Artillery: News & Discussion

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ramana
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Re: Artillery Discussion Thread

Postby ramana » 16 Nov 2017 03:21

Some root cause for the Dhanush and M777 shell bursts in barrel

Arty shells broke up in barrel during recent misfires



Artillery shells broke up within barrels during recent misfires
Shishir Arya | tnn |
Updated: Sep 28, 2017, 19:24 IST

Nagpur: Misfires have been reported over the last five months in two artillery guns, US' M777 howitzers recently delivered to India, and the home made Dhanush, modelled on the Swedish Bofors. In all these incidents between May and September, the shell did not explode, but had fractured within the barrel before coming out, probably due to pressure.

The shell had hit the muzzle of Dhanush's barrel during test fires in May and July. The muzzle, which is on the top of the barrel was damaged in the incident. A similar incident was reported in the American M777 ultralight howitzers on September 2. Sources say the damage to M777 was much more severe as compared to Dhanush. The first batch of 25 M777s were delivered by BAE Systems in May this year.


However, it is too early to say whether the shell or the gun is faulty, say sources involved in the matter. The Ordnance Factory Board (OFB) has said a joint investigation is underway in the M777 incident. Primary investigation into May's incident with the Dhanush points to problems in the shell. Now, the entire case is being studied with a fresh perspective, said sources. This is a peculiar situation, say experts involved in the case, as shell fracturing is not common.

Artillery shells used by the Army are manufactured in ordnance factories located across Vidarbha. The shells are made in the ordnance factory at Ambajhari and the explosives are manufactured at Bhandara. In all the three incidents, the shells used were made by the ordnance factories. Now, due to the similar problems, a relation is being suspected in all the cases.


Sources involved in the probe say that the reason cannot be easily pinpointed and a detailed investigation is underway. If needed, changes may be made in the Dhanush guns. However, before this, the need for the changes will have to be confirmed. Since misfires have happened once in 1,200 rounds, it's difficult to ascertain the exact cause. There are plans to conduct intense internal trials of the gun before going for another round with the Army, said sources.

{What they are saying is its rare event and hence cant pin down the exact cause.}

In 2013 too, there had been a barrel burst in the Dhanush. It had led to major damage to the barrel but there were no casualties. At that time, it was a rouge ammunition that had burst within the barrel, says the report.


Data accessed by TOI shows that there were cases of muzzle hit and barrel burst in the original Bofors too. In three instances, 'bore premature' has been mentioned as the reason. This means the shell exploded prematurely, within the barrel. There are a couple of reports in which the inquiry says that neither the gun nor ammunition could be blamed. :?: :?: :?:

Earlier, shells manufactured by South African firm — Naschem — were used in the original Bofors guns. [u]Nearly a dozen instances of barrel or muzzle being damaged took place with the Naschem ammunition, says data with TOI.[/u]

There have been earlier instances of accidents in the M777 guns too. This year, two soldiers died in an explosion within the barrel during an engagement with the IS in Iraq. There were two separate incidents in 2014 in the US and Australia, apart from March 2011.

{So its not impossible but rare event and has occurred in other countries also. Not unique to India only.}

Record range achieved using same shells

Recently, developers of the ATAGS, another 155mm gun, claimed that it set a world record by achieving a range of 48km. Based on a design by Armament Research and Development Establishment (ARDE), a unit of the DRDO, the gun is being developed by Tatas and Bharat Forge.

Incidentally, the shell used during the trials when the record was achieved has also been made by the ordnance factories. A source in one of companies engaged as development partner of ATAGS said, "Though the shell had achieved a record range, it was with the barrel manufactured by us." :((

"Range is a function of propellent charge and capacity of the weapon to withstand pressure. Earlier imported, the propellent is now made by the ordnance factory," the source said.


To my one track mind this is a very clear case of balloting or spinning top issue.

