Ontos, officially the Rifle, Multiple 106 mm, Self-propelled, M50, was a U.S. light armored tracked anti-tank vehicle developed in the 1950s.
It mounted six 106 mm manually loaded M40 recoilless rifles as its main armament, which could be fired in rapid succession against single targets to guarantee 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 the U.S. Marines after 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 the Vietnam War. The American stock of Ontos was largely expended towards the end of the conflict and the Ontos was removed from service in 1969.
|Rifle, Multiple 106 mm, Self-propelled, M50 "Ontos"|
Ontos M50A1, the 50-cal spotting rifles can be seen on the upper guns
|Place of origin||United States|
|Used by||United States|
Operation Power Pack
|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)|
|6 × M40A1C recoilless rifles|
|1 × .30 M1919 Browning machine gun|
|Engine||GM 6-cylinder inline 302 in³ gasoline engine|
|185 km (115 mi)|
|Speed||48 km/h (30 mph)|
The Ontos (Greek for "thing") 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 20 metric tons. The Ontos also had to use the six-cylinder engine then widely used in the Army's GMC trucks. Allis-Chalmers was awarded a contract on August 12, 1955, for 297 vehicles.
Allis-Chalmers' first vehicle, completed in 1952, was based on the running gear of the M56 Scorpion light anti-tank vehicle. The vehicle mounted a cast steel turret with 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 same trajectory as 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 106 mm recoilless rifles with the target. The Ontos also carried a single .30 caliber M1919A4 machine gun for anti-infantry use.
The vehicle was taken to the Aberdeen Proving Ground where 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, the Marine Corps were 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.
Several variants were also studied. The Utility Vehicle, Tracked, Infantry, T55 was a light Armored 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 the Utility Vehicle, Tracked, Infantry, T56 was 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.
Another proposed upgrade was replacing the GMC engine with a newer Chrysler 361 cu in V8 engine. This upgrade was implemented and the variant was named Rifle, 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.
While the M50 was designed as a tank destroyer, during the Vietnam War most M50s did not engage enemy armor as the North Vietnamese Army deployed 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 and rocket-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 the Battle of Hue, Colonel Stanley S. Hughes felt 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. In Operation Desoto, the introduction of the large CH-53 Sea Stallion helicopter made possible moving a platoon 25 miles (40 km) south of Quan Ngai City carrying Ontos in slings underneath the aircraft.
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. 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 the Dominican Civil War: on 29 April 1965 an M50 Ontos and an M48 Patton of the 6th MEU engaged and destroyed two rebel L/60L light tanks, each destroying one. In another instance, an Ontos destroyed an AMX-13.
There are Ontos on display at the following US locations:
An assault gun is a form of self-propelled artillery which uses an infantry support gun mounted on a motorized chassis, normally an armored fighting vehicle. Assault guns are designed to provide direct fire support for infantry attacks, especially against other infantry or fortified positions. The term is a literal translation of the German word Sturmgeschütz, which was applied to the first purpose-built assault gun, the StuG III, in 1940.Historically, the concept of assault guns was very similar to that of the infantry tank, as both were combat vehicles intended to accompany infantry formations into battle. However, during World War II assault guns were more mobile than tanks and could be utilized as both direct and indirect fire artillery. Although they could approximate the firepower of a tank, assault guns mostly fired high explosive shells at relatively low velocities, which were well suited for their role of knocking out hard points such as fortified positions and buildings. They were not intended to be deployed as tank substitutes or dedicated tank destroyers. Nevertheless, as the conflict progressed, the increasing proliferation of tanks on the battlefield forced many assault gun units to engage armor in defense of the infantry, and led to armies becoming more dependent on multipurpose designs which combined the traditionally separate roles of an assault gun and a tank destroyer.German and Soviet assault guns introduced during World War II usually carried their main armament in a fully enclosed casemate rather than a gun turret. Although this limited the field of fire and traverse of the armament, it also had the advantage of a reduced silhouette and simplified the manufacturing process. The United States never developed a purpose-built assault gun during the war, although it did modify preexisting armored fighting vehicles for that role, including the M4 Sherman and M5 Stuart tanks and the M3 Half-track.The assault gun concept was largely abandoned during the postwar era in favor of tanks or multipurpose tank destroyers attached to infantry formations which were also capable of providing direct fire support as needed. In the United States and most Western countries, the assault gun ceased to be recognized as a unique niche, with individual examples being classified either as a self-propelled howitzer or a tank. The Soviet Union continued funding development of new assault guns as late as 1967, although few of its postwar designs were adopted in large numbers. In Soviet and other Eastern European armies, the traditional assault gun was primarily superseded by tank destroyers such as the SU-100 capable of supporting either infantry or armor.Beehive anti-personnel round
Beehive was a Vietnam war era anti-personnel round packed with metal flechettes fired from an artillery gun most popularly deployed during that conflict. It is also known as flechette rounds or their official designation, antipersonnel-tracer (APERS-T).
