T31 (20 mm)

Description

The 20 mm T31 is an American aircraft autocannon used on several strike aircraft in the game. A shortened and lightweight version of the AN/M2, the T31 fires at a slightly higher rate due to its design.

Vehicles equipped with this weapon

• A2D-1
• AM-1

General info

Tell us about the tactical and technical characteristics of the cannon or machine gun.

Available ammunition

• Default: HEF-I · HEF-I · AP-T
• Universal: HEF-I · AP-T
• Ground targets: AP-T · AP-T · HEF-I · P
• Air targets: HEF-I · AP-T · HEF-I · HEF-I
• Stealth: HEF-I · HEF-I · HEF-I · P

Penetration statistics
Ammunition	Penetration @ 0° Angle of Attack (mm)
	10 m	100 m	500 m	1,000 m	1,500 m	2,000 m
AP-T	36	33	23	15	9	6
HEF-I	5	4	3	2	2	2
P	17	15	12	7	6	4

Shell details
Ammunition	Velocity (m/s)	Projectile mass (kg)	Fuse delay (m)	Fuse sensitivity (mm)	Explosive mass (TNT equivalent) (g)	Ricochet
						0%	50%	100%
AP-T	832	0.13	-	-	-	47°	60°	65°
HEF-I	832	0.13	0.2	0.1	12.41	79°	80°	81°
P	832	0.13	-	-	-	47°	56°	65°

Comparison with analogues

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Usage in battles

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Pros and cons

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Pros:

Cons:

History

The United States Navy first requested a shortened version of the AN/M2 cannon in December 1942. The Army, which handled production of the M2 began testing different barrel lengths at Aberdeen Proving Grounds, Maryland in January 1943 and concluded that 15 inches could be removed from the barrel without adversely affecting the muzzle velocity. The Army Ordnance Department would soon issue their requirements for a new variant of the AN/M2 that along with being shorter, had to use the same action and ammunition, accept cartridges of different lengths, use the M3 disintegrating belt link instead of the M2's 60-round drum magazine, have left or right-side feeding with no extra parts needed, a fire rate of 575-650 rounds per minute, and weigh 75 pounds or less. However, the specifications would change in July after the US got work from Britain's Hispano Mk.V. Developed along similar lines as a shorter version of their 20 mm autocannon which was 27 pounds lighter and 12 inches shorter. The Army Ordnance Department made their new specifications to have the guns have the same weight and length shaved off as the Mark Vs did, along with the ability to use the M1 Adapter, a rate of fire of 750 rpm, a muzzle velocity drop of no more than 80 feet per second, use a non-adjustable ring spring adapter, and fire from a closed-bolt.

The T26 was built by Oldsmobile to meet the requirement of a lighter AN/M2, but it did not fire from a closed bolt as requested. The development for a version capable of firing when locked was given to Watervliet Arsenal in New York who came up with two possible designs. The T28 used a percussion bolt while the T29 used an electrically primed bolt. Both bolts were tested interchangeably at Aberdeen Proving Grounds so by December, the guns were merged into one design which was designated the T31. In January 1944, the Navy asked for 25 for testing which was closely followed by an order for 51 by the Army Air Forces. In February the Navy order was increased to 23,326 guns to be delivered by the end of the year while the Army Air Force ordered another thousand guns. The International Harvester Plant in Saint Paul, Minnesota began manufacturing the T31 in January, a significant number were converted AN/M2 cannons that didn't meet the requirements from a prior design revision and were mothballed. Between International Harvester and Oldsmobile, 32,426 T31 cannons were built. The T31 was mounted on the US AM-1 Mauler which was part of the first attempt to make a new generation of carrier-based attack aircraft and alongside the venerable AD Skyraider. It was also mounted on the A2D-1 Skyshark intended for smaller escort carriers that were retired not long after the aircraft entered service.

Media

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See also

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• reference to the article about the variant of the cannon/machine gun;
• references to approximate analogues by other nations and research trees.

External links

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• topic on the official game forum;
• other literature.