M51 Skysweeper

Overview

M51 Skysweeper

Ex-US Army M51 Skysweeper on display with bogies attached.
Source: Mark Pellegrini - © GNU Attribution Share Alike license

Origin

United States

Type

Anti-aircraft gun

Entered service

1953

Status

Out of service

Development

1948 - 1951

Developer

United States - Watervliet Arsenal

Production

1950's

Producer

United States - Rock Island Arsenal

Designations

Gun, M51, Antiaircraft (official designation)
M51 75mm高射砲 (Japanese service)

Notable users

United States
Japan
Greece
Turkey

Description

Introduction

The M51 Skysweeper is an early Cold War era towed anti-aircraft gun of US origin. It was designed to combat fast moving jet aircraft in a zone where surface to air missiles weren't very effective at the time. The M51 Skysweeper is the first anti-aircraft gun to combine gun, radar and fire director on a single mount. Compared to the World War 2 era 40mm Bofors M1 the M51 Skysweeper proved far more capable. It is also a larger, more complex and much more expensive to acquire and operate.

Design

The M51 Skysweeper is based on a box platform with four outriggers. The single 75mm cannon is fitted with an autoloading mechanism. The gunner is seated on the right and the radar system is located on the left. Despite the high level of automation the gun crew numbers 6 (minimum) to 9 (regular) people.

Guidance

The M51 Skysweeper is fitted with a T-38 radar on the left side of the gun mount. This radar doubles as detection and tracking radar and has a range of about 30 km. Since the radar only scans the forward sector the M51 is best used with longer range early warning radar. The fire director is an analog computer system. Manual fire control using a gunsight is available as backup, or for use against ground targets.

Firepower

The armament of the M51 Skysweeper consists of a single 75mm M35 (a.k.a. T81E6 or E7) gun firing 75mm shells with fixed cases. Cyclic rate of fire is 45 to 55 rpm. The autoloader feeds from two 10 round drum magazines. The 75mm gun reportedly has a flat trajectory and can be used out to 9 km. Slant range against ground targets is quoted as 13 km.

Mobility

The M51 Skysweeper is a towed anti-aircraft gun, but can only be used from a prepared static position. In the firing position the two-wheel bogies are removed and four outriggers provide a stable platform. A heavy 6x6 truck or M8 Tractor are used to tow the M51.

Users

The M51 Skysweeper was used by the US Air Force and the Army. It was also supplied to several allies, possibly after being retired from active US service. The M51 is a mobile system, but mostly served to protect important sites. It served as a closer range system alongside SAM systems, which in the early days were most effective at longer ranges.