Cold War, Experimental, News, Soviet-Russia

Object 277 – One of the Last Heavy Tanks

The Object 277 was one of the final hurrahs of the illustrious heavy tanks. It was created in the late 1950s to serve as a replacement for the T-10, competing against the “nuke-proof” Object 279. The Object 277 proved to have some of the best armor, firepower and mobility of any heavy tank at the time, with its 130 mm gun capable of threatening modern main battle tanks.

The Object 277 had many features of what we expect from main battle tanks today, like a stabilised gun, an overpressure system to keep radioactive contaimants out, and a 1,000 hp engine to give it good mobility despite its heavy weight.

Even with these features though, the Object 277 was not strong enough to beat politics, and the tank was cancelled in 1960 after just two prototypes were built.



About half way into the Second World War the Soviet Union introduced the IS-1 heavy tank, the first of an important family of tanks that would not only continue to be developed after the war, but remain in service in some way or another until the end of the Cold War.

Their designation, “IS”, comes from the initials of Joseph Stalin, the infamous Soviet Premier at the time of the family’s creation. His actual name, Ио́сиф Ста́лин, is adapted into English to Iosif Stalin, hence why the designation is “IS” and not “JS”.

The IS-1 (initially known as the KV-85) was introduced in 1943, followed by the IS-2 that same year. At the war’s end came the IS-3, a tank that stunned the Allies with its low height and thick, highly sloped armor.

At the same time the Soviets were working on yet another tank, the IS-4, as a backup plan in case the IS-3 proved to be a poor design. As it turned out though, both the IS-3 and IS-4 had significant defects.

IS-4 at Kubinka.
The IS-4 heavy tank. It had some of the thickest armor ever put on a tank, but suffered terribly from poor production quality and mechanical issues.

This left the USSR in a tough situation as they had no tank in the pipeline that would be able to replace them any time soon. They settled on keeping the IS-3 and IS-4 in service as stopgaps and began developing a series of new and advanced vehicles through the latter half of the 1940s that would replace them.

This resulted in the IS-6 and the famous IS-7. You can read about that tank here.

All of these tanks proved to be either too advanced, expensive, complex or heavy. Or, in the IS-7’s case, a combination of them all.

In 1948, the GBTU (the Soviet overseer of armored vehicles and their supply) laid out requirements for a more grounded heavy tank that would solve the issues of the IS-3, while remaining simple to produce and maintain.

T-10M heavy tank.
A T-10M heavy tank.

This resulted in the Soviet Union’s last heavy tank to enter service, the T-10. It was initially known as the IS-5, then IS-8, then briefly IS-9 before being redesignated to T-10 in the “unfriendly” political attitudes toward Stalin after his death

The T-10 entered service in 1953, and became the primary heavy tank of the USSR. It was by all accounts a good machine that combined the best features from the IS-series into one design.

Finding a Replacement

Almost as soon as the T-10 entered service, the Soviets were already looking for its successor. Remember, the T-10 had initially been developed to solve the problems caused by the IS-3 and IS-4 at the end of the Second World War, so a next-generation heavy tank was sought after.

In 1956 the GBTU laid out requirements for such a vehicle. Three designs were submitted in response; two from the Kirov Plant in Leningrad, and one from the Chelyabinsk Plant in Chelyabinsk.

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Chelyabinsk’s submission was the Object 770, a completely new design with large road wheels and a two-stroke V10 diesel engine.

Object 770 heavy tank.
The Object 770 was an entirely new design and not based on a pre-existing chassis.

The Kirov Plant proposed the Object 279 and the Object 277, the focus of this article.

The Object 279 was one of the weirdest tanks ever made, designed to survive the blast wave of a nuclear explosion with a flying-saucer-shaped hull and four tracks. We covered that tank here.

Meanwhile, the Object 277 was a much more conventional design, but still brought many impressive features.

The Object 277

The Object 277 was visually similar to the T-10 it hoped to replace, but it was much larger: almost 20 percent longer than the T-10.

The Object 277 discarded the welded “pike-nosed” glacis armor from previous tanks, and instead had a large, curved, cast piece that covered the entire upper front.

This armor was angled 60 to 70 degrees, and had a maximum thickness of 140 mm. The lower glacis was slightly less angled at 55 degrees, so it was made thicker to compensate, with its maximum reaching 153 mm.

On the other hand, the hull sides were similar to previous designs, with the upper sides steeply angled inwards, and the lower sides mounted vertically to produce a form “V” shape, when viewed from the front and back.

Object 277 heavy tank.
An Object 277 prototype. Note the curved front plate, instead of the “pike nose” found on the IS-3 and T-10.

