Arjun vs T90 MBT

[Damian]

@sayareakd I will however wait to Dejawolf answer. He is proffesional 3d artist who made as he said more than 100 3d models of AFV's, many of them incredibly detailed. For Esim Games which is company that developed Steel Beasts AFV simulators used by several militaries around the world, among them also Polish Army. So his opinion is backed up by credibility of his work.

 

[ersakthivel]

i have. i've made over 100 3d models of armoured vehicles in my 10 years of working for Esim games.

here, let me show you with a quick and dirty 3d model what me and damian is seeing, and you fail to see:

in the 2 lower interior pictures, the marked edges of the real picture and 3d model is comparable, yes?
camera is in a similar angle.
well, look what happends when you turn the camera a bit...

In the first attempt you tried your hand at comparing an older turret belonging to Tank -ex to a newer ajun crew compartment,

Tank =ex doesnot have the frontal armor side protrusion of arjun.So how can you can you compare both of them?

Even in this picture your 3D drawing of the turret top view doesnot have the side protrusion in the top left picture.

Also we dont know the purpose of the round knob with a handle on arjun turret top just besides the crew hatch.

well we dont know whether there is a hole under the knob or it is welded on turret top to house some fitments ?


Whether it is for mounting some external fitting and does not reach the bottom of the turret top (so that we can try to match it with a fixture inside)or it is a round hole which extends into crew compartment and corresponds to the fitting inside to which you relate is not certain.

Because if this hole extends right through then what is the purpose of covering it with a knob like thing?You can see the hole before the crew hatch on the other side is not covered.


Damian's attempt to equate it to air vent corresponding to it in the inside pic was corrected by kunal as a mistake well,

Since you said that you have done 100 3d models do you accept my points regarding the mistakes in your first post or not?

for example the radio antena is aligned almost to the center of the crew hatch circle in the turret top of tank ex.
But you have equated it to a stuff that lies almost at the edge of the crew hatch circle in the arjun inside crew compartment.No one who has any practice in the field of drawing does that.

 

[ersakthivel]

@sayareakd I will however wait to Dejawolf answer. He is proffesional 3d artist who made as he said more than 100 3d models of AFV's, many of them incredibly detailed. For Esim Games which is company that developed Steel Beasts AFV simulators used by several militaries around the world, among them also Polish Army. So his opinion is backed up by credibility of his work.

If at all I made the mistakes he made in his first post my engineering drawing professor would have banned me for a couple of classes.

How can you equate something that is aligned to the center(the radio antena) of the crew hatch circle in the top view of the turret to something that lies at the left side edge of crew hatch circle in the inside crew compartment picture?

Each and every red line he draws linking outside features to the features inside crew compartments are wrong.

Don't you see such elementary mistakes yourself?

Also we don't know the purpose of the round knob with a handle on arjun turret top just besides the crew hatch hole.

Your attempt to equate it to air vent corresponding to it in the inside pic was corrected by kunal as a mistake well,

So please give a guess to what may be the purpose of the knob ,so that we can equate it with something inside in a proper manner.

well we don't know whether there is a hole under the knob or it is welded on turret top to house some fitments ?

Because if this supposed to be hole extends right through the turret top plate ,then what is the purpose of covering it with a knob like thing?You can see the hole before the crew hatch on the other side is not covered.

Whether it is for mounting some external fitting and does not reach the bottom of the turret top (so that we can try to match it with a fixture inside)or it is a round hole which extends into crew compartment and corresponds to the fitting inside to which you relate is not certain.

 

[pmaitra]

The only issue I have with Damian's diagram is depicted below:

To me, it appears, that one of the correlations drawn by @Damian is a mistake, and has been marked with orange crosses.

