Difference between revisions of "IS-1"

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{{Specs-Card|code=ussr_is_1}}
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{{Specs-Card
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|code=ussr_is_1
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|images={{Specs-Card-Image|GarageImage_{{PAGENAME}}.jpg|ArtImage2_{{PAGENAME}}.png}}
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}}
  
 
== Description ==
 
== Description ==
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''In the description, the first part needs to be about the history of the creation and combat usage of the vehicle, as well as its key features. In the second part, tell the reader about the ground vehicle in the game. Insert the screenshot of the vehicle. If the novice player does not remember the vehicle by name, they will immediately understand what kind of vehicle it is talking about.''
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<!-- ''In the description, the first part should be about the history of the creation and combat usage of the vehicle, as well as its key features. In the second part, tell the reader about the ground vehicle in the game. Insert a screenshot of the vehicle, so that if the novice player does not remember the vehicle by name, he will immediately understand what kind of vehicle the article is talking about.'' -->
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The '''IS-1''' is the first variant of the IS heavy tank family. The new IS-1 was intended to overcome the lack of firepower and protection issues of the KV series with a whole new sloped hull design. This was a strong armour design intended to deflect or withstand projectiles from all sides. The only major design requirement was that the weight not surpass that of the interim [[KV-85]]. The new armament was the same as the KV-85, an outstanding 85 mm D-5T tank gun with significantly higher range and muzzle velocity than prior Soviet heavy tanks. The turret was also identical to that of the KV-85, with three crews. The drivetrain was similar to that of the KV-85, with enormous tracks supported by three pairs of double return rollers and six double-tired wheels suspended by massive torsion arms. Extra fuel tanks were fitted to the rear of the hull, as with all earlier heavy tanks, and massive mudguards housed storage boxes. The engine was replaced with a new V2-IS 12-cylinder diesel engine producing 520 horsepower. The typical top speed was 37 km/h, and the practical range was only 150 km. Chelyabinsk Kirov Plant was responsible for the IS-1 manufacturing, and the first IS-1 rolled off the line in October 1943, but production was halted in January 1944 as the IS-1 was swiftly replaced by the all-round better [[IS-2]]. As a result, only 200-207 units were produced in total.
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 +
Introduced in the Closed Beta Test for Ground Forces before Update 1.41, the IS-1 has slightly superior hull protection than the interim KV-85. Tank shells can be easily deflected at long ranges thanks to a unique sloped frontal hull. However, the hull's lower front armour plate remains a weakness, and nearly all opponents in its rank are able to penetrate it. The visual characteristics of the IS-1 are also comparable to those of the KV-85. Players who have previously played the KV-85 should have little difficulty adjusting to this vehicle. The IS-1, unlike its predecessor, was developed with the purpose of breaching enemy heavy defences and engaging hostile armoured vehicles in mind and, as such, has thicker sloping armour, a slightly longer chassis, a more powerful 85 mm D-5T tank gun, and a larger, rounder turret.
  
 
== General info ==
 
== General info ==
 
=== Survivability and armour ===
 
=== Survivability and armour ===
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''Describe armour protection. Note the most well protected and key weak areas. Appreciate the layout of modules as well as the number and location of crew members. Is the level of armour protection sufficient, is the placement of modules helpfull for survival in combat?''
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{{Specs-Tank-Armour}}
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<!-- ''Describe armour protection. Note the most well protected and key weak areas. Appreciate the layout of modules as well as the number and location of crew members. Is the level of armour protection sufficient, is the placement of modules helpful for survival in combat? If necessary use a visual template to indicate the most secure and weak zones of the armour.'' -->
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The IS-1 has an excellent armour overall: its strong well sloped turret can bounce a few shells with an improved hull compared to the [[KV-85]]. The tank's heavy armour has similar properties of its previous KV-1 line, but the introduction of sloped armour on the front plate and turret mantlet can allow operators to withstand a significant amount of damage at most ranges, especially when armour is angled. The unique curvature of the upper front portion of hull armour can sometimes effectively bounce incoming shells from high penetrating cannons. It is a trait that remains in the IS-2 series. A huge and easy to hit weak spot is the commander's cupola that will easily knock out the turret crew if penetrated by APHE shells. It is impossible to angle the tank due to the unique curvature of the upper front portion of hull armour; while it serves to be an advantage when facing directly forward, any angling will be counterproductive, turning the upper front portion of the hull armour to a major weak spot. Taking too much ammunition will risk easy explosion from penetrating enemy shells due to the widespread storage of tank ammunition around the hull and in turret.
  
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''If necessary use a visual template to indicate the most secure and weak zones of the armour.''
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'''Armour type:'''
 +
 
 +
* Cast homogeneous armour (Front hull, Turret)
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* Rolled homogeneous armour (Rear hull, Gun mantlet)
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 +
{| class="wikitable"
 +
|-
 +
! Armour !! Front !! Sides !! Rear !! Roof
 +
|-
 +
| Hull || 120 mm (35°) ''Front plate'' <br> 60 mm (75°) ''Front glacis'' <br> 100 mm (28-36°) ''Lower glacis'' || 100 mm (11-27°)''Top front'' <br> 90 mm (11°) ''Top rear'' <br> 90 mm ''Bottom'' || 60 mm (48°) ''Top'' <br> 60 mm (35°) ''Lower'' || 30 mm
 +
|-
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| Turret || 100 mm (0-89°) ''Turret front'' <br> 100 mm (4-59°) ''Gun mantlet'' || 100 mm (19-21°) || 100 mm (2-36°) || 30 mm <br> 35 mm ''Turret hatches''
 +
|-
 +
| Cupola || 90 mm || 90 mm || 90 mm || 35 mm
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|-
 +
|}
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'''Notes:'''
 +
 
 +
* Suspension wheels are 20 mm thick and tracks are 30 mm thick.
 +
* Though the front plate is 120 mm thick, it is not very sloped in comparison to the front glacis. Despite front glacis, 60 mm thickness, slope effect up to ~130 mm and ricochet chances improve protection.
  
