Artillery Corps: News & Discussion

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ramana
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Re: Artillery Corps: News & Discussion

Post by ramana »

Pratyush wrote:Looking at the images of the shattered gun barrels.

As someone with a non engeneering background. I have a question regarding the testing of the metallurgy and strength of different materials.

In oil and natural gas industry or even for municipal applications it is required that the pipes be fit to handle certain amount of flow and pressure on a daily basis for a certain period of time. Before it reaches a point of failure and needs to be replaced.

1) How is this quality assured for customers?

2) Is it possible for non invasive means such as x-rays or ultrasound be used to check for flaws in materials?

3) Can such techniques be used to assure the quality of the arty gun barrels as well?
Pratyush thanks for asking questions.
As Niran also wrote the shattered barrels show it's a failure due to premature bore explosions. In other words, it's not due to defective gun barrels. See the tank barrel splitting like leaves shows how good the metal is. Its ductile fracture.
The other barrel failures are mid-way and not at the end. This means the shell travelled some distance and exploded. Now every shell has a fuze that has safety features to ensure it gets armed after a set distance. Here the shells burst before the shell leaves the barrel. So Fuze is not the problem.
So having ruled out the barrel and fuze it's the shell that is a problem.
Now, the shell can explode if the base is compromised like a loose rotating band, weak materials of the shell casing etc. These are observable defects. Shells are forged and machined from certified steel ingots. And the forces of the forging process are as severe as those in an explosion. So if the shell survives the forging process intact to the machining stage, we can be assured it's not a metallurgy defect.
As to every gun barrel, it is proofed and test-fired for acceptance just like the oil and gas pipelines.

There is a process to replace gun barrels after a certain number of firings.
All these are for the quality assurance of guns.
We need a proper COI that creates a root cause diagram and goes into shell manufacture, explosive filling, and packing and storing, the batch number of the shells that blew up. In other words, a pedigree analysis to find out what caused the flaw to be hidden and emerge to cause the accident.
What is happening is an inherent latent flaw in the process that emerges occasionally but is catastrophic when it happens. If it was more common we would have more frequent flaws.
Looks like all COIs done so far is to deduce the shell as the root cause.
They have not gone one step below to find out why the shell blows up even without a fuze.
During the late 60s the USN found that they were having premature bore explosions due to the shells being filled with Composition B which is TNT based.
From open sources, we know OFB uses TNT for filling the ERFB shells.
We know TNT exudation in anti-tank mines led to the Pulagoan Depot fire.
So COI should go to the OFB factory and bird dog the shell filling process to see what introduces latent flaws.

* The USN found that the TNT melting process introduces small bubbles in the filling. And with time and temperature gases fill the voids. When the shell is fired the base sees compression force and when it travels in the barrel the shell springs back. This happens in milliseconds and is almost an adiabatic expansion of the trapped gases that auto detonates leading to the shell explosion. So no need for Fuze.
The way they solved the problem is to use Insensitive explosive filling.
That could be the long term solution.
However, COI should look at how they are storing the shells and transporting them.
ramana
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Re: Artillery Corps: News & Discussion

Post by ramana »

My one month old post on this subject:
viewtopic.php?p=2515857#p2515857

OK OFB ERFB BT/BB shells filling is mostly TNT

http://ddpdoo.gov.in/product/products/p ... erfb-bt-bb
HE Composition
TNT - 99%
N.C - 0.5%
PNT - 0.2%
HNS - 0.3%


Compatible Fuzes
PDM - 572 CI & M85 P13 A3

Compatible Charge Charge 8 & Charge 9

It is the filling process that has different density spots or voids. This causes rare blowups.
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Re: Artillery Corps: News & Discussion

Post by shaun »

Ramana Saab , what a great write up , there should be features to bookmark.
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Re: Artillery Corps: News & Discussion

Post by Suresh S »

tx ramana even a non engineer like me could understand it.that was good
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Re: Artillery Corps: News & Discussion

Post by Pratyush »

Ramana, modern explosives are so inert that in the absence of a detonator it will not go off. Unless there is a flaw in the chemical formulation it self. Or has so degraded with age that it has become very unstable.

If the issue is with the filling of explosive in the shell, even then the detonation will not happen in barrel. Due to the insensitive nature of the explosive.

