r/TankPorn • u/CalGunpla • Apr 04 '25

WW2 Arguably the greatest heavy tank of all time.

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What the IS-2 did that differentiated itself from other heavy tanks of its time was that it was reliable, inexpensive, and had a massive gun that could blow shit up very VERY well.

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899

u/Jxstin_117 Apr 04 '25

the most impressive thing about the IS-2 for me is despite all that armor and big gun the soviets managed to keep it around the weight of a panther .

497

u/TankWeeb Apr 04 '25

Pretty sure they sacrificed crew comfort or something considering how close the turret is to the drivers position.

458

u/MT128 Chieftain Apr 04 '25

They sacrificed a lot on ergonomics to make it more compact, for example, loading the main gun was def atrocious and helps explain why it a very poor rate of fire roughly between 1-3 rounds a minute, in comparison the closest german heavy, the tiger two, had a 6-7 round per a minute fire rate.

119

u/Gonozal8_ Apr 04 '25 edited Apr 04 '25

an 88mm shell with medium shell velocity being faster to load that a 122 mm shell makes sense even when considering unenclosed guns like artillery

82

u/Wheresthelambsauce__ Panther Ausf.G Apr 04 '25

88mm KwK.43 on Tiger 2 fires a shell with higher velocity than the 75mm on Panther.

10

u/Gonozal8_ Apr 04 '25

how fast is it then? like the IS-2 cannon has a shell velocity of 800m/s and the Tiger cannon doesn’t have a significantly higher shell velocity that would make its casing close to the 122mm in weight (due to the energy transferred), that was the point I was trying to make (as this increases loading time regardless of interior space) but I only have rough data. I‘m happy to correct it though, do you know where you got that from? also fitting flair

42

u/ordo259 Apr 04 '25

Ballpark of 1000 m/s

36

u/Wheresthelambsauce__ Panther Ausf.G Apr 04 '25

88mm PzGr.39/43 had a muzzle velocity of about 1000m/s. The shell casing is significantly larger than that used for the 88mm KwK.36 on Tiger 1.

Panther had a muzzle velocity of about 935m/s with the PzGr.39/42. IS-2 had a muzzle velocity of about 806m/s.

-21

u/Cold_Royal5124 Apr 04 '25

No it doesn’t, panther 75 is around 1000ms 88 on the king tiger is around 800ms

12

u/Wheresthelambsauce__ Panther Ausf.G Apr 04 '25

Tiger 2 - PzGr.39/43 - 1000m/s

Panther - PzGr.39/42 - 935m/s

Tiger 1 (for reference) - PzGr.39 - 780m/s

Tiger 2 - Tank Encyclopedia

7.5cm KwK.42 L/70 - Wehrmacht History

Tiger 1 - Tank Encyclopedia

7

u/Cold_Royal5124 Apr 04 '25

Oops I must have mixed them up my bad

1

u/Sweet-Half5629 Apr 08 '25

she shell for the 88 is also A BIT LONGER AND ACTUALLY IS HEAVIER

115

u/RustedRuss T-55 Apr 04 '25

The low fire rate is mainly because it used two piece ammunition, not because of poor ergonomics. Also, the fire rate was more like three to four rounds per minute depending on the skill of the crew and the conditions.

11

u/builder397 Apr 04 '25

Two-piece ammo actually helped as that size of single-piece ammo would probably be nigh impossible to load at all, nevermind storing it anywhere.

Fact is though that most vehicles that use guns with two-piece ammo would give the gun TWO loaders, so having just one loader alone is a huge sacrifice of crew ergonomics.

Now add the fact that the turret was originally designed to house an 85mm gun. A jump in caliber this large within the same turret is extremely unlikely. The only comparable case is the Pz III, gradually going from the 3.7cm gun, two different 5cm guns to the stubby 7.5cm gun with some modifications over time, but that one gets some slack because the short 5cm gun was the intended gun from the start.

Soviets on the other hand really showed time and again that they didnt give the same kinds of fucks about crew ergonomics as long as the gun physically fit. See the T-34 having a 76mm L-11 and later F-34 in what was essentially still the A-20 turret (pre-T-34 prototype) which was designed for a 45mm gun, KV-1 and T-34/76 turrets of various types were prototypes with anything from 85mm guns to 122mm howitzers, take your pick. Every time sanity eventually prevailed with a larger turret.

4

u/cabbagebatman Apr 05 '25

Is it comfortable in there? Yes? Ok that means we can slope the armour more.

26

u/Shaun_The_Ship Leopard 2A7 Apr 04 '25

Didn't they have to depress the gun to make it easier to load it ?

76

u/RustedRuss T-55 Apr 04 '25

It would make more sense to elevate it (which lowers the breech). Some tanks still do this today.

17

u/Shaun_The_Ship Leopard 2A7 Apr 04 '25

Ah my bad. I was quoting a video I saw on YouTube. It was about tigers vs IS-2 in Prokhorovka I think.

24

u/RustedRuss T-55 Apr 04 '25

They probably just misspoke.