 
=== Mobility ===
 
=== Mobility ===
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''Write about the mobility of the ground vehicle. Estimate the specific power and maneuverability as well as the maximum speed forward and backward.''
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{{Specs-Tank-Mobility}}
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<!-- ''Write about the mobility of the ground vehicle. Estimate the specific power and manoeuvrability, as well as the maximum speed forwards and backwards.'' -->
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The IS-1 has a good overall mobility and maneuverability for a heavy tank. Its respectable reverse speed allows for getting back to cover fast enough to avoid retaliatory fire. The mobility can be sluggish when attempting to turn or steer from previous stationary position, it is advised to build up speed first.
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 +
{{tankMobility|abMinHp=671|abMaxHp=827|rbMinHp=460}}
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 +
=== Modifications and economy ===
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{{Specs-Economy}}
  
 
== Armaments ==
 
== Armaments ==
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{{Specs-Tank-Armaments}}
 
=== Main armament ===
 
=== Main armament ===
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''Give the reader information about the characteristics of the main gun. Assess its effectiveness in a battle based on the reloading speed, ballistics and the power of shells. Do not forget about the flexibilty of the fire, that is how quickly the cannon can be aimed at the target, open fire on it and aim at another enemy. Add a link to the main article on the gun: <code><nowiki>{{main|Name of the weapon}}</nowiki></code>. Describe in general terms the ammunition available for the main gun. Give advice on how to use them and how to fill the ammunition storage.''
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{{Specs-Tank-Weapon|1}}
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<!-- ''Give the reader information about the characteristics of the main gun. Assess its effectiveness in a battle based on the reloading speed, ballistics and the power of shells. Do not forget about the flexibility of the fire, that is how quickly the cannon can be aimed at the target, open fire on it and aim at another enemy. Add a link to the main article on the gun: <code><nowiki>{{main|Name of the weapon}}</nowiki></code>. Describe in general terms the ammunition available for the main gun. Give advice on how to use them and how to fill the ammunition storage.'' -->
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{{main|D-5T (85 mm)}}
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The 85 mm D-5T is a very strong and potent cannon for this BR that can deal with a range of enemies with relative ease; careful aiming is required against Tiger Is and Panthers. The poor gun depression makes fighting in mountainous terrain very difficult.
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 +
{| class="wikitable" style="text-align:center" width="100%"
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|-
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! colspan="5" | [[D-5T (85 mm)|85 mm D-5T]] || colspan="5" | Turret rotation speed (°/s) || colspan="4" | Reloading rate (seconds)
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|-
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! Mode !! Capacity !! Vertical !! Horizontal !! Stabilizer
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! Stock !! Upgraded !! Full !! Expert !! Aced
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! Stock !! Full !! Expert !! Aced
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|-
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! ''Arcade''
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| rowspan="2" | 59 || rowspan="2" | -5°/+25° || rowspan="2" | ±180° || rowspan="2" | - || 11.7 || 16.1 || 19.6 || 21.7 || 23.0 || rowspan="2" | 9.62 || rowspan="2" | 8.51 || rowspan="2" | 7.84 || rowspan="2" | 7.40
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|-
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! ''Realistic''
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| 8.6 || 10.1 || 12.2 || 13.5 || 14.4
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|-
 +
|}
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 +
==== Ammunition ====
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{{:D-5T (85 mm)/Ammunition|BR-365K, BR-365A, BR-365P, O-365K}}
  
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=== Additional armament ===
+
==== [[Ammo racks]] ====
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''Some tanks are armed with several guns in one or more turrets. Evaluate the additional weaponry and give advice on its use. Describe the ammunition available for additional weaponry. Give advice on how to use them and how to fill the ammunition storage. If there is no additional weaponry remove this subsection.''
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[[File:Ammoracks_{{PAGENAME}}.png|right|thumb|x250px|[[Ammo racks]] of the {{PAGENAME}}]]
 +
<!-- '''Last updated: 2.13.0.53''' -->
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{| class="wikitable" style="text-align:center"
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|-
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! Full<br>ammo
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! 1st<br>rack empty
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! 2nd<br>rack empty
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! 3rd<br>rack empty
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! 4th<br>rack empty
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! 5th<br>rack empty
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! 6th<br>rack empty
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! Visual<br>discrepancy
 +
|-
 +
| '''59''' || 55&nbsp;''(+4)'' || 37&nbsp;''(+22)'' || 27&nbsp;''(+32)'' || 21&nbsp;''(+38)'' || 11&nbsp;''(+48)'' || 1&nbsp;''(+58)'' || No
 +
|-
 +
|}
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'''Notes''':
 +
 
 +
* As they are modeled by sets of 2, shells disappear from the rack only after you've fired both shells in the set.
 +
* Turret empty: 37&nbsp;''(+22)'' shells.
  
 
=== Machine guns ===
 
=== Machine guns ===
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''Offensive and anti-aircraft machine guns not only allow you to fight some aircraft, but also are effective against lightly armoured vehicles. Evaluate machine guns and give recommendations on its use.''
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{{Specs-Tank-Weapon|2}}
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<!-- ''Offensive and anti-aircraft machine guns not only allow you to fight some aircraft but also are effective against lightly armoured vehicles. Evaluate machine guns and give recommendations on its use.'' -->
 +
{{main|DT (7.62 mm)}}
 +
The IS-1 has no roof-mounted heavy machine gun lime they are found in later Soviet heavy tanks and SPGs to defend against incoming enemy aircraft. The only machine gun available is a 7.62 mm coaxial MG. Useful for taking out unarmoured trucks and exposed crew.
  