The flechette rounds were developed under a contract administered by Picatinny Arsenal and let to the Whirlpool Corporation in April 1957. The contract was named the "Beehive Program" referring to the way the flechettes were compartmentalized and stacked, looking like the traditional image of a conical beehive. It was commonly assumed by users in the service that the term referred to a supposed 'buzzing' sound its darts made when flying through the air. The first example was the 105mm howitzer M546 anti-personnel tracer (APERS-T), first fired in combat in 1966 and thereafter used extensively in the Vietnam War. Intended for direct fire against enemy troops, the M546 was direct fired from a near horizontally leveled 105 mm howitzer and ejected 8000 flechettes during flight by a mechanical time fuze. Green starshells were shot into the air prior to their use to warn friendly troops that such a round was being shot.The 105mm howitzer round was not the only artillery piece provided with APERS-T. Beehive rounds were also created for recoilless anti-tank weapons: the 90 mm and 106 mm mounted on the M50 Ontos. APERS-T rounds were available for 90mm gun on M48 tanks and the 152mm gun on the M551 Sheridan armored reconnaissance/airborne assault vehicle. After the Vietnam War the 105mm tank gun M68 was also provided APER-T ammunition M494. 40mm APERS-T rounds were also available for the M79, M203, and M320 grenade launchers.
Subsequently, it was reported that the USSR had developed similar rounds for 122 mm and 152 mm artillery for use in indirect fire.
Beehive rounds became less popular in the United States following Vietnam, with low-angle air burst techniques such as Killer Junior supplanting the use of beehive.FV4401 Contentious
FV 4401 Contentious was a prototype British air-portable tank destroyer of the early 1960s. At least one prototype was constructed and tested, although no production vehicles were built or saw service.Landsverk L-60
Landsverk L-60, was a Swedish tank developed in 1934. It was developed by AB Landsverk as a light tank which included several advanced design features such as torsion bar suspension, periscopes rather than view slits and all-welded construction.The L-60 was progressively improved with several turrets, engines and guns offered by Landsverk. The L-60 entered the international market in 1935 and was eventually adopted by the Swedish army in 4 main variants: Stridsvagn m/38, Stridsvagn m/39, Stridsvagn m/40L and Stridsvagn m/40K.List of Allis-Chalmers tractors
This is a list of farm and industrial tractors produced by Allis-Chalmers Corporation, as well as tractors that were produced by other manufacturers and then sold under the Allis-Chalmers brand name.
For clarity, tractors are listed by series and separated by major models as needed.M551 Sheridan
The M551 "Sheridan" AR/AAV (Armored Reconnaissance/Airborne Assault Vehicle) was a light tank developed by the United States and named after Civil War General Philip Sheridan. It was designed to be landed by parachute and to swim across rivers. It was armed with the technically advanced but troublesome M81/M81 Modified/M81E1 152mm gun/launcher, which fired both conventional ammunition and the MGM-51 Shillelagh guided anti-tank missile.
The M551 Sheridan entered service with the United States Army in 1967. At the urging of General Creighton Abrams, the U.S. Commander of Military Forces in Vietnam at the time, the M551 was rushed into combat service in Vietnam in January 1969. In April and August 1969, M551s were deployed to units in Europe and Korea, respectively. Now retired from service, it saw extensive combat in Vietnam, and limited service in Operation Just Cause (Panama), and the Gulf War (Kuwait). The Australian Army also trialled two Sheridans during 1967 and 1968, but judged that the type did not meet its requirements.
The Sheridan was retired without replacement officially in 1996. A large bulk of Sheridans were retained into service at the National Training Center (NTC) at Fort Irwin, California and as Armor Officer Basic training at Armor Training Center, then located at Fort Knox, Kentucky. They worked as simulated Soviet armored opposition force (OPFOR) to train U.S. military units on simulated tank on tank armored combat to test on combat effectiveness in a desert environment. They were finally retired from the NTC in 2003.M56 Scorpion
The M56 Scorpion is an American unarmored, airmobile self-propelled anti-tank gun, which was armed with a 90mm M54 gun with a simple blast shield, and an unprotected crew compartment.Model 1968 recoilless gun
The Model 1968 recoilless gun is a 105-mm antitank weapon developed and employed by Argentina. The weapon has been in active service since 1968 and 150 were still operational with Argentine forces as of 2000. A similar weapon is the Argentine 105-mm Model 1974 FMK-1 recoilless gun.Operation Kingfisher
Operation Kingfisher was a US Marine Corps operation that took place during the Vietnam War. The operation was carried out in the western part of "Leatherneck Square" near Con Thien, lasting from 16 July to 31 October 1967.Operation Macon
Operation Macon was a US Marine Corps search and destroy operation in western Quảng Nam Province, lasting from 4 July to 28 October 1966.Operation Maine Crag
Operation Maine Crag was a US Marine Corps, United States Army and Army of the Republic of Vietnam (ARVN) operation that took place in northwest Quảng Trị Province, lasting from 15 March – 2 May 1969.Recoilless rifle
A recoilless rifle, recoilless launcher or recoilless gun, sometimes abbreviated "RR" or "RCL" (for ReCoilLess) is a type of lightweight artillery system or man-portable launcher that is designed to eject some form of countermass such as propellant gas from the rear of the weapon at the moment of firing, creating forward thrust that counteracts most of the weapon's recoil. This allows for the elimination of much of the heavy and bulky recoil-counteracting equipment of a conventional cannon as well as a thinner-walled barrel, and thus the launch of a relatively large projectile from a platform that would not be capable of handling the weight or recoil of a conventional gun of the same size. Technically, only devices that use spin-stabilized projectiles fired from a rifled barrel are recoilless rifles, while smoothbore variants (which can be fin-stabilized or unstabilized) are recoilless guns. This distinction is often lost, and both are often called recoilless rifles.Though similar in appearance to a tube-based rocket launcher (since these also operate on a recoilless launch principle), a recoilless weapon fires shells that use conventional gun propellant. The key difference from rocket launchers (whether man-portable or not) is that the projectile of the recoilless rifle or gun is initially launched using conventional explosive propellant rather than a rocket motor. While there are rocket-assisted rounds for recoilless launchers, they are still ejected from the barrel by the detonation of an initial explosive propelling charge.
