KV I/II heavy tanks

KV-1A (1941)

Weigth 47,5 tons Crew 5 Weapons 76,2mm L41,2 M40 gun with 111 rounds, 3 DT-type MG with 3024 rounds Armor hull 25-110mm (nose 70mm+25mm, sloped plate 75mm, front 75mm+35mm, sides 75-77mm, top 25mm, bottom 35mm, rear 75mm); turret 35-110mm (front 75mm+35mm, sides 75mm, top 35mm) Engine 580hp diesel V2 K, 12-cylinders on V, liquid cooled Speed 35Km/h Autonomy 225Km Length (max) 6,85m Width 3,34m Height 3,24m

Advantages: armor protection, mobility (autonomy, diesel engine, large tracks), powerful gun (adequate against any Panzer III and IV)

Disadvantages: turret was badly designed, being too tight and with an inefficient sight system, engine and chassis had to be improved because too prone to mechanical faults.

Designing the best heavy tank ...

In the 1939 the Red Army Command put request for a heavy breaktrough tank armed with a 76,2mm gun and an armor protection capable of resisting to anti-tank weapons up to the same caliber: it was decided to select the SMK heavy tank prototype for the job. This tank was equipped with two turret, one carrying the 76,2mm low-velocity gun and the other carrying a 45mm anti-tank gun.

After a radical re-design, in September 1939, it was marked as the KV-1 (from Klimenti Voroscilov, the Soviet Commisaire of Defence) heavy tank with only one turret, armed with the higher velocity 76,2mm L30,5 gun and more armor protection while maintaining its weight around the 43 tons. In an attempt to decide which one was better between the various heavy tank designs between the T-100, the SMK and KV, the prototypes were sent in Finland (manned by factory crews) for being tested on real ground. Actions soon proved the ineffectiveness of multi-turreted designs and instead show the superiority of the single turreted KV. Shortly afterwards the order for serial production was signed.

KV-1 model 1939 armor scheme (Photo by Valera Potapov)

The KV-1 model 1939 was armored with a 75mm hull front and side plates and 75mm thick front turret (with a maximum value of 90mm). Although it was prone to mechanical failures (in both engine and chassis) the Soviets decided to put it in production without waiting for the improvements that would have undoubtely slowed the program down. Out of these design problems, the KV was also much expensive to manufature because of the thick armored plates and their machining (such as creating holes for torsion bars in 75 mm thick plates): to cut costs and times down the use of bolts was severly reduced, replaced by extensive welding of the plates. Both modern KV and T-34 sufferend teething problems with transmission and engine, many carried spare parts over the hull to provide ready repairs (but also because Soviet logistics was unable to ship them in time).

In Spring 1941, after German propaganda the KV-1 went under a general up-armoring: because it was still impossible to provide thicker cast turrets and hulls it was decided to bolt new armor plates on the previous tanks: 25mm thick plates on the nose, 35mm ones on the front (for a total of 110mm) and on the front turret (same thickness): new tank is often referred as KV-1E (after the Russian word "ekranirovaniy", shielded).

Although the problem remained serious. A 1942 German report about this tank said that mechanically it "[...] is a poor job. Gears can only be shifted and engaged at the halt, so the maximum speed of 35 Km/h is an illusion. The clutch is too lightly constructed. Almost all abandoned tanks had clutch problems. [...]"

Early KV-1 with additional welded plates moves towards the frontline, Leningrad sector, 1941

The command model was instead equipped with the more powerful 76,2mm L41,2 gun but this soon became a standard for all the tanks built from late Summer 1941 which used new bolted and thicker armor (KV-1A or KV-1 model 1940). For "Operation Barbarossa" 508 all models KVs were ready but due to the ill-fated strategical leadership they were dispersed between the far less competitive light or old light or medium tanks's formations in an attempt to strengthen their formations. Single KVs were capable of stopping occasionally the German advance (because of their invulnerability to German anti-tank fire) but could not make more other and many were abandoned from their crews when the mechanical faults begin to make feel their presence. In addition it must be noted that many of these modern tanks (as happened for the T-34) had been received by the troops as late as three months before the war started: this mean that many crews had no experiece at all with them, experienced drivers were lacking, training and knowledge for properly maintaing these tanks was also lacking and the 7.62 cm ammunition (both high explosive and armor pierce) were at levels as low as 10 percent and sometimes totally lacking.