The shell might deform as a result of the stress of firing. Which in tern might cause the barrel to be sheared off due to the forward momentum of the shell and expansion of gasses in the barrel which now has no way to leave the barrel. Due to a deformed shell which got stuck in the barrel.

The breach block and recoil mechanism might remain intact but the barrel will be ruined.

So how the army can assure that the shell has no issues with explosive filling.
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Re: Artillery Corps: News & Discussion

Post by Rakesh »

VIDEO. Please click on link below...

https://twitter.com/Kunal_Biswas707/sta ... 57697?s=20 ---> Rare clip of IAF Mi-17V5 lifting Indian Army 105mm IFG.
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Re: Artillery Corps: News & Discussion

Post by Rakesh »

Karan M
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Re: Artillery Corps: News & Discussion

Post by Karan M »

Pratyush wrote:Ramana, modern explosives are so inert that in the absence of a detonator it will not go off. Unless there is a flaw in the chemical formulation it self. Or has so degraded with age that it has become very unstable.

If the issue is with the filling of explosive in the shell, even then the detonation will not happen in barrel. Due to the insensitive nature of the explosive.

The shell might deform as a result of the stress of firing. Which in tern might cause the barrel to be sheared off due to the forward momentum of the shell and expansion of gasses in the barrel which now has no way to leave the barrel. Due to a deformed shell which got stuck in the barrel.

The breach block and recoil mechanism might remain intact but the barrel will be ruined.

So how the army can assure that the shell has no issues with explosive filling.
They xray based on statistics.
ramana
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Re: Artillery Corps: News & Discussion

Post by ramana »

Pratyush wrote:Ramana, modern explosives are so inert that in the absence of a detonator it will not go off. Unless there is a flaw in the chemical formulation it self. Or has so degraded with age that it has become very unstable.

If the issue is with the filling of explosive in the shell, even then the detonation will not happen in barrel. Due to the insensitive nature of the explosive.

The shell might deform as a result of the stress of firing. Which in turn might cause the barrel to be sheared off due to the forward momentum of the shell and expansion of gasses in the barrel which now has no way to leave the barrel. Due to a deformed shell that got stuck in the barrel.

The breech block and recoil mechanism might remain intact but the barrel will be ruined.

So how the army can assure that the shell has no issues with explosive filling.
What you say is correct for a block of TNT without being subject to gun firing shocks. It needs a much higher shock from a detonator.
However, USN has shown that low-density areas in the shell filling or air gaps cause premature detonation even without fuzes. Please read the link I put about a month ago.

As to how they find such defects, can be found by X-ray exam. And the USN report says they did find.
Now how to improve the process to not have low-density areas?
They need to melt the mixture at a uniform temperature and outgas in a vacuum and pour.
The problem is neither OFB nor IA is willing to acknowledge they have an issue.
If you agree you have an issue you will find a solution.

Maybe what I found is all wrong but it explains the rare and catastrophic failures of shell burst we see.
Not one report except the very first one on Dhanush wobble burst gives the age of shell. It's unconscionable to send a ten-year-old shell for proof testing a brand new design stage gun. Shelf life is 12 years per OFB page now since taken down.
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Re: Artillery Corps: News & Discussion

Post by ramana »

The shell might deform as a result of the stress of firing.
Plausible but not probable.
Somewhere an OFB engineer speaks about the ultimate strength of the shell steel and the forces that are created by the firing.
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Re: Artillery Corps: News & Discussion

Post by Vips »

According to an AV of a Defense Channel on YouTube:

There is delay in the Guided Pinaka program (Range 75 Kms). Case for Procuring the guided rocket has not progressed due to technicalities related to testing and validation. An upgrade would be required in the launcher system for the extended range rockets and without the upgrade the rockets would not be able to demonstrate accurate hits at the range of 75 Kms. The Pinaka launchers are currently not available for validation tests while efforts are being made to upgrade the launchers in the newer systems which have been ordered by the Indian army but no progress has been made on it yet.
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Re: Artillery Corps: News & Discussion

Post by SSridhar »

Vips wrote:According to an AV of a Defense Channel on YouTube:
. . . An upgrade would be required in the launcher system for the extended range rockets . . . efforts are being made to upgrade the launchers in the newer systems which have been ordered by the Indian army but no progress has been made on it yet.
DRDO has been testing them since 2017 and claimed range has been even 90 Kms which was even confirmed by an ex DG, Arty, IIRC.
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Re: Artillery Corps: News & Discussion

Post by Vips »

Good to know the increased range but the army here is behaving as if it has the luxury of unlimited time to take the necessary further steps to induct it into service. We do not have any long range rocket system whose range crosses even the three figure mark whereas our adversary has deployed on it side systems with range in excess of 300 KMS!!!
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Re: Artillery Corps: News & Discussion

Post by ramana »

An upgrade would be required in the launcher system for the extended range rockets and without the upgrade the rockets would not be able to demonstrate accurate hits at the range of 75 Kms
What do they mean? What upgrade to launcher system would effect accuracy of the rocket system?

