M3 Light Tank, Stuart

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 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

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. 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.

Production

When production ended in October 1943, 13,859 were built.⁸

Layout

The engines were in the rear with the drive going to the front sprockets, which was controlled by differential steering.⁷

Crew

The driver was on the left and the hull gunner/assistant driver on the right.⁷

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

M3:

Aberdeen Tank Museum

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:

Aberdeen Tank Museum

Standardized in August 1941. Started production in April 1942.⁷ Declared obsolete in July 1943.

Had gyrostabilizer installed and a turret basket with seats for the commander and gunner.⁷ Cupola was removed from new turret design.^1,7 A periscope with 360° traverse was installed in the turret roof.

Riveted hulls in early production and then replaced by welded hulls. Sponson machine guns removed.^1,7 This allowed for more ammunition storage.⁷

The Combination Gun Mount, M23, was installed. It had a periscopic sight.

An improved radio and interphone system was installed.

The US Marine Corps requested the tanks have diesel engines installed and approximately 500 had radial air-cooled engines installed.

The muzzle velocity of the 37 mm gun AP ammunition was 2,600'/sec and weighed 1.9 lb.⁹

M3A1 Diesel⁹:

Aberdeen Tank Museum

The 37 mm gun fired a 1.91 lb round at a muzzle velocity of 2,600'/sec.⁹

M3A2:

Was going to be made welded like A1 but never produced.

M3A3:

Aberdeen Tank Museum

Standardized in August 1942, and classified as Limited Standard in April 1943.

Had an improved turret with a bulge in the rear for the radio installed.¹⁰ Three additional periscopes are installed.

The 37 mm gun fired a 1.9 lb AP shell at a muzzle velocity of 2,900'/sec.¹⁰ The .30 cal MG fired at 2,800'/sec.¹⁰

The hull was redesigned with all welded one piece hull front.¹ The front plate was extended which allowed for more room for storage and improved the safety for the driver and assistant driver. The driver's hatches are moved to the top of the hull. Periscopes are installed to provide vision for the driver and assistant driver. The sponsons were extended to the rear and this allowed for more gasoline and ammunition storage.¹⁰ A storage box is added at the rear of the hull.

A sand shield is extended over the top of the suspension.

Additional improvements included easier steering, improved fire protection and ventilation, detachable head lamps, and a detachable windshield. A Combination Gun Mount, M44, with a telescope was installed.

Phased out of production in 1943.

M3 Command Tank:

Removal of turret and putting welded box superstructure with .50 cal MG on mount.

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

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.

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.

United Kingdom Use

Stuart I:

M3 with Continental engine.

Stuart II:

M3 with Guiberson diesel.

Stuart III:

M3A1 with Continental engine.

Stuart IV:

M3A1 with Guiberson diesel.

Stuart V:

M3A3

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.

