I don't know much about tanks but this one was on quora.
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The Arjun MKI & II are both very disappointing vehicles, with significantly reduced capabilities compared to other modern third and fourth generation MBTs.
Let´s start with
mobility:
The Arjun MkI is powered by a German
MTU MB 838 Ka-501 diesel engine. This engine is a modernized version of the
MTU MB 838 CaM 500 multi-fuel engine that was first fitted to the Leopard 1 MBT in 1965. Thanks to various upgrades, and the addition of a supercharger, the Ka-501 can reach 1400 hp while the CaM 500 can only reach 800 hp.
So fans of the Arjun MBT (and its manufacturer) would have you believe that this tank has excellent mobility thanks to a hp/weight ratio of 23,5 (slightly below average for a modern MBT but still within acceptable norms).
However, raw engine power is only one of the factors that determines a tank´s mobility. The problem is that because of its outdated design, the Ka-501 engine is
big,
heavy,
extremely fuel inefficient (a pitiful 200km range on good terrain while other MBTs can easily reach 500 km) and has
very poor performance in terms of rpm and torque. These problems are worsened by the vehicles heavy weight (58 tons for the MkI and 68 for the MkII, the heaviest MBT in the world), meaning that the Arjun struggles to crest even a slight hill.
Big, heavy, and terrible fuel efficiency...
The current version of the MkII still uses the same outdated, crappy engine, although there are plans to upgrade to a modern American Cummins engine coupled with a French suspension. So far, these plans have yet to materialize.
Protection:
On paper, the Arjun´s armor is supposedly quite good.
On paper.
The manufacturer of the Arjun MBT claims that its "Kanchan heavy composite armor" is on par to the British Chobham armor from which it was developed. The Arjun MkI&II can also use locally manufactured ERA blocks, said to equal the performance of Russian Kontact-5 ERA from which they were developed as well.
So theoretically, the Arjun´s armor uses excellent materials. The problem here is the design of the armor itself.
The arjun´s gun shield is significantly thinner than other modern MBTs. In addition, the primary gunner sight does not have a extra armor module.
Notice how the left side of the turret is completely bereft of any composite armor (those white layers on the other side of the turret front). The gunner sits behind 250mm of spaced steel armor, and that´s it. Any modern APFSDS round will cut through that like it´s butter and vaporize the gunner.
Notice the huge weak spot created by the primary gunner sight.
So the turret front is terrible. But the turret sides are even worse.
Notice how the vaunted "Kanchan heavy composite armor" (the white layers of armor) leave 2/3rds of the turret sides exposed. The turret sides of the Arjun I&II are literally paper thin. Worse,
contrary to what the manufacturer claims there are no blowout panels on the Arjun MBT, nor is it equipped with a separate ammunition compartment.
Where is that separate ammo compartment you´ve been talking about?
This means that virtually round penetrating the turret will ignite the tank´s ammunition and vaporize it in a big fireball.
Moving on...
Firepower:
If you thought the Arjun was a bad tank before, you haven´seen anything yet.
The Arjun MKI&II both use the same gun: a 120/55 mm rifled gun inspired by the British L30 rifled tank gun used by the British Challenger 2. Proponents of the tanks will tell you that because the gun is rifled, it is more accurate than the smoothbore guns used on the Abrams or the T-90.
That´s bullshit, to put it simple.
A rifled gun applies a spinning motion to the round it fires, meaning those rounds will be more stable when travelling through the air and more accurate over range. However, modern ammunition doesn´t need a rifled barrel to be accurate and stable, since they are equipped with little fins at the end of their penetrator, that apply a spinning motion to the round as it travels through the air. Put simply, modern ammunition spins itself, and doesn´t need a rifled gun to be accurate.
Notice the little fins at the end of the round.
Therefore, the claims that the manufacturer makes about the gun´s accuracy are very doubtful at best. It is claimed that the Arjun has a First Hit Probability (FHP) of 90%, even on the move, thanks to an excellent stabilizing system and Fire Control System (FCS). Comparative trials were conducted between the Arjun MkII and the T-90, where it was claimed that the Arjun MkII outperformed the T-90.
However, Indian Army Generals have since come out to say that those trials were rigged by corrupt defense officials, and that the accuracy of the Arjun MBT is vastly overestimated.
But the worst of all is the penetrating power of the Arjun´s main gun. At 2km, a round fired by the Arjun can only penetrate 300mm of Rolled Homogenous Armour (RHA).
This is pitifully bad.
At 2km, this tank won´t even be able to penetrate the side armor of most modern MBTs.
As a comparison, most modern APFSDS rounds can penetrate between 700 and 900 mm of armor at 2 km.
That´s 3x the penetration of the Arjun.
The poor penetrating power of the Arjun is attributed to poor materials used for the penetrators, a low-pressure firing chamber and a short penetrator length.
Soooo, if we recap:
The mobility of the Arjun is terrible. Its armor is virtually non-existent with huge weak spots all around the turret, and its gun is horrendously inadequate by modern standards.
There is a reason why even the Indian Army refuses to use the bloody thing. Only 100-200 Arjuns have been ordered to placate the government and DRDO (the Arjun manufacturer), while the Army relies on 1250 T-90 and 2500 T-72 MBTs
https://www.quora.com/How-does-the-Arjun-MBT-compare-with-other-battle-tanks-in-the-world#
Are these accusations baseless?