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United States' M3 light tank¹², "General Stuart"¹²

M3 light tank at the Aberdeen Proving Grounds, Maryland: LIFE Magazine (Mark Holloway)	M3 Light Tank:	M3 Light Tank in Casablanca: U.S. Army in World War II - Pictorial Record, 1951, pg 28	M3 Light Tank: Aberdeen Tank Museum
M3 Light Tank during war games in Tennessee: Mark Holloway	M3 Light Tank captured by the Germans in North Africa: U.S. Army in World War II - Pictorial Record, 1951, pg 56	M3 Light Tank purchased in July 1942, with war bonds by the community of Banning, California.	M3 Light Tank
M3 light tank with rounded homogeneous welded turret¹²: U.S. Ordnance Dept.	M3 light tank's pistol port and protectoscope¹²: U.S. Ordnance Dept.	M3 light tank with a seven sided welded turret and a riveted hull¹²: U.S. Ordnance Dept.	M3 light tank's rounded homogeneous turret¹²: U.S. Ordnance Dept.
M44 gun mount¹²: U.S. Ordnance Dept.			M3A2 Light Tank:

Design

With events in Europe in 1940, the Army realized the M2 was inadequate and the decision was made to modernize it. A new design with thicker armor was standardized on July 5, 1940.^7,12 Production started in March 1941 at the American Car & Foundry.⁷ It was based on the M2A4, but had thicker armor that was homogeneous rolled and the idler wheel was placed on the ground to act as another road wheel to help distribute the weight.^1,11,12

Initially the engine was the Continental but shortages caused it to be replaced by the Guiberson T-1020 diesel, and fitted into 500 M3s.⁸

Tracks could often last 1,000 miles, whereas other models required replacement at 500 miles.

During production the riveted turret was replaced by a welded one 7-sided one.¹² Also in early 1942 an all welded hull was produced.

It had volute spring suspension with the rear idler on the ground. This reduced the ground pressure and gave support to the rear of the tank.

Layout

The engines were in the rear with the drive going to the front sprockets, which was controlled by differential steering.⁷ The rear idler was located on the ground which helped in supporting the rear of the M3.¹²

Crew

The driver was on the left and the hull gunner/assistant driver on the right.^7,12 They could see out through windshields in their hatches.¹²

The gunner and commander/loader were in seats that were in the M3's turret basket.¹²

Engine

Internally the M3 carried 56 gallons of fuel.¹² Some tanks had two 25 gallon external tanks added, and these were jettisonable once combat started.¹²

Prototype

Production

M3: 5,811^5,7,11
- Production: 1941 - August 1942⁵, March 1941 - August 1942⁷
- Manufacturer: American Car Foundry
M3A1: 4,621
- Production: May 1942 - February 1943
- Manufacturer: American Car Foundry
M3A1 Diesel:
- Manufacturer: American Car Foundary⁹
M3A3: 3,427⁷
- Production: December 1942 -⁷
- Manufacturer: American Car Foundry
Total: 13,859⁸
- Production: - October 1943⁸

Variants

M3: Production started in March 1941 right after the last M2 was produced.¹ In July 1943, the Ordnance Committee declared it obsolete. From mid-1941 a gyrostabilizer was installed with the gun. Had cupola on the left side of the turret. There was a sponson on each side of the vehicle which had a .30 caliber MG installed. The radios were in the left sponson and were usually the SCR508.
M3A1:
M3A1 Diesel:
M3A2: Was going to be made welded like A1 but never produced.^11,12
M3A3:
M3 Command Tank: Removal of turret and putting welded box superstructure with .50 cal MG on mount.¹¹
M3 with Maxson Turret: In 1942 a quad Maxson .50 cal MG turret was put on in place of the turret. Rejected as similar equipment was on half-tracks.
M3 and T2 Light Mine Exploder: In 1942 a T2 mine exploder on a boom was developed and rejected as too unwieldy.
M3 or M3A1 with Satan Flame-gun: Produced in Hawaii for use by USMC. Gun was removed and flame thrower was installed.⁸ Capacity was 170 gallons and range of 40-60 yards. 20 converted in 1943. Used at Saipan, Tinian, and Guam.⁸
M3A1 with E5R2-M3 Flame-gun: Flame thrower put in place of hull machine gun.⁸ 10 gallon capacity. Used at Saipan, Tinian, and Guam.⁸
M3E2: Cadillac engines.¹¹ Became the M5.¹¹
T18 75 mm Howitzer Motor Carriage: Design started in September 1941. It was to provide a close support vehicle for the M3. Two test vehicles with mild steel superstructures were sent to the Aberdeen Proving Ground. This project was abandoned in April 1942 as it was unsatisfactory with it's high profile and being nose heavy.
T56 3" Gun Motor Carriage: Project started in September 1942 to mount a 3" in a modified M3A3 chassis. The gun was placed in the rear, and the engine was moved to the center. Had limited crew protection and was very heavy. Project dropped in February 1943.
T57 3" Gun Motor Carriage: Same as the T56, but with an up-rated Continental engine from the M3 medium. Project dropped in February 1943.

