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United States' M22 light tank, Locust


T9E1 Light Tank prototype:
United State's T9E1 Prototype Light Tank
US Ordnance Dept.
M22 Light Tank mounted under plane wing.
United States' M22 Light Tank, Locust, mounted under a plane's wing
US Ordnance Dept.

M22 Light Tank. Looking inside turret basket with turret removed.
United States' M22 Light Tank, Locust. Looking inside turret basket with turret removed.
US Ordnance Dept.
M22 Light Tank's top view of the hatches and combination gun mount.
United States' M22 Light Tank, Locust
US Ordnance Dept.
M22 Light Tank:
United States' M22 Light Tank, Locust
US Ordnance Dept.

M22's Tracks and Tools:
United States' M22 Light Tank's Tracks and Tools
US Ordnance Dept.


Based on the development of airborne forces by the Germans and Russians, the US Army decided in February 1941 that it should have airborne forces with armor support. General Motors, Christie, and Marmon-Herrington were asked to submit designs in May 1941.1,4 Marmon-Herrington Corp. was selected and worked with the U.S. Army Ordnance Department Tank Engineering Division.4

It was built with a welded hull and cast turret. The engine was located on the right side in the rear of the hull. The power train was located in the front and consisted of a fixed-ratio transfer case, a 4-speed transmission, and controlled differential.

To save on weight there was no power traverse or a gyrostabilizer.8


The turret could be moved and four brackets were mounted above the suspension on the hull to allow for the tank to be attached to a C-54 Skymaster cargo airplane.4,7

The British could carry the M22 in their Hamilcar glider.7

Crew Compartment

The driver's hatch could be fastened open for driving in non-combat areas.8 A detachable windshield with cover was also provided. Two hatches in the roof of the turret and and escape hatch in the hull provided exit points.

Main Armament

The gun was mounted in a Combination Gun Mount, M53.

The 37 mm gun can fire a 1.9 lb AP shell with a muzzle velocity of 2,600'/sec.6


There were two bogie assemblies that contained two wheels each side that used volute springs with two support rollers.5 The idler trailed on the ground in the rear.8


The armor on the M22 wasn't thick enough to protect against .50 caliber guns.4


The first prototype, the T9, was delivered in late 1941 and designated the Light Tank T9 (Airborne).4

In January 1942, two pilot models designated T9E1 were ordered.4 The shape of the turret was altered, the power traverse, gyrostabilizers and bow machine guns were not installed to save weight.4 These were tested by the 28th Airborne Tank Battalion. One of the prototypes was sent to England for testing.4

Tests were conducted even after production was ordered in 1943 to 1944.4 These were conducted by the Ordnance Department at the Aberdeen and General Motors Proving Grounds.4 The Armored Board conducted their tests at Fort Knox.4

The Army Air Corps conducted tests with a C-54.4 Brackets were added to the hull sides to allow for lifting hooks to be used to attach the tank to the aircraft.4 However, it was found the turret had to be removed first.4


500 were ordered in April 1942 before service tests had begun.4 Eventually 1,900 were ordered but due to design changes and manufacturing problems only 830 were delivered.4,5

Standardized as the M22 in early 1943.7

The Ordnance Committee redesignated it Limited Standard in September 1944.8

  • T9: 14
  • T9E1: 24
    • Production: November 19424
  • T9E2: 27
  • M22: >8009, 8301,4,5
    • Production: April 1942 - March 19451, April 1943 - February 19444,5, ? - February 19447
    • Manufacturer: Marmon-Herrington5,6


  • T9: Prototype.4,7 Had 37 mm main gun.4,7
  • T9E1: Prototype.4,7 Hull shape changed.4,7 Powered traverse for the turret and the gyrostabilizer for the main armament was removed to save weight.4,7 Hull machine guns were removed to save weight.4
  • T9E2: Design.4 Was to carry an 81 mm breech loading mortar.4
  • M22: Production model.4
  • T18 Light Tractor: M22 with no turret.4 Could carry the five member crew of a 105mm airborne howitzer that it towed.4 Only one converted and project cancelled in late 1943.4


Never used in combat by US forces.4,5,9 No suitable glider or aircraft to transport it.

