HistoryThe British Mark IX tank was the first specialised armoured personnel carrier. The genesis of the armoured personnel carrier was on the Western Front of World War I. In the later stage of the war, Allied tanks could break through enemy lines, but the infantry following — who were needed to consolidate the gains — still faced small arms and artillery fire. Without infantry support, the tanks were isolated and more easily destroyed. In response, the British experimented with carrying a squad of infantry in a lengthened version of the Mark V tank. When that proved unworkable, Britain designed the first purpose built armoured troop transport, the Mark IX — but it arrived too late to see combat.
During World War II, half-tracks like the American M3 and German SdKfz 251 played a role similar to post-war APCs. Over the course of the war, APCs evolved from simple armoured cars with transport capacity, to purpose built vehicles. Obsolete armoured vehicles were also repurposed as APCs, such as the various "Kangaroos" converted from M7 Priest self-propelled guns and from Churchill, M3 Stuart and Ram tanks.
During the Cold War, more specialized APCs were developed. The United States introduced a series of them, including successors to the wartime Landing Vehicle Tracked; but the most prolific was the M113 armored personnel carrier, of which 80,000 were produced. Western nations have since retired most M113s, replacing them with newer APCs, many of these wheeled. The Soviet Union produced the BTR-40, BTR-152, BTR-60, BTR-70, BTR-80 and BTR-90 in large numbers. The BTR-60, 80, and 90 remain in production. A cold war example of a "Kangaroo" is the heavily armoured Israeli Achzarit, converted from captured T-55s tanks.
Weight can vary from 6 to 40 tons or more, but 9 to 20 tons is typical. Most have a capacity of between 8 and 12 dismountable troops, though some can carry over 20. In addition, it has a crew of at least one driver, many with a gunner and/or commander as well. Most armoured personnel carriers use a diesel engine comparable to that used in a large truck or in a typical city bus. The M113 for instance used the same engine as the standard GM city bus.
An APC is either wheeled or tracked, or occasionally a combination of the two, as in a half-track. Both systems have advantages and limitations.
Tracked vehicles have more traction off-road and more maneuverability, including a minute turn radius. Due to the limited service life of their treads, plus the wear they cause on roads, tracked vehicles are typically transported cross country by rail, flatbed trucks or purpose built transporters.
Wheeled APCs are faster on road, and can cross long distances. Wheeled vehicles have higher ground pressure than tracked vehicles with a comparable weight, due to tracks having more surface area in contact with the ground. The higher ground pressure increases the likelihood of becoming immobilized by terrains such as mud, snow, or sand.
Many APCs are amphibious. Their tracks can propel the APC in the water. Wheeled APCs will include propellers or water jets. Preparation for amphibious operations usually comprises checking the integrity of the hull and folding down a trim vane in front. Water traverse speed varies greatly between vehicles. The maximum swim speed of the M113 is 3.8 mph, whereas the LAV-25 and AAVP-7 about double that at 6.5 and 8.2 mph, respectively.
LVTP-5 amphibious armored fighting vehicles, 1966 APCs must provide a minimum amount of protection against small arms fire to be considered as such, though some provide as much protection as a main battle tank, as is the case of the IDF Namer, which is based on a Merkava tank. Armour is usually composed of steel or aluminium. Some APCs also come with NBC protection, which is intended to provide protection from weapons of mass destruction.
Generally APCs will be lighter and less armoured than tanks or IFVs, often being open topped and featuring doors and windows, as seen in the French VAB.
An APC carries a primary weapon no larger than a 20mm autocannon, before falling into the "infantry fighting vehicle" sub-classification, and will most likely be outfitted with one or more machine guns ranging from 5.56mm to 7.62mm. The primary weapon is usually on the top of the vehicle, mounted with either a simple pintle mount, in a small turret, or a remote weapon system.
Pintle mounted weapons are now rare, due to the lack of crew protection. In World War II, the German Sd.Kfz. 251 half-track was equipped with at least one MG42 or MG34, which could only be aimed in a small arc from whichever end of the vehicle the weapon was mounted and offered minimal protection to the gunner. Turrets provides a traverse of 360 degrees and operator protection. Most APC turrets include a coaxial machine gun (MG) alongside the primary weapon. A recent advent, remote weapon systems (RWS) are used in lieu of pintle mounts and provide the same level of operator protection as a turret, with the added benefit of increased visibility without increasing the overall profile of the vehicle. However, unlike in a turret, the weapon cannot be reloaded from inside the vehicle.
A common primary gun on an APC is a 50 caliber M2 Browning machine gun, or the equivalent 14.5mm KPV heavy machine gun. The Stryker carries an M2 on a CROWS RWS. 7.62mm machine guns are commonly used as coaxial or secondary weapons. Several Eastern personnel carriers have forward facing machine guns, or firing ports in the crew compartment. The AAVP7 mounts an M2 50 caliber as a coaxial machine gun, beside a Mark 19 automatic grenade launcher. Occasionally APCs will be equipped with anti-tank missiles.
In a fight against the undead, APCs will be used by military forces for the same purpose of protecting infantrymen from harm until they can dismount. If zombies try to storm one to try and attack the occupants, it would be a futile effort on their part. APCs are designed to protect the crew from (varies on design) small and medium caliber rounds, RPGs, and mines and IEDs; against a horde of zombies, clawing at the hull or even armored glass would do nothing but scrape their fingers down to the bone. If the crew closes up all hatches they may not even be aware there are people in a vehicle sitting on the side of the road. If needed, the vehicle can simply drive through a horde to get out of being surrounded, although that would crush and cripple a number of zombies and require a careful sweep later on. A potential tactic to keep troops safe while still fighting is for them to sit on the roof and fire their weapons on the undead, as the top is usually too high to reach and zombies are too uncoordinated to climb, especially when any that could figure it out would get shot quickly. This tactic may not work with APCs that are short like the Soviet/Russian BMP series. Using APCs would work against zombies like they would in any other combat situation, but they aren't the most efficient way of moving things around in a battle with the undead. APCs are heavy from armor and require higher maintenance, while military trucks would be more suited for the situation because they are lighter, cheaper, require less fuel and maintenance, and have acceptable mobility, while armor protection is not a main concern when the enemy is not shooting anything.