	M3 (Stuart I)	Stuart II	M3A1 (Stuart III)	M3A1 (Diesel)	M3A3 (Stuart V)
Crew	Commander, gunner, driver, co-driver.3 42,3,4,8		Commander, gunner, driver, co-driver.3 41,2,3,4,5,9	49	Commander, gunner, driver, co-driver.3 42,3,4,10
Physical Characteristics
Weight	27,400 lb3,8 12.2 tons7, 12.3 tons4, 12.5 tons6, 13 tons2 12,428 kg8		28,500 lb3 12.2 tons8, 12.7 tons1,4, 14.3 tons9 12,400 kg8, 12,927 kg1,5	14.3 tons9	12.3 tons4, 14.4 tons6 29,700 lb10, 31,752 lb3
Length w/gun	14.8'8, 14' 10"4,7, 14' 10.75"3 4.5 m8, 4.52 m6, 4.53 m2		14.8'9, 14' 10"1,4, 14' 10.75"3,5 4.54 m1,5	14.6'9	14' 10"10, 16' 6"3,4 4.53 m2, 5.03 m6
Length w/o gun
Height	8' 3"3,4,7, 8.3'8 2.5 m8, 2.51 m6, 2.65 m2		7.5'9, 7' 6"4, 7' 6.5"3,5, 7' 7"1 2.3 m1,5	7.7'9	7' 6.5"3,4, 8' 8"10 2.29 m6
Width	7.3'8, 7' 4"3,4,7 2.2 m8, 2.24 m6, 2.46 m2		7.3'9, 7' 4"1,3,4,5 2.22 m1, 2.24 m5	7.3'9	7' 4", 8' 3"3,4,10 2.46 m2, 2.51 m6
Width over tracks
Ground clearance	16.5" 0.42 m2		15"9, 16.5" 0.42 m2	16.5"9	16.5"10 0.42 m2
Ground contact length	117"		116"9, 117"	116"9	116"10, 117"
Ground pressure	10.47 psi, 10.5 psi8 0.7 (kg/cm2)8, 1 (kg/cm2)2		10.56 psi, 10.6 psi9	10.6 psi9	10.4 psi10
Turret ring diameter	46.75"		46.75"		46.75"
Armament
Main	37 mm M5 or M6 L/561 37 mm L/562 37 mm M5 or M63,6,8 37 mm4		37 mm M5 or M6 L/561 37 mm L/562 37 mm M5 or M63 37 mm4,5 37 mm QF M6 L/53 9	37 mm9	37 mm M5 or M6 L/561 37 mm L/562 37 mm M5 or M63 37 mm4 37 mm M6, gyrostabilized10
Secondary
MG	5: MG4 .30 cal Browning M1919A4, coaxial, hull, AA, 2 in sponsoons. 2: MGs2 3: .30 cal Browning MGs3 2: .30 cal Browning MGs in sponsoons.3 5: .30 cal MG, coaxial, hull, AA, sponsons (2)6 3: 0.3" M1919A4, coaxial, hull8 0.3" MG, AA8		4: MG4 .30 cal Browning M1919A4, coaxial, hull. 3: 7.62 mm MG1 3: .30 cal Browning MGs3 5: 7.62 mm MG, coaxial, AA, hull, sponsoons (2).5 2: .30 cal MG9	.30 cal M1919A59 2: .30 cal M1919A49	3: MG4 3: .30 cal Browning MGs3 3: .30 cal M1919A4 MG, coaxial, hull, AA10
Side arms	.30 cal M2 tripod mount .45 cal submachine gun Hand grenades		.30 cal M2 tripod mount .45 cal submachine gun Hand grenades	.45 1928A1 Submachine gun9	.30 cal M2 tripod mount .45 cal submachine gun 12: Hand grenades10
Quantity
Main	1033, 832		1139, 1163	1069	1743,10
Secondary
MG	6,400-8,2703, 5,4352		5,1509, 6,400-8,2703	7,2209	7,50010, 6,400-8,2703
Side arms	.45: 500-540 Grenades: 12		.45: 500-540 Grenades: 12	3509	.45: 500-540 Grenades: 12
Armor Thickness (mm)	103, 513 10 - 458 Front: 376 Side: 256		15 - 435 103, 513 Front: 1.5"9 Side: 1"9	Front: 1.5"9 Side: 1"9	103, 513 Front: 376 Side: 256
Hull Front, Upper	1.5" (1.75") 1" - 1.5"4 38.12		1.5" (1.75") 1" - 1.5"4 38.12		1.5" (1.75"), 1.5"@0°10 1" - 1.5"4 38.12
Hull Front, Lower	5/8-1.75" (1.75-3")		5/8-1.75" (1.75-3")		5/8-1.75" (1.75-3")
Hull Sides, Upper	1"@0° 25.42		1"@0° 25.42		1"@0°10 25.42
Hull Sides, Lower
Hull Rear	1"@0° 25.42		1"@0° 25.42		1"@0°10 25.42
Hull Top	3/8" 9.52		3/8" 9.52		3/8" 9.52
Hull Bottom	3/8-0.5" 6.4 - 12.72		3/8-0.5" 6.4 - 12.72		3/8-0.5" 6.4 - 12.72
Turret Front	1.5" (1.75") 38.1 m2		1.5"9 (1.75") Mantlet: 1"9 38.1 m2	1.5"9 Mantlet: 1"9	1.5" (1.75"), 1.5"@0°10 38.1 m2
Turret Sides	1.25"@0° 25.42		1.25"@0°, 1.25"9 25.42	1.25"9	1.25"@0°10 25.42
Turret Rear	1.25"@0° 25.42		1.25"@0° 25.42		1.25"@0° 25.42
Turret Top	0.5"@90° 9.52		0.5"@90° 9.52		0.5"@90° 9.52
Engine (Make / Model)	Continental W-670-9A Continetal Wright2 Continental W-670 OR Guiberson T1020.3,6 Continental Radial4,54 Guiberson or Continental7 Continental W-6708	Guiberson T-10205	Guiberson T1020-4 OR Continental W-670.1,6 Continetal Wright2 Continental W-670 OR Guiberson T1020.3 Continental W-970-9A, radial 5 Continental radial4 Continental W670-9a, radial 9	Guiberson Buda T-1020 Series 49	Continetal Wright2 Continental W-670 OR Guiberson T1020.3 Continental radial4 Guiberson T1020-410 Continental W670-A10
Bore / stroke				4-cycle9
Cooling	Air2,4,8		Air2,4,9	Air9	Air2,4,10
Cylinders	72,5,6,8 Continental: 77 Guiberson: 97		72,5,9	R-99	72 Continental: R-710 Guiberson: R-910
Capacity
Net HP	250@2,400 rpm2,8 2504,6		250@2,400 rpm2,9 2504,5		2502 @ 2,400 rpm2 2504,6 Continental: 25010 Guiberson: 18510
Power to weight ratio	18 hp/ton7, 20.4 hp/ton8
Compression ratio
Transmission (Type)	Synchromesh 5 forward, 1 reverse2		Synchromesh9 5 forward, 1 reverse2,9	Synchromesh9 5 forward, 1 reverse9	Synchromesh10 5 forward, 1 reverse2,10
Steering				Controlled differential9	Controlled differential10
Steering ratio
Starter				Electric9
Electrical system				12-volt9
Ignition				Injection9
Fuel (Type)	Gasoline2,8		Gasoline2,5	Diesel9	Gasoline2 Guiberson: Diesel10 Continental: Gasoline10
Octane
Quantity	54 gallons 151 liters2 56 (+50 in external tanks) gallons		54 gallons9 151 liters2	50 gallons9	54 gallons 151 liters2 102 gallons
Road consumption				1.5 mpg9
Cross country consumption
Performance
Traverse	360°3, hand		360°3, hydraulic hand9	Oilgear hydraulic9	360°3,10 Manual and hydraulic10
Max speed	35 mph4, 36 mph3,7,8 57.9 kph2, 58 kph8, 60 kph6		34 mph4,9, 36 mph1,3,5 58 kph1,5	37 mph9	31 mph10, 34 mph4, 36 mph3 57.9 kph2, 60 kph6
Cross country	15 - 20 mph4, 20 mph3,8 32 kph8		15 - 20 mph4,9, 20 mph3	15-20 mph9	15 - 20 mph4, 20 mph3
Road radius	70 miles3,7,8, 135 miles 112 km8, 120 km2		70 miles1,3,5, 124 miles9 112.6 km5, 113 km1	84 miles9	70 miles3, 125 miles10, 135 miles 120 km2
Cross country radius			100 miles9
Turning radius	21' 13 m2		21' 13 m2		21' 13 m2
Elevation limits	-10° to +20°3		-10° to +20°3		-10° to +20°3
Fording depth	3'3 0.9 m2		3'3,5, 42"9 0.9 m2, 0.91 m5	42"9	3'3, 3' 4"10 0.9 m2
Trench crossing	6'3,8 1.8 m8		6'3,5 1.83 m5	6'9	6'3, 7'10
Vertical obstacle	2'3		2'3,5 0.61 m5	24"9	2'3,10
Climbing ability			26° (50%) slope9	26° (50%) slope9	30° slope10
Suspension (Type)	Vertical volute and trailing idler.3 Volute Springs2		Vertical volute and trailing idler.3 Volute Springs2 Vertical volute spring, 2 double wheel bogies9	Bogies bolted to the hull, support the vehicle on vertical volute springs9	Vertical volute and trailing idler.3 Volute Springs2 Vertical volute springing10
Wheels each side	42		42	49	42 2 double wheeled bogies10
Return rollers each side	3		29, 3	39	210, 3
Tracks (Type)
Length					Steel, rubber blocks and rubber bushed track pins10
Width	11 5/8" 295 mm2		11 5/8", 11.6"9 295 mm2	11.5"9	11 5/8"10 295 mm2
Diameter
Number of links				679	6610
Pitch				5.5"9	5.5"10
Tire tread				Rubber9	Rubber10
Track centers/tread	6' 1"		6.1'9, 6' 1"	6.1'9	6' 1"10
Production	American Car Foundry: 1941-8/1942: 5,8115 3/1941-8/1942: 5,8117		American Car Foundry: 5/1942-2/1943: 4,621	American Car Foundary9	American Car Foundry: 3,427 12/1942-: 3,4277

Sources:

1. 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
2. Panzer Truppen The Complete Guide to the Creation and Combat Employment of Germany's Tank Force 1933-1942, Thomas L. Jentz, 1996
3. 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
4. Tanks of the World, 1915-1945, Peter Chamberlain, Chris Ellis, 1972
5. The Encyclopedia of Weapons of World War II, Chris Bishop, 1998
6. Jane's World War II Tanks and Fighting Vehicles The Complete Guide, Leland Ness, 2002
7. Tanks of World War II, Duncan Crow, 1979
8. Battle Winning Tanks, Aircraft & Warships of World War II, David Miller, 2000
9. Tank Data, Aberdeen Proving Grounds Series, 1968?
10. Tank Data 2, Aberdeen Proving Grounds Series, E. J. Hoffschmidt and W. H. Tantum IV, 1969

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