The M113 is an armored personnel carrier family of vehicles in use with the US military and many other nations.
It is a fully tracked vehicle capable of limited amphibious operation in lakes and streams, extended cross-country travel over rough terrain, and high speed operation on improved roads. The M113 family has many variants and modifications that are used in a variety of combat and combat support roles. Approximately 80,000 units of all types have been produced worldwide making it the most widely used armored fighting vehicle of all time. Although not a tank, or even designed as a fighting vehicle, the M113 was the most utilised armored vehicle of the Vietnam War. It inspired newer generations of more heavily armored and armed infantry fighting vehicles. Yet it remains in front-line service and production in the 21st century.
The M113 was first introduced in 1960 and in 1962 was fielded in Vietnam, but without the added ACAV sets, which consisted of gun shields and belly armor. The M113 was developed from the M59 and M75 Armored Personnel Carrier which were designed by Food Machinery Corp. and Kaiser Aluminium and Chemical Co. in the late 1950s.
Two vehicles were initially considered, the T113 and T117. The T113, effectively the prototype of the M113, was chosen because it was marginally lighter than the T117. This was a product of the T113 being made of aluminum rather than steel. This difference on construction material was the major difference between the two vehicles. The T113 design was improved upon as the T113E1, and adopted by the US Army in 1960 as the M113. A diesel prototype T113E2 was put into production in 1964 as the M113A1. The M113A1 quickly supplanted the gasoline engined M113 in service.
Design and development
The M113 first entered service with the U.S. Army in 1960. It was developed to provide a highly mobile, survivable, and reliable tracked-vehicle platform that is able to keep pace with the current armored vehicles and tanks of the day. It requires only two crewmen, a driver and a commander, and carries eleven passengers inside the vehicle. Its main armament is a single .50 cal (12.7 mm) M2 Browning machine gun operated by the commander.
The M113 was designed to transport troops, protected against small arms fire and shell fragments, to the front line where they would disembark. During early engagements in the Vietnam War, when Army of the Republic of Vietnam (ARVN) troops were pinned down by fire, they found that they could not simply return fire from within and overwhelm opposing forces. The exposed .50 caliber machinegunner's position made the gunner vulnerable to enemy small arms fire, even if the opposing force lacked the firepower to stop their lightly armored M113s. They soon fitted makeshift shields for the vulnerable machine gun.
Modified versions of the Vietnam War ACAV sets have been deployed to Iraq (Formally referred to as Southwest Asia within the US military) for installation on the current M113 series vehicles in use. An improved circular shield turret deployed to Iraq, and such vehicles have been utilized without the 2 rear stations. However, they reportedly are modified with armor to protect the Track Commander (TC) position and are NOT employing the two rear left and right machine gun stations.
The M113 is built of aircraft quality aluminum which gives it some of the same strength as steel at a slightly reduced weight (the vehicle weighs approximately 10.5 tons), as the greater thickness allows structural stiffness. Its weight allows the use of a relatively small engine to power the vehicle, a Detroit 2-stroke six cylinder diesel, as well as allowing the vehicle to carry a large payload cross-country and to be transported by fixed and rotary-wing aircraft. It can also swim without deploying any flotation curtains, powered by tracks, which was of tactical importance in battlefields like Vietnam which required crossing a multitude of terrain features; such as jungles, swamps, muddy dirt roads, forests, and rice fields.
The current M113A3 has a 480 km range and a maximum speed of 64 km/h. The upgraded M113A3 has added spall suppression liners, armored external fuel tanks, a more powerful engine and transmission, and mounting plates for the option of bolt-on titanium, aluminum, ceramic, or high-hardness steel appliqué armor. Band tracks and hybrid-electric drive features can make the M113 stealthy and travel faster than 60 mph on roads while doubling range from 300 to 600 miles on one load of fuel, but these features have not be added to operational vehicles.
The basic M113 armored personnel carrier can itself be fitted with a number of weapon systems. Most common is a single .50 caliber M2 machine gun or 40mm Mk 19 automatic grenade launcher. A number of anti-tank weapons were also fitted. Armored Cavalry units in Vietnam removed jeep mounted M40 106mm recoilless rifles fitting them to their M113s instead. The US Army also developed a kit that allowed the Dragon anti-tank missile system to be mounted to the existing machine gun mount, without having to remove the machine gun. This allowed the commander to use the weapon, as well as the machine gun.