Armoured Vehicles Discussion Thread - Jan 12, 2012

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Sanku
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

rohitvats wrote:The whole auto-loader plus ammo stowage thing would need to be put in place a fresh. Not happening, IMO.
True enough, I really dont know how this can be retro fitted either.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by pragnya »

Austin wrote:Eventually our T-90 Bhishma will get upgraded to T-90MS standard during their life cycle time when they are eventually modernised , its just an add on kit for existing T-90
rohitvats wrote:^^^How on god's earth are you going to add a bustle auto loader on IA's T-90 without tearing up the turret???? Or are we looking at replacing the turret lock-stock and barrel? Whatever it is - I don't see bustle auto-loader making it to IA. Otherwise, the cost would be too much. The whole auto-loader plus ammo stowage thing would need to be put in place a fresh. Not happening, IMO.
right rohit, igor's report long back detailed it.
New bigger turret without weakened frontal areas and with the all-aspect ERA covering.
- ERA 'Relict'
- Additional roof protection against atop attacking munition.
- New additional autoloader, placed on the aft part of the turret and able using the new longer sub-caliber rods.
- Aft ammo storage.
- Panoramic 3-channel IR commander site with improved anti-split/rounds protection.
- 7.62 mm automatic turret instead of 12.7mm.
- Totally new 2A82 125 mm MG (2A46M5 - optional).
- FCS with the net-centric module.
- New radio.
- New navigation system.
- New anti-split kevlar layer instead of the standard Russian anti-neutron layer.
- new anti-fire system.
T-90M

that is altogether as good as a new tank!!! will cost not less than any modern tank apart from a huge time for the changeover. why on earth IA should go for T-90M upgrade when Arjun does even better!!!

surprisingly even Prasun says Arjun is better compared to T-90M!!! :wink:
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

VibhavS wrote:(of course they are simaltaneously trying to lighten the round).
It is important to be precise here. What they are trying to lighten is NOT the round, but if you read carefully, the SABOT alone. Why is that ? For that you have to answer the high school level Physics question that gets asked in JEE sometimes. It is on these lines.

"A shell is fired at a certain angle theta with a velocity v, after 2 seconds it breaks into two pieces, one is 1/3rd the mass of the shell, the other is 2/3rds the mass. The 1/3rd mass stops instantaneously in mid air and falls directly below the point where the shell split into two. Find out the how much further horizontally the 2/3rd mass piece will travel and the point of impact of the center of mass of the system" .. If you can answer that question, you will know why it makes tremendous sense to lighten the sabot as much as possible.
VibhavS wrote: It is this shear that reduces the effectiveness of sabot rounds fired from rifled guns. The lack of this force when firing from smoothbores results in ability to achieve higher muzzle velocities plus retain structural integrity of the sabot for more effectiveness.
Ok. This is Maharji Ji "Physics" and I have to ask the "Shear ' equivalent of the Bhoomi Devi ki Keenchayi question .

How does the "Shear Devata" know that penetrator X was fired from smooth bore , while Y was fired from rifled bore, because when they are both flying and you take a movie, they will be exactly same. So how does "Shear Devta" exert differential force ?

Shear forces comes from bending moments when the penetrator rods hit the target and that has nothing to do with smooth bore or rifled bore. That really is a function of L/D. A long thin road will tend to break because of lack of shear strength (thinner diameter, less material to resist shear loads) when bent, and that is the fundamental challenge in making the long rod penetrators, as speeds get higher.

And no, there are no shearing forces on the rod inside the gun barrel. If it was there, the round will break inside the barrel itself.