United Kingdom Use

Stuart I: M3 with Continental engine.¹¹
Stuart II: 500 M3s with Guiberson diesel.¹¹
Stuart III: M3A1 with Continental engine.¹¹
Stuart IV: M3A1 with Guiberson diesel.¹¹
Stuart V: M3A3.¹¹
Stuart VI: M5 and M5A1.
Stuart Kangaroo: Removed turret and added seats.
Stuart Recce: As Kangaroo but with various MGs on pindle mounts.
Stuart Command: As Kangaroo but with extra radios.
Stuart 18 pdr. SP: At least one Stuart had it's turret replaced by an 18 pdr field gun.

Usage

Experience in Africa

Some vehicles also had two 25 gallon jettisonable fuel tanks mounted on the side of the rear deck based on British experience in North Africa.

Sturdiness

During the retreat in Burma in 1942, Stuarts of the 2nd Royal Tanks went 2,400 miles in eleven weeks with very little maintenance.⁷

First Action

M3s were used by the 8th King Royal Irish Hussars in August 1941 in Egypt.⁷ Fought their first battle at Sidi Rezegh on November 19, 1941.⁷

Organization

There were 72 M3s in a Marine Light Tank Battalion.⁸

British Service:

Nicknamed "Honey" by British calvary regiments. 84 sent to 8th Army in July 1941.¹ Used in Burma⁷, New Guinea⁷, Iraq⁷, Britain, NW Europe⁷, Italy⁷, and North Africa⁷. Russia¹, China¹, New Zealand¹, and France received some as well.

The British were reported to like this tank at the time of its introduction. It could go about 10-20 mph faster than their own or enemy tanks, and required less maintenance.

