Arjun vs T90 MBT

[Kunal Biswas]

This is my view on MK2 side Armour, I recommend lets wait until there are more clear images..

As we can see, here is also some space for improvements.

Some of the issues can be improved with dynamic addon protections...

Though a complete makeover is best, But again this is 2nd prototype and there are reports of 3rd, hope to see improvement in that..

Many will ask, how to get a knowledge about tanks armor, without being in a tank personally, nothing more simple, you just need good exterior and interior photos.



Someone might ask, however, why on these photos like one of our dear fanboys said, there is space between man standing in hatches and the turret edge.

What is marked in Interior photos is gunner periscope..

 

[pmaitra]

So obviously:

Blue = strong.
Red = weak.
Orange = slightly weaker protected zone, typical for all tanks, made by main sight or gun mantled.

Explanation. The Arjun Mk1 have addition orange/slightly weaker protected zone, because it have a main gunner sight, placed in the front armor "window", it makes armor there less protective. Very similiar problem had Leopard 2, which was more or less eliminated by the KWS upgrade program from variant A5 to A7. M1 series and T-90S have sights placed on the turret roof, behind frontal armor, so such problem do not exist.

Good diagrams, but there is an error, well actually two errors, in the left most diagram.

Look at the image below, and see if you can figure that out:

 

[Damian]

What is marked in Interior photos is gunner periscope..

Take a better look.

And the gunner is sitting on the other side of turret.

This is my view on MK2 side Armour, I recommend lets wait until there are more clear images..

IMHO it is storage box only, there is no sence to make such module that can be deattached on a new tank, where armor can be semi modular (and semi modular have some advantages over fully modular).

Good diagrams, but there is an error, well actually two errors, in the left most diagram.

Look at the image below, and see if you can figure that out:

Please explain, I compared it with other materials avaiable, and I do not see where I could make any error.

 

[Kunal Biswas]

Take a better look.

And the gunner is sitting on the other side of turret.

My bad..

IMHO it is storage box only, there is no sence to make such module that can be deattached on a new tank, where armor can be semi modular (and semi modular have some advantages over fully modular).

It cannot be a storage box, I am sure of it..

 

[Damian]

@Kunal Biswas, by a long time people who looked at French Leclerc, were sure that storage boxes mounted around the turret, were modular armor, untill photos of these storage boxes opened were posted somewhere in the internet.

To be honest I would be very happy to travel some day to India to some military exhibition, and hopefully take a closer to Arjun myself, to learn more and verify my knowledge.

 

[pmaitra]

Let us assume there is an obstacle O in the middle of a free space, and a robot A has to move in a way it does not collide with the obstacle. The robot has 2 degrees of freedom (can move in x and y direction, but cannot rotate), and is represented as a triangle, with the dot as a reference point.

Image courtesy Steven LaValle.

Now, what are the positions that the robot can be in? That will be defined by a locus traced by the reference point keeping the robot at all places as close as possible to the obstacle without colliding. This is shown by the larger polygon in the image below, which contains the obstacle and is called the obstacle space. Whatever is outside this polygon is the free space.

Image courtesy Steven LaValle.

You can understand more about motion planning in free space involving obstacles if you read Chapter 4 (The Confguration Space) of the book PLANNING ALGORITHMS by Steven M. LaValle. The book is freely available, and is a great collection to have. [LINK]

[HR][/HR]

Now, let us assume the robot is the shell, and the obstacle is the armour, thus imparting a strong zone.

If we are to define a 30 degree attack angle from the medial axis of the turrent, it looks something like this:

Note the following:

• The Blue line is the 30 degree line with the medial turret axis on each side from the back of the turret.
• The Orange line the start of the weak zone if the shell were a point (hypothetical).
• The Red line is the actual start of the weak zone, where, the perpendicular distance from the Red and Orange lines would be half the diameter of the shell (real).
• The Blue Dots represent the turret edges.

The blue boxes are squares, and they are provided as a mark of authenticity of the angles.

This is what you had missed while marking your weak zones.

[HR][/HR]

Finally, the other error you made was the protrusions of the turret edges, shown below:

The correct lines are the dotted lines.