British Use:

Some had a Littlejohn adaptor installed which increased the barrel length.1,4

British used them in the Normandy landings.6
British forces did not use them in Normandy despite advertising by Marmon-Herington.4

The British named it Locust and used it in the 6th Airborne Division in the Rhine crossing on March 22, 1945 / March 24, 19454.1,7,9 Were carried in the Hamilcar glider.9 Used with the Tetrarch during the crossing on March 24, 1945.5


In July 1945, the M22 was declared obsolete as it was no longer going to be used.4

Some of the surviving M22s were sold to Belgian scrap dealers and some of those may have ended up in Egypt.4
Some were supplied to Egypt after the war.1


Physical Characteristics  
Weight - empty  
Width over tracks  
Ground clearance  
Ground contact length  
Ground pressure  
Turret ring diameter  
Main 37 mm4,7
MG - coaxial 1: .30 cal MG4
MG - hull 2: .30 cal MG4
Side arms  
Side arms  
Armor Thickness 1"4
Hull Front, Upper  
Hull Front, Lower  
Hull Sides, Upper  
Hull Sides, Lower  
Hull Rear  
Hull Top  
Hull Bottom  
Turret Front  
Turret Sides  
Turret Rear  
Turret Top  
Engine (Make / Model)  
Bore / stroke  
Net HP  
Power to weight ratio  
Compression ratio  
Transmission (Type)  
Gear ratios - 1st speed  
- 2nd speed  
- 3rd speed  
- 4th speed  
- reverse  
Steering ratio  
Electrical system  
Fuel (Type)  
Road consumption  
Cross country consumption  
Speed - Road  
Speed - Cross Country  
Range - Road  
Range - Cross Country  
Turning radius  
Elevation limits  
Fording depth  
Trench crossing  
Vertical obstacle  
Climbing ability  
Suspension (Type) Two bogies with volute springs4
Wheel size  
Wheels each side 44
Return rollers each side 24
Tracks (Type) T78 Carden-Loyd iron4
Width 11.25"4
Number of links  
Pitch 3"4
Tire tread  
Track centers/tread  
  M22 light tank
Crew Commander, gunner, driver.2
Radio SCR-5108
Physical Characteristics  
Weight 16,000 lb8, 16,400 lb2,3,7, 16,452 lb4, 17,024 lb
7.3 tons1,9, 7.4 tons5, 8.5 tons6
7,417 kg9, 7,439 kg1 , 7,445 kg7
Weight - empty 14,490 lb4
Length 12.9'6, 12' 11"1,2,3,4,5,7,8,9
3.937 m7, 3.94 m1,9
Height 4' 1"4, 5' 4"5, 5' 8"1,9, 5' 8.5"3,8, 6' 1"2,7, 6.1'6
1.73 m9, 1.74 m1, 1.854 m7
Width 7' 1"2,7, 7' 3.75"3,8, 7' 4"1,5,9, 7' 4.5"4, 7.5'6
2.159 m7, 2.23 m1, 2.24 m9
Width over tracks  
Ground clearance 9.5"4,6, 10"8
Ground contact length 8' 8"8, 109"6
Ground pressure 6.7 psi6, 7.03 psi8, 7.2 psi
Turret ring diameter 47.5"8
Main 1: 37 mm M61,2,8,9
1: 37 mm3,5,7
1: 37 mm M6 L/374
1: 37 mm M6, L/536
MG 1: MG3
1: 7.62 mm (.30 cal) MG1
1: .30 cal Browning MG2
1: .30" Browning MG5
1: .30 cal MG7
MG - coaxial 1: .30 cal Browning M1919A4 MG6,8
1: .30 cal Browning MG4
1: 7.62 mm / 0.3" MG9
