M102 105mm Lightweight Towed Howitzer
The M-102 105mm howitzer is used in air mobile (helicopter) and light infantry operations. The weapon carriage is lightweight welded aluminum, mounted on a variable recoil mechanism. The weapon is manually loaded and positioned, and can be towed by a 2 ton truck or High Mobility Multipurpose Wheeled Vehicle (HMMWV), can be transported by UH-60 Black Hawk helicopters, or can be dropped by parachute with airborne units. When emplaced, the howitzer's high volume of fire compensates in large measure for the lower explosive weight of the projectile compared to the Army's 155mm and 8-inch howitzers. Since 1964, the Army has acquired 1,150 M-102 towed howitzers. This weapon is being replaced by the M-119-series 105mm howitzer.
Units were initially equipped with the M101A1 howitzer, virtually the same 105-mm. howitzer that had been used to support U.S. forces since World War II. In 1966 a new 105-mm. towed howitzer, the M102, was received in Vietnam. The first M102's were issued to the 1st Battalion, 21st Field Artillery, in March 1966. Replacement of the old howitzers continued steadily over the next four years.
Many of the more seasoned artillerymen did not want the old cannon replaced. Over the years they had become familiar with its every detail and were confident that it would not disappoint them in the clutch. Old Redlegs could offer some seemingly convincing reasons why the M101 was still the superior weapon: its waist-high breech made it easier to load; it had higher ground clearance when in tow; but most important, it was considerably less expensive than the M102. Their arguments, however, were futile.
The new M102 was by far the better weapon. It weighed little more than 1 1/2 tons whereas the M101A1 weighed approximately 2 1/2 tons; as a result, more ammunition could be carried during heliborne operations, and a 3/4-ton truck rather than a 2 1/2-ton truck was its prime mover for ground operations. Another major advantage of the M102 was that it could be traversed a full 6,400 mils. The M101A1 had a limited on-carriage traverse, which required its trails (stabilizing legs) to be shifted if further traverse was necessary. A low silhouette made the new weapon a more difficult target for the enemy, an advantage that far outweighed the disadvantage of being somewhat less convenient to load.
The 105-mm howitzer M102 is a lightweight towed weapon, which has a very low silhouette when in the firing position. The M102 howitzer fires a 33-pound projectile of semifixed ammunition and at charge 7 will fire 11,500 meters. It has a muzzle velocity of 494 meters per second. The maximum rate of fire is 10 rounds per minute for the first 3 minutes, with a sustained rate: 3 rounds per minute.
A roller tire attached to the trail assembly of the M102 permits the weapon to be rotated 6,400 mils around a firing platform, which provides the pivot for the weapon. The weapon can be elevated from -89 mils(-5 degrees) to a maximum of 1,333 mils (75 degrees). The panoramic telescope has a four power, fixed focus optical system, with 178 mils field of view. It contains dry nitrogen gas to retard fogging and condensation. The parallax shield used during boresighting protects the lens.
The trails are made of aluminum alloy. They are a single box trail in wishbone shape, and serve three purposes, which are: MOBILITY, STABILITY, and STOWAGE OF SECTION EQUIPMENT. The lunette is the towing pintle that allows the weapon to be connected to the vehicle. When towing, vehicle has a fixed or seized tow pintle; remove the lock plate located under the lunette. The drawbar has two positions. The drawbar is lowered for travel, and raised for firing.
There are two lifting brackets to connect slings to, when the howitzer is being lifted by helicopter. A third bracket is located on front yoke. The carriage handles are used by crew members to lifting and shifting the howitzer during loading, unloading, and emplacing the howitzer.
The firing platform attaches to the howitzer lower carriage by using a socket and a locking handle. The eight holes are for the stakes needed to stake the howitzer in position. Platform stakes are issued in three sizes. There are 4 fifteen inch stakes issued. These are used for frozen or rocky terrain, and are normally issued only where needed, such as extremely cold areas. There are 8 twenty four inch stakes issued, and they are used for hard packed ground. Thirty eight inch stakes are used for soft ground and there are 4 issued.
TM 9-100-202-14, TM 9-1015-234-12, TM 9-1015-234-10, AND LO 9-1015-234-10.
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