120mm Gun M1
4.7-inch Gun M1
Overview
120mm Gun M1
120mm M1 anti-aircraft gun on public display at Battleship Memorial Park, as seen in 2012
Source: Vitaly Barsov -
© CC BY-SA 3.0
Over 100 sets of gun directors and radars
120mm Gun M1 (post war designation
Stratosphere gun (popular nickname)
Canada
Desciption
Introduction
The 120mm Gun M1 is a World War 2 era heavy anti-aircraft gun of American origin. It was developed during the early stages of World War 2, but only produced and adopted near the end of the war. It was developed alongside the 90mm Gun M1, which proved to be far more mobile and versatile.
Design
The 120mm Gun M1 was designed to be a mobile system. It is based on a cruciform mount with folding legs. Two double wheel external bogies are attached in transport model. To be of any use at longer ranges and high altitude the it was designed from the outset to be used with external fire control systems.
Fire control
Firing the 120mm Gun M1 was intended only by the M10 gun director, receiving inputs from radar and M4 Gun Data Computer. There likely also was back-up local fire control. The SCR-268 2D air search radar with a range of over 35 km was used during World War 2. The more accurate shorter wavelength SCR-584 was introducing in the later stages of World War 2 and became the primary radar system as part of the 120mm Gun M1 battery. In Canadian service the AN/CPS-5 system long range early warning radar was used.
Firepower
The 120mm Gun M1 uses single piece ammunition. Loading is assisted since the gun is meant to be operated at a high angle. The 120mm Gun M1 has a significant effective range, being 25 km. Maximum altitude was 17.5 km. This gave it the popular nickname of "Stratosphere gun". Rate of fire is 10 to 12 rpm. Ammunition types include high explosive and shrapnel rounds. Both rounds used a time fuse to detonate at a predicted point in the flight path.
Mobility
The 120mm Gun M1 is intended as a static system that can be relocated if necessary. It is a road mobile system that requires significant time to set up and incorporate with the fire control systems. Two double wheel detachable bogies are fitted in transport configuration. The M6 High Speed Tractor was the main prime mover, although it could be towed by heavy trucks when operating only on good roods and prepared locations.
Users
The 120mm Gun M1 was accepted in US service in 1940. Priority went to the 90mm alternative, and the first unit was only operational in 1944. The first battalion was deployed in the Philippines in February of 1945. One battery of four guns was sent to Northern Ireland, UK. Its unlikely any guns fired in anger during World War 2. After World War 2 the main role was defense of the continental USA from Soviet long range bombers. In this role it was supplemented and replaced since 1954 by the MIM-3 Nike Ajax surface to air missile. Two battalions were in Canadian service and part of the Canadian air defense network. By 1960 these guns were obsolete and the final units were deactivated.
Details
Media
120mm Gun M1
120mm M1 anti-aircraft gun on public display at Battleship Memorial Park, as seen in 2012
Source: Greg Goebel
Copyright: CC BY-SA 2.0
120mm Gun M1
A 120mm Gun M1 anti-aircraft gun in transport configuration. Note on wheel of the bogie is missing. Seen at the United States Army Ordnance Museum (Aberdeen Proving Ground) in 2007.
Source: Mark Pellegrini
Copyright: CC BY-SA 2.5
120mm Gun M1
Frontal view of 120mm Gun M1 anti-aircraft gun in transport configuration. Note on wheel of the bogie is missing. Seen at the United States Army Ordnance Museum (Aberdeen Proving Ground) in 2007.
Source: Mark Pellegrini
Copyright: CC BY-SA 2.5
120mm Gun M1
A 120mm Gun M1 is being set up near a scheduled nuclear explosion at the Nevada Test Site to determine the blast effect at a distance of 4.000 yards.
Source: United States Department of Energy
Copyright: Public domain