HMS Repulse

From the beginning of her service life HMS Repulse’s AA capability was very poor indeed. In 1916 the ship’s AA protection consisted of five Maxim machine guns and only two 3”/45 (76.2 mm) 20cwt QF HA Mk I guns on unprotected Mk II mounts (placed on each side of the smoke stack). The guns were the first weapons purpose built as naval AA pieces, but they were also widely used by ground units during World War I. By 1922 two more guns of that type were added (they replaced obsolete 4”/42 BL Mk IX weapons). Two years later all 3” guns were removed and replaced by the 4” units. From 1936 the ship carried two eight-gun stations equipped with 2- pdr (40 mm/39) Mk VII guns, better known as pom-poms due to the characteristic sound they made while firing. The guns were mounted on each side of the fore stack, just aft of the triple 4” gun mounts. In 1940 Repulse received a third pom-pom station, which replaced a 4”  mount behind the mainmast. Although the work on pom-pom design began as early as 1921, the guns were not installed on the Royal Navy vessels until 1930. At the time of their service entry pom-poms were considered very advanced weapons: their multiple mount arrangement and 14-round linked ammunition stowed in 140 round magazines provided very good rate of fire. However, the weapon had its weaknesses, too. The gun’s internal mechanisms were very complex and required a lot of specialized care and attention. Stoppages and jams were not infrequent. The weapon’s greatest drawback, however, was its very low muzzle velocity (due to a short barrel design) and completely ineffective ammunition. By the 1940s rapid improvements in aircraft design rendered the guns obsolete.

2-pdr (40 mm/39) Mk VII guns on Mk VI mounts

Caliber    40 mm

Gun weight    259.5 kg
Gun length oa    2.606 m
Bore length    1.575 m
Grooves    12
Chamber volume    0.165 dm3
Rate of fire    96-115 rounds per minute
Ammunition    fixed, HE 1.34 kg (including a 2 lb projectile)
Barrel life    about 5 000 rounds
Magazine capacity    1800 rounds per gun
Range    3 475 m
AA ceiling    1 555 m
Mount weight    15.68 t
Elevation    -10° to +80°
Train    360°

Repulse’s AA armament was supplemented by Vickers 0,50’’/62 (12.7 mm) Mk III machine guns on quad Mk II mounts. The first two sets were installed in 1936 and placed on two small platforms each side of the stack, above the pom-poms. Two more stations were added in 1939 (mounted on platforms in the lower part of the mainmast). Although the Vickers guns were manufactured in large numbers and used on virtually all RN warships during World War II, they proved utterly ineffective against ever faster and more resilient aircraft.

0,50’’/62 (12.7 mm) Mk III machine guns on Mk II mounts

Caliber    0,5’’ (12.7 mm)
Gun weight    25.4 kg
Gun length oa    89 cm
Bore length    79.4 cm
Rate of fire    600-700 rpm (in practice 150-200 rpm)
Ammunition    fixed, 0.08 kg
Magazine capacity     2 500 rounds per gun
Range    730 m
Mount weight    1 310 kg
Elevation    -10° to +80°
Train    360°

During her last modernization in 1941 the ship received eight 20 mm/70 Mk II AA guns manufactured by Oerlikon (4 on each side of the conning tower, 2 on each side of the aft superstructure and 2 on the roof of turret Y). The weapon was a very successful design and was perhaps the most widely used AA gun of World War II. The Oerlikons were very effective at close range against virtually all aircraft types. The full combat potential of the guns was limited on Repulse due to a small number of installed weapons.

20 mm/70 Mk II guns
Caliber    20 mm