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[History] Object 260 - The IS-7 heavy tank

Welcome to another first-time for my on this blog. Todays subject is talking about one of our modelling subjects with an interesting story - the IS-7. Wether you´re familiar with this Russian tank or you´re asking "Waht the heck is an IS-7?", this should be quiet an interesting read.

I´ll generally try to cover a subject as well history- and performance-wise as well as in modelling terms. The resulting articles will likely not be able to keep up with expert literature, but should give you a nice overview of our modelling subjects, in this case the IS-7. Let´s begin!

Object 260 - the IS-7

The final form of the IS-7, photo taken in 1948. Source: Wikimedia 
History:
Sometimes going big is the only way to prevent going down - this definetly was the case for the Soviet Army´s heavy tanks when they faced German powerful anti-tank guns in the closing years of the war. Building heavy tanks for breaktrough role in response was a logical step concerning those challenges.
After the Factory No.100 was reoccupied, a design team was tasked to start a project to create a modern, well protected heavy tank named the Object 260 in 1944. Not wanting to sit around, they managed to produve several drafts for the vehicle (designations were Object 257 to 259) from late 1944 to early 1945. After evaluating the different designs, they made drafts for the "real" Object 260, which they completed in September to December of 1945. they were lucky, as their project was one that wasn´t terminated due to the end of the war. Object 260 was to be the next step in Soviet heavy tank design, which resulted in many new elements being put into the vehicle.

The 1945-version of the vehicle. Source
First plans saw a 65ton vehicle with 150mm of frontal armor with a pike-nose inherited from the IS-3. Armament was a new 122mm gun. For mobility, the vehicle should be equiped with a 900-1200hp engine.
In 1946 plans changed again and several features were altered. For example, a new gun with a 130mm caliber was to be installed coupled with a loading-assistant-device. Also a machine gun platform was added to the turret rear extending backwards.
The 1946 blueprints even made it into mock-up form. Source
But again some changes were applied before the prototypes were built and tested in 1947 to 1948. For example, the turret shape again changed a bit and the rear machine guns were removed (and later replaced by fixed ones). Also the weight rose to 68tons.

Performance:
When prototypes were tested in 1947-1948, they were mounting the 1050hp M-50T engine and the 130mm S-70 gun which was derived from naval weaponry. Test results documented the vehicle reaching impressive speeds of up to 33mp/h (68kp/h) and revealed a very good cross-country mobility. As far as I´m aware, one prototype was lost due to fire in its canvas-lined external fuel tanks.
Apart from this, the IS-7 proved to reliable bounce 12,8cm and 130mm rounds from the front due to its angled 150mm hull armor and the 25cm thick turret front. Track reliability was improved by adding rubber rims to the wheels and fixed locking pins to the tracks eliminating the need for a ramp to slam them back in (T-34 wants it, too). The wheels were suppported by individual torsion bars and had shock absorbers to guarantee a smooth ride. Below the sloped hull side, the spare fuel-tanks and boxes for tools/stowage were added.
The turret housed four average Soviet tankmen quie comfortably with the two loaders at the rear in front of the ammunition, the commander below his cupola in the front right and the gunner left of the main gun which itself was flanked by three machine guns of 14.5mm and 7.62mm caliber. For anti-air purposes another KPVT 14.5mm machine gun was added to the turret top. There also were two rear-facing 7.2mm SGS machine guns.
The front hull was the drivers home and was somewhat cramped due to the hulls sloped nature. He aimed two fixed SGS machine guns at the hull sides via turning the tank. Test drivers claimed the vehicle to maneuver quite well for its size and weight.
Over the course of the prototype-run, elements were changed when it came to details, so don´t expect every IS-7 to have for example rear-facing machine guns.

Fate and influence:
The IS-7 truly was a pinnacle of heavy tank design, but unfortunately missed the call for such tanks, as the growing threat of nuclear weapons and air-attacks demanded for another type of vehicle - the MBT. Thus, the potential predator was to late to duell his German enemies on the fields of the Eastern Front and slipped into a new era, where the vehicle was considered too heavy.
Elements were carried over to the T-10 heavy tank, which served until the 90s, but this tank never truly was the apex of heavy tanks like the IS-7 was intended to be. The sole surviving prototype from 1948 can be found in the Kubinka Tank Museum in Russia together with some other steel giants.

The IS-7 in it´s full glory next to the IS-4 which partially blocked the IS-7 from service. Source
 
Sources/reads:
http://tankarchives.blogspot.de/2016/05/is-7-titan-late-for-war.html
http://www.tanks-encyclopedia.com/coldwar/USSR/is-7-object-260
 
I hope the read was helpfull and/or interesting and as such this kind of articles will appear again in the future.
 
Sincerely,
 
Tom



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