@Damian

 

[Damian]

@pmaitra you are nearly correct. However You are forgeting about one small detail. The protrusions at their edges, where space for storage boxes and weak zone starts, will not give the same protection as the rest of protrusions surface will. So both of us are correct, although I take in to account the armor itself and the fact that armor at the edges is allways weaker.

I will try to do a proper drawing next day or something, because I am tired.

 

[pmaitra]

@pmaitra you are nearly correct. However You are forgeting about one small detail. The protrusions at their edges, where space for storage boxes and weak zone starts, will not give the same protection as the rest of protrusions surface will. So both of us are correct, although I take in to account the armor itself and the fact that armor at the edges is allways weaker.

I will try to do a proper drawing next day or something, because I am tired.

True, the edges might be weaker, so it is debatable how much they will be able to deflect the projectile.

Do read the book though. It is very informative.

 

[Damian]

@pmaitra

Today deflecting ammunition is near immposible. Shaped charge warheads explode in some distance to the armor to allow jet properly form, and jet itself is probably immposible to deflect anyway. While APFSDS penetrators are designed to penetrate even very sloped armor.

Composite armor itself work in different way than homogeneus armor, composite armor working mechanism is closer to Explosive Reactive Armor, Non Explosive Reactive Armor or Non Energetic Reactive Armor. So the projectile defeating mechanism is based on breaking jet or penetrator in to smaller pieces, easier for armor layers to stop, to yaw penetrator, increase erosion of both penetrator or jet, and other mechanisms.

The question is if the edges at that angle will have enough increased thickness for attacking projectile that it will make any difference. I seriously doubt this. Afterall there was a good reason why in NATO, due to same turret geometry, side armor have cavities for composite filler to protect crew compartment, or in extreme case like the M1 Abrams series, not only crew compartment but also turret bustle.

And yeah I will read book if I will have opprotunity, thanks for tip.

 

[Godless-Kafir]

The discussion has gotten a LOT more interesting and detailed. Very good observation by @ersakthivel, @ananymouse and kunal on safe zone and Mk-2 armour. :clap:

So looks like the Mk-2 has a modular kanchan armor at the sides?

 

[Godless-Kafir]

@Damian one more thing, i dont think the orange zone is week. The gun mantel looks massive and has enough armor on it to with stand a frontal attack. Also the sights on the turret seem to be disconnected from the crew compartment and probably vented with blow off panels at the bottom.

Also how do we know they are not cammo latches like on Type-90 and not took box hinges? They could be armor blocks.

 

[Godless-Kafir]

My post is not meant to be hostile for Indians, but to show, where are obvious weak zones, and where improvements are nececary. Otherwise some tank crew might pay in their blood.

Actually you have made everyone here more aware of the arjun than we would have ever been, you have brought out some excellent points. Kudos for that.

However people have made some good observations to counter the discussion and i think they are valid to, i think you should look into it and give a second chance on details.

 

[ersakthivel]

this image exposes everything that has gone wrong with your proportionally wrong and dimensionally inaccurate drawing.
Notice how far back the crew compartment is and notice how far upfront of tank you marked the crew compartment in the drawing you made below.

in fact the drawing you produced below has no proportional or dimensional relation to the schema of arjun.

The holes for the crew entry and exit are well behind the centerline of tank and you have marked them well before the centerline of the tank.

In the production line photo of arjun the crew entry holes are at the point all most 2/3rds of the entire tank length and in your drawing they are before the mid point of the tank.


why?

any true professional would produce a proportionally accurate and dimensionally proper drawing especially while discussing things like angles of attack.

You are once again drawing the horizantal datumn line at the crew hole on on the T-90 and drawing it at the back of the turret for arjun why are you doing it again and again?

The crew compartment ends well in front of the turret back as shown in arjun assembly line pictures why are you repeatedly producing wrong drawing again and again?

You are resting the horizantal datumn line on the engine compartment for arjun and on the crew compartment for T-90. WHY?

This is where the crew compartment begins on the opposite side of the ammo storage space and and stops at the ammo container. Your horizantal datumn line should stop at the starting point of ammo container as it is the end of the crew compartment.
But you are again and again drawing the horizantal line on the engine compartment for arjun .

 

[Godless-Kafir]

@ersakthivel How do we know those are storage boxes?

Those are not hinges on the boxes but latches for cammo cover like on the Type-90 i think.