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== Usage in the battles ==
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{| class="wikitable" style="text-align:center" width="50%"
−
''Describe the tactics of playing in the vehicle, the features of using vehicles in the team and advice on tactics. Refrain from creating a "guide" - do not impose a single point of view but give the reader food for thought. Describe the most dangerous enemies and give recommendations on fighting them. If necessary, note the specifics of the game in different modes (AB, RB, SB).''
+
|-
 +
! colspan="5" | [[DT (7.62 mm)|7.62 mm DT]]
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|-
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! Mount !! Capacity (Belt) !! Fire rate !! Vertical !! Horizontal
 +
|-
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| Coaxial || 2,520 (63) || 600 || - || -
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|-
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|}
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== Usage in battles ==
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<!-- ''Describe the tactics of playing in the vehicle, the features of using vehicles in the team and advice on tactics. Refrain from creating a "guide" - do not impose a single point of view but instead give the reader food for thought. Describe the most dangerous enemies and give recommendations on fighting them. If necessary, note the specifics of the game in different modes (AB, RB, SB).'' -->
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As the tank's design purpose suggests, the IS-1 is a heavy tank built with an emphasis on engaging hostile armoured vehicles as well as a breakthrough tank. It has a relatively similar playstyle compared to the previous [[KV-85]] tank, reducing the learning curve. The fast reloads speed of the 85 mm gun (on par with its T-34 and KV-85 mounted sisters) also allows it to be an effective brawler in close quarters combat against multiple targets. When encountering better-protected targets, the IS tank (although equipped with the same type of cannon) has access to APCR rounds to better deal with heavier opponents, something the KV and T-34 models lack.
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Although classified as a heavy tank and an upgraded improved design over the KV predecessor, the tank is not invulnerable. The vehicle's armour thickness is quite effective in its class.  Unlike its Tiger rivals and KV predecessors, the IS-1 has better or equal thickness armour on almost all sides except the rear hull and is sloped increasing the chance of ricochet and damage reduction when struck. Of note is the large turret and exposed turret mount which is commonly targeted at engaging hostile vehicles from the front. Armaments and ammunition options aside, the IS tank can perform similarly if not better at engaging targets than the common T-34, albeit with more satisfactory armour protection, able to allow users to lead a charge from the front with relative confidence or provide fire support from the sides or rear. This tank is quite sufficient in holding its own on the battlefield in many situations where a lighter vehicle cannot.
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Another significant note of this vehicle is its considerably fast reverse rate, the highest of its Rank and Battle-Rating for the nation's faction, topping at 17 km/h. During situations where close-quarters engagement is expected, an unorthodox strategy can be utilized when the operator of the IS tank re-positions the vehicle 90 degrees and drive in reverse towards the enemy. By driving in reverse with the rear-facing the opposition, the engine blocks make a crude yet somewhat effective shield and protecting the more delicate crew. As the fuel tanks are mostly stored at the front on the left and right side of the driver's station, the risk of fire and fuel-tank explosion is reduced significantly (but not completely eliminated) and thus, the tank is able to resist even the most powerful of shots. Be aware that more experienced players may attempt to instead fire at the more exposed turret of the IS tank and instantly knocking out the crew with a common APHE penetrating the shell.
 +
 
 +
When engaging the common Tiger tank and Panzer IV models, each of these vehicles retains the design flaw of 90 degree flat armour plates on the front and sides of each respective vehicle. The IS-1's 85 mm cannon should have little no difficulty in penetrating this and destroying the opposition's vehicle in a single shot if this weakness is exploited. The Panther and occasional Tiger II models are more considerably dangerous and difficult to dispatch when encountering them head-on due to the thicker and sloped armour of which the 85 mm cannon of the IS-1 cannot penetrate. In head-on engagements, operators of this vehicle should note to precisely target the right and left side turret mantlet of each respective vehicles instead. Time expended in attempting to find a penetration confirmation indication on the cross-hair when inspecting the sloped front plate is time wasted and instead, should be diverted on precise targeting of the mantlet.  Other more common tanks such as opposition USSR KV, IS and T-34 models are usually less of a concern than the common Panther tank, as most of these respective tanks also inherit the weakness of somewhat slopped frontal chassis and turret armour which can be easily penetrated even from significant distances with a precise aim.
 +
 
 +
If you are to apply bushes onto the IS-1, consider putting most of them on upper frontal hull and the curved sides next to it. This is because that quite some opponents will automatically target the curved armour, knowing that area is a common weak spot when the IS is angling. By covering up the hull front and the curves, the IS's frontal hull will now look flatter, somewhat resembling the hull of an IS-2 1944. This will cause some confusion and delay the enemy's reaction & aiming time, as they now cannot directly see where your curved armour is, gifting you a precious few seconds before they open fire. For any leftover bushes, the turret front and the lower front plate are also good spots to put them on.
  
 
=== Pros and cons ===
 
=== Pros and cons ===
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''Summarize and briefly evaluate the vehicle in terms of its characteristics and combat effectiveness. Mark its pros and cons in a bulleted list. Do not use more than 6 points for each of the characteristics. Avoid using categorical definitions such as "bad", "good" and the like - they have a substitution in the form of softer "inadequate", "effective".''
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<!-- ''Summarise and briefly evaluate the vehicle in terms of its characteristics and combat effectiveness. Mark its pros and cons in a bulleted list. Try not to use more than 6 points for each of the characteristics. Avoid using categorical definitions such as "bad", "good" and the like - use substitutions with softer forms such as "inadequate" and "effective".'' -->
  
 
'''Pros:'''
 
'''Pros:'''
−
*
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 +
* Good armour
 +
* Extremely durable against in down-tiered battles (when encountering lower rank M4 Shermans, Valentines, Pz.IV etc.)
 +
* Re-positioning of fuel tanks reducing chances of fires.
 +
* Good mobility with a fast reverse speed
 +
* Sufficient firepower
 +
** High rate of fire
 +
** Ability to fire APCR
 +
* Player skill compatibility between older and newer KV and IS models
  
 
'''Cons:'''
 
'''Cons:'''
−
*
+
 
 +
* Large tank (slightly longer than the KV-1)
 +
* Difficult to angle armour due to weaker hull cheeks
 +
* Turret cheeks are easy to penetrate even at long distance
 +
* Commander cupola is a big weak spot
 +
* Poor gun depression (a common trait in all Soviet tanks)
 +
* Frontal shot trap underneath the turret will allow non-penetrating shells to ricochet and penetrate weaker armor when turret is hull-aligned.
  