Anyways, I am waiting for Shri Shri Sanku Maharaj Ji's "spin" after reading the torque graphs in the presentation and the results of his experiment from cranking his bicycle pedal backwards with cycle on the stand (the SDRE kind which raises the rear wheel of the ground) and come back with his findings of whether the slip rings are "100%" effective or not as in his own words "no mechanical system can uncouple 100%" and how many revolutions the rear wheel made for every revolution of the crank in reverse! 8)
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Singha »

someone please update me - what is the status of Russia's next tank project? have they selected an idea or still kicking around proposals? their fanboys on tanknet are still singing the songs of a bygone era in russian/ukrainian tank design prowress. fact of the matter is they have no ability to defeat western products which havent even seen much of a update in the last 10 yrs...let alone the M1A3 unkil is cooking up or the L55 equiped leoA6. yet they continue to sing the songs of distant lands...right up until the next round of thrashing.

imo its far better DRDO rope in the domestic auto majors and their foreign partners like Soko, BAE, IMI , Cummins and develop something out of the arjun template than waste our time on a T100 that will not develop any technology locally.
Last edited by Singha on 05 Apr 2012 23:17, edited 1 time in total.
GeorgeM
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by GeorgeM »

sudeepj wrote:Made a mistake in the calculation above, the ratio is


E_spin : E_linear = 1 : 800 (R/Pi. r)^2
~= 1 : 80 (R/r) ^2
..............
V . t = 20D
w . t . R = 2. Pi. R (Since one rotation is completed in time t).
Therefore
w = (V . Pi) / (20 . R)

Still, not more than 1.25% of the total energy imparted to a spinning projectile, will be imparted as spin..

Also correcting the post above to avoid confusion.
Sudeepj, you are considering steady state. Consider adding time 't' where you accelerate from 0 to 1-in-20 rotations in a matter of say 5 milli-secs. How much energy is needed. Compare that to a smooth bore which is no spin, all linear. See how much energy is 'wasted' when you accelerate spin.
But then again we dont know how much energy is released from the powder. We do know given the mass of the projectile how much is used up by the projectile. Appreciate elevating the discussion. I really need to 'undust' my high school physics books.
vina wrote:3) Velocity. I think you need to be conceptually clear on this. Tanks fire APFSDS and other types (HEAT and if rifled HESH in addition)
a) APFSDS -
b) For all other rounds
I am sure the ring around the sabot can be designed to mitigate the loss to rotation. Not familiar the application side of each projectile, what goes into which bore etc. My take is purely from a physics/efficiency standpoint. But one minor point about Arjun type projectiles not having lift induced drag- I think there could be some, for the projectile while it spins, forces the fin to follow a spiral path. So the leading edge of the fin is always at an angle to the incoming air due to relative velocity. This could generate aerodynamic forces similar to lift. But the lift forces on all the fins would cancel out hence no resultant force direction, but there will be a lift induced drag from each fin adding up. But I do agree that spun projectiles could carry more explosive more accurately. But then golf balls due to its eddies around the skin from ball rotation + dimples do make it go farther. Oh well ! But are there spinning projectiles that mimic golf ball principles ? Would be interesting. I guess at high mach numbers all these would show a completely different behavior.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by sudeepj »

Sidharth wrote:Sudeepj, you are considering steady state. Consider adding time 't' where you accelerate from 0 to 1-in-20 rotations in a matter of say 5 milli-secs. How much energy is needed. Compare that to a smooth bore which is no spin, all linear. See how much energy is 'wasted' when you accelerate spin.
But then again we dont know how much energy is released from the powder. We do know given the mass of the projectile how much is used up by the projectile. Appreciate elevating the discussion. I really need to 'undust' my high school physics books.
Yes, I am considering steady state, and all I am comparing is the amount of KE in the spin vs the amount of linear KE. At the end of the day, the work done by the friction with the rifling will be apparent as KE, heat and sound. The heat and sound will be the same as in the case of a smooth bore.. Theres no apparent reason why they wont. So the only difference between the smooth bore and the rifled gun would the KE given to the spin, which going by the admittedly rough calculations above is small.