The lack of an effective sight system and the bad crew positioning where the three turret's crewmen had an unhappy job division with the commander used to be also the loader and the third man with the duty of aiming the rear machine-gun: exhghanging position between this latter and commander was unuseful because the rear turret position lacked any observing device. Job were carried on to solve these problems and a new KV, named KV-3, was prototyped with heavier armor and commanders cupola plus other minor enhancements. But such a project, designed to enter production in August 1941, would have stopped the production facilties too long for the conversion. The need of tanks took the project to be cancelled.

KVs in action

While many crews were unexperienced with the new tank, some were able to make the German to pay a heavy price for their advance. Here they are some accounts:

Extracts from Thomas Jentz's "Panzertruppen", vol. 1 (posted on the Tanker's Forum by Dr. Leo Niehorster)

6. Panzer-Division war diary, 25 June 41 "Unfortunately, the Russian 52 ton heavy tanks showed that it was almost insensitive to hits from the 10.5cm [field howitzer]. Several hits from a 15cm [field howitzer] were ineffective and bounced off. " "... a Russian heavy tank had blocked the communications route ... An 8.8cm Flak battery was sent up by the commander to fight this tank. It was just as unseccessful as the 10.5cm battery whose fire was directed by a forward observer. In addition, an attempt by a Pionier assault troop using balled explosives failed. It was impossible to get close to the tank because of heavy machine gun fire." 3. Panzer-Division war diary, 10 Jan 42 "It is noteworthy that the Pz-III ... hit a T34 tank driving along the village street at a range of about 20 meters and four times at a range of 50 meters with 5cm Pzgr 40 without observing any effect." 12. Panzer-Division war diary, 30 March 42 "... encountered a 52 ton tank and a T34. Under the covering fire from one Panzer, the other pair circled to the left and from a range of 50 to 80 meters opened fire on the enemy tanks. All three Pz-IV scored hits that showed no effect other than on the enemy morale.... the 53 ton ton tank drove off at high speed ... the T34 followed him." Hit over 30(!) times only on the turret side (without any sign of penetration), this KV model 1940 (with F-32 gun, 39 calibres long) was finished by side hit by an 88 The only way the Germans were able to achieve successes against the heavies in the early months was 1. by concentrating the fire of many tanks, in some cases an entire battalion (!) at ranges of 100 meters or less, which in many cases only caused damage. 2. by maneouvering to the flanks and rear and opening fire at ranges of 50 meters or less, which in many cases again only caused immobilization. 3. by coordinated fire on the tanks of all weapons, (which destroyed or separated the enemy infantry). Infantry and pioneers would then climb up on isolated or immobilzed enemy tanks and apply bundled stick grenades to less impervious areas, such as turret overhangs, etc. 4. repeated non-damaging hits which caused the enemy crews to abandon their vehicles because of the noise and concussion.

On 19 August 1941, a platoon of four KV-1s of the 1st Tank Division succesfully ambushed a German tank column advancing near the Voiskovitsy collective farm near Leningrad. The platoon leader, Sr. Lt. Zinoviy Kolobanov, knocked out the two lead tanks in the column. The following tanks apparently did not relize what had happened and continued to move forward. Kolobanov's platoon moved into the midst of German battalion and, in the melee that followed, Kolobanov destroyed 22 German tanks, ramming at least one in the process. His tank was hit 135(!) times during the firefight. The other three KVs destroyed a total of 16 other tanks. Kolobanov's feat made him the second highest ranking Soviet tank ace of the war.

More, during the Operation Taifun (the assault on Moscow) many of the most savage firefights took place. Near Volokolamski, a KV-1 of the 89th indipendent Tank Battalion commanded by Lt. Pavel Gudz knocked out ten tanks while receiving 29 hits from enemy tanks and AT guns.

