Saturday, 9 January 2016

T-220: Prototype in Combat

There is an opinion that the Red Army dropped other tank projects for some time after the appearance of the KV tank. Indeed the SMK and T-100 heavy tanks were cancelled in the summer of 1940. However, it became necessary to improve the armour and armament of the tank immediately afterwards, resulting in even heavier tanks like the KV-4 and KV-5. The first step in this journey of increasing firepower, armour, and eventually size and mass was the KV-220 tank, later renamed T-220. Even though only two were made, both participated in battle during the Great Patriotic War.

Big Gun

The first signs that neither the "small turret" KV nor the "large turret" variant were satisfactory for the army were seen in June of 1940. According to a proposal for improvement of tank guns, the KV-1 should be armed with a 76 mm gun with the ballistics of the model 1931 AA gun (3-K). It was also proposed that the front armour be increased to 90-100 mm.

Some doubts arose regarding the 3-K. According to calculations, the 76 mm AA gun could penetrate 70 mm of armour at 1000 meters at an angle of 30 degrees. This is a good amount, but it turned out that the thickness of the KV-1's armour would be greater than this value. In addition, the 3-K was already removed from production, replaced with a new more powerful 85 mm AA gun that could penetrate 88 mm of armour under the same conditions.

It is not surprising that two new guns appeared of tank, SPG, and anti-tank guns: a 76 mm gun with AA ballistics and an 85 mm gun with AA ballistics. The due date for arming a KV with a small turret with both of the guns was set as September 1st, 1940. Factory #92 was chosen to develop both systems.

The gun with 3-K ballistics was indexed F-27, and the gun with 52-K ballistics was indexed F-30. The factory's chief designer, V.G. Grabin, was in charge of both projects. Much hope rested on the F-30: according to defense plans for 1940, 50% of KV tanks would be armed with this gun.

Both guns were ready by the due date and already began trials. Factory #92 didn't reinvent the wheel and followed the development path of the F-34. Using that gun as the basis, the design bureau installed new barrels and strengthened the recoil mechanisms. Thanks to this approach, the design of the guns took a short time. By September 2nd, 1940, the F-27 performed 5 trials of 122 shots in total, with satisfactory results.

By that time, the F-30 performed 2 trials of 68 shots in total. Some design flaws were discovered in the process, and the factory began working on improvements. By September 24th, the gun made 90 shots, after which a crack in the breech was discovered. Trials of the F-30 continued until October 29th, after which the gun was removed from the T-28 and sent to the Kirov factory. At the same time, factory #92 began building another F-30 prototype, which they finished in late October, but further trials stalled.

Growing Appetites

On July 17th, 1940, SNK and VKP(b) decree #1288-495ss was issued, according to which Kirov factory was tasked with producing two prototypes of improved KV tanks by December 1st, 1940. Both prototypes were to have 100 mm of front armour, but differed in armament; the first prototype got the 76 mm F-27 gun, and the second the 85 mm F-30. However, changes were soon made. Instead of the F-27, the 76 mm F-32 gun was used, and the front armour was decreased to 90 mm. In addition, it turned out that the F-30 did not fit into the existing KV-1 turret, and a new turret was necessary.

It was not possible to just change the turret, as the required changes snowballed. In the end, the tank that was referred to as KV-220, Object 220, and T-220 significantly differed from the initial KV-1, having almost caught up to the SMK in size and surpassed it in mass. The T-220 was also called KV-4 in writing at least once.

The design of this tank is connected with the 212A SPG, whose design was ordered by the same decree #1288-495ss. As the mass of the "bunker buster" crawled over 60 tons, it needed a new engine. This engine, indexed V-2SN, was developed at factory #75 in Kharkov. It differed from the stock V-2 by the addition of the mechanical supercharger from the AM-38 aircraft engine. The supercharger increased the power output of the engine to 850 hp. This engine was also installed in the T-220, along with a new gearbox, main clutch, and final drives.

All these changes lengthened the hull to 7820 mm, one meter longer than the KV-1. This increase resulted in a change to the running gear: there were now 7 road wheels and 4 return rollers. The front of the hull was 100 mm thick, same as the sides. Initially, the mass of the T-220 was estimated at 56 tons, but the tank grew to 62.7 tons.

The turret that led to this growth of mass and size was a further development of a lowered KV-2 turret. The front was taken up by the massive F-30 gun mount and a coaxial machinegun. A hatch in the rear of the turret, much like the one on the KV-2, was added for removal of the gun. Another machinegun was installed in a rotating commander's cupola. A second loader increased the number of turret crewmen to 4. The ammunition, 91 rounds in total, was also partially stored in the turret.

The development of the T-220 was not cheap. According to calculations made by the Kirov factory, the total budget of this project reached 4 million roubles. 100,000 of them were spent on the technical project, 25,000 on the model, 250,000 on design documentation, and 75,000 on corrections made after trials. Two experimental prototypes would cost 1.2 million apiece. Trials would cost half a million, and another 900,000 would be used to improve the prototypes after trials, and all this doesn't include the cost of the armament.