 

[Dejawolf]

Dejawolf can you then estimate Arjun Mk1 armor thickness by using a 3d model? At least for the turret side surfaces?

well, i can try. i created a rudimentary turret model based on drawings i found here on this website

the extreme side turret should be about 80-90mm thick. whether this is plain RHA steel, or composite is impossible to tell. maybe in the latest variant of the Arjun, it's NERA. who knows.
anyways, if it's pure RHA steel,
it should be 90*1.25 = ~112mm KE. the stowage box is sheet metal, probably 1-2mm so a total of ~114mm vs KE
vs HEAT: (90*1.0)+(280*0.26) = ~163mm

another possibility is that it's steel+Kanchan+steel.
lets say it's 50/50 composite and steel
assuming kanchan is roughly equivalent to non-DU chobham:
vs KE: (45*1.25)+(45*0.92) = 97.65mm RHAe
vs HEAT(45*1.0)+(45*1.4)+(280*0.26) = 180mm RHAe

which means the middle side turret should be immune to russian 30mm which at best can penetrate around 60mm RHA steel.
the front side turret is around 348mm total.
assuming a backing plate of 90mm, faceplate of 45mm, and kanchan composite of 213mm
vs KE: (213*0.92)+(90+45)*1.25 = ~364mm RHAe
vs HEAT: (213*1.4)+(90+45) = ~433mm RHAe

front turret
i'd say is approximately 653mm, or LOS thickness of 760mm.
lets assume a similar arrangement to leopard 2A4
50mm steel face plate, and 130mm backing plate. that'd be 473mm of composites.
let's say 25% fiberglass, 75% ceramics.

Cmp = 354
fbgl = 118
steel = 130+50
(Cmp*0.92)+(fbgl*0.4)+(steel*1.25) = 597mm RHAe vs KE (688mm LOS)
(Cmp*1.4)+(fbgl*0.6)+(steel) = 746mm RHAe vs HEAT (861mm LOS)
so frontally it might be comparable to a leopard 2A4, and thus immune to one of the best fielded russian rounds, the 3BM-42.
keep in mind however, this estimation is SHS. AFAIK, the russians use plain RHA steel in their T-90's. and if the indians have trouble building T-90s with comparable quality to the to the russians.. well.., in the estimations above, remove the *1.25
KE protection then ends up at 640mm LOS, which is still enough to defeat 3BM-42 frontally.
the MK.II seems to have a K5 ERA equivalent applied which adds 250mm KE, and 600mm HEAT.

 

[Dejawolf]

Also we dont know the purpose of the round knob with a handle on arjun turret top just besides the crew hatch.
well we dont know whether there is a hole under the knob or it is welded on turret top to house some fitments ?

Whether it is for mounting some external fitting and does not reach the bottom of the turret top (so that we can try to match it with a fixture inside)or it is a round hole which extends into crew compartment and corresponds to the fitting inside to which you relate is not certain.

from this picture, you can see it's bolted to the turret, not welded. it's not some sort of strapdown point or lifting eye, it's far too fragile for that.
it has a screwed on endpiece as well.

Damian's attempt to equate it to air vent corresponding to it in the inside pic was corrected by kunal as a mistake well,

Since you said that you have done 100 3d models do you accept my points regarding the mistakes in your first post or not?

i'll concede that i could be wrong about the rectangular piece inside the turret with the black square in it is the loaders periscope. but i dunno why you would want to assume that. the further from the wall the loaders periscope is, the thinner the wall is...

for example the radio antena is aligned almost to the center of the crew hatch circle in the turret top of tank ex.
But you have equated it to a stuff that lies almost at the edge of the crew hatch circle in the arjun inside crew compartment.No one who has any practice in the field of drawing does that.

well the antenna doesn't matter either. what matters is the dome shape and the hooked tube. both supports a thin turret side.

 

[ersakthivel]

The only issue I have with Damian's diagram is depicted below:

To me, it appears, that one of the correlations drawn by @Damian is a mistake, and has been marked with orange crosses.

Almost every correlation marked by Dejawolf is wrong by the same criterian including the radio antena.

 

[Damian]

Thanks @Dejawolf.

 

[Dejawolf]

Almost every correlation marked by Dejawolf is wrong by the same criterian including the radio antena.

it's obvious that you're basing your decisions on emotions rather than facts.