Side arms Tripod M2 .30 cal MG8
3: .45 cal M3 submachine guns8
Main 501,2,4,6,7,8
APC M51B1 or M51B28, AP M748, HE M638, Canister M28
MG 2,5001,2,4,6,7,8
Side arms .45 cal: 4508
Grenades: 128 (4: Fragmentation Mk II, 4: Smoke M8, 2: Thermite, 2: Offensive Mk III)8
Armor Thickness 259
0.75" - 1"3
Front: 0.98"7, 1"6
Side: 0.4"6
Hull Front, Upper 1"4,8
Hull Front, Lower 1"8
Hull Sides, Upper 0.375@45°4, 0.75"8
Hull Sides, Lower 0.5"8
Hull Rear 0.5"4,8
Hull Top 3/8"8
Hull Bottom 0.5"4,8
Turret Front 0.6"6, 1"4,8
Mantlet: 0.6"6
Turret Sides 1"6,8
Turret Rear 0.75" 8
Turret Top 0.375 - 0.75"4, 0.75"8
Engine (Make / Model) Lycoming 0-435T1,2,4,9, Lycoming3,5, Lycoming O-435-T8
Bore / stroke  
Cooling Air3,4,5,6,8
Cylinders Radial 69, 63,8, 6 horizontally opposed6
Net HP 1623,4,5,6,7,9, 162@2,800 rpm8
Power to weight ratio  
Compression ratio  
Transmission (Type) Marmon-Herrington Synchromesh4
4 forward, 1 reverse4,6
Gear ratios - 1st speed 1.857:18
- 2nd speed 1:18
- 3rd speed 0.463:18
- 4th speed 0.304:18
- reverse 1.666:18
Steering Controlled differntial4,6
Steering ratio  
Starter Electric6
Electrical system 12 volt8
Fuel (Type)  
Octane 808
Quantity 55 gallons8, 57 gallons4,6
Road consumption 2.5 mpg6
Cross country consumption  
Traverse 360°2,8, hand6
Speed - Road 35 mph8, 40 mph1,2,4,6,7,9
64 kph1,7,9
Speed - Cross Country 27 mph, 30 mph2,7, 35 mph3
48 kph7
Range - Road 110 miles8, 135 miles1,2,4,6,7,9
217 km7,9
Range - Cross Country  
Turning radius 20'8, 40'4
Elevation limits -10° to +30°2,4,8
Fording depth 3'8, 3' 2"2,4, 3' 6"6
Trench crossing 5' 5"2,4,8
Vertical obstacle 1' - 1' 6"4, 12.4"6, 1' 0.5"2, 1' 4"8
Climbing ability 27°4, 32° (63%) slope6, 50%8
Suspension (Type) Two bogie assemblies that contained two wheels each side that used volute springs with two support rollers5
Vertical volute springs4,6,8
Wheel size 15" x 6"4,8
Wheels each side 44,6
Return rollers each side 24,6
Tracks (Type) Dry pin6, Steel T788
Width 11.25"2,4,7,8, 11.5"6
0.286 m7
Number of links 1066,8
Pitch 3"4,8, 3.1"6
Tire tread  
Track centers/tread 5.4'6, 5.9'6, 5' 10.5"2,6,8
1.791 m7


  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. 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
  3. Tanks of the World, 1915-1945, Peter Chamberlain, Chris Ellis, 1972
  4. Profile AFV Weapons #46 Light Tanks M22 Locust and M24 Chaffee, Colonel Robert J. Icks, 1972
  5. Tanks of World War II, Duncan Crow, 1979
  6. Tank Data, Aberdeen Proving Grounds Series, 1968?
  7. Airfix Magazine Guide #26 American Tanks of World War 2, Terry Gander and Peter Chamberlain, 1977
  8. The American Arsenal, 1996
  9. World War I and II Tanks, George Forty, 2012
20th Century American Military History Crucial Site