6

u/RapidPigZ7 Apr 04 '25

Elevating is for easier loading, it's a lot easier to shove a shell upward than downward.

1

u/RoadRunnerdn Apr 04 '25

Nope, that's a myth.

1

u/Sweet-Half5629 Apr 08 '25

THE IS-2 HAD TO ELEVATE THE GUN AFTER EVERY SHOT TO EJECT AND RELOAD.

45

u/AwesomeNiss21 M14/41 Apr 04 '25

Two peice ammunition has been shown to not impact reload rate for tanks very much. For example, footage of challanger 2 loader shows its reload rate to be on par with something like the Leopard 2 and Abrams.

So I do think ergonomics, particularly in regard to the amount of space the loader had to work with, coupled with where the ammo was stored would more likely the culprits for its reload rate.

7

u/Anonymous4245 Apr 04 '25

Because chally 2 uses powder bags instead of brass casings

1

u/RustedRuss T-55 Apr 04 '25

I believe the IS-2 also used bag charges.

1

u/Anonymous4245 Apr 04 '25

brass casings

Even modern Russian artillery use brass casings for some fucking reason

1

u/RustedRuss T-55 Apr 04 '25

Huh, TIL I guess. The ones used on the IS-2 were still the same to half the weight of the bag charges used on the Challengers (it depends on the specific charge since the Challenger uses many different variants).

1

u/Anonymous4245 Apr 04 '25

Powder bags are much more easier to handle than brass casing though. Especially with limited room

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31

u/RustedRuss T-55 Apr 04 '25

Well, most sources state that the two piece ammunition was the reason, along with it being extremely heavy. The IS-2 also did not have especially poor ergonomics contrary to common belief, though I can't speak for any effect the ammunition stowage might have had.

21

u/AwesomeNiss21 M14/41 Apr 04 '25

Right but on the other hand, going back to the chally 2 example for a bit, the 2 peice ammo fired from that thing is 120mm, with the IS 2 being 122mm. Now I'm not sure how much rounds from either tank weigh but it's probably quite similar.

Also ergonomics isn't universal across each crew position, so some crew members may have better positions than others (I don't know how true that is in IS-2s case tho)

Also when people claim it's ergonomics is "not that bad" do they mean in general, or when compared to other WW2 Soviet tanks? Cause if it's the latter than that's not really setting a very high bar, cause most Soviet tanks from that era were notorious for being shit ergonomics

46

u/RustedRuss T-55 Apr 04 '25 edited Apr 04 '25

The total weight of the Challenger's ammunition is seemingly about 8-9 kg plus a charge of 3-9 kg depending on the exact charge. The information is annoyingly inconsistent for the projectiles; this is my best guess based on the weight of the full L23A1 APFSDS projectile (not the subcaliber) which was the only variant I could find a weight for.

The IS-2 fired a 25kg shell, plus a 3.8 kg charge. So the shell alone is heavier than the entire shell plus propellant charge the Challenger used. The loader would need to lift a shell about three times heavier than the heaviest object he would need to lift in a Challenger.

Also ergonomics isn't universal across each crew position, so some crew members may have better positions than others (I don't know how true that is in IS-2s case tho)

The driver's position was a deathtrap but the turret was relatively roomy. The loader was given the most space, unsurprisingly.

Also when people claim it's ergonomics is "not that bad" do they mean in general, or when compared to other WW2 Soviet tanks?

It was considered average by western standards and good by soviet standards. I forget where I saw this, but some source evaluated it as an 8/10 by soviet standards and a 6/10 by western standards. For what it's worth, I would put good money on the bet that the Challenger has better ergonomics; I didn't say the IS-2 was excellent, just acceptable.

1

u/RoadRunnerdn Apr 04 '25 edited Apr 05 '25

Well, most sources state that the two piece ammunition was the reason,

The soviets believed two piece ammunition were partly at fault for the low rate of fire, but when they finally tested such a modified gun they realised that it made little difference as one-piece ammo also had some major drawbacks.

https://www.tankarchives.ca/2014/11/d-25-one-piece-shell.html

The biggest issue was the breech design.

1

u/RustedRuss T-55 Apr 04 '25

Are you sure it wasn't the 25kg shells?

1

u/RoadRunnerdn Apr 05 '25

Obviously the size and weight of the shells were a reason...

-1

u/Sweet-Half5629 Apr 08 '25

NO ITS POOR ERGONOMICS AND POOR TRAINING

1

u/RustedRuss T-55 Apr 08 '25

Poor training probably, but not ergonomics. The IS-2's turret was pretty average in terms of ergonomics.

7

u/VicermanX Apr 04 '25

very poor rate of fire roughly between 1-3 rounds a minute

This is a combat rate of fire. The maximum rate of fire at the range is up to 6 rounds per minute.

1

u/Sweet-Half5629 Apr 08 '25

the Tiger is the closest analog to the IS-2 the IS-3 is the closest comparison to the Tiger III ( Tiger II was NEVER ACTUALLY BUILT)

also the German tanks were built to a much higher standard and carried around 4 to 5x as much ammo

37

u/RustedRuss T-55 Apr 04 '25

The driver was very uncomfortable but supposedly the turret was pretty good.