 

[Dejawolf]

here's another line of evidence that the walls are thin:

 

[ersakthivel]

well, i can try. i created a rudimentary turret model based on drawings i found here on this website

the extreme side turret should be about 80-90mm thick. whether this is plain RHA steel, or composite is impossible to tell. maybe in the latest variant of the Arjun, it's NERA. who knows.
anyways, if it's pure RHA steel,
it should be 90*1.25 = ~112mm KE. the stowage box is sheet metal, probably 1-2mm so a total of ~114mm vs KE
vs HEAT: (90*1.0)+(280*0.26) = ~163mm

another possibility is that it's steel+Kanchan+steel.
lets say it's 50/50 composite and steel
assuming kanchan is roughly equivalent to non-DU chobham:
vs KE: (45*1.25)+(45*0.92) = 97.65mm RHAe
vs HEAT(45*1.0)+(45*1.4)+(280*0.26) = 180mm RHAe

which means the middle side turret should be immune to russian 30mm which at best can penetrate around 60mm RHA steel.
the front side turret is around 348mm total.
assuming a backing plate of 90mm, faceplate of 45mm, and kanchan composite of 213mm
vs KE: (213*0.92)+(90+45)*1.25 = ~364mm RHAe
vs HEAT: (213*1.4)+(90+45) = ~433mm RHAe

front turret
i'd say is approximately 653mm, or LOS thickness of 760mm.
lets assume a similar arrangement to leopard 2A4
50mm steel face plate, and 130mm backing plate. that'd be 473mm of composites.
let's say 25% fiberglass, 75% ceramics.

Cmp = 354
fbgl = 118
steel = 130+50
(Cmp*0.92)+(fbgl*0.4)+(steel*1.25) = 597mm RHAe vs KE (688mm LOS)
(Cmp*1.4)+(fbgl*0.6)+(steel) = 746mm RHAe vs HEAT (861mm LOS)
so frontally it might be comparable to a leopard 2A4, and thus immune to one of the best fielded russian rounds, the 3BM-42.
keep in mind however, this estimation is SHS. AFAIK, the russians use plain RHA steel in their T-90's. and if the indians have trouble building T-90s with comparable quality to the to the russians.. well.., in the estimations above, remove the *1.25
KE protection then ends up at 640mm LOS, which is still enough to defeat 3BM-42 frontally.
the MK.II seems to have a K5 ERA equivalent applied which adds 250mm KE, and 600mm HEAT.

The one on top is leo if I am not mistaken.

From a simple glance the distance beween the center point of crew hatch hole and the side turret wall looks the same for both arjun and the tank it was modeled on LEO.

Already the first tool box space seems to have been armored in the ARJUN MK-I, Now all the tool boxes have been replaced with armor if we go by the photos provided by kunal.

Instead of trying to determine the side armor thickness of arjun from various wrong photos like the discarded tank-ex you can use the proper photos with dimensions given by KUNAL BISAWS.

The pictures below are the insides of other tanks.the one in the middle is the arjun inside I think.
If you can accurately guess the distance between crew hatch hole and side wall and plot it in your drawing you can get some more accurate projection rather than arriving at inaccurate conclusions by comparing the outside fitments and inside fittings of two different turret models.

in the bottom pictures Damian has pointed out the lack of side turret armor of arjun compared to LEo.This is not true since in the arjun mk-1 itself the first tool box has been replaced by armor making the side armor protection same for both the tanks.In mk-2 it goes even further.

 

[ersakthivel]

the picture above is leo.The one below is arjun.In arjun mk-1 too the first tool box besides the crew hatch has been replaced by armor plates.So the thickness of the frontal side protrusion extends till crew hatch in mk-1 itself same protection level as leo in the photo..

Since Damian's armor thickness chart for leo marks the side armor plate thickness at 330 mm(B1 in his drawing) it wont be very different for ARJUN MK-I either.Comparing the bigger turret size of arjun it must be more for arjun even in mk-1.

So the photos posted here will actually help you to come to more accurate conclusions than basing our assumptions on wrong co relation between inside and external fittings that don't correspond to each other.

The drawing below is produced by Damian after it became clear to him that part of turret side has been armored in ARJUN in MK_I oppsed to the unarmored discarded experimental light tank model the TANK-EX.

Even here the red lines present no vulnarability because the crew compartment ceiling cover will prevent explosions from the red line area from reaching crew hole in the tank hull.IMHO sufficient armor plating would have been given to the ammo stored in arjun turret to prevent it from being hit directly as it is quite common sense.

Any way there will be extra explosive reactor armor for further protection.Considering the accuracy of arjun firing on the move as certified by army any other tank before it in the sub continent would have been already shot by arjun before these remote eventualities of being hit repeatedly in the same place from the side happening.

