M50 Ontos
Rifle, Multiple 106 mm, Self-propelled, M50 "Ontos" | |
---|---|
Type | Tank destroyer |
Place of origin | United States |
Service history | |
In service | 1956–69 |
Used by | United States |
Wars | Vietnam War Dominican Civil War 1958 Lebanon Crisis |
Production history | |
Designer | Allis-Chalmers |
Designed | 1952 |
Manufacturer | Allis-Chalmers |
Produced | 1955–57 |
No.built | 297 |
Variants | M50A1 |
Specifications | |
Mass | 8,600 kg (19,000 lb) |
Length | 3.83 m (12 ft 7 in) |
Width | 2.59 m (8 ft 6 in) |
Height | 2.13 m (7 ft 0 in) |
Crew | 3 (driver, gunner and loader) |
Sights | x6.50 Single-Shot Spotting Rifles |
Main armament | 6 ×M40A1C recoilless rifles |
Secondary armament | 1 ×.30 (7.62 mm)M1919 Browning machine gun |
Engine | GM 6-cylinder inline 302 cu in (4.95 L) gasoline engine 145 hp (108 kW) |
Operational range | 185 km (115 mi) |
Maximum speed | 48 km/h (30 mph) |
Ontos,officially theRifle, Multiple 106 mm, Self-propelled, M50,was an American light armored trackedanti-tankvehicle developed in the 1950s.
It mounted six 106 mm manually loadedM40 recoilless riflesas its main armament, which could be fired in rapid succession against single targets to increase the probability of a kill. Although the actual caliber of the main guns was 105 mm, it was designated 106 mm to prevent confusion with the ammunition for the 105 mm M27 recoilless rifle, which the M40 replaced.
It was produced in limited numbers for theU.S. Marinesafter the U.S. Army cancelled the project. The Marines consistently reported excellent results when they used the Ontos for direct fire support against infantry in numerous battles and operations during theVietnam War.The American stock of Ontos was largely expended towards the end of the conflict and the Ontos was removed from service in 1969.
Development[edit]
TheOntos(Greek for "thing"[1]) project was created to be an air transportable tank destroyer capable of being lifted by the cargo aircraft of the 1950s. This limited the vehicle to a weight between 10 and 20metric tons.The Ontos also had to use the six-cylinder engine then widely used in the Army's GMC trucks.Allis-Chalmerswas awarded a contract on August 12, 1955, for 297 vehicles.
Allis-Chalmers' first vehicle, completed in 1952, was based on the running gear of theM56 Scorpionlight anti-tank vehicle. The vehicle mounted a cast steelturretwith two arms holding three rifles each. This early model could traverse the turret only about 15 degrees. A second prototype used a new suspension system, new tracks, and a newer turret with about 40 degrees traverse. The vehicle could carry only eighteen rounds for the main guns inside the vehicle due to limited space. Four of the recoilless rifles also had.50 BAT (12.7x77mm) M8C spotting rifles attached, each of which fired a tracer round with the sametrajectoryas the 106 mm round, and that gave off a flash and puff of white smoke on impact. The spotting rifles were used to line up the 105 mm recoilless rifles with the target. The Ontos also carried a single.30 caliber (7.62 mm)M1919A4 machine gunfor anti-infantry use.
The vehicle was taken to theAberdeen Proving Groundwhere single rifles had been tested earlier. When all six weapons were fired at once, the back blast from the firing knocked bricks out of a nearby building and knocked the rear windows out of several cars. The prototype and testing stage was completed by 1955, at which point the Army canceled its order.
As an anti-tank vehicle the Ontos had several problems, including a small ammunition load, a very high profile for such a small vehicle, and the need for the crew to exit the vehicle in order to reload the guns, exposing them to enemy fire. Although the Army canceled their order, theMarine Corpswere desperate for any anti-tank vehicles they could get, and ordered 297. Production ran from 1955 through 1957. The Marine Corps accepted its first vehicle on 31 October 1956.
Variants and upgrades[edit]
Several variants were also studied. TheUtility Vehicle, Tracked, Infantry, T55was a lightArmored personnel carrier(APC), but only two versions of the prototype were built. It proved impractical due to the limited room inside, carrying only five infantry and forcing the driver to lie prone. A "stretched" version known as theUtility Vehicle, Tracked, Infantry, T56was also built, and while it held a complete eight-man team, their equipment had to be carried on the outside. Neither was considered very useful.
In 1960 there was a brief study made to replace the Ontos's 106 mm rifles with a new 105 mm design that included arevolver-styleautoloader.This project was not accepted.
Another proposed upgrade was replacing the GMC engine with a newer Chrysler 361 cu in (5.92 L) V8 engine. This upgrade was implemented and the variant was namedRifle, Multiple 106 mm, Self-propelled, M50A1.However of the 297 vehicles initially accepted by the Marines, only 176 were converted between 1963 and 1965 to this standard.
Service[edit]
While the M50 was designed as a tank destroyer, during theVietnam Warmost M50s did not engage enemy armor as theNorth Vietnamese Armydeployed few tanks. The Ontos was therefore more widely used by the US Marines for direct fire support for the infantry in combat, a role that was never emphasized in training or doctrine. Its light armor was effective against small arms but vulnerable to mines andRocket-propelled grenades.Consequently, many Ontos were deployed in static defense positions.
