View source for 90 mm Gun M1/M2/M3

{{Infobox Weapon|is_artillery=yes|
|image= [[Image:90mm M1 AAgun CFB Borden.jpg|300px]]
|caption= 90 mm M1 at [[CFB Borden]]
|name= 90 mm M1A1
|origin= {{Flag|United States}}
|era=WW II
|target=aircraft
|type= [[Anti-aircraft warfare|Anti-Aircraft gun]]
|date= [[1940]]
|prod_date=[[1940]] -
|service=[[1940]] -
|used_by={{Flag|United States}}
|wars=[[World War II|Second World War]]
|carriage=mobile 
|caliber=90 mm.
|part_length=  53 calibers
|breech= 
|rate= 20 rpm
|velocity= 823 m/s
|cartridge= 90×600 mm. R
|ammo_wt= 10.61 kg 
|range=Maximum horizontal 17,823 m</br> Maximum slant  </br>Ceiling 10,380 m  
|recoil= 
|weight= 8.618 metric tons  
|length= 
|crew= 
|number= 
}}

The [[United States|American]] 90&nbsp;mm family of guns served as primary heavy [[anti-aircraft gun|anti-aircraft]] and [[anti-tank]] guns, playing a role similar to the renowned [[Germany|German]] [[88 mm gun]]. They were the US's primary anti-aircraft guns from just prior to the opening of [[World War II]] into the 1950s when most AAA was replaced by missile systems. As a tank gun, it was the weapon featured on the [[M36 (tank destroyer)|90mm Gun Motor Carriage M36]] and [[M26 Pershing|Heavy Tank M26 Pershing]], as well as a number of post-war tanks.

==History==
Prior to World War II, the primary US anti-aircraft gun was the [[3-inch M1918 gun]] (76.2&nbsp;mm L/50), a widely-used caliber for this class of weapon. Similar weapons were in [[United Kingdom|British]], [[USSR|Soviet]] and other arsenals. There had been several upgrades to the weapon over its history, including the experimental T8 and T9 versions developed in the early 1930s that were intended to enter service later in the decade.

However the Army became interested in a much more capable weapon instead, and on June 9, 1938 they issued a development contract calling for two new guns, one of 90&nbsp;mm which they felt was the largest possible size that was still capable of being manually loaded at high elevations, and another, using assisted loading, of 120&nbsp;mm caliber. The new design seemed so much better than developments of the older 3-inch that work on the 3-inch T9 was canceled in 1938 just as it became production-ready. By 1940 the second development of the 90&nbsp;mm design, the T2, was standardized as the '''90&nbsp;mm M1''', while its larger cousin became the [[120 mm M1 gun]].

[[Image:M26 Pershing.jpg|thumb|right|An [[M26 Pershing]] armed with the 90 mm gun]] A few hundred M1's were completed when several improvements were added to produce the '''90&nbsp;mm M1A1''', which entered production in late 1940 and was accepted as the standard on May 22, 1941. The M1A1 included an improved mount and spring-rammer on the breach with the result that firing rates went up to 20 rounds per minute. Several thousand were available when the US entered the war, and the M1A1 was their standard AA gun for the rest of the war. Production rates continued to improve, topping out in the low thousands per month.

Like the German 88, and the British [[QF 3.7 inch AA gun]], the M1A1 found itself facing tanks in combat, but unlike the others it could not be depressed to fire against them. On September 11, 1942 the Army issued specifications for a new mount to allow it to be used in this role, which resulted in the '''90&nbsp;mm M2''', introducing yet another new mount that could be depressed to 10 degrees below horizontal and featured a new electrically-assisted rammer. It became the standard weapon from May 13, 1943.

==AA operation==

[[Image:90mm-aa-gun-okinawa.gif|left|thumb|View of 90 mm anti-aircraft gun emplacement, Okinawa, 1945.]]
[[Image:M7 director.jpg|thumb|upright|right|M7 gun director 1944]]

In AA use the guns were normally operated in groups of four, directed by the M7 or M9 [[Director (military)|Director]] or [[Kerrison Predictor]]s. Radar direction was common, starting with the [[SCR-268]] in 1941, which was not accurate enough to directly lay the guns, but provided accurate ranging throughout the engagement. For night-time use, a [[searchlight]] was slaved to the radar with a beam width set so that the target would be somewhere in the beam when it was turned on, at which point the engagement continued as in the day. In 1944 the system was dramatically upgraded with the addition of the [[SCR-584]] microwave radar, which was accurate to about 0.06 degrees (1 mil) and provided automatic tracking as well. With the SCR-584, direction and range information was sent directly to the [[Bell Labs]] [[M3 Gun Data Computer]], and M9 Director, which could direct and lay the guns automatically. All the operators had to do was load the guns. With the SCR-584 the 90&nbsp;mm became arguably the best anti-aircraft weapon of the war.

