Army Tank Design (new)

The three traditional factors determining a tank's effectiveness in battle are its firepower, protection, and mobility. Since the Second World War, the economics of tank production governed by the ease of manufacture and cost, and the impact of a given tank design on logistics and field maintenance capabilities, have also been accepted as important in determining how many tanks a nation can afford to field in its force structure.?


















No tank design has ever been fielded in significant numbers that proved to be too complex or expensive to manufacture, and made unsustainable demands on the logistics services support of the armed forces. The affordability of the design therefore takes precedence over the field performance characteristics. Nowhere was this principle illustrated better than during the Second World War when two Allied designs, the T-34 and the M4 Sherman, although both simple designs which accepted engineering compromises, were used successfully against more sophisticated designs by Germany which were harder to produce, were more expensive and demanding on overstretched logistics of the Wehrmacht. Given that a tank crew will spend most of its time occupied with maintenance of the vehicle, engineering simplicity has become the primary constraint on tank design since the Second World War despite advances in mechanical, electrical and electronics technologies.

Firepower is the ability of a tank to identify, engage, and destroy. Protection is the tank's ability to resist being detected, engaged, and disabled or destroyed. Mobility includes tactical (short range) movement over the battlefield including over rough terrain and obstacles, as well as strategic (long range) mobility, the ability of the tank to be transported by road, rail, sea, or air to the battlefield.

Tank design is a compromise; it is not possible to maximise firepower, protection and mobility simultaneously. For example, increasing protection by adding armour will result in an increase in weight and therefore decrease mobility; increasing firepower by installing a larger gun will force the designer to sacrifice speed or armour to compensate for the added weight and cost. Even in the case of the Abrams MBT which has good firepower, speed and armour, these advantages are counterbalanced by its notably thirsty engine, which ultimately reduces its range and in a larger sense its mobility.

Since World War II tank development has shifted focus from experimenting with large scale mechanical changes to the tank design to focusing on technological advances in the tank's subsystems to improve its performance. However, a number of novel designs have appeared throughout this period with mixed success, including the Soviet IT-1, the Swedish S-tank, the Israeli Merkava, and the incorporation of autoloaders to reduce the crew complement in a number of tanks.

Firepower

The main weapon of all modern tanks is a single, large-calibre gun mounted in a fully traversing turret. The typical tank gun is a smoothbore weapon capable of firing armour-piercing kinetic energy penetrators (KEP), also known as armour-piercing discarding sabot (APDS), and/or armour piercing fin stabilised discarding sabot (APFSDS) and high explosive anti-tank (HEAT) shells, and/or high explosive squash head (HESH) and/or anti-tank guided missiles (ATGM) to destroy armoured targets, as well as high explosive (HE) shells for engaging soft targets or fortifications. Canister shot may be used in close or urban combat situations where the risk of hitting friendly forces with shrapnel from HE rounds is unacceptably high.

A gyroscope is used to stabilise the main gun, allowing it to be effectively aimed and fired at the "short halt" or on the move. Modern tank guns are also commonly fitted with insulating thermal jackets to reduce gun-barrel warping caused by uneven thermal expansion, bore evacuators to minimise fumes entering the crew compartment and sometimes muzzle brakes to minimise the effect of recoil on accuracy and rate of fire.

Traditionally, target detection relied on visual identification. This was accomplished from within the tank through telescopic periscopes; occasionally however, tank commanders would open up the hatch to view the outside surroundings, which improved situational awareness but incurred the penalty of vulnerability to sniper fire, especially in jungle and urban conditions. Though several developments in target detection have taken place especially recently, these methods are still common practice.

In some cases spotting rifles were used confirm proper trajectory and range to a target. These spotting rifles were mounted co-axially to the main gun, and fired tracer ammunition ballistically matched to the gun itself. The gunner would track the movement of the tracer round in flight, and upon impact with a hard surface, it would give off a flash and a puff of smoke, after which the main gun was immediately fired. However these have been mostly superseded by laser rangefinding equipment.