A KV-1 model 1941 passes away a smoking Pz. IV in a nice propaganda photo. This action shots let us to take a look to: 1) the particular plates added to the hull to protect the turret ring which proved to be extremely prone to jam when hit; 2) the early style roadwheels; 3) the periscopes forming the complex (and very poor) sight system on the turret roof; 4) the additional fuel tank (left).

In the heavy tank mellees at Brody-Dubno in Ukraine the KV still played a big role. But as on the other fronts their technical advantage could not supply to the Red Army's shortcomings and made only pay the German tank regiments and ill-protected infantry an heavy price. Gen. Maj. Morgunov, the armoured commander in Ukraine in 1941 wrote in a secret report: "Special mention should be made of the good work of the 4th, 8th and 15th Mechanized Corps who showed that a single KV tank was worth 10-14 enemy tanks in battle". Army commanders appreciated the tank's near invulnerability and pleaded for more. Gen. Maj. Rokossowkiy said: "The KV tanks literally stunned the enemy. They withstood the fire of every type of gun that the German tanks were armed with". Disappointed by the performance of almost untrained crews which abandoned tanks as soon as they were hit (and not penetrated), Russian commands often manned the KVs with hand-picked crews.

Action on the field soon proved the need (by Soviet intentions) of heavier armor protection and some badly needed improvements in the trasmission/engine and chassis systems. One of the main problems, infact, remained its weak traction system which joined by the heavy forced marches the Russian units had to cover to reach the front lines resulted in heavy losses as that of the 10th Tank Division (15th Mechanized Corps) which lost 56 of its 63 KV in early August 1941, 11 knocked out by action, 11 missing in action and 34 abandoned or scuttled due to breakdowns). Another result was the in addition of armor plates to front-side hull and turret, with additional strips added to the hull to protect the turret ring which proved to be extermely jammable when hit.

New thicker armored tanks were named KV-1B and KV-1C (Western designation) or KV-1 model 1941 (Russian designation) with welded or casted armor. Both had cast 90mm thick hull with additional 40mm plates bolted on the front and side up to a 130mm front hull and a new thicker turret which reached 92-110 mm. Cast turret were more rounded, with 110-100mm thickness, taking tank weight well over 50 tons while reducing its speed to only 30Km/h. As soon the current flamethrower tanks proved to be too lightly armored 'as' priority targets for AT defences, more heavily armored tanks were need: the KV hull went under some modifications. Some vehicles were converted in flamethrower tanks with the 76,2mm gun replaced by a 45mm AT gun and flamethrower device: they were referred as the KV-8, with a total fuel capacity of 960 litres.

The KV-8 heavy flamethrower tank in a German intelligence photo of 1942

In spite of the big quantities of resources employed in the manufacture (at least till the KV-1 model 1941) major efforts were carried out to simplify the tank production in order to increase the numbers. This was fairly succesfull as the price of a 1941 model passed from 635,000 roubles to 295,000 in 1942 and 225,000 roubles in 1943 (with the KV-1s in production).

At this time the slower KV had trobles (or caused troubles) when employed in the mixed Soviet brigades where the fast T-34 and T-60/70 were the majority. Front commanders required the production of the KV to be stopped at once as well: since it had disrupted the provisions of tanks in the time the Red Army was rebuilding its armored force a compromise solution was adopted: the heavy tanks were to be concetrated in separated heavy tanks regiments with the duty of supporting the infantry. Studies were carried to solve the gap in performance and reliability between the heavy and medium tanks: the efforts finally produced lighter armored vehicles with improved mechanics speed trading off with armor, the KV-1s.

Witnessing a disaster: some KV-1 heavy tank lay on the battlefield. That on the left is a model 1941 with the up-armored cast turret (sometimes referred as the model 1942 and recognizable for the armor ring around the turret's rear MG); note also the flat rear plate used to speed up production. The other has the previous model up-armored cast turret.