==Anti-tank developments==
[[Image:90 mm gun antitank 1.JPG|right|thumb|An experimental 90 mm anti-tank gun.]]
The M3 was also adapted as a main gun for various armored vehicles, starting with the experimental T7 which was accepted as the '''90&nbsp;mm M3'''. The test firing of the M3 took place on an [[M10 Tank Destroyer|3in Gun Motor Carriage M10]] in early [[1943]]. The gun was used on the [[M36 (tank destroyer)|90mm Gun Motor Carriage M36]], and the [[M26 Pershing|Heavy Tank M26 Pershing]].

A number of experimental versions were developed on the basic M3 pattern, including the T14 which included a standard [[muzzle brake]], the T15 series with an improved [[muzzle velocity]] of about 975 meters per second, the even higher velocity T18, the T19 which was an attempt to reduce barrel wear, the T21 intended for wheeled vehicles, and the T22, which used the breech from the standard [[M101 howitzer|105 mm M2]] howitzer to take larger charge cartridges. None of these versions entered service.

In the post-war era development of the T15 continued as the T54, which included the ability to fire [[tungsten]]-cored shells at much higher velocities. The T54 was the main armament of the M47 and [[M48 Patton]] tanks, and the [[M56 Scorpion]] anti-tank vehicle.

==Variants==
[[Image:90-mm-guns-korea-2.jpg|right|thumb|90 mm guns M2, Korea.]]
===M1===
*Towed [[anti-aircraft gun]]. Approved for service in 1940.
*Fixed on M3 mount for [[Coast Artillery]]

===M1A1===
<!-- [[M1A1]] links here -->

Towed [[anti-aircraft gun]]. Production began in 1940. Featured the M8A1 spring rammer. Rate of fire 20 rounds per minute.

===M2===
A complete redesign to make the gun dual role, functioning as an [[anti-tank gun]] as well as an anti-aircraft gun. The ammunition feed was upgraded and an automatic fuze setter/rammer the M20 was added. This enabled the rate of fire to reach up to 24 rounds per minute. Elevation was improved with the gun able  to depress to &minus;10 degrees. To protect the crew a large metal shield was added. The M2 was the standard weapon by May 13, 1943. From the march it could fire from its wheels in 3 minutes, and from a fully emplaced position in 7 minutes. In 1944 the weapon was enhanced with the addition of [[proximity fuse]]d shells.
===M3===
[[Image:M36-GMC-Danbury.0004zx4t.jpg|thumb|right|An M36 tank destroyer with the 90 mm gun]] An [[anti-tank]] version of the gun. It was used to equip the [[M36 (tank destroyer)|90mm Gun Motor Carriage M36]] and [[M26 Pershing|Heavy Tank M26 Pershing]].  It is also known as '''90&nbsp;mm L/53'''.

==General characteristics (M1A1)==
* '''Caliber''': 90&nbsp;mm L/53
* '''Total weight''': 8,618&nbsp;kg (18,999&nbsp;lb) 
* '''Barrel weight''': 1,109&nbsp;kg (2,445&nbsp;lb)
* '''Length with the carriage''': 4.73&nbsp;m (15.5&nbsp;ft)
* '''Length''': 4.60&nbsp;m (15&nbsp;ft)
* '''Width''': 4.16&nbsp;m (13.64&nbsp;ft)
* '''Height''': 3.07&nbsp;m (10&nbsp;ft)
* '''Weight of the projectile''': 10.61&nbsp;kg (23.39&nbsp;lb)
* '''Rate of fire''':  25 rounds per minute (at most)
* '''Muzzle velocity''': 823 m/s (2,700&nbsp;ft/s)
* '''Range''': 17,823 m (20,585 yd)
* '''Ceiling''': 10,380 m (34,050&nbsp;ft) (limited by 30 second fuse)
* '''Elevation''' : +80 to &minus;5 degrees
* '''Traverse''' : 360 degrees.

==Surviving examples==
* [[CFB Borden]], [[Ontario]], [[Canada]]
* Pre-Fair [[army surplus]] sales, at [[Belœil, Quebec|Belœil]], near [[Montreal]], [[Quebec]], [[Canada]] (three)

==See also==
* [[Rangekeeper]]
* [[Fire-control system]]

==References==
* TM 9-2300 standard artillery and fire control material. dated 1944
* TM 9-370
* TM 9-1370
* SNL D-28

==External links==
{{Commons|90 mm gun M1/M2}}
* [http://www.ibiblio.org/hyperwar/USA/ref/TM/PDFs/TM_9_374.PDF United States War Department TM 9-374 Technical Manual 90-MM Gun M3 Mounted in Combat Vehicles. 11 September 1944]
* [http://gva.freeweb.hu/weapons/usa_guns7.html M3 armor penetration table]
* http://images.google.com/hosted/life/l?imgurl=2bf0edfbc39f5ef7&q=antiaircraft+source:life&usg=__lomzjGHj1yX6tAq-EY_2gyOR8_o=&prev=/images%3Fq%3Dantiaircraft%2Bsource:life%26hl%3Den AAA unit
{{WWIIUSGuns}}

{{DEFAULTSORT:90 Mm Gun M1/M2/M3}}
[[Category:World War II anti-aircraft guns]]
[[Category:World War II anti-tank guns]]
[[Category:Anti-aircraft guns of the United States]]
[[Category:Anti-tank guns of the United States]]
[[Category:90 mm artillery]]

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