 
== History ==
 
== History ==
−
''Describe the history of the creation and combat usage of the ground vehicle in more detail than in the introduction. If the historical reference turns out to be too big, take it to a separate article, taking a link to an article about the vehicle and adding a block "/historical reference" (example: https://wiki.warthunder.com/Name-vehicles/historical reference) and add a link to it here using the <code>main</code> template. Be sure to include links to sources at the end of the article.''
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<!-- ''Describe the history of the creation and combat usage of the vehicle in more detail than in the introduction. If the historical reference turns out to be too long, take it to a separate article, taking a link to the article about the vehicle and adding a block "/History" (example: <nowiki>https://wiki.warthunder.com/(Vehicle-name)/History</nowiki>) and add a link to it here using the <code>main</code> template. Be sure to reference text and sources by using <code><nowiki><ref></ref></nowiki></code>, as well as adding them at the end of the article with <code><nowiki><references /></nowiki></code>. This section may also include the vehicle's dev blog entry (if applicable) and the in-game encyclopedia description (under <code><nowiki>=== In-game description ===</nowiki></code>, also if applicable).'' -->
 +
===Development===
 +
The start of the development for a new heavy tank in the Red Army came from the many criticisms of their current heavy tank, the [[KV-1 (ZiS-5)|KV-1]]. The KV-1 had poor mobility and a lack of firepower and armour advantage over the standard [[T-34 (1942)|T-34]], plus the KV-1 was more expensive to produce for no real advantage. Attempts to remedy this problem produced the ''KV-1S'' and the ''[[KV-85]]'', which tried to make the KV-1 more mobile, more ergonomic, and have better firepower. Though they were improvements over the original KV-1 design, it was already determined that the KV-1 designs are to be replaced by a new heavy tank design and the newer KV-1 developments were to be interim designs until the heavy tank development is complete.
 +
 
 +
The heavy tank project, code-named ''Object 237'', had its basis from the cancelled KV-13 program and was restarted from the discovery of the [[Tiger H1|Tiger I]] after one was captured in Leningrad, thus it began in January 1943. However, despite the ensuing development, the intense tank fighting in 1943 in Kursk and ensuing operations forced the Object 237 to see action early, with its turret used on the KV-85, which itself was built atop the KV-1S hull. The turret mounted the new 85 mm D-5T gun and would be a great firepower advantage enjoyed by the Soviet tank forces as it gave them a heavy tank with comparable firepower to the Tiger I's 88 mm cannon. At the end of 1943, the Object 237 project was finished and was accepted into service as the '''IS-85''', or the '''IS-1''', named after Iosef (Joseph) Stalin, the current leader of the Soviet Union during World War II, putting an end to the Voroshilov (KV) line of tanks. The IS-1 began to be delivered in October 1943 and went into service in the same month. The IS-1 stayed in service until January 1944, when its production also ended with about 200 units produced.
 +
 
 +
===Combat usage===
 +
The IS-1, like the KV-85 before it, was a great assist to the Soviet tank forces, giving them a heavily armoured tank with a great 85 mm gun that could defeat most of the German tanks in service except their heaviest ones such as the [[Tiger E|Tiger I]] and the [[Panther D|Panther]] tanks. The IS-1 was issued to Guards Heavy Tank Regiments for service, most notably the 1st, 8th, and 13th Guards Heavy Tank Regiments which saw service in Ukraine and Slovakia.  Within a standard IS-1 issue tank, there were often 59 85 mm rounds and 2,500 rounds for the three DT machine guns, which allowed it to have both superior armaments and capacity compared to the standard [[Tiger E|Tiger I]].
 +
 
 +
The IS-1 had a short-lived production due to advances in Soviet tank technology. Their standard [[T-34 (1942)|T-34]] medium tanks were upgraded with the same 85 mm gun on the IS-1 into the [[T-34-85]]. The lack of firepower advantage the IS-1 now presented due to this upgrade prompted an up-gunning of the IS tank with a much bigger gun. After further development in late 1943, the IS-1 evolved into the [[IS-2]], which has the larger and much more powerful 122 mm A-19 gun.
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 +
{{break}}
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{{Navigation-Start|{{Annotation|Archive of the in-game description|An archive of the historical description of the vehicle that was presented in-game prior to Update 1.55 'Royal Armour'}}}}
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{{Navigation-First-Simple-Line}}
 +
The IS-1 was developed in the spring and summer of 1943 by factory No. 100's design bureau led by Z.Y. Kotin. The tank's hull design and overall layout were taken from the previously developed experimental KV-13 tank. The main priority was creating reliable protection against the German 88 mm Flak 18 artillery cannon and making considerable mobility improvements by reducing the tank's mass and introducing a new epicyclic gearbox. The results of battles in 1943 revealed the need for a new heavy assault tank to replace the outdated mass-produced KV tanks. The prototype, designated IS, was built, tested and put into service in the Red Army in July-September 1943. Thanks to its new gearbox and the more streamlined placement of its strengthened armour, the new tank possessed superior mobility.
 +
 
 +
The IS's tight layout in its habitable section meant that a fifth crew member - the gunner/radio officer - would not fit inside. His duties were distributed between the commander and the driver.
 +
 
 +
Three crew were housed in the turret: the tank commander and the driver worked to the left of the gun, and the loader to the right. A command cupola with 82 mm thick vertical armour was installed in the tank's turret, and its hull had a hatch leading to the underside of the tank to allow the crew to evacuate in an emergency.
 +
 
 +
The IS-1 was armed with an 85 mm D-5T Mod. 1943 tank cannon and three machine guns.
 +
 
 +
It entered mass production in October 1943 at the ChKZ factory. In total, 130 of them were built.
 +
 
