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Prototype 701-A, object 701-A, object A, Kirovets-1, Object 703, IS-3, Pobeda (eng. Victory). The tank with many names.
This is the first IS-3 prototype. It had quite many names assigned to it (see caption above) during its extremely quick development period. But the most common one used today is Kirovets-1. It was intended as a stopgap tank between the IS-2 and IS-4, which is what the finalized version “successfully” did. It would likely occupy a space in game already quite nicely filled by the production IS-3. But fans of the IS-3 might want something familiar still. It obviously doesn’t need to be in the tech tree.
The biggest change compared to the IS-3 is the frontal hull armour, being angled straight back instead of having a pike nose. This means it would be slightly worse straight on, but instead, now possible to angle. Its lower plate is however weaker, though still enough to bounce KwK/PaK 43. Its side hull armour is also slightly thicker at 100mm instead of 90mm. The turret would be slightly worse, as it was less refined and featured thinner armour. Though its unclear if this gives it any major weakness from the front that can be exploited in game, or if its practically just as invulnerable. It was fitted with a new engine, the V-11. However, due to reliability issues it was rated to the same 520hp as the V-2-IS of the IS-2.
Front of Kirovets-1. Notice how the turret is not flat next to the mantlet, unlike later versions of the turret (see picture below).
Front of early production IS-3.
Developmental history
Click for history
The origin of this vehicle can be traced back to the introduction of the IS-1 and IS-2 on the eastern front in January and February 1943. Their guns were praised, especially the IS-2’s, but their armour was insufficient against the Panthers and german heavy anti-tank weapons. This had already been somewhat known before their production began, but proposals on improving their armour had been mostly egregious and thus shot down.
But with the combat reports from the front line, orders in April were issued out in, mainly, two directions. That of the creation of a new heavy tank, and that of improving the IS-2. A list of required improvements for the IS-2 was ready in May. The list included many more things than just armour protection of course. The second direction was then split further into a small modernisation, and a larger modernisation. The small modernisation. ChKZ had already been working on a new heavy tank, object 701, since July 1943, and the order from April had requested two prototypes to be built. This was high priority and thus ChKZ was too busy to bother much with the deeper IS-2 modernisation at that time.
Second object 701 prototype (No.1) built in May-June 1944. This would later become the IS-4.
ChKZ were also not interested in starting work on another design that could compete for the spotlight of the object 701. But they did begin work on making the small improvements. One of the most critized features of the IS-2 had been the stepped upper front plate. Inherited from the KV, and even T-35, it created a significant weakspot. The upper front was redesigned into a single sloped plate, and given a similar driver’s vision port as that of the object 701. This was then quickly rushed into production. The name of the vehicle didn’t change, but this version of the IS-2 is commonly known as the “IS-2 model 1944”. These improved hulls started being produced in July, other small improvements were also implemented into the IS-2 gradually.
IS-2 model 1944.
LKZ on the other hand were “only” preoccupied with another small IS-2 improvement program that had started in December '43. The issue of fixing the IS-2’s rate of fire, which had led to the creation of object 244 (IS-3), 245 (IS-4) and 248 (IS-5). Thus they began, already in April, working on a deeply improved IS-2. These improvements were, however, quite extensive, and it seems the project morphed* (see footnotes). Instead of creating an improved IS-2, LKZ was instead working on a completely new heavy tank. This was object 252 (IS-6), which for some of you might also shed a light on why the IS-6 was the “sixth” IS.
Two models produced from LKZ’s IS-2 modernisation program next to a model of the regular IS-2 (middle).
Object 252, what the work by LKZ eventually produced.
By summer, with the two object 701 prototypes mostly completed. ChKZ finally took on the additional project of creating a vastly improved IS-2. A finished design was ready in August. The sloped frontal plate from the smaller improvment was kept, but several other parts of the vehicle were redesigned. The engine compartment saw most of the changes. Many of these changes were inspired by the object 701, but also Panther and T-34. The turret was also redesigned to feature smaller cheeks by changing the mounting point of the gun, which could now be accessed through a hatch on the turret roof, just like on the object 701. Like the smaller improvements, even this major redesign was originally ordered to be put into production without prototyping. However a request was made to produce such a prototype.