To recollect this happens when the clearance between the bourrelet (the cylindrical portion of the shell) and the barrel has excess clearance, the shell center of gravity is off axis to one side i.e. eccentricity (this causes the shell to spin like a top and wobble around the rotating band), and if the charge is maximum(to give maximum range) which gives most energy to this spinning shell.As the shell travels along the barrel it hits the sides of the barrel due to the wobbling motions. As the shell slaps the barrel with a lot of force (up to 40,000 gs = 100 lbs (weight of shell) * 40,000 = 4 Million lbs force!). This huge force can shatter the shell and the fuze breaks off without functioning. To exacerbate the situation the shell is the ERFB/BB unit as the above report says was used on the ATAG models and achieved large range of 48km. The ERFB is made with frangible steel to give maximum fragmentation effect. The steel has low fracture toughness in order to break up into very small pieces. So its like a cast iron shell that shatters when dropped with high force or hit with sledge hammer.
And to confirm this recover the fuze and verify its state of functioning. I am willing to bet the fuze never functioned.

One avenue of investigation should be to take ten shells from each lot of those shells and measure the bourrelet diameter and to put them on a spin table (moment of inertia measuring machine) and see how they measure up. Then call the ARDE folks and conduct a balloting analysis on their software. I know they have this software for they write articles in Defence Science Journal.
Also tabulate all the incident with:
Date, Type of shell, Type of Charge, Fuze Comments

Comments can be if the shell was a first of firing or in the midst of a volley. The reason here is if there is residue due to tempo of firing, the shell does not seat properly. Looking at the shell shattering I think this unlikely.
And who made the shell OFB or foreign supplier

This table will point out what is common and what is different in all the above incidents that Shishir Arya notes with Bofors (3+2), Naschem (12), Dhansuh (1+2) and M 777 (1). Total 21 instances.

Based on results of this they need to put more controls on the shell manufacture at OFB Ambajhari where the shell is machined.

Do we have any BRF members in Nagpur who can contact Shishir Arya of TOI and take a dekko of the records if he still has them?

I don't think they need to make any changes to the Dhanush barrel.
Its the shell dimensional and procedures updated based on ARDE analysis.

Links to past posts:

Discussion on M107 vs. ERFB shells: viewtopic.php?p=2221916#p2221916

ERFB shell materials viewtopic.php?p=2222838#p2222838

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Re: Artillery Discussion Thread

Postby Vinay_GR » 16 Nov 2017 08:43

dear Gurus :) will the countless and endless trail's end and are we going to induct any on the indigenous artillery units any time soon

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Re: Artillery Discussion Thread

Postby Singha » 16 Nov 2017 09:10

the need for quality becomes more important as one moves to higher fire rates and higher pressures of 155mm from the old loosey goosey 105mm types.

clearly there are areas where our OFBs are not exactly running like a smoothly oiled Honda plant. the only way out is let ammo be manufactured by the private sector using whatever machinery and expertise they need to buy or import. their workers usually from machine tools and automotive background will be more disciplined as well. and their managers more watchful and process oriented.

we have already lost years of time .... how long will this circus go on? the new 155mm circus started in 1998 after kargil...today its on verge of 2018...I was unmarried brf fresher in 1998, today my son is in grade 7 .... :rotfl:

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Re: Artillery Discussion Thread

Postby Yagnasri » 16 Nov 2017 09:24

Please wait for your grandchildren to come we are in the fast track mode in a bullet train speed.

On the serious side, I think we have already made progress in this sir. I do not see any import lobby messing up things now. At least I hope they can not at this stage.

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Re: Artillery Discussion Thread

Postby Pratyush » 16 Nov 2017 10:16

Import lobby can only mess up things when domestic suppliers are only OFB. By involving OFB and pvt sector players the ATAGS has become too big to fail. The dhanush can still be scrapped. Bit of that happens. It will just be replaced with the ATAGS.

So no worries in any respect WRT Arty.

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Re: Artillery Discussion Thread

Postby ramana » 16 Nov 2017 10:39

I think the way ahead is to come up with ERFB shells from low carbon steel such that they have high fracture strength and don't shatter in the barrel. In other words make them with material from M107 type shells.

Have M107 shells ever burst in the barrel in Indian Army usage?

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Re: Artillery Discussion Thread

Postby Gyan » 16 Nov 2017 10:47

So import of M777 continues but Dhanush goes back for more trials?

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Re: Artillery Discussion Thread

Postby la.khan » 16 Nov 2017 14:36

Pratyush wrote:Import lobby can only mess up things when domestic suppliers are only OFB. By involving OFB and pvt sector players the ATAGS has become too big to fail. The dhanush can still be scrapped. Bit of that happens. It will just be replaced with the ATAGS.

So no worries in any respect WRT Arty.

Good to hear this! So, once the trials are completed and IA approves the gun, all pvt players (Tata or BF or ????) have to do is hit their production stride and churn out 4-5 guns per week? I hope we induct 200-250 guns a year. A 1000 ATAGS will be an awesome asset :twisted: on either of the borders.

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Re: Artillery Discussion Thread

Postby Will » 16 Nov 2017 18:53

Heard the OFB's are planning on going on strike pretty soon. Maybe a good idea for the govt to announce a lockout and get rid of those white elephants. But does anyone :mrgreen: have the will??

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Re: Artillery Discussion Thread

Postby Vips » 16 Nov 2017 19:02

The union leaders should be treated like anti-nationals that they are and made an example of. They are bound to be in touch with Opposition party leaders or even some outside elements, there should be a sting operation and they should be systematically targeted, tracked and exposed.

I would go even a step further and treat them as Naxals/Terrorists threatening India's security.

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Re: Artillery Discussion Thread

Postby ramana » 18 Nov 2017 07:34

ramana wrote:I think the way ahead is to come up with ERFB shells from low carbon steel such that they have high fracture strength and don't shatter in the barrel. In other words make them with material from M107 type shells.

Have M107 shells ever burst in the barrel in Indian Army usage?



Chances of Muzzle Strike or side slap happen in longer barrels.
When this happens with HF-1 family of high fragmentation steel then high probability of shell burst.

I looked at US M749A1 and M795 ERFB shells in the US Army manuals on line.
Both are HF-1 steel. These are high fragmentation steels.
Its matter of time they also get shell bursts.
One thing would be to fire them from 39 caliber guns to reduce the accidents.
If requirement is to fire from longer 45 and 52 caliber guns then revert to M 107 style high ductility shells that can withstand the side slap.

I would use M 107 with Base bleed motors for extra range and PGK type fuze,
We get range and target lethality with accuracy.
Crew Safety is bonus.

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Re: Artillery Discussion Thread

Postby ramana » 25 Nov 2017 01:52

Have the Dhanush and M777 trials resumed as stated in Frontline article?

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Re: Artillery Discussion Thread

Postby ramana » 25 Nov 2017 03:43

I wonder when.ARDE PGK will be tested? Would be major milestone.

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Re: Artillery Discussion Thread

Postby Pratyush » 25 Nov 2017 11:49

ramana wrote:I wonder when.ARDE PGK will be tested? Would be major milestone.

Indeed, when accepted into service it will address one of my biggest pet peeves regarding long range Arty.

But the numbers will have to go beyond khadi gram udyog numbers.

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Re: Artillery Discussion Thread

Postby shiv » 25 Nov 2017 16:55

Pratyush wrote:
ramana wrote:I wonder when.ARDE PGK will be tested? Would be major milestone.

Indeed, when accepted into service it will address one of my biggest pet peeves regarding long range Arty.

But the numbers will have to go beyond khadi gram udyog numbers.

Please do not use needlessly derogatory expressions about stuff that originates in India.

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Re: Artillery Discussion Thread

Postby tsarkar » 01 Dec 2017 20:47


Another shot in the arm came when DAC under the aegis of Hon’ble Raksha Mantri Smt Nirmala Sitharaman cleared the Limited Series Production (LSP) of 40 ATAGS.

Wonder which one was chosen, Tata or Kalyani?

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Re: Artillery Discussion Thread

Postby manjgu » 02 Dec 2017 12:31

tsarkar...i think its Kalyani as per someone in know in bharat forge. OT but in an interview Baba K said they can churn out 1 gun per day IIRC.

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Re: Artillery Discussion Thread

Postby shiv » 02 Dec 2017 13:10

manjgu wrote:tsarkar...i think its Kalyani as per someone in know in bharat forge. OT but in an interview Baba K said they can churn out 1 gun per day IIRC.