The relatively light weight of the M50 made it exceptionally mobile for the amount of firepower it carried. In one operation, the Ontos was the only tracked vehicle light enough to cross a pontoon bridge. In theBattle of Huế,ColonelStanley S. Hughesfelt the Ontos was the most effective of all Marine supporting arms. At ranges of 300 to 500 yards (270 to 460 m), its recoilless rifles could knock holes in or completely knock down walls. The appearance of an Ontos was sometimes enough to make the enemy break and run, and anecdotal accounts describe the enemy fleeing occupied buildings when an Ontos's spotting round entered a window. InOperation Desoto,the introduction of the largeCH-53 Sea Stallionhelicopter made possible moving a platoon 25 miles (40 km) south of Quảng Ngãi City carrying Ontos in slings underneath the aircraft.[2]
The Ontos units were deactivated in May 1969, and some of the vehicles were handed over to an Army light infantry brigade. They used them until they ran out of spare parts, and then removed the turrets and used them as fixed fortifications.[citation needed]Both these and the rest of the vehicles returned from Vietnam in 1970 and were cut up for scrap, with some of the chassis being sold off to be converted into construction vehicles. Some of the Ontos that were sold to construction companies were later acquired by collectors for restoration.
The Ontos did see use as an anti-tank weapon during the American involvement in theDominican Civil War:on 29 April 1965 an M50 Ontos and anM48 Pattonof the 6th MEU engaged and destroyed two rebelL/60Llight tanks, each destroying one. In another instance, an Ontos destroyed anAMX-13.[3]
Preserved vehicles on display[edit]
There are Ontos on display at the following US locations:
- The Patton Museum of Cavalry & Armor inFort Knox,Kentucky[4](no longer on display, may have moved with the Armor school to Fort Benning).[citation needed]
- TheRock Island ArsenalMuseum in Rock Island, Illinois.[citation needed]
- Camp Atterbury,Edinburgh, Indiana.[citation needed]
- The American Military Museum, inEl Monte, Californiahas an M50 that is missing its six recoilless rifles.[citation needed]TheAberdeen Proving Ground's Museum inAberdeen, Marylandhas a T165E2, the 19th prototype, though it is not currently on display. The vehicle is currently[when?]undergoing acosmetic restoration.[citation needed]
- Fred Ropkey, owner of theRopkey Armor MuseuminCrawfordsville, Indianaowns the first prototype T165, a later model Ontos, and a parts machine.[citation needed]
- TheNational Museum of the Marine CorpsinQuantico, Virginiahas completed the restoration of an M50A1 Ontos.
- The Museum of The Marine inJacksonville, North Carolinahas an operational M50A1 Ontos which is not on public display.[citation needed]
- There is an M50A1 Ontos on outside display at the Navy Facility atChina Lake,California.[citation needed]
- TheMarine Corps Air Ground Combat Center Twentynine Palms,Californiahas an M50A1 Ontos on outside display.[citation needed]
- TheMilitary Vehicle Technology FoundationinPortola Valley, Californiahas a T165E1 prototype with the original GM 302ci engine which is currently undergoing a complete operational restoration, and a second prototype T165E2 Ontos.[citation needed]
- TheU.S. Army Artillery MuseumatFt. Sill,Oklahoma.[citation needed]
- The Marine Corps Mechanized Museum,Camp Pendleton,displays a M50A1 Ontos that took part in the Battle of Hue.[5]
- There is an M50 Ontos on display inside of theNational Museum of Military Vehiclesin the Vietnam exhibit, near Dubois, Wyoming[6]
- Russell Military Museum in Zion, Illinois.
- The Museum of the American GI in College Station, Texas has one undergoing restoration.[7]
- Indiana Military Museum, Vincennes, Indiana.[8]
See also[edit]
- List of artillery
- List of self-propelled anti-tank guns
- List of artillery of the United States
- G-numbers(SNL G288)
- Similar vehicles
References[edit]
- ^Standard Catalog of U.S. Military Vehicles– 2nd Editionp. 376
- ^Sgt. T.D. Stephens (9 May 2006),Ontos-a mean thing feared by Viet Cong– via Newspaper clipping (Flickr)
- ^Roblin, Sebastien (22 June 2016)."In 1965, U.S. and Dominican Tanks Fought Brief, Violent Skirmishes".War is boring.
- ^Estes 2016,p. 47.
- ^Estes 2016,p. 36.
- ^"National Museum of Military Vehicles on Facebook".Facebook.Archived fromthe originalon 2022-04-30.[user-generated source]
- ^"Restoration – Museum of the American G.I."
- ^"Two weeks out. Put it on your calendar! Come see us".Facebook.Indiana Military Museum.9 July 2023.Retrieved21 June2024.
Sources[edit]
- Estes, Kenneth W (2016).M50 Ontos and M56 Scorpion 1956–70: US Tank Destroyers of the Vietnam War.New Vanguard 240.Osprey Publishing.ISBN9781472814739.
- Kutta, Timothy J., "ONTOS: The USMC's Most Famous Anti-Tank Weapon",Modern War magazine,no. #14 November/December 2014, Bakersfield, California: Strategy & Tactics Press (Decision Games), pp. 72–75
- McNab, Chris (2003).Military Vehicles.Hoo, Kent, UK: Grange Books. p. 56.ISBN1-84013-539-5.