 +
The IS-1 was deployed in battles from February 1944 up to and including the winter of 1945. The results of these battles led to the conclusion that the armament and armour of the new tank were not equal to those of German heavy tanks. At that time, it was recommended that the shape and armour of the frontal hull be changed and the tank's armament upgraded immediately.
 +
{{Navigation-End}}
  
 
== Media ==
 
== Media ==
−
''An excellent addition to the article will be video guides, as well as screenshots from the game and photos.''
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<!-- ''Excellent additions to the article would be video guides, screenshots from the game, and photos.'' -->
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 +
;Images
 +
<gallery mode="packed-hover" heights="200">
 +
File:ArtImage IS-1.png
 +
</gallery>
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 +
;Skins
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 +
* [https://live.warthunder.com/feed/camouflages/?vehicle=ussr_is_1 Skins and camouflages for the {{PAGENAME}} from live.warthunder.com.]
 +
 
 +
;Videos
 +
{{Youtube-gallery|EyD1M_Mi-dw|'''The Shooting Range #61''' - ''Pages of History'' section at 09:02 discusses the IS-1.|msh0K_NbTN0|'''The IS Family'''  - ''War Thunder Official Channel''}}
 +
 
 +
== See also ==
 +
''Links to the articles on the War Thunder Wiki that you think will be useful for the reader, for example:''
  
−
== Read also ==
 
−
''Links to the articles on the War Thunder Wiki that you think will be useful for the reader, for example,''
 
 
* ''reference to the series of the vehicles;''
 
* ''reference to the series of the vehicles;''
 
* ''links to approximate analogues of other nations and research trees.''
 
* ''links to approximate analogues of other nations and research trees.''
−
''ETC.''
 
  
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== Sources ==
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== External links ==
−
''Paste links to sources and external resources, such as:''
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<!-- ''Paste links to sources and external resources, such as:''
 
* ''topic on the official game forum;''
 
* ''topic on the official game forum;''
−
* ''page on the Wikipedia;''
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* ''other literature.'' -->
−
* ''other literature.''
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 +
=== References ===
 +
<references />
 +
 
 +
{{TankManufacturer ChTZ}}
 +
{{USSR heavy tanks}}

Latest revision as of 05:15, 15 October 2024

Rank VI USA | Premium | Golden Eagles
A-10A Thunderbolt (Early)
IS-1
ussr_is_1.png
GarageImage IS-1.jpg
ArtImage2 IS-1.png
IS-1
USSR flag.png USSR
III Rank
Battle rating:
AB RB SB
5.7 5.7 5.7
Class:
Research:40 000 Specs-Card-Exp.png
Purchase:135 000 Specs-Card-Lion.png
Show in game

Description

The IS-1 is the first variant of the IS heavy tank family. The new IS-1 was intended to overcome the lack of firepower and protection issues of the KV series with a whole new sloped hull design. This was a strong armour design intended to deflect or withstand projectiles from all sides. The only major design requirement was that the weight not surpass that of the interim KV-85. The new armament was the same as the KV-85, an outstanding 85 mm D-5T tank gun with significantly higher range and muzzle velocity than prior Soviet heavy tanks. The turret was also identical to that of the KV-85, with three crews. The drivetrain was similar to that of the KV-85, with enormous tracks supported by three pairs of double return rollers and six double-tired wheels suspended by massive torsion arms. Extra fuel tanks were fitted to the rear of the hull, as with all earlier heavy tanks, and massive mudguards housed storage boxes. The engine was replaced with a new V2-IS 12-cylinder diesel engine producing 520 horsepower. The typical top speed was 37 km/h, and the practical range was only 150 km. Chelyabinsk Kirov Plant was responsible for the IS-1 manufacturing, and the first IS-1 rolled off the line in October 1943, but production was halted in January 1944 as the IS-1 was swiftly replaced by the all-round better IS-2. As a result, only 200-207 units were produced in total.

Introduced in the Closed Beta Test for Ground Forces before Update 1.41, the IS-1 has slightly superior hull protection than the interim KV-85. Tank shells can be easily deflected at long ranges thanks to a unique sloped frontal hull. However, the hull's lower front armour plate remains a weakness, and nearly all opponents in its rank are able to penetrate it. The visual characteristics of the IS-1 are also comparable to those of the KV-85. Players who have previously played the KV-85 should have little difficulty adjusting to this vehicle. The IS-1, unlike its predecessor, was developed with the purpose of breaching enemy heavy defences and engaging hostile armoured vehicles in mind and, as such, has thicker sloping armour, a slightly longer chassis, a more powerful 85 mm D-5T tank gun, and a larger, rounder turret.

General info

Survivability and armour

Armourfront / side / back
Hull120 / 90 / 60
Turret100 / 100 / 100
Crew4 people
Visibility102 %

The IS-1 has an excellent armour overall: its strong well sloped turret can bounce a few shells with an improved hull compared to the KV-85. The tank's heavy armour has similar properties of its previous KV-1 line, but the introduction of sloped armour on the front plate and turret mantlet can allow operators to withstand a significant amount of damage at most ranges, especially when armour is angled. The unique curvature of the upper front portion of hull armour can sometimes effectively bounce incoming shells from high penetrating cannons. It is a trait that remains in the IS-2 series. A huge and easy to hit weak spot is the commander's cupola that will easily knock out the turret crew if penetrated by APHE shells. It is impossible to angle the tank due to the unique curvature of the upper front portion of hull armour; while it serves to be an advantage when facing directly forward, any angling will be counterproductive, turning the upper front portion of the hull armour to a major weak spot. Taking too much ammunition will risk easy explosion from penetrating enemy shells due to the widespread storage of tank ammunition around the hull and in turret.

