The self-propelled anti-aircraft gun M42 was developed as a variant of the M41 Walker Bulldog tank. It was intended to replace the M19 self-propelled anti-aircraft gun, which utilized the chassis of the M24 Chaffee tank. In 1950 the work started on the prototype designated T141. The vehicle utilized the chassis of the M41 tank. Its rear portion was almost unchanged; a turret with twin "Bofors" anti-aircraft gun was installed in the center of the vehicle. The turret was similar to that used in the M19, the most important modification to it was installation of hydraulic elevation and traverse mechanisms, working together with the M38 computing sight. The turret was also fitted with ready ammo bins. Additionally, the vehicle's driver's and commander's compartment was larger than in the M41 and had one large front hatch and two smaller hatches on the top plate.
After the testing, production of the vehicle started in 1952 under the designation M42. The vehicle had a 500 horsepower gasoline Continental AOS-895-3 engine, like M41 and M41A1, which gave a very poor mileage. In 1956 M42s were upgraded with improved AOS-895-5 fuel injected engine, which increased the range substantially. Vehicles with this, and other minor modifications were designated M42A1.
Main armament of the M42 are the famous "Bofors" guns, built in the USA under Swedish license, that proven their high value in the World War II and in Korea, although in the latter conflict they were mainly used for ground support. In the M42A1 the guns were fitted with improved optics. The ammunition was fed by two assistant gunners in four-round clips, 100 of which were carried on the vehicle in large boxes, one on each side. Lockheed and Sperry constructed prototypes of fire control radars for the M42, but none of the designs was put into service. With no radar the use of the gun was limited to slow moving targets and visibility allowing the use of optical sights. When the Soviet Union introduced the new generation of jets, the value of the M42 as anti-aircraft weapon largely decreased.
Cadillac/General Motors Company produced the M42. As the production ended in 1959 3700 of M42s and M42A1a were built. These vehicles replaced the M19s and various half-track mounted anti-aircraft guns, like the M16, M17 or similar. Later the M42 served in the National Guard and also in foreign armies under the Military Assistance Program. In the end of the sixties the limitations of the M42 were evident and the M163 "Vulcan" begun to replace it. About the same time three battalions using M42 were sent to Vietnam.
In Vietnam there wasn't enough work for which the M42 was built. Because of that it was decided to use it for ground support. M42 was very successful in perimeter defense, base security and convoy escort roles. The nickname "Duster" came from the clouds of dust the vehicle raised while traveling in a convoy. The parameters of the "Bofors" gun made the Duster very effective in the jungle, in the presence of dense vegetation. Like was the case with other kinds of weapons the crews converted their machines to better adopt them to the conditions of the Vietnam War. The operators of the Dusters removed their flash suppressors from the gun barrels and replaced the M1919A4 machine gun with the M60 machine gun or even two of them to increase short-range firepower.
Best-known instances when the Dusters were used in Vietnam are their service with the 9th Infantry Division in the Mekong delta and also their role in operation Pegasus which successfully reopened the supply route to the encircled Marine outpost of Khe Sanh.
The model shown above depicts a vehicle that was posted at Khe Sanh combat base before the siege. After the base was cut off, this vehicle helped to defend it throughout the siege. On July 13th, 1968 after the base was closed down and abandoned, it was the last American vehicle to leave the base.
|Length (without main gun):||5891 mm|
|Length (over main gun):||6429 mm|
|Service weight:||22600 kg|
|Main armament:||twin automatic 40 mm gun M2A1 (M4E1 mount in the turret)|
|Auxiliary armament:||7,62 mm M1919A4 machine gun in a flex mount and/or 7,62 mm M60 machine gun|
|Armour hull:||from 13 mm (top) to 25mm (front)|
|Armour turret:||from 8mm (sides) to 13mm (front)|
|Propulsion:||Continental AOS-895-3 6-cylinder, opposed, 4-cycle, turbodocharged gasoline engine|
|Power (gross/net):||373 kW @ 2400 rpm / 333 kW @ 2800 rpm|
|Torque:||1295 Nm @ 2400 rpm / 1207 Nm @ 2200 rpm|
|Fuel capacity:||530 L|
|Transmission:||General Motors CD-500-3, 2 ranges forward, 1 reverse|
|Speed (on road):||72 km/h|
|Trench crossing:||1,8 m|
|Vertical obstacle:||0,7 m|