But why get into all these details when someone has already done the work for us.. Take a look at this paper from 120 years (!!) ago, when a British gentleman tried shooting cylinders from barrels with rifling that was straight (no twist), uniform (twist at a uniform rate), and rifling with a gain (increasing twist rate as one approached the end of the barrel).. and compared the muzzle velocities of the cylinders. http://ia600701.us.archive.org/24/items ... 068440.pdf

The mean Loss of energy in uniform rifling (the kind that the Arjun gun has) he gets is 1.5%, remarkably close to the 1.25% I calculated. Note that this was before people had discovered chromium plating and other advanced techniques to reduce the friction in the rifling. I am willing to bet that with todays metallurgy and todays propellants, the frictional losses would be even lower.

As for the trolls, nothing is going to convince them, that their preconceived notions are wrong. They seem to be under the impression that the one who gets the last word and the one who screams the loudest/longest is right.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Austin »

rohitvats wrote:^^^How on god's earth are you going to add a bustle auto loader on IA's T-90 without tearing up the turret???? Or are we looking at replacing the turret lock-stock and barrel? Whatever it is - I don't see bustle auto-loader making it to IA. Otherwise, the cost would be too much. The whole auto-loader plus ammo stowage thing would need to be put in place a fresh. Not happening, IMO.
I have said this many times before and repeat it once again that T-90MS does not have a rear bustle auto loader , the rear bustle is just a place to store Ammo in a container which can store 10 ammo with blow up panel.

There is just the single autoloader that can fire ready rounds from under floor stored ammo which is 22 rounds , there is another 8 rounds inside the turret which is containerised , so no exposed ammo inside the turret.

The only thing difficult or expensive to change is the newer 1150 hp engine compared to 1000hp of T-90 Bishma and the new FCS. But consider this nearly 600 odd T-72 upgrade is being proposed with new FCS , Engine , TI systems , AC and other minor upgrades

You can live with the existing engine and FCS on Bhishma but key part of the upgrade like new ERA type , CITV and slightly modified carousel to fire longer rounds are worth the upgrade when ever that happens.

The other option is to keep the built T-90 as is and build the remaining batch of T-90 to MS standard , After all the Arjun Mk2 is itself undergoing through 92 major and minor upgrade over Mk1 batches and so is T-72 upgrade.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Singha »

the angular panels on the frontal turret of the ZTZ99 are apparently heavy ERA panels custom sized to fit the region instead of standard rectangular bricks. they are not additional bolted on armour per the web. gives a neater gapless look at the expense if any tile is replaced , not just any tile can be picked from the heap.
http://www.apl-chine.com/imagesv/terre/ ... e99_15.jpg

comparing to the T90
http://upload.wikimedia.org/wikipedia/c ... ropped.jpg
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

I think there could be some, for the projectile while it spins, forces the fin to follow a spiral path. So the leading edge of the fin is always at an angle to the incoming air due to relative velocity. This could generate aerodynamic forces similar to lift. But the lift forces on all the fins would cancel out hence no resultant force direction, but there will be a lift induced drag from each fin adding up.
Why would any spin stabilized projectile have FINS ? That lift induced drag is true only for fin stabilized projectiles.

Take a look at any standard artillery shell and point out where the fins are please.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by GeorgeM »

vina wrote: Why would any spin stabilized projectile have FINS ? That lift induced drag is true only for fin stabilized projectiles.

Take a look at any standard artillery shell and point out where the fins are please.
I thought all HE have fins. Looking up in Youtube for a check, found these.. see at 1:05 of below video



Also check this spinning projectile, not sure what explosive it is, but it sure does seem like spin stabilized with fins.

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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by shiv »

Unless fins are angled to deliberately cause spin as a result of airflow being deflected, any spin imparted to a projectile with fins will only be resisted by the fins. I suspect that such angling of fins may be done deliberately. I don't know the reason but I suspect that a slight spin may actually cause more stability than no spin by evening out minute differences in the shape and weight of seemingly symmetrical areas of the shell and fins themselves. That is my guess - the egg-sperts will have to knock this down.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

Sidharth wrote:I thought all HE have fins. Looking up in Youtube for a check, found these.. see at 1:05 of below video
Not true. Some thing like google search for images of HE shells should show you hundreds of artillery shell images. The pictures /videos you posted are all of typical shells fired out of smooth bore . These are not traditional spin stabilized shells.
Also check this spinning projectile, not sure what explosive it is, but it sure does seem like spin stabilized with fins.
I am not sure if that video is real or a hoax, but all the same, it seems like it is fired out of a Rheinmetall smoothbore gun!