 

[ersakthivel]

So the turret design of arjun like leo has enough protection level of the truncated turret designs of T-90 below.

The advantage of leo turret design is it gives even more space for storing ammo safely than truncated turret design.And the auxilary power unit too can be placed safely inside the turret for protection leading to overall better protection and better network centric warfare capability.

 

[ersakthivel]

A crew overhead cover like the one in the picture above will contain the inside crew compartment from any effects of shells getting through the redline areas,while at the same time protecting the hull top unless the truncated turret design which leaves the hull top open behind the smaller turret ,exposed for shells with little armor.

 

[ersakthivel]

here's another line of evidence that the walls are thin:

But they have already been beefed up from 2008 please go to the arjun thread and see the pictures of arjuns ready for delivery and you will notice heavy armor modules over the yellow line replacing the so called tool box picture.

Also it gives no evidence to the thickness of the side turret as the yellow line denotes the outer edge of the crew cavity not the inner edge.And armor modules have been added outside the yellow line.

You can clearly see there is no side step offset in the production model compared to the turret top view with your yellow line you have posted here.And the first box on the side is not a tool box.Only the second and third boxes have hatches on them.
In mk-2 even they were replaced by kanchan armor module.

 

[Dejawolf]

A crew overhead cover like the one in the picture above will contain the inside crew compartment from any effects of shells getting through the redline areas,while at the same time protecting the hull top unless the truncated turret design which leaves the hull top open behind the smaller turret ,exposed for shells with little armor.

this is like arguing with religious people..
crew overhead cover? it seems like you don't understand how compartmentalized ammunition works. the system is simple. you put the ammunition inside a separate ammunition bunker, like this one for example:

now the bunker side walls needs to be pretty damn thick, at least 40-50mm of steel. on the roof, you add a plate that is much thinner, and loosely bolted on, and you have a secure blast door for access into the bunker. now. if the ammunition bunker is hit, from the side for example, instead of the rounds exploding into the crew compartment, the propellant gases are vented upwards through the thinner roof plate blowing it off, thus saving the crew from being cooked alive. naturally, the tank is rendered combat-ineffective, while the ammunition cooks off, and it might catch fire, but it will give the crew time enough to escape alive, and possibly drive the tank out of danger

now, on the arjun, the ammunition storage looks like this:

this is an ammunition stowage rack. it is not a blast door. those round things grabs onto the back of the cartridge and holds it in place.
however, if any of the rounds in the ammunition bunker is hit, those levers will break, the stub of the round will fly into the interior with a propellant jet following it, and the heat of the round will cause the propellant of the nearby rounds to catch fire as well, causing a chain reaction of fiery death. finally, the heat and pressure will cause the plastic explosive in the HEAT and HE rounds to detonate, ripping the turret rear apart in the welds, and possibly partially ltugging the turret off at the race ring.

 

[ersakthivel]

this is like arguing with religious people..
crew overhead cover? it seems like you don't understand how compartmentalized ammunition works. the system is simple. you put the ammunition inside a separate ammunition bunker, like this one for example:

now the bunker side walls needs to be pretty damn thick, at least 40-50mm of steel. on the roof, you add a plate that is much thinner, and loosely bolted on, and you have a secure blast door for access into the bunker. now. if the ammunition bunker is hit, from the side for example, instead of the rounds exploding into the crew compartment, the propellant gases are vented upwards through the thinner roof plate blowing it off, thus saving the crew from being cooked alive. naturally, the tank is rendered combat-ineffective, while the ammunition cooks off, and it might catch fire, but it will give the crew time enough to escape alive, and possibly drive the tank out of danger

now, on the arjun, the ammunition storage looks like this:

this is an ammunition stowage rack. it is not a blast door. those round things grabs onto the back of the cartridge and holds it in place.
however, if any of the rounds in the ammunition bunker is hit, those levers will break, the stub of the round will fly into the interior with a propellant jet following it, and the heat of the round will cause the propellant of the nearby rounds to catch fire as well, causing a chain reaction of fiery death. finally, the heat and pressure will cause the plastic explosive in the HEAT and HE rounds to detonate, ripping the turret rear apart in the welds, and possibly partially ltugging the turret off at the race ring.