Chalo. Chalees din ki kamaaee

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Re: Artillery Discussion Thread

Postby Vips » 02 Dec 2017 19:52

Compare that to the time OFB is going to take to assemble the 114 improved/upgraded Bofors Guns. 3 Years. :x

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Re: Artillery Discussion Thread

Postby tsarkar » 02 Dec 2017 22:25

There are certain Indians like A M Naik & Baba Kalyani who deserve the Bharat Ratna for doing complex engineering in a way that also makes sound business sense and economics. They're the Walchand Hirachand of our times. Bharat Forge's & L&T's civil work acumen makes its military spinoffs seem effortless.

And makes Over Time demanding PSU workers look plain silly. Especially their contention that There Is No Alternative to Over Time.

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Re: Artillery Discussion Thread

Postby ramana » 02 Dec 2017 22:34

I knew A.M Naik when he was L&T Powai general manager.

Very can do person.

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Re: Artillery Discussion Thread

Postby Gyan » 02 Dec 2017 23:22

The pious intention of ordering 414 Dhanush has been in news for 2 years. Similarly there is at least 2 years of paperwork to be dealt with before actual order & payment of advance for 50 ATAGS

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Re: Artillery Discussion Thread

Postby Thakur_B » 03 Dec 2017 06:09

Vips wrote:Compare that to the time OFB is going to take to assemble the 114 improved/upgraded Bofors Guns. 3 Years. :x


manjgu wrote:tsarkar...i think its Kalyani as per someone in know in bharat forge. OT but in an interview Baba K said they can churn out 1 gun per day IIRC.


Actually, as far as I can remember, OFB autofrettages have the capacity to pump out one Dhanush barrel every hour, this was tweeted by saurav jha long back.

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Re: Artillery Discussion Thread

Postby la.khan » 06 Dec 2017 17:21

http://www.moneycontrol.com/news/business/stocks/bharat-forge-adds-2-as-clsa-retains-buy-on-strong-earnings-growth-ahead-2455411.html
On the defence business, Kalyani said the order pipeline is healthy and they are beginning to get export orders as well. Bharat Forge recently test-fired two artillery guns in Pokhran and will be going for winter-trial to Sikkim. He expects defence orders to come through in the next 24 months.

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Re: Artillery Discussion Thread

Postby ramana » 07 Dec 2017 02:32

^^^

This is good for the IA wants a very large number of these 155 mm 52 caliber artillery guns.

I only hope there is a task force setup to study the shell burst in barrel issue with the ERFB shells.

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Re: Artillery Discussion Thread

Postby ramana » 07 Dec 2017 23:02

Have the M 777 and Dhanush trials resumed?
The Frontline article implied the UET trials would resume in December November.

Senior OFB officials are confident that Dhanush will clear user trials. They said many of the problems reported in the user exploitation phase would be surmounted by “a fine-tuning of the gun’s subsystems”. This, they hope, will be achieved during the next phase of the user exploitation trials scheduled for November. This will be followed by a final round of firing trials in 2018, by which time it is hoped Dhanush will meet the Army’s standards for an indigenous 155 mm artillery gun that can replace the Bofors gun. Military experts suggest that a Dhanush Integration Centre,(DIC) staffed with personnel drawn from the OFB, the Army, the DGQA and the DRDO, could be set up with the best technical and manufacturing expertise. Expertise from BAE Systems, which is selling India the M777, could also be utilised.


And what is the progress in setting up the DIC?

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Re: Artillery Discussion Thread

Postby Philip » 08 Dec 2017 04:49

Ramana, your analysis is like a Poirot summing up of a murder! It does appear from your analysis that the shell is the problem not the barrel.Therefore the IA should give the green light for the guns, first batches and save time while the ammo problem is sorted out.

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Re: Artillery Discussion Thread

Postby ramana » 08 Dec 2017 05:10

Thanks.

I still think its one type of shell is the issue: ERFB with max charge.

Shell is made for low fracture resistant steel to ensure fragmentation and has 50% more HE.
Also its profile is more aerodynamic i.e. slender to attain the long range.

Its more like old time grape shot at long range.

The long caliber guns have more chances of muzzle strike due to barrel length.

I would suggest that these long caliber guns should use shells made with low carbon high ductility steel that has same aerodynamic profile as the ERFB.
They will be safer and more effective with a PGK fuze.