Because some projectile velocity is inevitably lost to the recoil compensation, recoilless rifles tend to have inferior range to traditional cannons, although with a far greater ease of transport, making them popular with paratroop, mountain warfare and special forces units, where portability is of particular concern, as well as with some light infantry and infantry fire support units. The greatly diminished recoil allows for devices that can be carried by individual infantrymen: heavier recoilless rifles are mounted on light tripods, wheeled light carriages, or small vehicles, and intended to be carried by crew of two to five. The largest versions retain enough bulk and recoil to be restricted to a towed mount or relatively heavy vehicle, but are still much lighter and more portable than cannons of the same scale. Such large systems have mostly been replaced by guided anti-tank missiles in first-world armies.Rock Island Arsenal
The Rock Island Arsenal comprises 946 acres (383 ha), located on Arsenal Island, originally known as Rock Island, on the Mississippi River between the cities of Davenport, Iowa, and Rock Island, Illinois. It lies within the state of Illinois. It is home of First Army headquarters. The island was originally established as a government site in 1816, with the building of Fort Armstrong. It is now the largest government-owned weapons manufacturing arsenal in the United States. It has manufactured military equipment and ordnance since the 1880s. In 1919–1920 one hundred of the Anglo-American or Liberty Mark VIII tanks were manufactured, although too late for World War I. It is designated as a National Historic Landmark.
Established as both an arsenal and a center for the manufacture of leather accoutrements and field gear, today it provides manufacturing, logistics, and base support services for the Armed Forces. The Arsenal is the only active U.S. Army foundry, and manufactures ordnance and equipment, including artillery, gun mounts, recoil mechanisms, small arms, aircraft weapons sub-systems, grenade launchers, weapons simulators, and a host of associated components. Some of the Arsenal's most successful products include the M198 and M119 towed howitzers, and the M1A1 gun mount. About 250 military personnel and 6,000 civilians work there. The 2000 census population was 145.Spotting rifle
A spotting rifle or ranging gun is a small-calibre rifle used as a sighting device for artillery. The ballistics of the spotting rifle are matched to those of the artillery piece, so that if a shot from the spotting rifle lands on the target, it may be assumed that the main weapon will also do so.Tankette
A tankette is a tracked armoured fighting vehicle that resembles a small tank, roughly the size of a car. It is mainly intended for light infantry support and scouting. Colloquially it may also simply mean a small tank.Several countries built tankettes between the 1920s and 1940s, and some saw limited combat in the early phases of World War II. The vulnerability of their light armor, however, eventually led armies to abandon the concept with some exceptions such as the more modern German Wiesel (Weasel) series.Type 60 Self-propelled 106 mm Recoilless Gun
The Type 60 Self-propelled 106 mm Recoilless Gun (60式自走無反動砲, roku-maru-shiki-jisou-muhandou-hou) is a light anti-tank vehicle developed by Japan in the late 1950s. It mounts two M40 106 mm recoilless rifles as its main armament.VT tank
The Versuchsträger 1-2 (abbreviated: VT, meaning "test-beds" or "experiment carrier") were two German prototype twin gun turretless main battle tanks. Since the early 1970s a number of West German companies have been working on conceptual designs for a successor to the Leopard 1. This project had the name Kampfpanzer 3 (KPz 3). The KPz 3 project was temporarily a British-German joint project, until the UK withdrew because they wanted a turreted tank. The Germans had already developed the Leopard 2 and therefore didn't see the need for another conventional tank. One of the companies involved was MaK, developing the VT 1-1 and VT 1-2. The test programme ended proving that a twin-gunned turretless tank could be created with enough technical effort, but had drawbacks in both practical and tactical use.