Most likely some navigation system that will pass on target coordinates.
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Re: Artillery Corps: News & Discussion

Post by Karan M »

There are 4 Pinaka rounds. Pinaka 1 (in service, 38km), Pinaka Extended Range (available as option, 40-50km), Pinaka 2 (60km, has cleared trials last year iirc), Pinaka Guided (needs user trials, 75-80km, is akin to a mid-accuracy PGM).

Pinaka launcher can carry all these rockets/missiles in 2 pods.

Pinaka launcher has its own guidance unit - a highly accurate Ring Laser Gyro. Pinaka guided has a homegrown inertial unit + satnav + actuation.

Now, Pinaka 1, Pinaka ER are approx the same dimensions and weight, Pinaka ER being slightly heavier and shorter, and are available in 6 per pod. Pinaka 2 and Pinaka Guided are approx the same dimensions and weight, and around 16% higher weight and 6% longer. Pinaka 2 is available in 6 per pod, and guided in 4 per pod.

This is the report the video is referencing. It has some good news - Pinaka ER is being acquired now, but what the report states about Pinaka guided requiring upgraded launchers is not (as of yet) backed up in literature, or even clearly stated in the report itself. As stated above, the standard Pinaka launcher can carry all 4 types of Pinaka rockets provided it has the correct pods.

Perhaps they mean modified kit for managing the new pods - seems relatively trivial to be honest.

https://economictimes.indiatimes.com/ne ... 265407.cms
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Re: Artillery Corps: News & Discussion

Post by Karan M »

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Re: Artillery Corps: News & Discussion

Post by KiranM »

I have been trying to reconcile the number of medium artillery and rocket regiments with the RSTA batteries. Unless there is dearth of open source information, we seem to be piss poor in this segment? Swathi WLR per Wiki is at 32 only.
With the UAVs now under Army Aviation for R&S function, artillery might be getting a shave on counter battery role.
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Re: Artillery Corps: News & Discussion

Post by Pratyush »

Fingers crossed.

We don't need Athos.
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Re: Artillery Corps: News & Discussion

Post by KSingh »

Whatever happened to Dhanush-52? If this could be developed then at least it would keep ATHOS out of the fray until the IA could be satisfied with the ATAGS?
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Re: Artillery Corps: News & Discussion

Post by ramana »

First let them clear Dhanush-45. Then -52 is next milestone.

It's frustrating that now they reveal the muzzle strikes are all at Charge 6.

Need to think why..
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Re: Artillery Corps: News & Discussion

Post by ramana »

Basically the unbalanced top (shell mode) is getting more energy to spin and hits the muzzle wall as it travels along the barrel. This could mean the -52 will have more muzzle strikes.
So what fixes were suggested?
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Re: Artillery Corps: News & Discussion

Post by V_Raman »

Bofors has been the workhorse of our artillery. We should pay them for consulting to fix all the issues with Dhanush and get it out asap.
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Re: Artillery Corps: News & Discussion

Post by Vivek K »

V_Raman wrote:Bofors has been the workhorse of our artillery. We should pay them for consulting to fix all the issues with Dhanush and get it out asap.
Not to be rude, but why do you believe they would help a competitor? We need to solve our own problems.
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Re: Artillery Corps: News & Discussion

Post by Vips »

KSingh wrote:
Whatever happened to Dhanush-52? If this could be developed then at least it would keep ATHOS out of the fray until the IA could be satisfied with the ATAGS?
DRDO had showcased its MGS in the recent Def Expo with model of Dhanush 52 on a Tatra 8X8. I am sure they will be doing the same in the Def Expo 2030 too!!!
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Re: Artillery Corps: News & Discussion

Post by Pratyush »

