Armour is the basic defense an entity has against threats. Armour can be found in both air and ground vehicles in War Thunder and plays a very important role to the vehicle's survivability.
Armour plays a very important role on tanks as they were conceived by it. The armour on the tanks at its inception made them invulnerable to the basic small arms fire, a trait that broke the stalemate of the trench warfare in World War I. During the interwar period, tank armour was prioritized on protection against firearms and artillery shrapnel. However, experience in the Spanish Civil War showed that this concept leaves the tank vulnerable to heavier guns. This is demonstrated when Italian tankettes and German Panzer I's, armed with only machine guns and simple 13 mm armour, went up against the Soviet T-26, which had a 45 mm gun on its turret. The tank arms race increased armament and armour, evident on the German Panzer IV when armour increased from the initial 14.5 mm in 1936 to 30 mm in 1938 before World War II broke out.
Early World War II
During World War II, tank armour played a huge part in tank design. More armour means more weight on the tank and thus must be sparingly used to the tank mobility in acceptable margins. Tank armour in this period is separated by the three tank categories, light, medium, and heavy tanks. It was in this period that tank armour went through many technological advances. One of the perfect example is the French SOMUA S35 and the Soviet T-34. The two vehicles made extensive usage of the concept of "sloped armour", which increased the armour effective thickness due to the difference in the line-of-sight thickness (See "Concepts" section). The Germans, which mainly used vertical-faced armour on their Panzers, struggled to take these vehicles out due to their strong armour against their inadequate guns. While the Battle of France did not incite Germany to quickly upgrade their armour and armament due to the small quantities of these kinds of tanks, the encounter with the T-34's in Operation Barbarossa came as a great shock due to the large number of T-34's available in Soviet inventory. The Germans, in a stage informally known as a "tank panic", rushed development to complete weapons able to destroy the T-34 and uparmour their tanks to withstand the Soviet 76 mm cannons. The Soviet T-34 and American M4 Shermans caused great headaches in the German armoured forces due to their strong, sloped front armour in 1942, but that all changed in 1943 and beyond.
Late World War II
The year 1943 changed everything in the balance of tank power from the Allies with their T-34 and Shermans to the Germans. Germany introduced their newest tanks in large quantities, the Panther and the Tiger I tanks. These vehicles introduced powerful cannons and a new redefinition of the term "armour" for tanks. The Tiger I came with an astounding 100 mm armour thickness in front. Though vertical-faced and thus did not have the benefit of "sloped armour", the guns on Shermans and T-34 at the time could not penetrate the front plate at standard combat ranges, forcing the Allied medium tanks to close in for a kill. The Panther had 80 mm of frontal armour, but that armour was sloped at a 55° from vertical and caused the effective armour to instead be 140 mm thick. Thus, the Panther was basically invulnerable in the hull front from any anti-tank weapon in existent in Allied inventory. The Germans also started to extensively used an armour called Schürzen, which is a form of "spaced armour" that provided additional protection to their tank's weak side armour. The two new tanks, plus a new one in the form of the Tiger II with 150 mm of frontal armour sloped for effective thickness of ~200 mm, caused turmoil in the Allied armoured forces as they find a way to easily destroy the new tanks. They were never able to compete against the German's in terms of armour thickness until after World War II.
By the end of World War II, sloping armour had become a ubiquitous concept and every tank designed has it from the American M60, British Centurion, and Soviet T-54/55 tanks. With increasing tank armour equaling to increased weight, countries try to keep their tank weight in manageable ranges while making the armour up to date with current threats. By early 1960s, anti-tank technology such as the anti-tank guided missiles (ATGM) has grown to the point where it requires a large amount of steel to make the armour thick enough to resist the threat, but the amount was prohibitive and made the tank too heavy. Some nations such as Germany tried to solve this by relying on mobility at the expense of armour such as the Leopard I, but it became clear a new type of armour is needed. It came in the form of "composite armour", which used steel combined with a variety of material such as plastic and ceramic that can resist penetration more effectively at a lighter weight. Composite armour soon became the new standard of tank armour throughout the world. Another armour developed in the Cold War was the "explosive reactive armour", which used an explosive to deflect a penetration property. Explosive reactive armour, or ERA, was highly effective against the ubiquitous HEATFS rounds used as anti-tank weapons. These armour technology saved the tanks from becoming obsolete during the Cold War against the new anti-tank missile threat that allows a small infantry crew to destroy a tank as far as 2000 meters away. Composite armour, ERA, and the increasing lethality of tank armament helped revolutionize the tank concept from light, medium, and heavy tanks into the new, universal "main battle tank".
