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The M76 amphibious combat vehicle, codenamed "Otter", was a combat vehicle in service in the 50s of the last century, developed by General Motors of the United States, using some new technologies that had just appeared at that time, such as the front engine. As a tracked combat vehicle, the "Otter" can travel on the water, and the cleats and rubber plates on the tracks allow the "Otter" amphibious transport vehicle to move freely in swampy terrain.
"Otter" M76 amphibious combat vehicle
A new harvest for the pick-up man
In World War II, the size of the U.S. Marine Corps swelled dramatically, becoming the main force of the U.S. military in amphibious landings and island operations, and in order to counter the enemy's anti-landing forces in the landing, the U.S. Marine Corps was equipped with a large number of tanks and armored vehicles. However, in the early landing operations, the front-line commanders found that not only were the tanks with high hopes often trapped in the soft sand and became a live target for enemy artillery fire, but even the various wheeled transport vehicles were often difficult to protect themselves, and even when they went deep inland to expand the results of the battle, these armored vehicles were often limited by the muddy terrain, thus falling into the dilemma of "a buffalo falling into a well - unable to use the strength", which was particularly obvious in the Pacific theater.
In order to solve this problem, both the U.S. Marine Corps and the Army have introduced the M29 "Weasel" series of transporters as a supplement, although the vehicle has poor protection, but the body is lightweight, not only passable, can pass through the shallows and water network areas that ordinary tracked vehicles cannot pass, and can even directly cross minefields without triggering anti-tank mines and anti-infantry mines (the track can be blown up when exploding), so it is widely used as personnel and vehicle transporters, armored command vehicles, armored ambulances and armored overhead vehicles, etc.
Although the performance of the M29 series is still excellent, with the passage of time, its performance has been unable to meet the needs of the US military, so the introduction of the next generation of amphibious transport vehicles is imperative, and the M76 came into being. Due to its amphibious characteristics, it was also given the nickname "Otter".
A prototype of the T46E1 in the U.S. Army livery that has survived to this day
Extremely thin and lightweight
M76 is a full crawler structure, the total length of the body is 4.9 meters, the width of the body is 2.5 meters, the height of the body is 2.31 meters, and the total combat weight is 1.5 tons. Compared with the American-made armored vehicles of the same period, the biggest feature of the M76 is the word "light".
In order to pursue "lightness", the car adopted an all-aluminum body structure that was shocking at the time, so as to minimize the overall weight of the vehicle while ensuring the structural strength, of course, this also caused the extreme lack of its protective ability, which laid the groundwork for a series of performances on the battlefield later.
Unlike other armored vehicles, where defense is emphasized, the M76 has an engine bay at the nose and a cockpit behind it, structurally similar to a civilian truck. The car uses a Continental AIO-268 air-cooled 4-cylinder gasoline engine, which is improved from an aero engine, with a rated power of 130 horsepower and a maximum road maneuvering speed of up to 50 km/h.
It is worth mentioning that the M76's wheels are inflatable like truck tires, which not only reduces the weight of the vehicle, but also provides additional buoyancy for the 30.1-inch (76.5 cm) wide tracks when traversing soft ground and wading through water. The M76 is suspended with torsion bars and 2 suspensions on each side, each of which is connected to 2 wheels.
An M76 put into the battlefield in Vietnam, the fuel tank of which was located in the rear of the side of the hull, the fixed weapon mount was not mounted with a machine gun
As an armored vehicle with amphibious capabilities, the nose of the M76 is divided into a boat-shaped structure, which favors its ability to reduce drag when wading through water. In order to improve maneuverability on the water, the M76 can not only use tracks to paddle, but also install a propeller-type thruster under the towing hook at the rear, allowing it to reach a maximum speed of 5.3 knots (about 10 km/h) on water. When the vehicle needs to steer in the water, one side of the track stops, thus creating resistance, so that the vehicle can complete the steering under differential action.
The cockpit of the M76 is a two-person layout, with the driver's seat on the left and the co-pilot seat on the right, separated by a large cylindrical structure wrapped around the propeller shaft, and the co-pilot is required to assist the driver not only in operating the vehicle, but also in the event of a combat operation of the vehicle's only fixed weapon, an M2HB 12.7mm machine gun, located on top of his seat. At the rear of the cockpit is a personnel and cargo compartment that can accommodate up to eight soldiers and a total of 3,000 pounds (1,360 kilograms) of cargo.
Since other armored vehicles do not have a strong passing ability, the M76, like its "predecessors", is endowed with a strong towing capacity, and the vehicle is equipped with a 5,000-pound (about 2,268 kg) towing winch in the personnel and cargo compartment, which can tow a variety of light vehicles.
An M76 with "casemate" protection
Fire and ice
On the battlefields of Vietnam, the M76 proved that its nickname "Otter" was not for nothing - although it was very tall (relative to its full combat weight), aluminum armor protection was better than nothing, and the only M2HB was more vulnerable to rocket attacks than self-defense, and the failure rate was extremely high, but it was able to move freely on the water, even through areas where other amphibious armored vehicles (such as the LTVP series) could not pass, "ignore" Various obstacles in the water, which play an even less role in sweeping missions than tanks.
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Although the M76 has a personnel and cargo compartment that can be closed, the crew often chooses to sit on the roof, on the one hand, because the environment of the Vietnamese battlefield is humid and hot, and it is easy to suffer from heat stroke and other symptoms in the closed cabin for a long time, and on the other hand, because the car has no lightning protection design and no shooting holes under the car, sitting on the roof is conducive to searching for the surrounding enemy, and using the light weapons carried in the event of an ambush to carry out firepower, while reducing their own damage when encountering mines. For added protection, some crews opted to create additional armor from local materials, including metal plates on the windows and ring armor around the M2HB machine gun mount (known as the "turret").
As the armed forces of the Vietnamese People's Army and the South Vietnam National Liberation Front continued to grow, not only did the US troops stationed in Vietnam who had penetrated deep into their base areas to carry out sweeping missions have almost no "safe" moments, but even second-line units in the "rear" were often attacked. In addition to the battlefields in Vietnam, the M76 was also used in polar regions, and the results showed that the vehicle not only performed well in tropical environments, but also in severe cold climates.
On the battlefield in Vietnam, an M116 convoy is passing through the swampy terrain
Unstopped relays
Although the M76 suffered heavy losses on the battlefield in Vietnam, it still showed good tactical value. After the car was gradually put into active service, the U.S. Marine Corps did not "retire" this model, but replaced it with the successor model M116 "Husky". Compared to the M76, the M116 has a larger body and a more reasonable design, and is still used in the United States even after retirement.
At the same time as the U.S. military was developing vehicles like the M76, other NATO member states and even some Warsaw Pact members also discovered the tactical value of such models and launched a series of similar products, eventually forming a new concept of "all-terrain vehicle". These vehicles generally do not pursue strong protection, but they have strong passing ability and large carrying capacity, which can not only be used for combat, but also for civilian purposes including scientific research and exploration, and are still widely popular today.