The KV-2

The KV hull was used also for a heavier tank, classified as artillery tank, the KV-2. This slow (25Km/h) 51,2 tons monster was equipped, at first with a 122mm high-velocity gun and in almost all other models built with a 152mm L20 field gun in a very high turret. The KV-2 was intended as heavy breaktrough tank, to help penetrate enemy defences reinforced with bunkers. The modified M-10 Model 1938/40 howitzer could fire a 52 Kg projectile at 436 m/s that was capable of piercing 72mm of steel armor at 1,500 mt. There was also a special 40 Kg concrete penetrating round for attacking pillboxes. The tank could carry 36 rounds of ammunitition, mainly in the rear turret bustle.

While the two pre-production KV-2 'dreadnaught' which appeared in Finland during the 1939-40 Winter campaign were popular between the Russian tankers (one of them was hit no less than 48 times without any penetration), the situation evolved differently when the Germans invaded Russia. Nevermore also this tank had the Germans to think twice about their own tanks' armor and guns.

On June 23rd the German 6th Panzerdivision established two bridgeheads over the Dubissa river, seizing the town of Rasyenya. The attack to this bridgeheads (formed by Pz 35(t), infantry, artillery and AT guns) begun the same day by the 12th Mechanized Corps and 2nd Tank Division and its KV heavy tanks of the 3rd Mechanized Corps as reinforcement. General Solyalyskin sent a single KV-2 and some infantry to sever the road connection with the rest of 6th Panzer.

It remained in that point for two days, destroying with its 152mm gun twelve trucks which tried to supply the isolated bridgeheads. Six 50mm PaK 39 were moved to dispatch the tank but as they succesfully scored five direct hits, the tank's gunner opened fire destroying the first gun and damaging the others. An 88mm gun (from the FlaK Abt. 298) was moved from its camouflaged position in the Northern bridgehead and with its halftracked prime mover used the wreckage of the trucks to reach a distance of 900 metres from its target where it was spotted by the tank crew a destroyed with two direct hits. Relief parties were kept away from MG fire. Night actions of the German Pz.Pionier Bn. 57 Engineers to blow it up failed due to heavy armor which remained unscatted from the explosive charge applied to the hull. A new attempt was only able to broke the track. Heavy MGs' fire prevented other tentatives.

This massive KV-2 stopped the whole 6th Panzerdivision! (1941)

So desperate was becoming the situation that the 6th Panzerdivision requested the 1st Panzer to come to the rescue by striking the Western flank of the 12th Mechanized Corps and 2nd Tank Division. The 1st Pz. Div. was largely equipped with the neawer Pz III and IV, whcih have proved to be more succesfull (although in very unusual circumstances) than the Pz. 35(t) which equipped the 6th. In its drive, the 1st Pz. Div. succeded in breaching the Russian lines and defeat their armored forces as many KV tanks among their ranks (29 were destroyed or abandoned in the actions). This helped the bridgeheads by a grave pressure and so a Platoon of Pz. 35(t)s was sent to distract the KV-2 tank while another 88mm was carefully brought forward. When in position it opened fire, scoring six direct hits apparently disabling the tank. Further examination proved that only two projectiles had penetrated and while the German crew climbed over the tank, its turret rotated against them. An engineer finished it by launching some explosive in.

Forced to act on high mobility contests, its poor weaknessed shown: the great unstability of the tank (expecially when the turret was turned sideway), the "easy target" high turret, the factories' overrun by German advance and the lack of any important success (out of that occasional stops to German advance by single tanks and crews) soon turned the KV-2 to be put out of the Soviet inventory in 1942.

Several of these tanks, captured intact by the Wehrmacht, seemed actually employable to serve as bunk busters. A special company (z.B.V. 66) was formed for the invasion of Malta. After the cancellation of the operation the unit was sent to fight in the Demyansk in August 1942.

About 330 of them had been built, while it was also though to further develop the design using 85mm and 122mm high velocity guns. The project was aborted because they were still difficult to mask on the battlefield: the appearance of German Tiger tank, though, speeded up the building of heavy self propelled gun, then known as the SU-152. Over 5,000 KVs of all types were built until production ceased in favour of the new IS heavy tanks.