop an advanced laser guidance kit for 1000 lb class dumb bombs, so as to improve the accuracy. We demonstrated the same and now the IAF has asked us to make 50 Sudarshans,” ADE director P S Krishnan told Express on Tuesday.
Krishnan says the laser-guidance seeker, fitted on the nose of the LGB, is the most critical desi component onboard. “It’s developed jointly by IIT Delhi and ADE, while BEL is the production agency. The guidance kit directs the bomb towards a target, which has been illuminated by laser energy using a laser designator (LD) system. The laser energy is reflected from the target and detected by the laser seeker unit on the LGB kit. The seeker provides information on the deviation of the laser spot from the centre line of the detector. The control system processes this information and generates suitable deflections on the canard surfaces to effect changes in bomb trajectory thereby guiding the bomb to the target,” he explained the features of the bomb.
Sudarshan has onboard a flight control computer with MEMS-based (microelectromechanical systems) rate gyros. It also has high-precision linear ball-lead-screw actuators (to move the control surface). The four tail fins get deployed during the flight. A next-generation bomb (NG-LGB) studded with new technologies is in the pipeline, but the scientists need to address the problem of rolling of the bomb, after its release. “The range of Sudrashan now is around 9 km, if dropped from a normal altitude, and for the NG-LGB we hope to increase the range to 50 km,” he said.
The IAF wants the circular error probability (CEP) of the LGB between 3 to 5 meters and ADE scientists are now working to achieve the same. Currently the CEP for Sudarshan is within the 10 meters. (CEP is measurement of a weapon’s precision.) In addition to the Jaguars and the Mig-27s, in future Sudarshan can be fitted on to Tejas too.

50 units will help establish the BEL production run.
The next gen LGB 50km range would require GPS integration in addition to the LGB mode. Leading to IAF flexibility and reduction in logistics trail.

Also have the solved the fuze problem that other IAF comments mention?

Singha · Post by **Singha** » 20 Feb 2013 22:28

here is one shaky paveway drop
http://www.youtube.com/watch?v=bRRXK7QnxaU
but in another test it seems to be rock solid and not rolling at all!
http://www.youtube.com/watch?v=FB6KZ7Z8 ... 9A8999F042
another nice release
http://www.youtube.com/watch?v=kjOx3_-oiUU

maybe they should let the puppy fall a while before springing those fins out..?

rgsrini · Post by **rgsrini** » 20 Feb 2013 22:48

It starts off pretty stable when it is released. It starts to wobble as the fins were getting deployed. I wish we have the video of the whole flight as it would tell us if it stabilizes after this brief period of wobble.

I am no expert. May be it is just a question of balancing the bomb. For example, they can add a weight to the bottom side of the bomb to make sure it quickly stabilizes with the heavier side pointing downwards. They can also do the same thing longitudinally.

vasu raya · Post by **vasu raya** » 20 Feb 2013 22:57

Believe that the dumb bombs have the roll charasteristic built into them for accuracy reasons, its the Sudarshan kit fins trying to counter act that roll motion thats causing the initial instability

ramana · Post by **ramana** » 20 Feb 2013 23:00

I dont think so. When the test article spins it could develop a spin rate that makes it awry. So control of the spin is important for unguided articles.

vasu raya · Post by **vasu raya** » 20 Feb 2013 23:04

In American football, they spin the ball during the throw, the angle of the throw matters and the spin rate is low else yes it will wobble

negi · Post by **negi** » 20 Feb 2013 23:12

^ That is for directional stability like firing a lug or a bullet from a rifle the spin gives it directional stability however if you were to fire a sabot or dart which has a higher L:D ratio with fins it does not require so much spin to achieve directional stability the fins do that job (does not mean that fin stabilized projectiles do not spin , the spin is negligible).

vasu raya · Post by **vasu raya** » 20 Feb 2013 23:21

self-deleted

Kanson · Post by **Kanson** » 20 Feb 2013 23:50

rgsrini wrote:It starts off pretty stable when it is released. It starts to wobble as the fins were getting deployed. I wish we have the video of the whole flight as it would tell us if it stabilizes after this brief period of wobble.