	M3 (Stuart I), M3 light tank¹²	Stuart II
Crew	Commander, gunner, driver, co-driver³ 4^2,3,4,8,12
Radio	SCR-245¹²
Physical Characteristics
Weight	27,400 lb^3,8,12 12.2 tons⁷, 12.3 tons⁴, 13 tons² 12,428 kg⁸
Length w/gun	14.8'⁸, 14' 10"^4,7, 14' 10 3/8"¹², 14' 10.75"³ 4.5 m⁸, 4.53 m²
Length w/o gun
Height	8' 3"^3,4,7,12, 8.3'⁸ 2.5 m⁸, 2.65 m²
Width	7.3'⁸, 7' 4"^3,4,7,12 2.2 m⁸, 2.46 m²
Width over tracks
Ground clearance	16.5"¹² 0.42 m²
Ground contact length	117"¹²
Ground pressure	10.47 psi¹², 10.5 psi⁸ 0.7 (kg/cm²)⁸, 1 (kg/cm²)²
Turret ring diameter	46.75"¹²
Armament
Main	37 mm M5 or M6 L/56¹ 37 mm L/56² 37 mm M5^3,8,12 37 mm⁴
OR	37 mm M6^3,8,12
Secondary
MG	5: MG⁴ 2: MGs² 3: .30 cal Browning MGs³
MG - coaxial	1: 0.3" M1919A4⁸ 1: .30 cal Browning M1919A4 1: .30 cal Browning MG¹²
MG - hull	1: 0.3" M1919A4⁸ 1: .30 cal Browning M1919A4 1: .30 cal Browning MG¹²
MG - antiaircraft	1: .30 cal Browning M1919A4 1: .30 cal Browning MG¹² 0.3" MG⁸
MG - sponsons	2: .30 cal Browning M1919A4 2: .30 cal Browning MG¹² 2: .30 cal Browning MGs in sponsoons³
Side arms	1" .30 cal M2 tripod mount¹² 1: .45 cal submachine gun¹² Hand grenades¹²
Quantity
Main	103³, 83² 103: APC M51B1, APC M51B2, HE M63, Canister M2¹²
Secondary
MG	6,400-8,270³, 5,435², 8,270¹²
Side arms	.45: 500¹², 500 - 540 Grenades: 12 (4: Fragmentation Mk II, 2: Offensive Mk IIIA2, 4: Smoke WP M15, 2: Thermite Incendiary)¹²
Armor Thickness (mm)	10³, 51³ 10 - 45⁸
Hull Front, Upper	1.5"¹², 1" - 1.5"⁴ 38.1²
Hull Front, Lower	5/8" - 1.75"¹²
Hull Sides, Upper	1"¹², 1"@0° 25.4²
Hull Sides, Lower
Hull Rear	1"¹², 1"@0° 25.4²
Hull Top	3/8"¹² 9.5²
Hull Bottom	3/8" - 0.5"¹² 6.4 - 12.7²
Turret Front	1.5"¹² 38.1 m²
Turret Sides	1.25"¹², 1.25"@0° 25.4²
Turret Rear	1.25"¹², 1.25"@0° 25.4²
Turret Top	0.5"¹², 0.5"@90° 9.5²
Engine (Make / Model)	Continental W-670-9A¹², Continental Wright², Continental W-670^3,8, Continental Radial^4,5, Continental⁷	Guiberson T-1020⁵
OR	Guiberson⁷, Guiberson T1020³, Guiberson T1020-4¹²
Bore / stroke
Cooling	Air^2,4,8,12
Cylinders	7^2,5,8,11 Continental: 7^7,12 Guiberson: 9^7,12
Capacity
Net HP	250⁴, 250@2,400 rpm^2,8 Continental: 250@2,400 rpm¹² Guiberson: 220@2,200 rpm¹²
Power to weight ratio	18 hp/ton⁷, 20.4 hp/ton⁸
Compression ratio
Transmission (Type)	Synchromesh 5 forward, 1 reverse²
Gear ratios - 1st gear	5.37:1¹²
- 2nd gear	2.82:1¹²
- 3rd gear	1.72:1¹²
- 4th gear	1.09:1¹²
- 5th gear	0.738:1¹²
- reverse	6.19:1¹²
Steering
Steering ratio
Starter
Electrical system	12 volt¹²
Ignition
Fuel (Type)	Gasoline^2,8 Continental: Gasoline¹² Guiberson: Diesel¹²
Octane	Continental: 80¹²
Cetane	Guiberson: 50¹²
Quantity	54 gallons, 56 gallons internal¹², 50 gallons jettisonable tanks¹² 151 liters²
Road consumption
Cross country consumption
Performance
Traverse	360°^3,12, hand¹²
Max speed	35 mph⁴, 36 mph^3,7,8,12 57.9 kph², 58 kph⁸
Cross country speed	15 - 20 mph⁴, 20 mph^3,8 32 kph⁸
Road radius	70 miles^3,7,8,12, 135 miles 112 km⁸, 120 km²
Cross country radius
Turning radius	21'¹² 13 m²
Elevation limits	-10° to +20°^3,12
Fording depth	3'^3,12 0.9 m²
Trench crossing	6'^3,8,12 1.8 m⁸
Vertical obstacle	2'³
Climbing ability	60%¹²
Suspension (Type)	Vertical volute and trailing idler³ Volute Springs^2,12
Wheels each side	4²
Wheel size	20x6¹²
Return rollers each side	3
Tracks (Type)	Rubber block¹²
Length
Width	11 5/8"¹² 295 mm²
Diameter
Number of links	132 or 134¹²
Pitch	5.5"¹²
Tire tread
Track centers/tread	6' 1"¹²

Sources:

The Encyclopedia of Tanks and Armored Fighting Vehicles - The Comprehensive Guide to Over 900 Armored Fighting Vehicles From 1915 to the Present Day, General Editor: Christopher F. Foss, 2002
Panzer Truppen The Complete Guide to the Creation and Combat Employment of Germany's Tank Force 1933-1942, Thomas L. Jentz, 1996
British and American Tanks of World War Two, The Complete Illustrated History of British, American, and Commonwealth Tanks 1933-1945, Peter Chamberlain and Chris Ellis, 1969
Tanks of the World, 1915-1945, Peter Chamberlain, Chris Ellis, 1972
The Encyclopedia of Weapons of World War II, Chris Bishop, 1998
-
Tanks of World War II, Duncan Crow, 1979
Battle Winning Tanks, Aircraft & Warships of World War II, David Miller, 2000
Tank Data, Aberdeen Proving Grounds Series, 1968?
Tank Data 2, Aberdeen Proving Grounds Series, E. J. Hoffschmidt and W. H. Tantum IV, 1969
Airfix Magazine Guide #26 American Tanks of World War 2, Terry Gander and Peter Chamberlain, 1977
The American Arsenal, 1996