That is a nice explanation for the aamo stored in turret.the chances of that happening is nill as there will be sufficient armor plate protection between the ammo compartment and the side turret wall.And extra ERA protection on the outside.Certainly you can give the design guy some measure of intelligence to design some safety measures.But this too is going to be upgraded in ARJUN mk-2 as separate compartmentalization of ammo. And these modifications can be done in mk-1 as well.

But I mentioned about the main ammo storage that inside the crew cavity in a very non religious way.Where will it blow off?.
That's where I wrote about the crew overhead cover or some kind of compartmentalizing mechanism providing a barrier between the main ammo storage in the hull below the turret and the effects of explosions from shells coming through the so called red lines on the turret sides.

This discussion is superfluous as most of the ARJUN MK-2 turret sides are going to be covered by kanchan composite armor module and mk-1 can be upgraded with armor as well besides the ERA tiles.

 

[Dejawolf]

The one on top is leo if I am not mistaken.

From a simple glance the distance beween the center point of crew hatch hole and the side turret wall looks the same for both arjun and the tank it was modeled on LEO.

Already the first tool box space seems to have been armored in the ARJUN MK-I, Now all the tool boxes have been replaced with armor if we go by the photos provided by kunal.

Instead of trying to determine the side armor thickness of arjun from various wrong photos like the discarded tank-ex you can use the proper photos with dimensions given by KUNAL BISAWS.

The pictures below are the insides of other tanks.the one in the middle is the arjun inside I think.
If you can accurately guess the distance between crew hatch hole and side wall and plot it in your drawing you can get some more accurate projection rather than arriving at inaccurate conclusions by comparing the outside fitments and inside fittings of two different turret models.

in the bottom pictures Damian has pointed out the lack of side turret armor of arjun compared to LEo.This is not true since in the arjun mk-1 itself the first tool box has been replaced by armor making the side armor protection same for both the tanks.In mk-2 it goes even further.

no:

also, did some measurements of the arjun based on the line drawings. the width of the tank is based on the real width of the Arjun.

 

[ersakthivel]

no:

also, did some measurements of the arjun based on the line drawings. the width of the tank is based on the real width of the Arjun.

the green lengthy rectangular box just behind the turret frontal protrusion is not a tool box in mk-1
width of the turret is supposed to be 3.2 meters.Any source for 2.86 meter cailm?

 

[Dejawolf]

That is a nice explanation for the aamo stored in turret.the chances of that happening is nill as there will be sufficient armor plate protection between the ammo compartment and the side turret wall.And extra ERA protection on the outside.Certainly you can give the design guy some measure of intelligence to design some safety measures.But this too is going to be upgraded in ARJUN mk-2 as separate compartmentalization of ammo. And these modifications can be done in mk-1 as well.

lol. no. btw, the ammunition safety measures was part of the leopard 2 prototype back in 1979. it took indian engineers 32 years to figure out how it's supposed to work?
as for all your talk about sufficient armour.. no, it is not.

in that red area, it is vulnerable to RPG, ATGM, 100/120/125mm tank rounds. so is the leopard 2A4, however, it's ammunition is compartmentalized.
so a hit in that area isn't going to kill the crew and completely destroy the tank. oh and btw, if you squint, notice the ammunition storage doors on the mk.2 are the same as on the mk.1 so no, i think the ammunition storage on the Mk.2 is the same as on the mk.1

But I mentioned about the main ammo storage that inside the crew cavity in a very non religious way.Where will it blow off?.
That's where I wrote about the crew overhead cover or some kind of compartmentalizing mechanism providing a barrier between the main ammo storage in the hull below the turret and the effects of explosions from shells coming through the so called red lines on the turret sides.

you obviously didn't understand what i was writing. like electricity,the hot expanding gases follow the path of least resistance. in the case of the leopard, it's through the thinner roof panel, simply because the ammunition blast walls and door is thicker than the roof.
on the Arjun, the cylindrical container of each round is more resistant, than the ammunition stub so the ammunition is vented INTO the turret interior where the crew is. the location is BAD, because even in a hulldown position, the turret ammunition is exposed. on a T-72 or T-90, at least the ammunition is down under the turret floor(if the crew doesn't store all the extra ammunition around the turret interior)