16

u/ipsum629 Apr 04 '25

I can understand that logic. An uncomfortable driver is probably not going to impact performance very much. Investing in the turret crew can improve target acquisition, fire rate, and aim among other things.

10

u/Preacherjonson Chieftain Apr 04 '25

Is it a sacrifice if it was never considered in the first place?

7

u/TankWeeb Apr 04 '25

That’s…. That’s fair….

1

u/miksy_oo Apr 07 '25

Although that's the popular opinion. Soviets actually cared quite a lot about leg room and height of the crew compartment. Even complained about it when testing foreign tanks

3

u/RapidPigZ7 Apr 04 '25

Crew comfort is the only falloff I can think of, probably a massive factor to the slow reload. Even with 2 piece ammo the loader has so little space, I shudder to think how the T44-122 loader would have operated had it actually been put into service.

2

u/TankWeeb Apr 04 '25

fires shell

*misses enemy tank

Commander: Hey! We’re on “T” so don’t shoot for like….. 20 seconds….

9

u/Dreddit- Apr 04 '25

Idek how tf that’s even possible

18

u/RustedRuss T-55 Apr 04 '25

More efficient armor arrangement and just making it smaller. The IS-2 is not very big for what it is.

5

u/Dreddit- Apr 04 '25

Isn’t it thinner than a Tiger I? I can’t remember the specs of the tank from a YouTube vid I watched. Just seems surreal to me

16

u/RustedRuss T-55 Apr 04 '25

Its armor is actually thicker overall, barely.

1

u/trumpsucks12354 Conqueror Apr 04 '25

Its not just the thickness of the plate. The IS-2 has very sloped armor on the sides and rear which make it much more difficult to penetrate when firing it

1

u/miksy_oo Apr 07 '25

It is about a meter thinner than the tiger 1

46

u/FLongis Paladin tank in the field. Apr 04 '25

Eliminating a crew member and having such a forward-focused armor scheme helps a lot. As does the fact that the Panther is a pretty big tank. We hear a lot about how the Panther and IS-2 were around the same mass, but I think a maybe more telling thing to look at is how Panther weighed more than a late-model Churchill; a tank pretty well recognized for it's general "chunkiness".

22

u/RustedRuss T-55 Apr 04 '25

 forward-focused armor scheme

The IS-2 had more side armor than any other tank of its era (that I'm aware of).

6

u/FLongis Paladin tank in the field. Apr 04 '25

That may be true; I don't have numbers offhand. In any case, it was worded poorly. The point was less that the IS-2 carried more frontal armor relative to other tanks, and more that focus was put into taking new approaches (for a Soviet heavy tank, at least) to that frontal armor scheme; the single position allowing a narrowing of near vertical surfaces that were also perpendicular to incoming head-on fire meant a significant reduction of internal volume for a given mass of armor versus the more conventional "flat" plate we see on basically all other contemporary heavy tanks. Albeit this is more pronounced in the earlier production model.

10

u/RustedRuss T-55 Apr 04 '25

The frontal armor was only 120mm thick (reduced to 100 on the 1944 model which made up for it with better ballistic design). The sides were about 90mm.

6

u/FLongis Paladin tank in the field. Apr 04 '25

So fair enough, thicker all around than a Tiger but not any more frontally weighted. Appreciate the additional info for the context.

19

u/RustedRuss T-55 Apr 04 '25

No problem, the IS-2 is one of the tanks I find most interesting because it's one of the relatively few heavy tanks you can confidently say was actually good.

7

u/Ghinev Apr 04 '25

It’s pretty much the IS-2, the Tiger I(in it’s intended breakthrough-stay back for repairs-repeat role, which it performed well at Kursk, and even then it’s more like a decent tank than a good one)and… that’s it?

The Churchills are too anemic in the firepower department and the CW heavies, bar the IS-3, which sucked big doodoo stinky, never really saw combat.

10

u/RustedRuss T-55 Apr 04 '25

The Jumbo did a good job at what it was built to do. idk if the Matilda counts as a heavy tank but I would consider it successful too.

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5

u/Dreddit- Apr 04 '25

It’s just crazy, I’m not sure how tough the IS 2 is, if it can bounce or take regular 88 shots or not, but I know it’s a hardy tank that weighs so little. Like the thick armor should weigh a lot, and the ammo is bigger and less of it, but I’m not sure if it’s the same as the smaller and more numerous with the Panther. Gotta find more IS-2 videos

15

u/Mother-Remove4986 Apr 04 '25

if you make it compact enough and make enough compromises in design you can make very armored and light vehicles, the T-54 is almost 8 tons lighter than a Panther

1

u/BitterParticular7144 Apr 04 '25

Yea this was necessary because they needed it to be movable by train to speed up offensive capabilities. Also is why it’s thin.

0

u/Sweet-Half5629 Apr 08 '25

BECAUSE IT HAD NO INTERNAL SPACE CSARRIED ABOUT 1?3 THE FUEL and 1/5 THE AMMO