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Early production M3
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M3A1
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Light Tank M3 Stuart, early production^1-11,20

The M3 Stuart, known to the British as Stuart I or Honey (it was a "Honey" of a tank), was an evolution of the light tank M2A4 that incorporated a trailing idler suspension to decrease ground pressure and improve weight distribution, a lengthened hull superstructure rear, and thicker armor. The turret of the M3 had three pistol ports, in contrast to the M2A4's seven. The recoil mechanism of the Stuart was also shortened so that it did not project from the gun shield. Early production M3s had riveted turrets.

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Light Tank M3 Stuart, late-production^1-13,20

The turrets for the M3 Stuart were changed from riveted to welded, but the bolted front plate was retained. Late production M3s had round rolled homogeneous steel turrets, and forged steel turret race rings replaced the cast steel turret rings of earlier tanks. The cupolas on the round turrets were also round, and all cupola vision slots ("peepholes") were eliminated, although four protected vision slots were reintroduced later. The hexagonal cupola's single hatch was replaced with a split hatch on the round cupola. The round turrets' pistol ports were also fitted with protectoscopes, and similar protectoscopes were also installed in the drivers' doors outboard of the peepholes. Two 25gal (95L) jettison fuel tanks were also fitted to late-model tanks, increasing the Stuart's range. A vertical gyrostabilizer was introduced in 1942.

As shown in the specification table, some late-model M3s were fitted with M3A1-style turrets lacking cupolas, but these turrets did not have a basket or power traverse as production facilities were unable to switch over to installing these components in time. Unfortunately, the gun mounts intended for tanks with power traverse had independent traverse eliminated. Consequently the gunner had no way to traverse his ordnance onto the target since the turret traverse was still controlled by a handwheel on the commander/loader's side of the turret, leading to a difficult fire control situation. The British dubbed these tanks Stuart Hybrid, as they were an amalgamation of the light tanks M3 and M3A1.

The 37mm gun M6 was 6" (15cm) longer than the earlier M5, and the M6 had a semiautomatic breechblock instead of the M5's manual breechblock.

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Light Tank M3(diesel) Stuart, mid-production^{1-3,6,8-10,12,14,20}

M3(diesel) tanks were called Stuart II by the British. The external difference between gasoline and diesel-powered Stuarts is the difference in length of the air intake pipes leading from the air cleaners on the rear hull to the engine compartment. The pipes on the gasoline-fueled tanks were shorter than those on the diesel tanks, and curved down into the rear deck plate immediately from the air cleaners. The pipes on the diesel tanks ran across the rear deck and through the screen above the engine.

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Light Tank M3A1 Stuart^{2-10,12,15-16,20}

M3A1, or Stuart III, was fitted with a power traverse mechanism and a turret basket. M3A1s lacked a turret cupola, and were externally identical to Stuart Hybrids. Besides the 4410 gas-powered M3A1s, 211 M3A1s were powered by the Guiberson T-1020 diesel engine, and were called Stuart IV by the British. The first M3A1(diesel)s were accepted in August 1942. The fixed sponson machine guns were eliminated on M3A1, since tanks were often confined on roadways or by terrain, and the sponson guns could not be brought to bear in those situations. An auxiliary generator and engine was installed behind the driver.

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Light Tank M3A3 Stuart^{3-6,8-10,12,15,17-20}

M3A3, or Stuart V, was modified to have a sloped hull similar to the light tank M5 Stuart. M3A3 was also fitted with a new turret incorporating a radio bustle and larger hatches. The new hull armor gave the drivers their own hatches (previously the assistant driver had to exit through the turret), and eliminated the drivers' doors in the front hull. The enlarged armor envelope allowed the air cleaners to be mounted internally, and two more fuel tanks were able to be incorporated into the vehicle. The M3A3's hull can be differentiated from that of the M5 Stuart by the fact that the rear deck on the M3A3 was flat, and the upper sides on the M3A3 were sloped. The increased weight imposed by the new hull design necessitated a change in the final drive ratio from 2.41:1 to 2.57:1. Steering effort was eased by the lengthening of the steering levers.

The designation of light tank M3A2 was reserved for a design of the M3A1 which was to have a welded homogeneous steel hull, but this tank never materialized.

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References

1. TM 9-726 Light Tank M3. Washington, DC: War Department, 15 July 1942.
2. Handbook on M2A4, M3 and M3A1 Light Tanks. Revised March 1942.
3. Hunnicutt, R.P. Stuart: A History of the American Light Tank, volume 1. Navato, CA: Presidio Press, 1992. Reprinted with permission from Stuart, R.P. Hunnicutt ©1992, available from Presidio Press, 505B San Martin Drive, Suite 160, Navato, CA 94945.
4. TM 9-1726 Ordnance Maintenance--Continental Engine, Model W670-9A. Washington, DC: War Department, 20 March 1942.
5. TM 9-1728 Ordnance Maintenance--Power Train for Light Tanks M3 and M3A1. Washington, DC: War Department, 8 April 1942.
6. Catalogue of Standard Ordnance Items, 2nd edition 1944, volume 1. Washington, DC: Office of the Chief of Ordnance Technical Division, 1 June 1945.
7. Tank Data, vol. 2. Aberdeen Proving Ground, MD: US Army Ordnance School, Jul 1958.
8. Chamberlain, Peter, and Chris Ellis. British and American Tanks of World War Two. Frome, England: Cassell & Co., 2000.
9. Miller, David. The Illustrated Directory of Tanks of the World. Osceola, WI: MBI Publishing Co., 2000.
10. Siemers, Cary. "USA's M3 and M5 Light Tanks." World War II Tanks & Vehicles and Advanced Squad Leader. 25 Nov 2000. 10 Dec 2000 <http://www.shadowsfolly.com/WWII/USA/LightM3_M5.htm>.
11. Zuljan, Ralph. "M3 Stuart." Second World War Armor. 16 Mar 2000. 10 Dec 2000 <http://www.onwar.com/tanks/usa/fltm3.htm>. Second World War Armor
12. TM 9-250 37-mm Gun M6, Mounted in Combat Vehicles. Washington, DC: War Department, 3 August 1944.
13. TM 9-1334 Ordnance Maintenance--Stabilizers. Washington, DC: War Department, 22 December 1943.
14. TM 9-1727 Guiberson Engine, Model T-1020. Washington, DC: War Department, 8 April 1942.
15. TM 9-727 Light Tanks M3A1 and M3A3. Washington, DC: War Department, 4 December 1943.
16. Zuljan, Ralph. "M3A1 Stuart." Second World War Armor. 16 Mar 2000. 10 Dec 2000 <http://www.onwar.com/tanks/usa/fltm3a1.htm>. Second World War Armor
17. Tank Data, vol. 2. Aberdeen Proving Ground, MD: US Army Ordnance School, Jul 1958.
18. TM 9-2800 Standard Military Motor Vehicles. Washington, DC: War Dept., 1 Sep 1943.
19. ---. "M3A3 Stuart." Second World War Armor. 16 Mar 2000. 10 Dec 2000 <http://www.onwar.com/tanks/usa/fltm3A3.htm>. Second World War Armor
20. Sola, Samuel, Vincent Bobkowski, and Kara Crocker. Weapon Mounts for Secondary Armament. Santa Monica, CA: G. O. Noville & Associates, Inc., April 1957.

Last updated 25 Nov 2023.
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