M50 Ontos
In 1950, the US Army issued a requirement for an antitank vehicle that had three, seemingly mutally opposed requirements: it had to be air-transportable, it had to use the same engine as the Army's truck units, and it had to be under 20 tons. Allis-Chalmers responded with a design based on the chassis of the M56 Scorpion assault gun; the story went that the designer wasn't sure what to call it. He settled on "Ontos"--Greek for "the Thing."
The Ontos was indeed a strange machine. It met all the Army's requirements, and armed no less than six 106mm recoilless rifles on a turret. When fired at once, the 106mms could destroy any target; the backblast alone might kill anything behind the Ontos. In spite of successful testing, the Army believed the M50 was too high-profile, had a limited ammunition load (only 18 rounds), and the crew had to get out of the cramped fighting compartment to reload the rifles. The Army cancelled the order in 1955, only for Allis-Chalmers to receive an order from the Marines for 300 M50s. At the bottom of the procurement chain, the Marines had no antitank vehicles at all, and the Ontos could easily fit inside a landing craft or slung under a transport helicopter.
In the end, the Ontos never engaged the enemy it was designed to. Instead, the M50 went to war in Vietnam. Since it lacked armor, it was not much use in the jungle, but in city fighting and in defending firebases, the Ontos was lethal. Often the six 106mm rifles would be loaded with "beehive" rounds: shells that would explode on leaving the barrel, sending out hundreds of darts at supersonic speeds. One Ontos could literally shred an attacking force. If the enemy took cover behind a wall or in a house, the M50 would load conventional rounds and blow the wall down.
With the drawdown of American forces, the M50s were retired in 1969, and most survivors were scrapped. However, at least 15 are known to survive in museums.
The National Museum of Military Vehicles actually has two Ontoses: one at the entrance to the museum, and this one in their Vietnam display. I've only seen one Ontos before, and it was still being restored, but both the NMMV M50s look like they just arrived from the factory. This fully restored Ontos definitely shows why this vehicle was feared.
M50 Ontos
In 1950, the US Army issued a requirement for an antitank vehicle that had three, seemingly mutally opposed requirements: it had to be air-transportable, it had to use the same engine as the Army's truck units, and it had to be under 20 tons. Allis-Chalmers responded with a design based on the chassis of the M56 Scorpion assault gun; the story went that the designer wasn't sure what to call it. He settled on "Ontos"--Greek for "the Thing."
The Ontos was indeed a strange machine. It met all the Army's requirements, and armed no less than six 106mm recoilless rifles on a turret. When fired at once, the 106mms could destroy any target; the backblast alone might kill anything behind the Ontos. In spite of successful testing, the Army believed the M50 was too high-profile, had a limited ammunition load (only 18 rounds), and the crew had to get out of the cramped fighting compartment to reload the rifles. The Army cancelled the order in 1955, only for Allis-Chalmers to receive an order from the Marines for 300 M50s. At the bottom of the procurement chain, the Marines had no antitank vehicles at all, and the Ontos could easily fit inside a landing craft or slung under a transport helicopter.
In the end, the Ontos never engaged the enemy it was designed to. Instead, the M50 went to war in Vietnam. Since it lacked armor, it was not much use in the jungle, but in city fighting and in defending firebases, the Ontos was lethal. Often the six 106mm rifles would be loaded with "beehive" rounds: shells that would explode on leaving the barrel, sending out hundreds of darts at supersonic speeds. One Ontos could literally shred an attacking force. If the enemy took cover behind a wall or in a house, the M50 would load conventional rounds and blow the wall down.
With the drawdown of American forces, the M50s were retired in 1969, and most survivors were scrapped. However, at least 15 are known to survive in museums.
The National Museum of Military Vehicles actually has two Ontoses: one at the entrance to the museum, and this one in their Vietnam display. I've only seen one Ontos before, and it was still being restored, but both the NMMV M50s look like they just arrived from the factory. This fully restored Ontos definitely shows why this vehicle was feared.