Modern tanks also use sophisticated light intensification and thermal imaging equipment to improve fighting capability at night, in poor weather and in smoke. The accuracy of modern tank guns is pushed to the mechanical limit by computerised fire-control systems. A fire-control system uses a laser rangefinder to determine the range to the target, a thermocouple, anemometer and wind vane to correct for weather effects and a muzzle referencing system to correct for gun-barrel temperature, warping and wear. Two sightings of a target with the range-finder enable calculation of the target movement vector. This information is combined with the known movement of the tank and the principles of ballistics to calculate the elevation and aim point that maximises the probability of hitting the target.

Usually, tanks carry smaller calibre armament for short-range defence where fire from the main weapon would be ineffective, for example when engaging infantry, light vehicles or aircraft. A typical complement of secondary weapons is a general-purpose machine gun mounted coaxially with the main gun, and a heavier antiaircraft machine gun on the turret roof. These weapons are often modified variants of those used by infantry, and so utilise the same kinds of ammunition.

Protection

The British Challenger II is protected by Dorchester armour: second-generation Chobham armour

The measure of a tank's protection is the combination of its ability to avoid detection, to avoid being hit by enemy fire, its resistance to the effects of enemy fire, and its capacity to sustain damage whilst still completing its objective, or at least protecting its crew. In common with most unit types, tanks are subject to additional hazards in wooded and urban combat environments which largely negate the advantages of the tank's long-range firepower and mobility, limit the crew's detection capabilities and can restrict turret traverse. Despite these disadvantages, tanks retain high survivability against previous-generation Rocket-Propelled Grenades in all combat environments by virtue of their armour.

Almost every advanced Main Battle Tank is fitted with the British 'Chobham Armour' design; with two examples being the American 'M1 Abrams' and the German 'Leopard II'. This is the most advanced armour plating available for any tank (with the exception of the British 'Challenger II') and has been proven against a wide array of Rocket Propelled Weaponry and Explosives.

However, as effective and advanced as armour plating has become, tank survivability against newer-generation tandem-warhead anti-tank missiles is a concern for military planners.

Avoiding detection

A tank avoids detection using the doctrine of CCD: camouflage (looks the same as the surroundings), concealment (cannot be seen) and deception (looks like something else).

Working against efforts to avoid detection is the fact that a tank is a large metallic object with a distinctive, angular silhouette that emits copious heat and noise. Consequently, it is difficult to effectively camouflage a hull-up tank in the absence of some form of cover or concealment (e.g., woods). The tank becomes easier to detect when moving (typically, whenever it is in use) due to the large, distinctive auditory, vibration and thermal signature of its power plant. Tank tracks and dust clouds also betray past or present tank movement. Switched-off tanks are vulnerable to infra-red detection due to differences between the thermal conductivity and therefore heat dissipation of the metallic tank and its surroundings. At close range the tank can be detected even when powered down and fully concealed due to the column of warmer air above the tank and the smell of diesel.

Thermal blankets slow the rate of heat emission and camouflage nets use a mix of materials with differing thermal properties to operate in the infra-red as well as the visible spectrum. Camouflage attempts to break up the distinctive appearance and silhouette of a tank. Adopting a turret-down or hull-down position reduces the visible silhouette of a tank as well as providing the added protection of a position in defilade.

Armour

M4 Sherman tank of 741st Tank Battalion, U.S. First Army, burns in a street in Leipzig, Germany, 1945.
The TUSK for the M1 Abrams is intended to improve survivability in urban environments
To effectively protect the tank and its crew, tank armour must counter a wide variety of antitank threats. Protection against kinetic energy penetrators and high explosive anti-tank (HEAT) shells fired by other tanks is of primary importance, but tank armour also aims to protect against infantry antitank missiles, antitank mines, bombs, direct artillery hits, and (less often) nuclear, biological and chemical threats, any of which could disable or destroy a tank or its crew.