Blueprint of ChKZ’s major IS-2 redesign. Sadly no pictures of the prototype are known, they are presumed to have been lost.
Nothing much happened with the project awaiting the permission to build it. Which might be when the team started on yet another design (see footnotes). Permission to build the massively improved IS-2 came in late August, and the tank was built and sent to trials in late September-October. ChKZ then received a list, of improvements the GABTU wanted to see implemented into the design. But work on this never occured. Instead ChKZ was fully invested in their new project, which at the time was called “Experimental prototype 701-A”. The vehicle was meant to be a transitional one between the IS-2 and object 701 (IS-4). Although it was a major redesign of the IS-2, it took a lot of inspiration from the object 701, hence its name. One major distinctive feature of the design was the turret. It was round and flattened all the way around, supposedly it was inspired by a bar of soap.
Object 701-A, or Kirovets-1. The similarities to a bar of soap is striking!
Even though work on it had only started in late August-September, a prototype was completed on November 24th. The tank ran smoothly on the day it was built, and it succeeded in a quick trial the day after too. Thus it was sent to the military proving grounds in December, where it appeared alongside LKZ’s object 252 (IS-6). The IS-6 had already suffered multiple automotive failures prior, and the full trials revealed many more defects. The 701-A had been relabeled as both Kirovets-1 and IS-3 in connection with the trials. And especially compared to the IS-6, it performed well.
Kirovets-1 during trials.
If you’re wondering how this vehicle turned into the IS-3, then we have to look at what LKZ was doing during the fall. They too had picked up work on creating a modernised IS-2, internally called the IS-2U. Instead of the flat frontal plate however, they had gone with another solution. A pike nose.
LKZ’s modernised IS-2, the IS-2U. Note the redesigned turret front, the same solution was made by ChKZ on their version.
Although the pike nose was of major interest, LKZ ignored several of the requirments set, and thus a prototype was never approved for construction. But following the Kirovets-1 trials, a number of improvements were ordered to be implemented. Among them were the pike nose design from the IS-2U.
The improved Kirovets-1 design, or perhaps simply, IS-3.
Specifications
Crew:
- Commander
- Gunner
- Driver
- Loader
Weaponry:
- 122mm D-25T (Ammo: 30)
Vertical traverse: -3°/+20°
Sights: TSh-17 - 7.62mm DT coaxial (Ammo: 1260)
Dimensions:
- Weight (total): 47 500kg
- Length (total): 10 170mm
Length (hull): 6740mm - Width (total): 3300mm
- Height (total): 2430mm
Drivetrain:
- Engine: V-11 (520hp)
- Top speed: 42km/h
Armour:
Hull:
-
Front:
Upper: 120mm at 60°
Lower: 90mm at 60° -
Sides:
Upper: 85-88mm at 60° + skirts: 16mm at 35°
Middle: 100mm at 0°
Lower: 30mm at ?°
At rear: 60mm at 0° -
Rear:
Upper 60mm at 50°
Lower: 60mm at 40° -
Roof: 20mm
Turret:
- Front: 170-175mm
Sides: 80-175mm at 50-15°
Footnotes:
See footnotes
-
It’s possible LKZ was working on both the IS-2 modernisations and a new tank concurrently, if that is the case, they simply dropped modernisation work on the IS-2 and focused on the new tank (IS-6) instead.
-
Its unclear when work began on the Kirovets-1. If it was in late August, September or even October.
-
The V-11 engine was originally rated for 700hp, it was downrated to 520 for reliability issues. It is unclear if this was done before or after being fitted into the prototype. The specification sheet for the vehicle lists 520hp however, and as such is what I write in its specifications.
Other images:
See images
Kirovets-1 rear. Note how the turret has vertical walls near the top compared to production IS-3.
Specification sheet.
Sources: