M101 - 105 mm Howitzer

Development

In 1919, the Westervelt Board recommended the development of a howitzer of about 105 mm calibre, firing a projectile weighing 30 to 35 lb (13.61 to 15.87 kg) with a maximum range of approximately 12,000 yards (10,973 m). The carriage would permit elevation of the howitzer from -5 to +65, and a total traverse of 360. In addition the carriage would have to accept a 75 mm gun. Development of the 105 mm howitzer M1920, 105 mm Howitzer Carriage M1920E (split trails) and the 105 mm Howitzer Carriage M1921E (box trail) followed. The M1921E was considered the superior of the two carriages and was then developed to become the M1925E1 while the howitzer became the M1925E. A further howitzer was developed, at the same time, under the designation T2 and a further carriage also under the designation of the T2. In 1928, these were standardised as the 105 mm Howitzer M1 and the 105 mm Howitzer Carriage M1 but, owing to a shortage of funds, neither was placed in production. In 1934, the M1 howitzer was modified enabling it to fire fixed ammunition. It was subsequently standardised as the 105 mm Howitzer M2. This, when modified for mounting on the M2 carriage, was standardised as the 105 mm Howitzer M2A1 in March 1940. In 1933, it was decided to redesign the existing M1 carriage, but three years later the decision was taken to develop new carriages under the designation of the T3 and the T4. The T4 was found to be the better of the two and further development resulted in the T4E1 and finally the T5. The T5 was standardised as the 105 mm Howitzer Carriage M2 early in 1940. Shortly afterwards the 105 mm Howitzer Carriage M2A1 was standardised. By the end of the Second World War, 8,536 105 mm towed howitzers had been built and post-war production continued at Rock Island Arsenal until 1953, by which time 10,202 had been built. In 1985 the US Army had six M101 and 494 M101A1 howitzers in its inventory. The M101 105 mm howitzer was replaced in US Army service by the M102 howitzer which in turn has now been replaced by the British Royal Ordnance 105 mm Light Gun.

Description

After the Second World War the complete weapon was redesignated the Howitzer, Light, Towed: 105 mm, M101 and M101A1. The M101 consists of Cannon M2A1 or M2A2, Carriage M2A1 and Recoil System (M2A1, M2A2, M2A3, M2A4 or M2A5). The M101A1 is identical apart from an M2A2 carriage. The difference between the Cannon M2A1 and the M2A2, is that the M2A1's muzzle end is straight and the M2A2's is bell-shaped. The M2A2 carriage is fitted with a main shield group composed of right and left upper and lower shields, right and left top flaps, a bottom flap, and left and right auxiliary shields; while the earlier M2A1 is equipped with left and right main shields and a top shield. The barrel consists of the barrel assembly, breech ring and locking ring. The carriage is of the single axle split trail type with a drawbar for securing to the prime mover. The carriage consists of the equilibrator, shield, elevating mechanism, cradle gears, elevating arcs, traversing mechanisms, top carriage, wheels and trails. Fire-control equipment consists of a Telescope Elbow M16A1D with a magnification of x3 and a 13 field of view, a Telescope Panoramic M12A7S with a magnification of x4 and a 10 field of view and Quadrant M4A1. The M101 fires the following semi-fixed ammunition: APERS-T (M546) with the complete round weighing 17.35 kg, maximum muzzle velocity of 504 m/s and a maximum range (charge 7) of 11,600 m HE (M1) with the complete round weighing 21.06 kg, maximum muzzle velocity of 472.4 m/s and a maximum range (charge 7) of 11,270 m HE (M444) (carries 18 M39 grenades) with the complete round weighing 19.05 kg, maximum muzzle velocity of 472.4 m/s and a maximum range (charge 7) of 11,270 m HEP (M327) with the complete round weighing 15.17 kg, maximum muzzle velocity of 559 m/s and a maximum range of 8,685 m HERA (M548) (RAP) with the complete round weighing 17.46 kg, maximum muzzle velocity of 548 m/s and a maximum range of 14,600 m Illuminating (M314 series) with the complete round weighing 21.06 kg, maximum muzzle velocity of 472.4 m/s and a maximum range (charge 7) of 11,270 m Smoke (M60 series) with the complete round weighing 19.46 kg, maximum muzzle velocity of 472.4 m/s and a maximum range (charge 7) of 11,270 m Smoke (M84 series) with the projectile weighing 19.03 kg, maximum muzzle velocity of 472.4 m/s and a maximum range of 11,270 m APERS-T (M546) with a maximum range of 11,600 m.

SPECIFICATIONS :

Calibre: 105 mm
Barrel length:
(muzzle to rear face of breech ring) 2.574 m
(bore) 2.363 m
Muzzle brake: none
Recoil system: hydropneumatic
Breech mechanism: horizontal sliding wedge
Carriage: split trail
Shield: yes
Weight:
(travelling order, M101) 2,030 kg
(travelling order, M101A1) 2,258 kg
(firing position, M101) 2,030 kg
(firing position, M101A1) 2,258 kg
Length:
(travelling) 5.991 m
Width:
(travelling) 2.159 m
(firing) 3.657 m
Height:
(travelling, M101) 1.524 m
(travelling, M101A1) 1.574 m
(firing) 3.124 m
Axis of bore:
(at 0) 1.3 m
Ground clearance: 0.356 m
Track: 1.778 m
Tyres: 9.00 x 20
Elevation/depression: +66/-5
Traverse:
(total) 46
Rate of fire:
(max) 10 rds/min
(sustained) 3 rds/min
Max range: 11,270 m
Crew: 8
Towing vehicle: 2{1/2} ton (6 x 6) truck

Status

Production complete. In service with Argentina, Australia, Austria, Bangladesh, Belgium, Benin, Bolivia, Brazil (251), Burkina Faso, Burma (Myanmar), Cambodia, Cameroon, Canada (called C1, some built in Canada in 1950s), Chile (66), Colombia, Cyprus, Denmark, Dominican Republic, Ecuador, El Salvador, Ethiopia, France, the Gambia, Germany, Greece, Guatemala, Guinea, Guinea-Bissau, Haiti, Honduras, Indonesia (in 1981 the Defense Department notified Congress of its intention to sell Indonesia 133 M101A1s at a cost of $16 million), Iran, Iraq, Israel, Italy, Ivory Coast, Japan, Jordan, South Korea, Laos, Lebanon, Liberia, Libya, Mexico, Morocco, Mozambique, the Netherlands, New Zealand, Nicaragua, Norway, Pakistan, Paraguay, Peru, the Philippines, Portugal, Saudi Arabia, Senegal, Sudan, Taiwan (local production as T64), Thailand (has a modified version which is sometimes called the M425), Togo, Tunisia, Turkey, Uruguay, Venezuela, Vietnam, the Yemen and the former Yugoslavia. Production for foreign customer requirements was completed by Rock Island Arsenal in November 1983.

COMPANY NAME : Rock Island Arsenal