Steel armour plate was the earliest type of armour. The Germans pioneered the use of face hardened steel during World War II and the Soviets also achieved improved protection with sloped armour technology. World War II developments also spelled the eventual doom of homogeneous steel armour with the development of shaped-charge warheads, exemplified by the Panzerfaust and bazooka infantry weapons which were lethally effective, despite some early success with spaced armour. Magnetic mines led to the development of anti-magnetic paste and paint.

British tank researchers took the next step with the development of Chobham armour, or more generally composite armour, incorporating ceramics and plastics in a resin matrix between steel plates, which provided good protection against HEAT weapons. Squash head warheads led to anti-spall armour linings, and KEPs led to the inclusion of exotic materials like a matrix of depleted uranium into a composite armour configuration. Reactive armour consists of small explosive-filled metal boxes that detonate when hit by the metallic jet projected by an exploding HEAT warhead, causing their metal plates to disrupt it. Tandem warheads defeat reactive armour by causing the armour to detonate prematurely. Grenade launchers which can rapidly deploy a smoke screen and the modern Shtora soft-kill countermeasure system provide additional protection by interfering with enemy targeting and fire-control systems.

The latest generation of protective measures for tanks are active protection systems, particularly hard-kill countermeasures. The Israeli TROPHY and Iron Fist, the American Quick Kill, the Soviet Drozd, and Russian Arena systems show the potential to dramatically improve protection for tanks against missiles, RPGs and potentially KEP attacks, but concerns regarding a danger zone for nearby dismounted troops remain.

Mobility

The mobility of a tank is described by its battlefield or tactical mobility, its operational mobility, and its strategic mobility. Tactical mobility can be broken down firstly into agility, describing the tank's acceleration, braking, speed and rate of turn on various terrain, and secondly obstacle clearance: the tank's ability to travel over vertical obstacles like low walls or trenches or through water. Operational mobility is a function of manoeuvre range; but also of size and weight, and the resulting limitations on options for manoeuvre. For example, in a given sector of front, a T-80 equipped tank formation might have many more potential axes for rapid advance than a heavier M-1 Abrams equipped formation, because of the capacity limits of roads and bridges. Strategic mobility is the relative ease with which a military asset can be transported between theatres of operation and falls within the scope of military logistics. For example, a smaller tank, able to travel through rail tunnels on flatbed rolling stock, might have greater strategic mobility than a larger one.

Tank agility is a function of the weight of the tank due to its inertia while manoeuvring and its ground pressure, the power output of the installed power plant and the tank transmission and track design. In addition, rough terrain effectively limits the tank's speed through the stress it puts on the suspension and the crew. A breakthrough in this area was achieved during World War II when improved suspension systems were developed that allowed better cross-country performance and limited firing on the move. Systems like the earlier Christie or later torsion-bar suspension developed by Ferdinand Porsche dramatically improved the tank's cross-country performance and overall mobility.[27]

A main battle tank is highly mobile and able to travel over most types of terrain due to its continuous tracks and advanced suspension. The tracks disperse the significant weight of the vehicle over a large area, resulting in a ground pressure comparable to that of a walking man.A tank can travel at approximately 40 kilometres per hour (25 mph) across flat terrain and up to 70 kilometres per hour (43 mph) on roads, but due to the mechanical strain this places on the vehicle and the logistical strain on fuel delivery and tank maintenance, these must be considered "burst" speeds that invite mechanical failure of engine and transmission systems. Consequently, wheeled tank transporters and rail infrastructure is used wherever possible for long-distance tank transport. The limitations of long-range tank mobility can be viewed in sharp contrast to that of wheeled armoured fighting vehicles. The majority of blitzkrieg operations were conducted at the pedestrian pace of 5 kilometres per hour (3.1 mph), that only was achieved on the roads of France.

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