Armour type:

  • Cast homogeneous armour (Front hull, Turret)
  • Rolled homogeneous armour (Rear hull, Gun mantlet)
Armour Front Sides Rear Roof
Hull 120 mm (35°) Front plate
60 mm (75°) Front glacis
100 mm (28-36°) Lower glacis 		100 mm (11-27°)Top front
90 mm (11°) Top rear
90 mm Bottom 		60 mm (48°) Top
60 mm (35°) Lower 		30 mm
Turret 100 mm (0-89°) Turret front
100 mm (4-59°) Gun mantlet 		100 mm (19-21°) 100 mm (2-36°) 30 mm
35 mm Turret hatches
Cupola 90 mm 90 mm 90 mm 35 mm

Notes:

  • Suspension wheels are 20 mm thick and tracks are 30 mm thick.
  • Though the front plate is 120 mm thick, it is not very sloped in comparison to the front glacis. Despite front glacis, 60 mm thickness, slope effect up to ~130 mm and ricochet chances improve protection.

Mobility

Speedforward / back
AB40 / 16 km/h
RB and SB38 / 15 km/h
Number of gears8 forward
2 back
Weight44.0 t
Engine power
AB992 hp
RB and SB520 hp
Power-to-weight ratio
AB22.5 hp/t
RB and SB11.8 hp/t

The IS-1 has a good overall mobility and maneuverability for a heavy tank. Its respectable reverse speed allows for getting back to cover fast enough to avoid retaliatory fire. The mobility can be sluggish when attempting to turn or steer from previous stationary position, it is advised to build up speed first.

Game Mode Max Speed (km/h) Weight (tons) Engine power (horsepower) Power-to-weight ratio (hp/ton)
Forward Reverse Stock Upgraded Stock Upgraded
Arcade 40 16 44 671 827 15.25 18.8
Realistic 38 15 460 520 10.45 11.82

Modifications and economy

Repair costBasic → Reference
AB2 010 → 2 486 Sl icon.png
RB2 176 → 2 691 Sl icon.png
SB3 022 → 3 738 Sl icon.png
Total cost of modifications34 400 Rp icon.png
67 200 Sl icon.png
Talisman cost1 300 Ge icon.png
Crew training39 000 Sl icon.png
Experts135 000 Sl icon.png
Aces550 Ge icon.png
Research Aces390 000 Rp icon.png
Reward for battleAB / RB / SB
90 / 140 / 150 % Sl icon.png
154 / 154 / 154 % Rp icon.png
Modifications
Mobility Protection Firepower
Mods new tank traks.png
Tracks
Research:
1 700 Rp icon.png
Cost:
3 300 Sl icon.png
105 Ge icon.png
Mods new tank suspension.png
Suspension
Research:
1 900 Rp icon.png
Cost:
3 700 Sl icon.png
120 Ge icon.png
Mods new tank break.png
Brake System
Research:
1 900 Rp icon.png
Cost:
3 700 Sl icon.png
120 Ge icon.png
Mods new tank filter.png
Filters
Research:
2 200 Rp icon.png
Cost:
4 300 Sl icon.png
140 Ge icon.png
Mods new tank transmission.png
Transmission
Research:
5 600 Rp icon.png
Cost:
11 000 Sl icon.png
350 Ge icon.png
Mods new tank engine.png
Engine
Research:
5 600 Rp icon.png
Cost:
11 000 Sl icon.png
350 Ge icon.png
Mods tank tool kit.png
Improved Parts
Research:
1 700 Rp icon.png
Cost:
3 300 Sl icon.png
105 Ge icon.png
Mods extinguisher.png
Improved FPE
Research:
1 900 Rp icon.png
Cost:
3 700 Sl icon.png
120 Ge icon.png
Mods tank reinforcement ussr.png
Crew Replenishment
Research:
2 200 Rp icon.png
Cost:
4 300 Sl icon.png
140 Ge icon.png
Mods new tank horizontal aiming.png
Horizontal Drive
Research:
1 700 Rp icon.png
Cost:
3 300 Sl icon.png
105 Ge icon.png
Mods tank ammo.png
85mm_APHE_ammo_pack
Research:
1 700 Rp icon.png
Cost:
3 300 Sl icon.png
105 Ge icon.png
Mods tank cannon.png
Adjustment of Fire
Research:
1 900 Rp icon.png
Cost:
3 700 Sl icon.png
120 Ge icon.png
Mods new tank vertical aiming.png
Elevation Mechanism
Research:
2 200 Rp icon.png
Cost:
4 300 Sl icon.png
140 Ge icon.png
Mods tank ammo.png
85mm_APCR_ammo_pack
Research:
2 200 Rp icon.png
Cost:
4 300 Sl icon.png
140 Ge icon.png

Armaments

Main armament

85 mm D-5T cannon
Ammunition59 rounds
Reloadbasic crew → aces
9.6 → 7.4 s
Vertical guidance-5° / 25°
Main article: D-5T (85 mm)

The 85 mm D-5T is a very strong and potent cannon for this BR that can deal with a range of enemies with relative ease; careful aiming is required against Tiger Is and Panthers. The poor gun depression makes fighting in mountainous terrain very difficult.

85 mm D-5T Turret rotation speed (°/s) Reloading rate (seconds)
Mode Capacity Vertical Horizontal Stabilizer Stock Upgraded Full Expert Aced Stock Full Expert Aced
Arcade 59 -5°/+25° ±180° - 11.7 16.1 19.6 21.7 23.0 9.62 8.51 7.84 7.40
Realistic 8.6 10.1 12.2 13.5 14.4

Ammunition

Penetration statistics
Ammunition Type of
warhead 		Penetration @ 0° Angle of Attack (mm)
10 m 100 m 500 m 1,000 m 1,500 m 2,000 m
BR-365K APHE 148 143 126 106 90 77
BR-365A APHEBC 135 133 124 114 104 95
BR-365P APCR 195 187 154 122 96 76
O-365K HE 19 18 17 16 15 14
Shell details
Ammunition Type of
warhead 		Velocity
(m/s) 		Projectile
mass (kg) 		Fuse delay
(m) 		Fuse sensitivity
(mm) 		Explosive mass
(TNT equivalent) (g) 		Ricochet
0% 50% 100%
BR-365K APHE 792 9.2 1.2 14 77 47° 60° 65°
BR-365A APHEBC 792 9.2 1.2 14 164 48° 63° 71°
BR-365P APCR 1,050 4.99 - - - 66° 70° 72°
O-365K HE 785 9.54 0.2 0.1 741 79° 80° 81°

Ammo racks

Ammo racks of the IS-1
Full
ammo 		1st
rack empty 		2nd
rack empty 		3rd
rack empty 		4th
rack empty 		5th
rack empty 		6th
rack empty 		Visual
discrepancy
59 55 (+4) 37 (+22) 27 (+32) 21 (+38) 11 (+48) 1 (+58) No

Notes:

  • As they are modeled by sets of 2, shells disappear from the rack only after you've fired both shells in the set.
  • Turret empty: 37 (+22) shells.