Types of Armour
- Rolled homogeneous armour (x1.00 armour rating)
- Cast homogeneous armour (x0.94 armour rating)
- Structural steel (x0.45 armour rating)
- Aluminum Alloy 7039 (x0.47 armour rating)
- High hardness rolled armour (x1.25 armour rating)
- Face hardened armour (x1.05 armour rating)
- Gun steel (x1.10 armour rating)
- Suspension wheels (x0.60 armour rating)
- Armoured glass (x0.28 armour rating)
Sloped armour is effectively angling the armour of a tank on an angle rather than placed for a flat surface.
Slope armour presents the advantage of having a much thicker effective armour on a tanks for a lighter weight due to using a thinner armour plate. The sloped nature also increases the chance of the impacting shell to simply ricochet or deflect off, doing no effect to the armour. The disadvantage of the sloped armour was its more complicated manufacturing process and a reduction in internal space.
Calculating sloped armour effective thickness
A simple formula to calculate a tank's effective thickness on a horizontal plane (Line Of Sight, or LOS) due to sloping armour is with this:
LOS Effective Thickness = Armour thickness / cos (Armour angle)
For example, the Panther has a 80 mm front armour plate thickness, sloped at 55° from vertical. Thus, we input the values:
LOS Effective Thickness = 80 mm / cos (55°) = 80 mm / 0.574 = ~140 mm
Thus, we get the value of how thick the Panther's sloped frontal armour is in a line-of-sight angle.
NOTE: This formula does not take into any consideration of any compound angling of the armour.
Spaced armour helps against anti-tank rounds in a form of disruption and denial. Spaced armour was first widely used by the Germans in the form of Schürzen, attaching metal sheets away from the base armour of their Panzers. These metal sheets were intended to disrupt the kinetic energy of the Soviet anti-tank rifles, which could penetrate the weaker side armour of their tanks. It does this by forcing much of the energy on the rifle round to be expelled on the Schürzen sheets, passing through and causing negligible damage on the base side armour. The Schürzen may also disrupt tank rounds as well, but the much greater kinetic energy of tank shells means that its disruption will be ineffective to all but the most sloped shots. There is a highly-popular rumor that Schürzen and space armour can deny HEAT warheads from affecting the base amour, however this notion is false.
Main article: Add-on Armor
Add-on armour is a form of improvisation of the tank armour usually done by the crew or a maintenance unit in the front lines. Due to the rushed nature of tank technology in World War II, armour once considered adequate on tanks can quickly become obsolete with the introduction of a new gun piece in the field or a new equipment, such as the 8.8 cm KwK 36 on the Tiger I and the Panzerfaust anti-tank launcher, both could cut through Sherman and T-34 armour with little resistance. The declining armour effectiveness against these weapons prompted the tank crews to attempt an expedient method to improve the armour quality of their tanks. Troops went and attached logs, sand bags, tracks, concrete, and metal sheets onto their tanks to improve its effective thickness. The usefulness against anti-tank rounds from tank shells and HEAT rounds are controversial. Some tankers swear by it and claim they were saved by their improvised armour while analysts say that the add-on armour has no effect at all in interfering with incoming rounds. What was universally accepted was that these add-on armour helped improve the tank crew morale when fighting the enemy, renewed in confidence with their "improved" tank armour. However, add-on armour increases the weight of the tank due to the add-on of materials and thus can cause a strain on the power train and suspension of tanks, prompting some commanders like General George S. Patton to ban the usage of improvised armour to improve tank reliability. The most useful add-on armour was the welding of additional sheets of metal onto the tank, as seen in the well-received reception of the up-armoured M4 Sherman in the form of the "Jumbos".
From Update 1.57, a modification known as the Add-on Armor was added onto certain vehicles. The modification adds spare track links along the hull and turret of the vehicle. The track links, when added, give an average of 17 - 20 mm of additional armour where they are attached.