As for why it is spinning (if the video is true), go ask Sanku Maharaj Ji,why it is necessary to spin a finned round fired out of a smooth bore! :lol:
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by VibhavS »

Vina, ah my reply is pretty simple when the sabot is fired from a rifled gun "it" knows.. whether you or I know it is immaterial. It has to undergo stress due to the prevention of spinning that means shear on the round the moment it starts moving out of the barrel right?

Of course at impact there is the shear force and it is as you rightly put it a function of L/D. Therefore the switch to DU penetrators? They are very very heavy as compared to the tungsten rounds yet their use... because their ability to self sharpen (not my claim.. got this from a study on the M1 Abram below)
http://www.ndu.edu/CTNSP/docUploaded/DT ... 20Tank.pdf

I am yet again not saying that the rifled gun is not capable or cannot utilize cannot adequately fire... etc etc a APFSDS round, its just that to my simple brain if I have to stop the thing from spinning in the first place why fire it from a rifled gun?
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by member_22539 »

I have a question regarding the Arjun tank, what is that black fabric/lining material between the block that holds the gun and the rest of the turret?
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Austin »

Singha wrote:someone please update me - what is the status of Russia's next tank project?
A summary of Armoured and AFV program has been put up by Ilya Kramnik in his article recently

http://english.ruvr.ru/2012_03_26/69675961/
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

VibhavS wrote:Vina, ah my reply is pretty simple when the sabot is fired from a rifled gun "it" knows.. whether you or I know it is immaterial.
Unless you know, it is just talking in the air and degenerates into mere sloganeering and Maharaj Ji Physics
It has to undergo stress due to the prevention of spinning that means shear on the round the moment it starts moving out of the barrel right?
If you read the presentation carefully and the graph, there is a momentary blip of torque as the round enters the barrel via the gun cone and rapidly falls to zero as the band starts slipping and stops transmitting the torque to the sabot.

The net result is that there will be no (okay negligible, you wont be able to measure it) spin on the round, just as Maharaj Ji would have discovered when he cranked the pedal of the bicycle on the stand with wheels off the ground. There too, because of static friction, a blip would have got transmitted from the free wheel's ring to the hub, but that wont turn the wheel by any measurable distance backwards!

In this particular case because of the hoop stresses that get developed in the blip, the composite sabot fails because of lack of strength in that direction and they are seeing what to do about it!
my simple brain if I have to stop the thing from spinning in the first place why fire it from a rifled gun?
There are are other rounds that do better with spinning, because your tank has to do other things than kill other tanks alone
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by VibhavS »

Well let me decipher what you just said to confirm if I understood you:
1) Torque is negligible as per the graph. When I converted the peak figure that it shows it comes to about 18.354 kg/cm (a little more than that) in about 3 microseconds with a sudden drastic reduction when the round leaves the barrel, you also go on to state that composite rounds (composed of Tungsten and DU alloy I dont remember the correct composition) fail due to the same torque, hence the presentation to highlight the problems of firing a APFSDS round. This is still a 105mm gun, not a 120mm composite long rd round.

2) There are other rounds which do better with spinning, like... the HESH and APSSDS? if you could elaborate. Primary ammo types these days dont need spin to the extent provided by rifling, heat rounds have fins, APFSDS is self explanatory. The accurate computerized FCS get over the disadvantges of lesser accuracy of a smoothbore gun.

3) Yes tanks have to kill other things than tanks, bunkers, soft skinned vehicles, helicopters, men, buildings. I also agree with you HESH is good enough to do the job. But just to retain the capability of firing a unique round like HESH you want to discard the smoothbore and keep a rilfled gun.

