KV-1 tank Osa-1

Kirov tehtaan valmistavat SMK ja T100 panssarivaunut osoittautuivat rakenteeltaan
epäluotettaviksi ja heikoiksi, eikä niiden valmistusta jatkettu.

Kolmas vaunu tyyppi jossa oli vain yksi torni sai nimen Kliment Voroshilov mukaan, KV-1 panssarivaunu. Vaunun pääsuunnittelija oli tehtaan johtaja Kotin määräyksellä N L Duchov. Vaunu esiteltiin Neuvostoliiton ylimmälle sotaneuvostolle samaan aikaan monen muun uuden panssarivaunun kanssa syyskuun alku 1939, moskovan lähellä
olevassa panssari koulutus keskuksessa.

Jokaiseen aikaisemmin valmistuneeseen panssarivaunuun verrattuna KV-1 tankit
oli hyvin vahvasti panssaroitu. Tähän päästiin vaunun koko pienentämällä ja torni
määrä oli vain yksi. Samalla oli miehistön tarve jäänyt pieneksi. Kun vaunun koko oli pieni, pieni tila voitiin panssaroida vahvaksi, eikä vaunun painon nouse liian suureksi
kuten tapahtui vanhemmissa T-35 tai SMK ja T100 panssarivaunuissa.
(Jos verrataan nykyaikaiseen panssarivaunuun KV-1 vaunu oli huomattavan tilava)

Verrattuna SMK ja T100 vaunuihin KV-1 oli 3 metriä lyhyempi ja siis paljon helpompi
kääntyä, ketterämpi, mutta kömpelö, verrattuna pieneniin panssarivaunuihin.
Vaunun teho-paino suhde oli huono, syynä pieni tehoinen moottori, ja vaunun suuri
paino, josta syystä kääntö-vastus oli liian suuri.
Vaunun jousitus oli sauva-jousitus, joka otettiin ensimmäistä kertaa käyttöön 1938 
Pz-III vaunussa. KV-1 vaunun prototyyppiä valmistettiin monta kappaletta. 

Vaunun ensi esiintyminen tapahtui talvisodassa, joita oli kaksi talvisodan kokeilussa mukana kaksi vaunua.

Vaunut ajoivat maantietä tehtaalta suoraan rintamalle, heti kun miehistö oli saanut 
pika-koulutuksen 
Nämä kaksi vaunua osallistui läpi-murto taisteluun 17.12.1939 ensimmäisen kerran.

KV-1 vaunusta saadut kokemukset oli hyviä. Vanun panssarointi oli vahva ja kesti hyvin kevyiden tykkien tulta. Kun vaunujen vaurioita tutkittiin toisen vaunun tornista
löytyi 48 kpl 37 mm tykin osumaa, mutta panssarointi oli saanut vain pinta naarmuja.

Joulukuu 19. 1939 Neuvostoliiton ylin sotaneuvosto teki päätöksen ottaa KV-1 tankit
osaksi neuvostoliiton aseistukseen ja antoi luvan aloittaa vaunujen sarjavalmistus välittömästi. 
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KV-1 
Type: Heavy tank
Place of origin: Soviet Union
Service history:  1939 >  
Wars: Winter War, World War II
Production history:
Designer: Zh. Kotin, TsKB-2
Designed: 1938–39
Manufacturer: Kirov Factory, ChTZ
Produced: 1939–43
Number built: 5,219
KV-1: Model 1939
Weight: 42,5 tonnes
Length: 6.68 m 
Width: 3.32 m 
Height: 2.66 m
Crew: 5
Armour: 75 mm 
Armament: 76.2 mm M1941 ZiS-5 gun + 3 × DT machine guns
Engine: Model V12 Diesel V-2K engine 600 hp / 450 kW or 550 hp / 404kw /1900 rpm
Power/weight: 12,9 hp/tonne
Suspension: Torsion bar
Range: 335 km
Speed: 35 km/h (22 mph)

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After disappointing results with the multi-turreted T-35 heavy tank, Soviet tank designers started drawing up replacements. The T-35 conformed to the 1920s notion of a 'breakthrough tank' with very heavy firepower and armour protection, but suffered from poor mobility. The Spanish Civil War demonstrated the need for much heavier armor on tanks, and was the main influence on Soviet tank design just prior to World War II.

 The doctrine of Soviet deep battle called for the existence of relatively immobile, but heavily fortified, siege tanks that were supposed to keep pressure on enemy troops during the siege phase. Thus, the requirements for KV-1 were heavily skewed towards a potentially not-so agile, but heavy tank that was supposed to dominate the field.

Several competing designs were offered, and even more were drawn up prior to reaching prototype stage. All had heavy armour, torsion-bar suspension, wide tracks, and were of welded and cast construction. One of the main competing designs was the SMK, which in its final form had two turrets, mounting the same combination of 76.2 mm and 45 mm weapons. The designers of the SMK independently drew up a single-turreted variant and this received approval at the highest level. Two of these, named after the People's Defence Commissioner were ordered alongside a single SMK. The smaller hull and single turret enabled the designer to install heavy frontal and turret armour while keeping the weight within manageable limits.

When the Soviets entered the Winter War, the SMK, KV and a third design, the T-100, were sent to be tested in combat conditions. The KV outperformed the SMK and T-100 designs. 

The KV's heavy armour proved highly resistant to Finnish anti-tank weapons, making it more difficult to stop. In 1939, the production of 50 KVs was ordered. During the War, the Soviets found it difficult to deal with the concrete bunkers used by the Finns and a request was made for a tank with a large howitzer. One of the rush projects to meet the request put the howitzer in a new turret on one of the KV tanks.

The KV's strengths included armor that was impenetrable by any tank-mounted weapon then in service except at point-blank range, that it had good firepower, and that it had good traction on soft ground. It also had serious flaws: it was difficult to steer, the transmission (which was a twenty year old Caterpillar design) was unreliable (and was known to have to be shifted with a hammer), and the ergonomics were poor, with limited visibility and no turret basket. Furthermore, at 45 tons, it was simply too heavy. This severely impacted the maneuverability, not so much in terms of maximum speed, as through inability to cross many bridges medium tanks could cross.

The KV outweighed most other tanks of the era, being about twice as heavy as the heaviest contemporary German tank. KVs were never equipped with a snorkelling system to ford shallow rivers, so they had to be left to travel to an adequate bridge. As applique armor and other improvements were added without increasing engine power, later models were less capable of keeping up to speed with medium tanks and had more trouble with difficult terrain. In addition, its firepower was no better than the T-34. It took field reports from senior commanders "and certified heroes", who could be honest without risk of punishment, to reveal "what a dog the KV-1 really was."

While initially the Soviets made a lot of poor defense decisions, worsened by recent "cleansings" of Soviet military command, the KV-1 was unlike anything the German army had expected to encounter, and some of the battles against numerically superior Axis forces became legendary. Even though the operations of the KV family of tanks were severely hampered by restrictions due to its weight, it was a fearsome and formidable weapon through most of the Second World War.