Vivek K wrote:
V_Raman wrote:Bofors has been the workhorse of our artillery. We should pay them for consulting to fix all the issues with Dhanush and get it out asap.
Not to be rude, but why do you believe they would help a competitor? We need to solve our own problems.
Because they are contractually obligated to help India produce the weapon as a part of the original FH77B purchase.
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Re: Artillery Corps: News & Discussion

Post by ramana »

You are hung up on law and justice when they don't care for that? They took the money long back and how do you enforce the contract when you are the receiver i.e. the importer? Go to Swedish courts? Please don't be naive.
We know enough about what causes muzzle strike and barrel burst but there is no gumption to solve the problems.
IA should be the one to take the lead as its is most effected by the problem.
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Re: Artillery Corps: News & Discussion

Post by Pratyush »

The contract was not followed through because of the Indian sanctions on Bofors.

Not because of any action taken by Bofors other than alleged bribing of then Indian prime minister.

That doesn't mean that the contract was abandoned by us, does it?
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Re: Artillery Corps: News & Discussion

Post by Pratyush »

The OFB has been building Sarang 155 mm gun's by upgrading M46 guns. These are 45 calibre weapons in 155mm. In terms of range they are nearly identical to the Dhanush.

I am curious if the Sarang also faced barrel strikes when it was fired with full change?
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Re: Artillery Corps: News & Discussion

Post by ramana »

Don't know about due to full charge but Sarang did have muzzle strikes.
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Re: Artillery Corps: News & Discussion

Post by ks_sachin »

ramana wrote:Don't know about due to full charge but Sarang did have muzzle strikes.
As long as the ammo is OFB we will have strikes. They will even manage a strike in pea shooter!!!
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Re: Artillery Corps: News & Discussion

Post by ramana »

Sad to inform you but even with imported ammo from both NASCHEM, Sweden, and OFB the IA used to see barrel bursts and muzzle strikes. We documented it in this forum only.
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Re: Artillery Corps: News & Discussion

Post by SinghS »

ks_sachin wrote:
ramana wrote:Don't know about due to full charge but Sarang did have muzzle strikes.
As long as the ammo is OFB we will have strikes. They will even manage a strike in pea shooter!!!
Probability is used in manufacturing; as it is not perfect. Thus each process is designed with probability of error. Even qc has a probability of error. Lets' say we achieve final probability of 99.99% in production. so in each 10,000 shells you will have 1 faulty shell. Where would it be in stock...you don't know. When the army will fire it, nobody knows.

Muzzle strikes can't be prevented altogether. Its a reality.

The problem is not muzzle strike, it attitude towards using desi and lack of funding & will to update desi factories.
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Re: Artillery Corps: News & Discussion

Post by Thakur_B »

https://thediplomat.com/2021/11/indias- ... ket-force/

Saurav jha talks about rocket force.
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Re: Artillery Corps: News & Discussion

Post by Barath »

ks_sachin wrote: As long as the ammo is OFB we will have strikes.!
If the ammo isn't from OFB, we will have strikes. Though i don't think the GoI is as worried about labor strikes..
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Re: Artillery Corps: News & Discussion

Post by niran »

ks_sachin wrote:
ramana wrote:Don't know about due to full charge but Sarang did have muzzle strikes.
As long as the ammo is OFB we will have strikes. They will even manage a strike in pea shooter!!!
do you know why ATAGS has permanent sensor to measure mid barrel shell velocity barrel distortion? to prevent barrel strike from the gun, leaves Ammo side of the equation, as a first step acknowledge the problem.
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Re: Artillery Corps: News & Discussion

Post by Rakesh »

Army to get firepower boost in mountains with more M777 guns
https://www.hindustantimes.com/india-ne ... 49075.html
14 Nov 2021
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Re: Artillery Corps: News & Discussion

Post by Vivek K »

Yay! More trials for Indian guns!!! Hallelujah!!
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Re: Artillery Corps: News & Discussion

Post by Prem Kumar »

The title makes it look like more M777s. Its just that the remaining guns from the original order are on the way
ramana
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Re: Artillery Corps: News & Discussion

Post by ramana »

Rakesh wrote:Army to get firepower boost in mountains with more M777 guns
https://www.hindustantimes.com/india-ne ... 49075.html
14 Nov 2021
So much fluff in article.
Can't make out if rest of the guns will be delivered or more te ordered!

I think more will be ordered.
The 145 number was too low to begin with.
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