Again let me reitirate a basic claim that I have been making for a while, rifled guns for tanks went out of fashion since the primary anti-tank rounds like APFSDS and HEAT dont need rifling. Added to benefits of having a cheaper gun and less complications in coming up with new rounds unlike the rifled gun. Rifling is still required for all weapons firing full caliber rounds where the L/D ratio is quite large, because spin stabilized is better. Therefore rifles (why would I want a sabot bullet, when the usual ball ammunition works so well?) , artillery guns, naval guns are still rifled, because of the ranges involved.
I hope I have been able to get my point across to you.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

VibhavS wrote:1) Torque is negligible as per the graph. ..snip.
You are confused. What they are doing , is take an existing APFSDS round ,which has aluminum sabots (which are the piece that get discarded the moment it exits the barrel) and are changing the SABOT material from aluminum to carbon composite! That is all. The penetrator is untouched /same as before .. penetrator is the part that continues flying and hits the target .And there is NO,"composite" penetrator.

That said, it is getting OT and pedantic. I pulled up the work cited, along with the other ammo and it's cost, just to make a few limited points.

1) The slip rings work fine, they are a pretty decent mechanism, cheap, well proven, simple and gets the job done brilliantly and with negligible effects on real world performance

2) The smooth bore choices were dictated by different set of circumstances and requirements. We made a different engineering choice based on our requirements

3) It is by no means "obsolete" or cant fire this or that or anything. All that is simple FUD by ignorant and/or malevolently interested parties.

The T-90 is a dead end and it makes no sense to make the 1500 or so we are supposed to make. We will be the only suckers buying them. The T-90 AM will be an even bigger disaster. The Russians are not going to be even a single one and we will be the biggest suckers holding the can in the world if we do so. Natashas can whine all they want. But that is the cold hard facts.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by hnair »

Sidharth wrote:
Also check this spinning projectile, not sure what explosive it is, but it sure does seem like spin stabilized with fins.

That video's ending is odd. Was expecting a strike of a target.

Sort of like a kindergartner mode camera work "must...keep...focus on missile.......focus on missile.....oooh bushes!" :P
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by shiv »

hnair wrote: Sort of like a kindergartner mode camera work "must...keep...focus on missile.......focus on missile.....oooh bushes!" :P
:rotfl: I thought about that when I saw the video and then realized that the video camera has panned from left to right in a few milliseconds. At 1000 meters per sec - catching the first 50 meters of flight should take 50 msec I guess. i want that camera. If you notice the camera stops panning and then rebounds a bit like it was mechanically stopped from panning further.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Gurneesh »

Also only the rear 3/4ths of the rounds spins !!!
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by shiv »

Gurneesh wrote:Also only the rear 3/4ths of the rounds spins !!!
Gurneesh if you watch after 23 seconds you see the pale bit in front (behind the cone) spinning too.

As an aside that round spins about 12 to 13 times in that video which I am guesstimating is about 50 to 100 millisec. Taking the latter figure you get a rotation of over 7000 RPM! :eek:
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by sudeepj »

Well consider a 1 in 20 twist rate, 120mm bore, 1650 meters/sec muzzle velocity.

At the muzzle, a full bore round would be spinning at:

1 rotation in 120mm X 20 = 2.4 meters.
therefore 1650/2.4 rotations in a second = 687.5 rotations per second.
= 41250 rpm

Yikes!
* Even at this rate of rotation, if one shoots a 3cm diameter APFSDS shot, with a sabot without bearings, the ratio of linear to rotational energy is ~ 1300: 1. So much for work done and 'energy wasted' in spinning the round.
** These rounds truly pack a tremendous amount of energy!
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Austin »

My 2 Cents

Smooth Bore is here to stay and it will only get better with the ability to fire Darts at higher velocity ( ~ 1750-1800 m/sec ) and at higher chamber pressure.

Darts or APFSDS are here to stay , there is no cheaper and cost effective substitute yet developed for Darts , if any thing development globally shows Darts are getting Longer and Skinnier all the more they need Smooth Bore as they can work only best its spin stabilised. There is no point in wasting energy by introducing anti-spin mechanism in Darts.

