M-551A1 SHERIDAN TANK (Air droppable)

Sheridan

DESCRIPTION: A light tank with airdrop capability    SERVICE: US Army. Served in Viet Nam. 

FEATURES:
The M-551A1 Sheridan is a lightly armoured, tracked, air droppable, direct fire tank used in airdrop missions by the 82nd Airborne Division, Fort Bragg, N.C., and by the Opposing Forces Regiment, National Training Centre at Fort Irwin, Calif. It uses a Laser Range Finder and Tank Thermal Sight.

BACKGROUND:
The Army received the Sheridan in 1967. In 1969, the 11th ACR received a small quantity of Sheridans for use in the war in Vietnam.  It has been out of production since 1970 and is only in service in limited numbers. The 82nd Airborne Division has 57, using them instead of the M-1A1, which cannot be parachuted from an aircraft). 300 Sheridans are used by the Opposing Forces Regiment at the National Training Centre as "enemy" tanks in combat training.

Armoured Reconnaissance Airborne Assault Vehicle (Sheridan)

The M551 Sheridan was developed to provide the US Army with a light armoured reconnaissance vehicle with heavy firepower. The main armament consists of an 152mm M81 gun/missile launcher capable of firing conventional ammunition and the MGM-51 Shillelagh antitank missile (20 conventional rounds and 8 missiles). Due to problems with the gun-tube-launched antitank missile, the Sheridan was not fielded widely throughout the Army. The gun would foul with caseless ammunition, gun firing would interfere with missile electronics, and the entire vehicle recoiled with unusual vigour when the gun was fired, since the 152mm gun was too big for the light-weight chassis. The Shillelagh missiles were evidently never used in anger. In addition to the main gun/missile launcher, the M551 is armed with a 7.62mm M240 machine gun and a 12.7mm M2 HB antiaircraft machine gun. A Detroit Diesel 6V-53T 300hp turbo-charged V-6 diesel engine and an Allison TG-250-2A powershift transmission provide the Sheridan's power. Protection for the four-man crew is provided by an aluminium hull and steel turret. Although light enough to be airdrop-capable, the aluminium armour was thin enough to be pierced by heavy machine-gun rounds, and the vehicle was particularly vulnerable to mines.

Initially produced in 1966, the M551 was fielded in 1968. 1,562 M551s were built between 1966 and 1970. The Sheridan saw limited action in Vietnam, where many deficiencies were revealed. The missile system was useless against an enemy that employed tanks, though the Sheridan saw a lot of use towards the end of the war because of its mobility. Sheridan-equipped units participated in Operation Just Cause in Panama (1989), and was deployed to Saudi Arabia during Operation Desert Shield. As projectile technology advanced, the Sheridan's potential declined and it was phased out of the US inventory beginning in 1978. However, the M551 is still used by the 82nd Airborne Division. Some 330 "visually-modified" Sheridans represent threat tanks and armoured vehicles at the National Training Centre in Fort Irwin, California.