This arrangement was made with a single plate that had been bent into the correct shape. The true shape of this armor was hidden under a layer of sheet metal that could be used for storage.

We were unable to verify the Object 277’s side armor thickness, but by using the T-10’s hull as a reference, it was likely between 80 and 90 mm thick.

The entire hull was longer than the T-10’s with an extra road wheel added on each side as a consequence.

On top of the hull was a large, hemispherical cast turret that was extremely thick. The front was, at most, 290 mm thick! This extended around to the sides, thinning to around 138 mm.

Object 277 turret diagram.
A diagram showing the Object 277’s turret. Note the mechanical loading assist device and the incredibly thick armor.

Inside was a large 130 mm M-65 gun. This 59-caliber beast could fire 30 kg armor-piercing (AP) rounds at 1,000 meters per second, and it also had access to armor-piercing fin-stabilized discarding sabot (APFSDS) rounds.

During tests, the M-65 was shown to penetrate 280 mm of steel from 1,000 meters with its standard AP rounds. Its APFSDS rounds had a muzzle velocity of over 1,500 meters per second and could penetrate 350 mm of steel from 1,000 meters.

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It was fitted with a fume extractor near the seven-baffle muzzle brake. It was also paired with an automatic fire control system.

No Western tank in service at the time would have been able to withstand a hit from the Object 277’s M-65.

Object 277 length.
The Object 277’s 7.3-meter-long (23 ft 11 in) barrel caused a large overhang. This was a concern, as the gun could strike the ground on uneven terrain.

It was fed by a loading assistance device in the rear of the turret, which was likely similar to the one used in the IS-7.

Coaxially mounted next to the main gun was a 14.5mm KPVT machine gun.

The turret contained a crew of three; the commander, gunner and loader. Night vision sights were fitted, as was a stereoscopic rangefinder. The rangefinder was mounted above the gun, and the openings for the optics can be seen above the gun on either side.

The driver was situated at the front of the hull in the center, bringing the crew total to four. They were protected by an overpressure system that kept nuclear contaminants out – a sign that this tank was built for the nuclear age of warfare.

All in the Object 277 weighed 60 tons. Considering its levels of protection and firepower, it’s quite an impressive feat that engineers were able to keep the weight this low.

277 from the back.
The Object 277 engine and gearbox were located in the rear.

To move this beast along, a 62 liter 1,090 hp M-850 V12 diesel engine was fitted. This engine was a derivative of the M-50T, a naval engine that was used in the IS-7. Both were based on the ACh-30, which was originally designed as an aircraft engine.

With this muscle, the Object 277, despite weighing 60 tons, had a top speed of 34 mph (55 kph).


Two Object 277 prototypes were built between 1958 and 1959. An additional set of armor was made for ballistic testing.

During trials the Object 277 showed some impressive abilities, particularly relating to its M-65 gun and excellent mobility for its weight. On the other hand, it also had some flaws which would need to be rectified and was regarded as an overall lesser design than its competitor, the Object 770.

One of the main drawbacks of the Object 277 was its extremely long gun and forward-mounted turret. This produced an unacceptably large overhang. Overhangs were something of a bane to Soviet designers, and they tried to avoid them as much as possible due to experiences with vehicles like the SU-100 and SU-122-54.

One of the Object 277 prototypes was modified and fitted with a GTD-1 gas turbine engine for testing and redesignated Object 278.

However, in the end, it was a politician that would kill off the Object 277, rather than any failings of the tank itself.

Object 277 heavy tank today.
The Object 277 today at the Kubinka Tank Museum. Image by Alan Wilson CC BY-SA 2.0.

Nikita Khrushchev became the Soviet Premier in 1953 after the death of Joseph Stalin. Krushchev placed a large emphasis on adapting new technologies and believed lightweight, small tanks carrying missiles were the future.

Missiles were small enough to be mounted on virtually any vehicle, yet possessed enough firepower to kill the most armored heavy tanks from much greater ranges. In contrast, Krushchev had a personal dislike of heavy tanks, believing that they were physically and logistically inefficient and expensive.

After watching a heavy tank demonstration in 1960, he declared that any future tanks must not exceed 37 tonnes, instantly killing off the 60-ton Object 277. Its competitors, the Object 279 and Object 770 also met the same fate.

With no direct successor, the T-10 remained in service as the USSR’s primary heavy tank and soon made completely obsolete by tanks like the T-64. Interestingly, by the time the T-10 was completely removed from service, the Soviet Union no longer existed. It was removed from the Russian Federation’s reserves in 1997.

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Today single examples of all three of these tanks survive, and are parked together at the Kubinka Tank Museum in Russia.