Machine guns

7.62 mm DT machine gun (coaxial)
Ammunition2 520 rounds
Belt capacity63 rounds
Reloadbasic crew → aces
10.4 → 8.0 s
Fire rate600 shots/min
Main article: DT (7.62 mm)

The IS-1 has no roof-mounted heavy machine gun lime they are found in later Soviet heavy tanks and SPGs to defend against incoming enemy aircraft. The only machine gun available is a 7.62 mm coaxial MG. Useful for taking out unarmoured trucks and exposed crew.

7.62 mm DT
Mount Capacity (Belt) Fire rate Vertical Horizontal
Coaxial 2,520 (63) 600 - -

Usage in battles

As the tank's design purpose suggests, the IS-1 is a heavy tank built with an emphasis on engaging hostile armoured vehicles as well as a breakthrough tank. It has a relatively similar playstyle compared to the previous KV-85 tank, reducing the learning curve. The fast reloads speed of the 85 mm gun (on par with its T-34 and KV-85 mounted sisters) also allows it to be an effective brawler in close quarters combat against multiple targets. When encountering better-protected targets, the IS tank (although equipped with the same type of cannon) has access to APCR rounds to better deal with heavier opponents, something the KV and T-34 models lack.

Although classified as a heavy tank and an upgraded improved design over the KV predecessor, the tank is not invulnerable. The vehicle's armour thickness is quite effective in its class. Unlike its Tiger rivals and KV predecessors, the IS-1 has better or equal thickness armour on almost all sides except the rear hull and is sloped increasing the chance of ricochet and damage reduction when struck. Of note is the large turret and exposed turret mount which is commonly targeted at engaging hostile vehicles from the front. Armaments and ammunition options aside, the IS tank can perform similarly if not better at engaging targets than the common T-34, albeit with more satisfactory armour protection, able to allow users to lead a charge from the front with relative confidence or provide fire support from the sides or rear. This tank is quite sufficient in holding its own on the battlefield in many situations where a lighter vehicle cannot.

Another significant note of this vehicle is its considerably fast reverse rate, the highest of its Rank and Battle-Rating for the nation's faction, topping at 17 km/h. During situations where close-quarters engagement is expected, an unorthodox strategy can be utilized when the operator of the IS tank re-positions the vehicle 90 degrees and drive in reverse towards the enemy. By driving in reverse with the rear-facing the opposition, the engine blocks make a crude yet somewhat effective shield and protecting the more delicate crew. As the fuel tanks are mostly stored at the front on the left and right side of the driver's station, the risk of fire and fuel-tank explosion is reduced significantly (but not completely eliminated) and thus, the tank is able to resist even the most powerful of shots. Be aware that more experienced players may attempt to instead fire at the more exposed turret of the IS tank and instantly knocking out the crew with a common APHE penetrating the shell.

When engaging the common Tiger tank and Panzer IV models, each of these vehicles retains the design flaw of 90 degree flat armour plates on the front and sides of each respective vehicle. The IS-1's 85 mm cannon should have little no difficulty in penetrating this and destroying the opposition's vehicle in a single shot if this weakness is exploited. The Panther and occasional Tiger II models are more considerably dangerous and difficult to dispatch when encountering them head-on due to the thicker and sloped armour of which the 85 mm cannon of the IS-1 cannot penetrate. In head-on engagements, operators of this vehicle should note to precisely target the right and left side turret mantlet of each respective vehicles instead. Time expended in attempting to find a penetration confirmation indication on the cross-hair when inspecting the sloped front plate is time wasted and instead, should be diverted on precise targeting of the mantlet. Other more common tanks such as opposition USSR KV, IS and T-34 models are usually less of a concern than the common Panther tank, as most of these respective tanks also inherit the weakness of somewhat slopped frontal chassis and turret armour which can be easily penetrated even from significant distances with a precise aim.

If you are to apply bushes onto the IS-1, consider putting most of them on upper frontal hull and the curved sides next to it. This is because that quite some opponents will automatically target the curved armour, knowing that area is a common weak spot when the IS is angling. By covering up the hull front and the curves, the IS's frontal hull will now look flatter, somewhat resembling the hull of an IS-2 1944. This will cause some confusion and delay the enemy's reaction & aiming time, as they now cannot directly see where your curved armour is, gifting you a precious few seconds before they open fire. For any leftover bushes, the turret front and the lower front plate are also good spots to put them on.

Pros and cons

Pros:

  • Good armour
  • Extremely durable against in down-tiered battles (when encountering lower rank M4 Shermans, Valentines, Pz.IV etc.)
  • Re-positioning of fuel tanks reducing chances of fires.
  • Good mobility with a fast reverse speed
  • Sufficient firepower
    • High rate of fire
    • Ability to fire APCR
  • Player skill compatibility between older and newer KV and IS models

Cons:

  • Large tank (slightly longer than the KV-1)
  • Difficult to angle armour due to weaker hull cheeks
  • Turret cheeks are easy to penetrate even at long distance
  • Commander cupola is a big weak spot
  • Poor gun depression (a common trait in all Soviet tanks)
  • Frontal shot trap underneath the turret will allow non-penetrating shells to ricochet and penetrate weaker armor when turret is hull-aligned.

