M2A2 Experimental 105MM Auxiliary Propelled Howitzer

This experimental model was designed to improve the mobility of towed artillery weapons. The Terra-Star major/minor wheel running gear was fitted to a standard M2A2 105MM howitzer. When moving on hard surfaces, the two small wheels would rotate as on any normal wheeled vehicle. When moving on soft surfaces, the drive is transferred to the central axle and the whole three-wheeled assembly rotates. Lockheed and Rock Island Arsenal tested this weapon from 1969 to 1977, when the project was terminated. This howitzer has a carriage manufactured at Rock Island Arsenal in 1954, and a recoil mechanism manufactured in 1945.

The Artillery Take on the Tri-Star Wheel

The M101 105MM howitzer, later referred to as M2A1, was the standard light howitzer deployed with the U.S. Army during World War II. Over 10,000 were produced, with the majority of them manufactured and assembled at Rock Island Arsenal. Production ran from 1941 through the end of the Korean War in 1953. The United States exported the weapon to over 50 countries, including some nations through the World War II-era Lend-Lease Program.

The M2A1 was capable of deploying a large assortment of artillery shells. The standard shell was a 42-pound high explosive shell with a range of just over seven miles. The howitzer was also capable of firing smoke, chemical rounds and armor-piercing rounds. Eleven variants of the gun carriage, and 12 variants of the carriage, were drafted, designed, and produced, including the M2A2 Terra-Star Auxiliary Propelled Howitzer.

From 1969 through 1977, Lockheed Aircraft Service Company and Rock Island Arsenal experimented with the tri-star wheel arrangement concept. This concept utilized an assembly of three wheels, coupled with a single spinning axle. The design was meant to act as an alternative to a track design and allow for smoother transit on paved and rough surfaces. On a smooth surface, the two bottom wheels would spin in motion, just like a typical automotive wheel. However, if the howitzer was off-road or approached a hole, the entire wheel assembly would rotate, allowing the howitzer to move beyond the obstacle with ease.

The M2A2 on display at Rock Island Arsenal is the only Terra-Star known to have survived, and it is believe that only two were ever manufactured.

Quick Facts & Specifications (M2A2)

Weight: Unknown
Dimensions: Unknown
Firing Range: ~7 miles
Caliber: 105 mm
Rate of Fire: 6~8 RPM
Crew: 5
Variants: Variant of M101 105 MM Howitzer
Number Built: 1
Origin: United States
Service History: Production Begins, 1941
New Recoil Mechanism Developed, 1945
Production Ends, 1953
New Carriage Designed, 1954
M2A2 Testing Begins, 1969
M2A2 Testing Ends, 1977


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