M50 Ontos

An M50 Ontos of the Marines

The M50 Ontos ( Ontos in Greek : the thing ) was an air-transportable, lightly armored self-propelled anti-tank gun.

development

In November 1950, the US Army placed an order for the development of a light anti-tank vehicle with the agricultural machinery manufacturer Allis-Chalmers from Wisconsin . The vehicle was to replace the recoilless M40 guns mounted on jeeps in the anti-tank troops and to provide the crews with a lightly armored vehicle. An order of 1,000 pieces was planned by the army. When Allison-Chalmers presented the design called T165 in 1953, the Army rejected it and instead stayed with the original equipment of the anti-tank troops. The Marine Corps was looking for at this time replacement for their Sherman tank and the Ontos met the requirements for a lightweight vehicle that promised a high degree of mobility. The Corps ordered 300 copies, which were given the designation M50 . In 1963, the conversion to the A1 standard with more powerful engines began. 167 of the 297 tanks delivered were converted.

technical description

The Ontos had the same chassis as the M56 Scorpion with 50 centimeter wide tracks. Above this, the approximately 13 millimeter thick armor of the hull tapered in a pyramid shape towards the tower. At the stern, the Ontos had a double-leaf door through which the crew could get in and out. The tower consisted of two arms, on which three M40 Recoilless Rifles were mounted on the left and right . The top four guns were home to the 12.7mm target marker rifles . In the center, on a pivot, was a 7.62 mm M1919 machine gun for defense. This and the two lower guns could be dismantled and used on mounts . The tower could be swiveled 40 ° to each side and tilted 20 ° up and 10 ° down. Ammunition was 1000 rounds for the machine gun, 20 rounds each for the target marker rifles and 18 rounds for the 106 mm guns (six in the barrels, four in the interior, eight in a container under the rear door). The ammunition for the main weapon was the M344A1 HEAT , M346A1 HEP-T or M581 Flechette projectile APERS-T "Beehive", filled with 10,000 Flechettes .

The driver was seated in the front left, the engine and transmission were to his right. The commander and the loader shared the space behind it, together with the ammunition, the radio and the personal armament ( M3 submachine guns ). The operation of the artillery and the machine gun was in the hands of the commandant.

commitment

A crew member of an Ontos rests on the tank during the Battle of Huế

The M50 was first used during the American intervention in the Dominican Republic, where it performed very well against the rebel AMX-13 and L-60 tanks. In 1965 the first Ontos came to Vietnam with the 1st and 3rd Antitank Battalions of the 1st U.S. Marine Division . Since the North Vietnamese army had only a few tanks and only rarely used them in open field battles, the Ontos was assigned to the basic defense. Here it proved itself because of its high firepower, especially in the battle of Khe Sanh . When fighting in the thick undergrowth of the jungle, the “Beehive” -lechette ammunition also proved its worth. Sometimes the Viet Cong are said to have fled when they saw the Ontos. The small tank was also used during the Tet offensive and the battle for Huế . The Marines particularly valued its firepower in urban warfare.

In the Vietnam War , however, the model's weaknesses also emerged: once the six rounds of the barrel had been fired, the loader had to leave the protected interior to reload and was then exposed to enemy fire. In addition, the huge "backblast" betrayed the Ontos after firing the first shot, so the position had to be changed often. Since the tank could also only carry twelve rounds of ammunition in the interior and in the storage container, most of the crews drove into the battle with loaded tubes, contrary to the instructions. In May 1969, the USMC began decommissioning the Ontos, some copies were handed over to the US Army, which continued to use them until the spare parts were used up. The towers of some M50s were also dismantled and used as fixed basic defenses. Most of the vehicles in the United States have been demilitarized and sold to forestry and farms.

Technical specifications

The data refer to the M50 model; data of the M50A1 that differ from this are shown in brackets

Parameter	Data
Construction year	1955–1957 (1963–1969)
Manufacturer	Allis-Chalmers Manufacturing Co.
Length over all	3.83 m
Width over everything	2.59 m
height	2.13 m
Combat weight	8600 kg
crew	3
Top speed	48 km / h (road)
Driving range	185 km (160 km)
engine	General Motors M302 petrol engine with 145 hp ( Chrysler HT-361-318 petrol engine with 180 hp)
Armament	6 × recoilless 106 mm M40A1c guns , 4 × 12.7 mm M8C target marker rifles , 1 × 7.62 mm machine gun

Web links

Commons : M50 Ontos  - Album with pictures, videos and audio files

• M50 Ontos at waffenhq.de
• Ontos crewmen website (Engl.)
• The Ontos on diggerhistory.com (Engl.)