History

Development

The start of the development for a new heavy tank in the Red Army came from the many criticisms of their current heavy tank, the KV-1. The KV-1 had poor mobility and a lack of firepower and armour advantage over the standard T-34, plus the KV-1 was more expensive to produce for no real advantage. Attempts to remedy this problem produced the KV-1S and the KV-85, which tried to make the KV-1 more mobile, more ergonomic, and have better firepower. Though they were improvements over the original KV-1 design, it was already determined that the KV-1 designs are to be replaced by a new heavy tank design and the newer KV-1 developments were to be interim designs until the heavy tank development is complete.

The heavy tank project, code-named Object 237, had its basis from the cancelled KV-13 program and was restarted from the discovery of the Tiger I after one was captured in Leningrad, thus it began in January 1943. However, despite the ensuing development, the intense tank fighting in 1943 in Kursk and ensuing operations forced the Object 237 to see action early, with its turret used on the KV-85, which itself was built atop the KV-1S hull. The turret mounted the new 85 mm D-5T gun and would be a great firepower advantage enjoyed by the Soviet tank forces as it gave them a heavy tank with comparable firepower to the Tiger I's 88 mm cannon. At the end of 1943, the Object 237 project was finished and was accepted into service as the IS-85, or the IS-1, named after Iosef (Joseph) Stalin, the current leader of the Soviet Union during World War II, putting an end to the Voroshilov (KV) line of tanks. The IS-1 began to be delivered in October 1943 and went into service in the same month. The IS-1 stayed in service until January 1944, when its production also ended with about 200 units produced.

Combat usage

The IS-1, like the KV-85 before it, was a great assist to the Soviet tank forces, giving them a heavily armoured tank with a great 85 mm gun that could defeat most of the German tanks in service except their heaviest ones such as the Tiger I and the Panther tanks. The IS-1 was issued to Guards Heavy Tank Regiments for service, most notably the 1st, 8th, and 13th Guards Heavy Tank Regiments which saw service in Ukraine and Slovakia. Within a standard IS-1 issue tank, there were often 59 85 mm rounds and 2,500 rounds for the three DT machine guns, which allowed it to have both superior armaments and capacity compared to the standard Tiger I.

The IS-1 had a short-lived production due to advances in Soviet tank technology. Their standard T-34 medium tanks were upgraded with the same 85 mm gun on the IS-1 into the T-34-85. The lack of firepower advantage the IS-1 now presented due to this upgrade prompted an up-gunning of the IS tank with a much bigger gun. After further development in late 1943, the IS-1 evolved into the IS-2, which has the larger and much more powerful 122 mm A-19 gun.


Archive of the in-game description

The IS-1 was developed in the spring and summer of 1943 by factory No. 100's design bureau led by Z.Y. Kotin. The tank's hull design and overall layout were taken from the previously developed experimental KV-13 tank. The main priority was creating reliable protection against the German 88 mm Flak 18 artillery cannon and making considerable mobility improvements by reducing the tank's mass and introducing a new epicyclic gearbox. The results of battles in 1943 revealed the need for a new heavy assault tank to replace the outdated mass-produced KV tanks. The prototype, designated IS, was built, tested and put into service in the Red Army in July-September 1943. Thanks to its new gearbox and the more streamlined placement of its strengthened armour, the new tank possessed superior mobility.

The IS's tight layout in its habitable section meant that a fifth crew member - the gunner/radio officer - would not fit inside. His duties were distributed between the commander and the driver.

Three crew were housed in the turret: the tank commander and the driver worked to the left of the gun, and the loader to the right. A command cupola with 82 mm thick vertical armour was installed in the tank's turret, and its hull had a hatch leading to the underside of the tank to allow the crew to evacuate in an emergency.

The IS-1 was armed with an 85 mm D-5T Mod. 1943 tank cannon and three machine guns.

It entered mass production in October 1943 at the ChKZ factory. In total, 130 of them were built.

The IS-1 was deployed in battles from February 1944 up to and including the winter of 1945. The results of these battles led to the conclusion that the armament and armour of the new tank were not equal to those of German heavy tanks. At that time, it was recommended that the shape and armour of the frontal hull be changed and the tank's armament upgraded immediately.


Media

Images
  • ArtImage IS-1.png
Skins
Videos
The Shooting Range #61 - Pages of History section at 09:02 discusses the IS-1.
The IS Family - War Thunder Official Channel

See also

Links to the articles on the War Thunder Wiki that you think will be useful for the reader, for example:

  • reference to the series of the vehicles;
  • links to approximate analogues of other nations and research trees.

External links

References


Chelyabinsk Tractor Plant (Челябинский тракторный завод)
IFVs 
BMP-1  BMP-1
Heavy Tanks 
KV  KV-85 · KV-122
IS-1/2  IS-1 · IS-2 · IS-2 (1944) · IS-2 "Revenge" · IS-2 No.321
T-10  T-10A · T-10M
Other IS Tanks  IS-3 · IS-4M
Tank Destroyers 
KV Derivatives  SU-152
IS Derivatives  ISU-152 · ISU-122 · ISU-122S · Object 268
Export 
IS-2  ␗IS-2 · IS-2 No.402 · ␗IS-2 (1944)
ISU  ␗ISU-152 · ␗ISU-122
IFVs  SPz BMP-1
See Also  Leningrad Kirov Plant

USSR heavy tanks
KV-1  KV-1 (L-11) · KV-1 (ZiS-5) · KV-1E · KV-1S
KV-2  KV-2 (1939) · KV-2 (1940) · KV-2 (ZiS-6)
Other KVs  KV-85 · KV-122 · KV-220
IS-1/2  IS-1 · IS-2 · IS-2 (1944) · IS-2 No.321 · IS-2 "Revenge" · Object 248
Other IS tanks  IS-3 · IS-4M · IS-6 · IS-7
T-10  T-10A · T-10M
Multi-turreted  T-35 · SMK
Other  Object 279
Lend-Lease  ▂MK-II "Matilda"

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