They may not be storage boxes but add on armor blocks. Kunal has pointed it out on Mk-2 photo.

 

[ersakthivel]

because damian and methos are insisting they are storage box so I assumed them to be.
As kunal said it is no rocket science to put extar armor in place of those storage boxes.

But that will be further point for future debate.

Right now what is the basis of their assumption that there may not be more than 100 mm armor thickness of RHA on arjun side turret?

But the point is there is a thick armor behind those storage box. But both the guys are insisting that there is no thick armor or composite armor behind those storage box or whatever contraption that is.

And they are arguin that there may not be more than 100 mm armor thickness of RHA on arjun side turret. Thats why I am asking for proof.

 

[Decklander]

Let us assume there is an obstacle O in the middle of a free space, and a robot A has to move in a way it does not collide with the obstacle. The robot has 2 degrees of freedom (can move in x and y direction, but cannot rotate), and is represented as a triangle, with the dot as a reference point.

Image courtesy Steven LaValle.

Now, what are the positions that the robot can be in? That will be defined by a locus traced by the reference point keeping the robot at all places as close as possible to the obstacle without colliding. This is shown by the larger polygon in the image below, which contains the obstacle and is called the obstacle space. Whatever is outside this polygon is the free space.

Image courtesy Steven LaValle.

You can understand more about motion planning in free space involving obstacles if you read Chapter 4 (The Confguration Space) of the book PLANNING ALGORITHMS by Steven M. LaValle. The book is freely available, and is a great collection to have. [LINK]

[HR][/HR]

Now, let us assume the robot is the shell, and the obstacle is the armour, thus imparting a strong zone.

If we are to define a 30 degree attack angle from the medial axis of the turrent, it looks something like this:

Note the following:

• The Blue line is the 30 degree line with the medial turret axis on each side from the back of the turret.
• The Orange line the start of the weak zone if the shell were a point (hypothetical).
• The Red line is the actual start of the weak zone, where, the perpendicular distance from the Red and Orange lines would be half the diameter of the shell (real).
• The Blue Dots represent the turret edges.

The blue boxes are squares, and they are provided as a mark of authenticity of the angles.

This is what you had missed while marking your weak zones.

[HR][/HR]

Finally, the other error you made was the protrusions of the turret edges, shown below:

The correct lines are the dotted lines.

@Damian

Thanks bro for creating these lines. This is what I had been debating till now that Arjun is well protected within frontal 60* arc and there is no scope of an argument w.r.t T-90 as both are well protected in that zone. However Damian tried to create an unneccessary debate by wrongly depicting the arcs of T-90 and supeiimposing them with wide rear on Arjun.
That is what I had asked him to explain as what happens if the arcs are parallel. he never replied to that and now he has muck on his face as your drawing clearly shows that the armour protrusions do provide frontal 60* protection to Arjun something which is impossible for people like Methos, Damian etc to digest.

@Damian, so who is a fanboy now? remember my words, I know tanks better than you.

 

[ersakthivel]

also the ammo storage is in a very safe spot below the turret it seems and at the center of the tank hull.

So there is no way it can be hit from the front with a shot on turret side.

So arjun ammo is very well protected it seems.

 

[asianobserve]

also the ammo storage is in a very safe spot below the turret it seems and at the center of the tank hull.

So there is no way it can be hit from the front with a shot on turret side.

So arjun ammo is very well protected it seems.

It seems well protected, but not totally (100%) protected. And in war it's simply too hard to ensure things. What if in the remotest of possibilities fire gets inside the crew compartment or enemy shell or RPG is able to perforate the tank side where the ammo rack is and the ammos cook-off? So the crew will also be cooked-off together with the ammos...

 

[ersakthivel]

How are you so sure that the so called air ventialtion port(seen from the inside of the crew compartment you marked with the red circle) is the one marked with a red circle on the left hand side ?
You are once again indulging in mighty guesswork.
From the inside crew compartment photo you posted there seems to be a lot of space between the supposed air vent(no one knows what it actually is ,so lets take your word for it) and the side turret wall.


Also there is no weakness on the gunners main sight as there is armored wall behind the gunners main sight.

 

[ersakthivel]

How can we be sure there is a connection between the two circles.