Main Battle Tank

Overview

A main battle tank is the heaviest direct-fire weapon in a land army, built to deliver a large gun anywhere on the battlefield while surviving the fire of every other weapon there. Its design is the constant negotiation between three demands that fight one another: firepower, protection, and mobility. Add armor and the tank grows too heavy to move; lighten it and it cannot survive; add a bigger gun and the turret and ammunition stowage grow. A modern tank of 50 to 70 tonnes is the balance point reached with composite armor, a high-output engine, and a fire-control system that lets it hit first.

The major systems are the Armored Hull and Main Gun Turret that form the armored body, the Power Pack and Running Gear that move it, the Fire Control System that aims the gun, and the Armor Suite and Active Protection Systems that keep it alive.

Hull and crew layout

The Armored Hull is a welded steel structure. The steeply sloped Glacis Plate is the most heavily protected face, designed to defeat both kinetic penetrators and shaped charges. Hull Side Armor armor and skirts guard the flanks, and a reinforced Belly Plate resists mine blast. The driver lies reclined at the Driver Station low in the front, clear of the rotating turret basket that sits on the Turret Slewing Ring. A Spall Liner lines the crew spaces to catch fragments.

The gun and turret

The Main Gun Turret carries the firepower. Its Main Gun is a 120 or 125 mm smoothbore firing fin-stabilized kinetic penetrators, shaped-charge rounds, and guided projectiles. Many tanks use an Autoloader that rams the round and charge into the breech, raising the rate of fire and reducing the crew. A Coaxial Machine Gun handles infantry and light targets, the Recoil System absorbs the firing shock, and a Gun Mantlet protects the gun opening. The turret turns on a Turret Traverse Drive using a Servo Motor and Helical Gear Pair. Crucially, ammunition sits in a Ammunition Bustle behind blow-off panels, so that if a round cooks off, the explosion vents upward and away from the crew rather than into the fighting compartment.

Mobility

The Power Pack is one removable unit so a damaged engine can be swapped in under an hour. The Power Plant, a diesel or gas turbine of 900 to 1100 kW, gives the heavy tank the power-to-weight for sustained cross-country speed, driving a hydromechanical Hydromechanical Transmission that propels and steers through a Final Drive on each side. A Cooling Group rejects the heat, a Combat Air Cleaner filters battlefield dust, and a protected Protected Fuel Cell separates fuel from the crew.

The Running Gear carries the weight. Many Track Link units form the track, Road Wheel units carry the load, a Drive Sprocket propels it, and a Idler Wheel sets tension. Each wheel rides on a Torsion Bar with a Rotary Damper at the hardest-worked stations, and a Track Skirt shields the running gear from side attack.

Hitting first

The Fire Control System system is what wins tank duels. The gunner lays the gun through a stabilized Gunner Primary Sight with a built-in Laser Rangefinder and a Thermal Imager, while the commander hunts independently through a Commander Sight, a hunter-killer arrangement that keeps targets coming. A Ballistic Computer combines range, target motion, cant, and wind to lay the gun for a first-round hit, and a Gun Stabilizer holds the aim while the tank moves at speed. The advantage of firing first is decisive in tank combat, since a kinetic penetrator crosses two kilometres in about two seconds and the side that lands the first accurate round usually ends the engagement. This is why so much of the tank cost and complexity sits in the sights and the computer rather than in the gun itself, which has changed far less over recent decades than the systems that aim it.

Staying alive

The Armor Suite defeats the threats that the base hull cannot. A Composite Armor Module of steel, ceramic, and other layers defeats long-rod penetrators far better than steel of the same weight, a Reactive Armor Tile disrupts shaped-charge jets, a Slat Cage crushes shoulder-fired rockets, and added Roof Armor counters top-attack weapons.

Beyond passive armor, the Active Protection Systems try to stop the hit from landing. A Threat Radar detects an incoming missile and a Hard-Kill Interceptor destroys it a few metres out, while a Laser Warning Sensor sensor cues the Smoke Launcher to screen the tank. A Fire Suppression System system quenches any fire within milliseconds.

Electronics

The Vehicle Electronics tie the tank into its formation. A Vetronics Unit links the powerpack, turret, and protection systems, a Combat Net Radio carries encrypted traffic, a Battle Management Terminal shows the shared tactical map, a Navigation Unit keeps position under jamming, and a Driver Display lets the driver work closed-down in darkness.