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Re: Artillery Discussion Thread

Postby Philip » 08 Dec 2017 05:27

What reasonable timeframe would be required as repeated tests will further delay approval ,etc.

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Re: Artillery Discussion Thread

Postby ramana » 08 Dec 2017 05:50

No. Just go ahead with the current M107 shells and let a task forced start making the new shells.
The ERFB can be used up in 39 caliber barrels.

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Re: Artillery Discussion Thread

Postby Singha » 08 Dec 2017 09:18

logically the ER shells would be most useful in the shorter barrels 39cal. the 45cal and 52cal with non ER ammo have sufficient range.

imo the effect of the massive ranges is best felt in the mountains where it permits wider radius of fire from limited sites and roads but then M777 and 39cal is what goes into such terrains, not the heavier longer barrels.

the pursuit of perfection should not be allowed to delay a phased rollout of features onto the product. no real product ever shipped without serious existing flaws, be it non-lethal ones like apple antennagate or the A320 FCS problems.

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Re: Artillery Discussion Thread

Postby tsarkar » 08 Dec 2017 10:55

Thakur_B wrote:
Vips wrote:Compare that to the time OFB is going to take to assemble the 114 improved/upgraded Bofors Guns. 3 Years. :x
manjgu wrote:tsarkar...i think its Kalyani as per someone in know in bharat forge. OT but in an interview Baba K said they can churn out 1 gun per day IIRC.
Actually, as far as I can remember, OFB autofrettages have the capacity to pump out one Dhanush barrel every hour, this was tweeted by saurav jha long back.

Its not about OFB autofrettages, its about employees running OFB autofrettages who expect overtime. Imagine their motivation in pumping out one Dhanush barrel every hour.

Most OFB employees, like the ones at Amethi, are recruited for employment generation of political workers. Naval Dockyard, Bombay is the biggest central government employer in Bombay. Recruitment of its workers was earlier "influenced" by INTUC and now by BMS. Meritocracy and efficient indigenous defence industry is the last thing on anyone's mind.

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Re: Artillery Discussion Thread

Postby ramana » 09 Dec 2017 01:23

Singha wrote:logically the ER shells would be most useful in the shorter barrels 39cal. the 45cal and 52cal with non ER ammo have sufficient range.

imo the effect of the massive ranges is best felt in the mountains where it permits wider radius of fire from limited sites and roads but then M777 and 39cal is what goes into such terrains, not the heavier longer barrels.

the pursuit of perfection should not be allowed to delay a phased rollout of features onto the product. no real product ever shipped without serious existing flaws, be it non-lethal ones like apple antenna gate or the A320 FCS problems.


The ER i.e. Extended Range comes from the small rocket motor at the base of the shell. It also comes from the reduced drag of that ER shell geometry which gives it more range.

However the biggest contribution to range is the longer barrel that allows the charge pressure pulse to developed. Gerald Bull showed theoretically that best barrel length is 45 calibers.

I agree that ER shells in 39 caliber is best as the rocket motor aka base bleed gives the extra range.

However ER shell is a fragments effect shell, using low fracture toughness steel(alloy composition is more like a cast iron shell) unlike the low carbon steel (alloy has high fracture toughness i.e high elongation. It stretches and doesn't break up) shells of M 107 genre. And ER/BB has 50 % more HE (12kg vs 8 kg) than M 107 shell.

in other words its more fragile to survive side slap which is more probable in a 45 and 52 caliber system.

But thanks to mfg tolerances at OFB even 39 caliber guns both Bofors (at least 40 per Shishir Arya of TOI) and M777 (recent User Trials at Pokhran) got this barrel burst problem.


Mountains need the high angle feature of howitzers. So a clever artillery officer will use the low charge MC and not develop the undesirable high ballot forces.

Why not import 10,000 PGK fuzes for mountain warfare batteries or kick start the ARDE.

This increases the effectiveness.

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Re: Artillery Discussion Thread

Postby Gyan » 09 Dec 2017 08:37

OFB Large barrel manufacturing capacity is around 200 barrels per ANNUM. This capacity has to cater to T-72/90 barrels also, which requirement is itself around 100-200 barrels per annum. The project for augmenting this capacity is under execution for last 10+ years. Last I heard OFB has finalised the tender for the chairs of the committee for planning.