I am no expert. May be it is just a question of balancing the bomb. For example, they can add a weight to the bottom side of the bomb to make sure it quickly stabilizes with the heavier side pointing downwards. They can also do the same thing longitudinally.

Deployment of fins where the problem lies. Deployment should have to happen little earlier. But each weapon and its release trials from specific platform are saga of its own. Its not a major problem if you ask me.

It also has high-precision linear ball-lead-screw actuators

rgsrini · Post by **rgsrini** » 21 Feb 2013 00:04

In the case of a bullet, the rifle has groves in it causing the spin. How do you build roll into a dumb bomb. It doesn't go through a rifled bore. It just disengages from the bottom of an aircraft. One possibility is to cut helical groves on its exterior so that the airflow causes it to spin. I don't see any such thing on its exterior.

Are there any other way to do it?

I am sure we can find videos of dumb bomb drops to confirm if it actually has a spin.

Kanson: I fully agree. I don't think it is a major problem as well.

Besides the weight balance issue and the fin deployment issue, I am also thinking of another theory to explain the longitudinal wobble. May be the fins are too big for the bomb. The fins of the Sudharshan kit is intended to make the bomb glide, while the nose changes its angle and direct it to a particular target. If the fins are too big for the weight of the bomb, there could potentially be an alternating effective force acting on the bomb (atleast that is my theory). When the nose of the bomb is pointing downwards may be the drag (due to the fin) increases causing it to lift its nose up. When the nose is up, the drag reduces to less than the COG force, causing the bomb to tilt downwards (only to increase the drag). This could cause a longitudinal wobble.

Added later: Just noticed, that Ramana above has also alluded to the same. I think a larger test article will probably be more stable.

negi · Post by **negi** » 21 Feb 2013 00:31

rgsrini wrote:In the case of a bullet, the rifle has groves in it causing the spin. How do you build roll into a dumb bomb. It doesn't go through a rifled bore. It just disengages from the bottom of an aircraft.

You don't have to build it ; fins cut through the air during the free fall in case of dumb bomb they are fixed and symmetrical and depending on the timing and nature of release it can roll clockwise or anticlockwise; in absence of fins a bomb would have tumbled, fins kind of control the more irregular tumbling and keep the bomb on it's course.

See from 2:05 onwards (note the video is in slow motion) B-52 is simply releasing bombs from it's bomb bay and these are dumb bombs but they all are rolling.

rgsrini · Post by **rgsrini** » 21 Feb 2013 00:43

Thanks Negi. So simple, beautiful, balanced and peaceful until it hits the ground.

SagarAg · Post by **SagarAg** » 21 Feb 2013 01:06

What kind of missile is this ?

Indranil · Post by **Indranil** » 21 Feb 2013 01:11

SagarAg wrote:What kind of missile is this ?

Rockets from Mig 27.

Indranil · Post by **Indranil** » 21 Feb 2013 01:13

rgsrini wrote:May be it is just a question of balancing the bomb. For example, they can add a weight to the bottom side of the bomb to make sure it quickly stabilizes with the heavier side pointing downwards.

That does not happen. The gravitational acceleration is the same on all parts of a body.

Indranil · Post by **Indranil** » 21 Feb 2013 01:26

rgsrini wrote: Besides the weight balance issue and the fin deployment issue, I am also thinking of another theory to explain the longitudinal wobble. May be the fins are too big for the bomb. The fins of the Sudharshan kit is intended to make the bomb glide, while the nose changes its angle and direct it to a particular target. If the fins are too big for the weight of the bomb, there could potentially be an alternating effective force acting on the bomb (atleast that is my theory). When the nose of the bomb is pointing downwards may be the drag (due to the fin) increases causing it to lift its nose up. When the nose is up, the drag reduces to less than the COG force, causing the bomb to tilt downwards (only to increase the drag). This could cause a longitudinal wobble.

Could not follow this theory. Are you trying to say that the canards are trying to point the nose down while the fins are trying to keep it horizontal. and hence there is creating an SHM around the longitudinal axis. If yes, then it is wrong.

That condition happens when the flight is powered. If you are trying to move in the direction of the longitudinal axis and the control commands and reaction become out of sync. Then you would have that SHM about the longitudinal axis. For example you can see the F-22 crash.