Unlucky Sign

Due to a large amount of assignments for the Kirov factory and a general overload of work, the tanks were not finished on time. The hull only arrived at the factory on December 7th, 1940, and assembly was complete by early January 1940. A mix-up occurred during assembly: the F-30 gun was not properly balanced. Gunnery trials were moved to a later date that never came.

On January 14th, 1941, the trials plan was approved. Factory trials were skipped in a hurry. This fact contributed to the subsequent events. Trials showed a large amount of problems with the V-2SN engine. The piston rings wore out quickly, and the engine spat out oil. Oil consumption nearly reached one liter per kilometer.

The maximum speed on a highway was 33 kph, and average speed was 21.2 kph. However, the T-220 did not drive around for long. On January 25th, after 106 kilometers driven on a highway, the engine broke. As there were no spares, trials were halted. It's worth mentioning that this was not a surprise for factory #75 representatives. Chief designer of factory #75 T.P. Chupakhin said that the engine was experimental and that he gave no guarantees regarding its reliability.

Trials continued in late January after another engine was shipped from factory #75, if only briefly. According to a report by military engineer 1st class Glukhov, the second engine broke down completely on February 3rd, 1941. The next engine was expected to arrive on February 15th, and trials were falling behind schedule. Assembly of the second T-220 lagged behind due to missing parts. In early February 1941, the turret was still at factory #92 where the F-30 gun and its equipment were being installed.

Finally, instead of a V-2SN engine, a 700 hp V-5 arrived from factory #75. By the time it arrived, several important events happened that would change the fate of the T-220.

Grabin did not forget the idea to install a 107 mm gun with ballistics of the divisional M-60 gun in the KV-2 turret. In December of 1940, it became known that the design bureau of factory #92 developed such a gun on their own initiative and is already starting to build it. This gun, indexed F-42, was proposed for installation into the T-220 turret, but was rejected. It was decided that the lighter T-150 would be put into production under the index KV-3. The T-220 prototype would serve as a testbed for the V-5 engine, which would be used on the KV-3. The same thing happened to the V-5 as to the V-2SN: it didn't last long in the T-220.

The fate of the T-220 was sealed in March of 1941. Information on heavy tanks in the German army began to arrive. Information received by Soviet intelligence led to significant increase in activity regarding tanks and tank armament. This activity also touched domestic heavy designs. The T-220 with an 85 mm gun and 100 mm of armour was deemed insufficient. Instead, a new 72 ton KV-3 started development, with the factory index 223. Overall, this tank would be further development of the T-220, with more powerful armament and 120 mm of armour.

Work on the new KV-3 didn't mean that the existing T-220 was forgotten. On the contrary, the prototype was used as much as possible by the Kirov factory as a testbed for parts and assemblies meant for the new tank. A third V-2SN was installed, this one much more reliable than its predecessors. The tank was used to test new road wheels and Vortex air filters. By June 20th, 1941, it travelled a total of 1979 km. As for the other T-220 prototype, Kirov factory only got to it in early June. Assembly went along lazily, and was planned for no earlier than mid-July. This was how the experimental vehicles met the start of the Great Patriotic War.

Battles for Leningrad

All work on the T-220 stopped after the start of the war. The factory began hurriedly producing KV-1s, focusing their efforts on simplifying the design. When evacuation of the factory began, the KV-3 hull was evacuated. As for the T-220s, nobody had time for them. This changed when the Germans reached the city in the fall of 1941 and any tank at all was worth its weight in gold.

Suddenly, people remembered about the T-220s. Since the tanks never fired a shot and one turret was still in Gorkiy at factory #92, the first T-220 had its turret replaced with a stock KV-1 turret with an F-32 76 mm gun. The same turret was installed on the second tank. On October 5th, 1941, tank T-220 with serial number M-220-1 was sent to the 124th Tank Brigade. On October 16th, the second tank was sent there with the index M-220-2.

In November of 1941, the 124th Tank Brigade and the 43rd Infantry Division fought fierce battles near Ust-Tosno. The second T-220 burned up in these battles along with its crew, commanded by Junior Lieutenant Yakhnin. According to memoirs, the tank carried the slogan "For the Motherland!". As for the first prototype, its fate is unknown.

The story of the T-220 could end here, but it goes on. On February 8th, 1943, order #012 regarding assigning crews to the 12th Independent Training Tank Regiment. The eighth tank in the list is... "For the Motherland", serial number 220-2, whose commander was V.V. Strukov.

How could this be? Usually, burned up vehicles could not be repaired, but there are exceptions. It is known that at least several burned up KV-1s were evacuated and kept on fighting. It is also known that 17 tanks from the 124th Tank Brigade were recovered. One of them must have been M-220-2, repaired in the winter of 1942 at factory #371. During repairs, it was equipped with a V-2K engine, serial number 1193-03. The tank no longer had any worth as a combat vehicle, but it worked as a hands-on training aid for tankers until 1944.

The last episode in the life of the T-220 was the use of its turret. In September of 1941, the turret was replaced with a production KV-1 turret. The tankless turret was found a home. It was installed on a concrete foundation in the 22nd Karelian Fortified Region. The result was called Artillery BOT (KV) with 85 mm gun "Victory". Here, the turret survived the whole war.

Original article by Yuri Pasholok.