Tank are still primarily anti-tank weapons and darts are best bang for buck , missile is no substitute for darts for one that are slower compared to hypersonic darts , even simple missile like laser guided have shelf life , F&F missile are darn expensive and have issues with shelf life of missile , Chemical Energy lacks mass , it can work great at some areas and at others it wont even dent , check the Abrams verus RPG-29 videos.

Since Darts have mass they would end up doing some damage even in the most protected area and would end up shaking the crew , Current Anti-RPG/Missile Active Protection System developed for Tanks end up being effective counter even against top attack missile.

So the whole argument that Smooth Bore is not needed and Missile is the future still has a very long way to go , you can still get a 50 T tank with decent protection with logistics in mind and better tactical/strategic mobility but there is still nothing on drawing board of any country that can replace a smooth bore or Dart , if any thing they have simply developed better Smooth Bore Guns , Longer/better Darts.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by negi »

The round in that video is some kind of smart munition definitely not an APFSDS , also imho the impression that a SB gun fires KE penetrators without any spin is not entirely true there is a slight amount of spin on the penetrator (obviously I do not know the exact reason why).
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Austin »

Certainly its not APFSDS rounds , we can see it releasing some ammo at it flies and spins , most likely its the HE-FRAG/AP rounds
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by VibhavS »

vina wrote:
VibhavS wrote:1) Torque is negligible as per the graph. ..snip.
You are confused. What they are doing , is take an existing APFSDS round ,which has aluminum sabots (which are the piece that get discarded the moment it exits the barrel) and are changing the SABOT material from aluminum to carbon composite! That is all. The penetrator is untouched /same as before .. penetrator is the part that continues flying and hits the target .And there is NO,"composite" penetrator.

That said, it is getting OT and pedantic. I pulled up the work cited, along with the other ammo and it's cost, just to make a few limited points.

1) The slip rings work fine, they are a pretty decent mechanism, cheap, well proven, simple and gets the job done brilliantly and with negligible effects on real world performance

2) The smooth bore choices were dictated by different set of circumstances and requirements. We made a different engineering choice based on our requirements

3) It is by no means "obsolete" or cant fire this or that or anything. All that is simple FUD by ignorant and/or malevolently interested parties.

The T-90 is a dead end and it makes no sense to make the 1500 or so we are supposed to make. We will be the only suckers buying them. The T-90 AM will be an even bigger disaster. The Russians are not going to be even a single one and we will be the biggest suckers holding the can in the world if we do so. Natashas can whine all they want. But that is the cold hard facts.
Oh well I tried.. :) anyways Vina we must agree to disagree. Although when you say T90ASM will be a big disaster right with you mate. I think its a waste of time and resources as against the Arjun.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by wilson_th »

I found some good reading on British Challenger 2 & Hesh round and Rifled gun.

http://www.tanknutdave.com/component/content/article/47
Telic 1 Challenger 2 history was best known for a Royal Scots Dragoon Guards tank throwing its tracks and getting stuck in a ditch, which was reportedly hit by 14 RPG variants and a MILAN anti-tank missile. The attack saw the sights on the vehicle destroyed, but the armour was un-penetrated and the crew walked away when the vehicle was recovered.

The term “blue on blue” refers to Fratricide, or an accidental attack on friendly forces. On the 25th of March one Challenger 2 engaged another Challenger with HESH rounds. HESH is a typical high explosive lobed round meaning its firing trajectory is a high arch making it at range a top attack weapon. 1 round hit the back decks of the tank injuring the crew and another hitting the top of the turret reportingly with an open commanders hatch. This vicious explosion and enormous heat cooked off the tanks ammunition consequently destroying the tank. tragically killing two crewman. This engagement remains the only Challenger 2 to be catastrophically killed on operations.
The only fatal kill was using a Hesh round(though friendly fire)

regards to retaining the Rifiled gun..
There are two types of main guns used on tanks, rifled and smoothbore. Both have advantages and disadvantages. Rifling imparts a spin to the fired round which stabilizes its flight and prevents it from tumbling. This increases its range and accuracy compared to a smoothbore, which automatically starts to tumble as its left the muzzle.

