Vickers S

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Vickers 40 mm Class S
A Hawker Hurricane fitted with two S-gun Shandur, Egypt (1942)
Service history
Used by	Royal Air Force
Wars	Second World War
Production history
Produced	1942
Variants	Mk 1, Mk 2
Specifications
Mass	320 lb (134 kg)
Length	9 ft 9 inches (2.97 m)
Barrel length	5 ft 7 in (1.7 m)
Cartridge weight	4 lb (1.8 kg) 40x158R
Calibre	40 mm (1.6 in)
Rate of fire	100 rounds/min
Muzzle velocity	1,870 ft/s (569.98 m/s) with 3 lb (1.4 kg) shot
Feed system	12-round drum later 15 rounds

The Vickers 40 mm Class S^[a], often shortened to "S" gun,^[2] was a 40 mm (1.57 in) airborne cannon designed by Vickers-Armstrongs for use as aircraft armament. It was primarily used during World War II by British aircraft to attack ground targets.^[3] It was largely replaced by the RP-3 rocket from 1943 on.

History[]

The Vickers 40 mm Class S gun was developed in the late 1930s as an aircraft weapon. The ammunition was based on the 40x158R cartridge case of the naval 2 pdr Anti-aircraft gun (the "Pom-pom"). The weapon was a long-recoil design derived from the 37 mm 1½pdr "COW gun" from Coventry Ordnance Works.The gun was originally intended as a bomber defensive weapon and was tested as such in a turret fitted to a modified Vickers Wellington II. This was not adopted for service.

Combat history[]

Early operations by the Desert Air Force demonstrated that existing weapons were ineffective against newer German armor like the Panzer III. In April 1941 a group formed to study the issue, initially considering a series of 37 and 40 mm weapons including the "S", a similar Rolls-Royce model known as "BF", and the US-built M4 autocannon, all firing armour-piercing ammunition.^[4]

The "BF" was initially selected, as it used drum-fed ammunition rather than the "S" belt system, which was considered more reliable. About 200 BF's were produced, but after a series of misfires and ammunition explosions,^[2] the decision was made to introduce ground attack variants of the Hawker Hurricane with the "S". This had the added advantage that the "S" carried 15 rounds of ammunition compared to the "BF"'s 12.

Mark IID and Mark IV Hurricanes could mount one "S" under each wing, in conformal gun pods. The weight of the guns and ammunition, along with the dust filters and other equipment needed for desert operations, slowed the aircraft by a significant 40 miles per hour (64 km/h). In October 1941 it was decided that the autocannon would not be suitable in the future, and the same research group turned their attention to rockets, eventually leading to the introduction of the RP-3 in 1943.

The weapon was cleared for service on the Hurricane in April 1942 and formed up with No. 6 Squadron RAF at in Egypt in May. The weapon's champion, Wing Commander , trained the pilots on using the weapon, as it had so much recoil that the aircraft slowed significantly when fired. This caused the nose to drop, and while flying at a typical altitude of 50 feet during the approach, firing without first re-adjusting the flight path was dangerous. The pilots eventually concluded that the guns could be fired twice before the aircraft flew past the target, although on rare occasions a third shot was possible.^[2]

Claims by pilots using the Vickers S included 47 tanks destroyed (of 148 tanks hit), as well as nearly 200 other vehicles. However, the Hurricane IID was poorly armoured for the ground attack role and ground fire caused heavy losses. In addition, 40 mm ammunition was seldom effective against vehicles as well-armoured as the Tiger I tank.

Mark IV Hurricanes (operational from 1943) had improved armour around their engine, cockpit and fuel tanks.

From 1944, Hurricanes armed with the Vickers S served in the South East Asian theatre. In most cases HE ammunition was used against road vehicles and river craft.

Assessments carried out in South East Asia showed a relatively high level of accuracy: an average of 25% of shots fired at tanks hit their target. (By comparison, RP-3 60 pounds (27 kg) rocket projectiles only 5% against tank-sized targets.) However, 40 mm HE rounds were twice as accurate as AP rounds, possibly because the lower weight and higher velocity of the HE round gave it ballistics similar to that of the .303 in (7.7 mm) Browning machine gun that were used for sighting.

See also[]

Weapons of comparable role, performance and era[]

United Kingdom

• Rolls-Royce 40mm Cannon – Rolls Royce developed rival to the Vickers S gun
• QF 6pdr Class M – 57 mm British airborne anti-ship gun from WWII (part of the same naming family as the Vickers S)

Nazi Germany

• MK 103 – 30 mm German airborne anti-tank and anti-bomber gun from WWII
• BK 3,7 – 37 mm German airborne anti-tank and anti-bomber gun from WWII
• BK 5 – 50 mm German airborne anti-tank and anti-bomber gun from WWII

Japan

• Ho-203 – 37 mm Japanese airborne ground-attack and anti-bomber gun from WWII
• Ho-401 – 57 mm Japanese airborne ground-attack gun from WWII

Soviet union

• NS-37 – 37 mm Soviet airborne ground-attack gun from WWII
• NS-45 – 45 mm Soviet airborne ground-attack gun from WWII

Sweden

• 57 mm akan m/47 – 57 mm Swedish anti-ship gun from just after WWII

Footnotes[]

References[]

Citations[]

External links[]

Wikimedia Commons has media related to Vickers S.

• Anthony G Williams, 37MM AND 40MM GUNS IN BRITISH SERVICE