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Re: Artillery Discussion Thread

Postby Singha » 09 Dec 2017 10:55

^^ not so fast. who gave you permission to withdraw the files from central store to write the chair tender?
the eCoS - empowered committee on Stationary will need to approve this via quarterly meeting and employees union approvals.

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Re: Artillery Discussion Thread

Postby ramana » 10 Dec 2017 13:23

US Army has M549 shell made from HF1 steel. It's filled with Composition B explosive. However it's restricted from being fired with high M203 level charge. In simple English this shell should not be fired with high charge.

In order to comply with safety requirements, the explosive is switched to TNT.

Ref: https://en.m.wikipedia.org/wiki/M549
Now need to find out what type of explosive fill is used in OFB made ERFB shells. We know they are made from high fragmentation steel. So explosive fill could make a difference.

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Re: Artillery Discussion Thread

Postby ramana » 10 Dec 2017 13:28

Composition B
Is 60% RDX and 39 % TNT with 1% wax.
Velocity of detonation is 8050 m/sec

Ref: https://en.m.wikipedia.org/wiki/Composition_B


TNT has VoD of 6900 m/sec
So it is less sensitive to shock than RDX
Ref:
https://en.m.wikipedia.org/wiki/TNT

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Re: Artillery Discussion Thread

Postby ramana » 10 Dec 2017 13:40

:eek: Ok OFB makes ERFB shell which caused barrel burst.

http://ofbindia.gov.in/products/data/am ... add_41.htm

However filling is TNT. Yet causes burst.
:eek: :eek: :eek:

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Re: Artillery Discussion Thread

Postby ArjunPandit » 13 Dec 2017 23:18

As the year ends, wanted to summarize where we are on artillery issue, Things have not been upto 'brf' expectations even with this govt, but they are moving and looking way better than Donotony.

Here's my summary from googleshawsara swami


1. Dhanush: 3 delivered in 2016 (under trials). Plan was to induct 18 Guns in 2017, 36 Guns in 2018 and 60 Guns in 2019; completing the order for 114. because of the issues in tests, barrel redesign is considered (not sure if that impacts the deliveries). Ramana sir had detailed posts on the trial failure, which completely went over my head.

2. ATAGS: Summer trials and world record created. Winter trials to happen in Dec in sikkim. LSP of 40 cleared by NS. LSP Deliveries to start by 2019 end

3. K9 vajra: Provided the deal got signed in april'17 as chindu speculated, deliveries start in 18 months end by 42 months -> (Dec18-Dec 20) 100 guns. Poland signed a deal of 120 guns at less than half the price (http://www.armyrecognition.com/december ... oland.html): IDRW analysts are you reading this?

4. M777: Deliveries started; 145 guns, 2 guns received earlier this year, 1 damaged during testing. Three M777 guns will come to India in September 2018 and used for training. Thereafter, five guns will be inducted every month from March 2019 to June 2021.

5. Pinaka (Last but not the least): This one looks most promising, 2 pinaka regiments inducted, 4 ordered (2 in 2015, 2 in 2016 March), 6 ordered ( Nov 2016)not sure where does it lie in acquisition chain. Each regiment consists of three batteries of six Pinakas each, plus reserves. Assuming 20 in each regiment: we have 40 inducted, 80 +120 batteries ordered

so in a nutshell, we will receive at least 100+ guns starting from 2019 each year for may be next 3-5 years. If ATAGS orders materialize this number will go significantly up as those no.s are in ~2000s.

This is what i think primary roles of guns will be (obviously the gun works in both modes)
1. Dhanush: Defensive
2. ATAGS: Def/Offence
3. K9: Offense with IBGs
4. M777: Defence along with china border or in mountains
5. Pinaka: offence with IBGs for a breakthrough in their lines at critical nodes along with Grad, Smerch for hitting behind the lines and destroying C&C centers
Happy to be corrected in any of the information

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Re: Artillery Discussion Thread

Postby Karan M » 14 Dec 2017 00:05

Towed guns can follow formations. How are they only defensive?


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