The energy released from the combustion of the rounds charge builds up behind the round as it travels down the main gun. Some of the energy escapes through the grooving of the rifling. Energy doesn’t escape with a smoothbore, which requires a higher level of muzzle velocity to stop the round from tumbling. A number of tanks using shorter smoothbores are swapping to cal Length 55 main guns to increase muzzle velocity, AKA the L55. The increased length means that the round has further to travel down the barrel, which means the energy from the charge has longer to build up, pushing the round hard out of the muzzle, increasing its velocity. This then means the round takes longer to tumble and increases the range and accuracy as well as the punch to get through the enemies armour.

It was for this reason that a lot of people have mistakenly believed that the CR2 was swapping over to a L55 smoothbore. This is incorrect. The British do not name their main guns after their cal Length like the Germans, so people are unaware that the CR2 L30 main gun is a cal Length 55 and therefore already has a high muzzle velocity. The reason the British Army field tested the German L55 smoothbore was for a cost cutting exercise to purchase cheaper rounds.

It was found with previous generation rifled main guns, that as the round makes its way down the barrel it starts to wear down the rifling, shortening the main guns life, where as this wouldn't happen on smoothbores, therefore it was found to be more cost effective to use smoothbores when operating large tank fleets, like the USA's Abram and Germany's Leopard 2, which totalled ten thousand plus during the Cold War and why both vehicles were equipped with smoothbores. This means there are more smoothbores and as such, a higher demand for the number of smoothbore rounds, which in turn drives down their production costs and makes them cheaper to purchase.

The Challenger 2 will not be fitted with the German L55 smoothbore Main Gun!!
Aditya_V
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Aditya_V »

from the link posted by Wison-TH.
It was during this period in August 2006 that a Challenger 2 from the Queens Royal Hussars was struck by a deadly tandem charged RPG-29 anti-tank missile. Though there were various inaccurate reports on the web at the time, the missile dropped short, exploding on the ground sending shrapnel and blast up under the tank penetrating the then unprotected steel belly of the tank, The Driver; Trooper Sean Chance, lost three of his toes in that attack.
Hold on I thought all tanks had Armour underneath to protect the crew from Anti-Tank mines and IED's. I hope the Arjun's and T-90, T-72's in IA give some protection to crew like 15mm or 20mm of Armour from below.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Singha »

well I dont think any tank can take a RPG29 from below. armor on the bottom , hull sides and back, turret top is kept thin to minimize weight. only the Merkava apparently uses heavy armour on turret top and below due to its "watchover" or "patrol" role sometimes in hilly or built up areas where high angle RPG/ATGM hits or landmines can occur.

the rest of the worlds tanks mostly expect to have minefields cleared for them or else they will fix ploughs (some abrams did that in baghdad attack) and not to engage in high angle shooting matches with dispersed RPG Shooters - instead they will let IFV (their cannons and remote control HMG elevate to high angles) and infantry tackle that and if needed provide standoff firepower from a mile away....

if you notice once the abrams lost the speed and mass advantage of the real war, and started roaming around in ROPs/patrols the insurgents managed to target quite a few of them in youtube videos with mines, EFPs, RPGs from the back or side...in short order the abrams were all withdrawn out of Iraq hence. in a way wheeled strykers or bradleys with the slat armour are more survivable vs insurgents than big MBTs. they can also unleash a squad of infantry to go hunt in alleys or scout ahead.

the challenger must have been unlucky the shot didnt bounce up and hit the front of the hull where armour is very thick, but managed to squeeze below the vehicle somehow.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by keshavchandra »

With IMI Blacklisted, Hurdles For MBT Arjun Mk.2?
Before it was blacklisted last month, Israeli Military Industries (IMI) was steeped in a complex consultancy for the indigenous Arjun Mk.2 battle tank, a platform the DRDO is depending on for more solid orders from the Indian Army. IMI, which was one of six firms barred from business with the Indian MoD last month, was, along with compatriot firm Elbit, providing all manner of assistance to the Combat Vehicles R&D Establishment (CVRDE) to ready the improved Arjun Mk.2 for user trials in June this year.

The firm had been helping improve the overall design of the tank, specifically its turret and hull for more accurate and reliable firepower. Crucially, the firm was also helping the programme team optimise fuel consumption and mobility by bringing down overall weight. Finally, it was to provide assistance in optimising production line processes at the OFB's Heavy Vehicles Factory (It was an OFB related issue that led to the firm being blacklisted along with five others).
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by sum »

^^ Our MoD can be a text-book case study on how to creatively axe our own foot in 100 different ways!!
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Austin »

Russia To Supply Ammunition For India T-90 Tanks
India is likely to take delivery of 16,000 rounds of ammunition from Russia for its T-90 tanks this year.

“A contract for procurement of 16,000 rounds of Fin Stabilized Armor Piercing Discarding Sabot (FSAPDS) ammunition for T-90 tanks was signed with Rosoboronexport ... in December 2010. It became effective in March 2011, and the complete consignment is likely to be delivered in the first half of 2012,” a defense ministry official says.

The Indian army has been looking for high-quality 125mm FSAPDS ammunition for in-service T-72 and T-90 tanks. And the government was recently criticized after army chief Gen. V.K. Singh noted that there was a shortage of shells for armored regiments.

A contract for 66,000 rounds of ammunition for 84mm rocket launchers also was signed in March 2011 with Swedish firm Saab, the official says.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Singha »

IMI was also supplying various types of shells to us, since out OFB cant seem to produce much with tolerable and consistent levels of quality :(
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by krishnan »

sum wrote:^^ Our MoD can be a text-book case study on how to creatively axe our own foot in 100 different ways!!
not own foot...own head
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Aditya_V »

sum wrote:^^ Our MoD can be a text-book case study on how to creatively axe our own foot in 100 different ways!!
Sometimes I wonder whether there is Grand Aman Ki Asha plan behind these kind of decisions, since no matter what Pakis do we are resigned for peace. Sigh
Karan M
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Karan M »

More like grand incompetence at every level of the MOD.

Of course, guess who will get the flack from the Army, the media with the MOD remaining silent when Arjun MK2 is delayed? The DRDO and the Arjun program will be called more names. This of course means we need imports to tide us over the delay.

Of course, we have to now buy more T-90's, whose ammunition (already verging near the end of development potential thanks to the T-90's "famous" autoloader length issues) we have to buy from Russia (because we blacklisted IMI) .. what a sad sad joke this MOD is.

We won't go running either to KMW from Germany to seek their assistance either. A tender will be announced, a new cycle of RFP/RFI'ing will go on with another couple of years wasted to seek the next "partner", who of course, may get blacklisted too

By now, everyone should be well aware of the utter disaster that is GOI when it comes to defence and how they have been doing things all this while...

Meanwhile, lets talk of "indigenization" to replace "imports".
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by negi »

^Blacklisting of IMI or other OEMs by the lot that is in power is a classic case of the pot calling the kettle black, actually if you would observe it's only privately held entities which are being blacklisted as it's an easy thing to do when trying to shift blame for shady dealings on the vendor. It's an open secret as to how Ru manages to bag some of these contracts but looks like Anthony sir's morality comes into play only when he knows the party on the other side does not have any means to contest the allegation and there by show the Gobermund in bad light.
Karan M
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Karan M »

Exactly. He does not seem to be even bothered about defence preparedness or how local programs get affected. His only concern is his image and hence that of the UPA
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by srai »

^^^

IMO, even if a company is blacklisted, only new contracts should be barred. Existing contracts and work should continue as per agreement signed.

It is very stupid of the GoI/MoD to blacklist all the major defense players out there in the international market. Defense contracts, by their very nature, are all susceptible to "corruption" (or influence) of some sort. No where in the world are there a "clean" defense deal :!:
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