-H.M.S. Hood Technical Specifications & Armament Information-
Anti-Aircraft Armament
Updated 19-Jun-2014

Information on all the anti-aircraft weapon systems used by the battle cruiser H.M.S. Hood between 1920 and 1941.

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High Angle 4inch guns aboard H.M.S. Hood

High Angle 4" Anti-Aircraft Gun

Gun Type: Mk V
Calibre: 4" / 10.2 cm
Number of Barrels: 1
Barrel Length: 45 cal (180") / 457.2 cm
Gun Length (Overall): 187.8" / 477 cm
Barrel Rifling: 32 threads, right hand twist
Charge: Cordite MD16
Charge Mass: 7lbs 11oz / 3.5 kg
Chamber Gas Pressure: 18.5 tons psi / 297 MPa
Shell Weight (High Explosive): 31.4lbs / 14.25 kg
Muzzle Velocity: 2643 fs / 805.6 ms
Rate of Fire: 8 -13 per minute
Max. Range:16,300 yds / 14,905 m at 45°
Ceiling: 28,750 ft / 8,763 m at 80°
Elevation (max. / min.): +80° / 5°
Mount: Mk III and Mk IV
Fire Control: HACS Mk I with 12 ft/3.6 m rangefinder. Guns could also be individually locally directed.
Comments: Between 4 and 8 guns were carried on the Shelter Deck until the completion of the 1939 refit, at which point they were removed entirely.

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Pom pom guns aboard H.M.S. Hood

2 Pounder 8 Barrel"Pom-Pom" Mk VIII

Calibre: 40mm (1.6")
Number of Barrels: 8
Barrel Length: 40 cal (62") / 157.5 cm
Gun Length (Overall): 102.6" / 260.6 cm
Barrel Rifling: 12 grooves, right hand twist
Charge Weight: 3.4oz / 0.9 kg
Shell Weight (High Explosive): 2 lbs
Muzzle Velocity: 1920 fps / 585.2 mps
Rate of Fire: ? (high rate of fire)
Maximum Range: 3800 yds / 3,475 m
Elevation (max. / min.): 80° / 10°
Training: 360°
Mount: Mk V and Mk VI
Fire Control: One Mk I*, one Mk I** & one Mk II (fitted with C.O.F.A.S., "M" type transmission).
Comments: The first two mounts and Mk I series directors were added to the forward Shelter Deck in 1931. The starboard mounting was officially called "Pom-pom 1", but was nicknamed "Sammy" (some crew accounts also refer to the mount as "Sally"). The port mount was officially "Pom-pom 2", but nicknamed "Peter". A third and final mount was added (along with a bandstand base and the Mk II director) to the rear Shelter Deck in late 1937. This was officially called "Pom-pom 3", but due to its position "aft" was nicknamed "Auntie". All, plus their corresponding directors (also named 1, 2 and 3) were carried until the end. Note- All three mounts featured guns without conical flash suppressors.

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UP launchers

7" Naval Wire Barrage, Unrotating Projectile (UP) Rocket Launcher

Type: Mark I
Number of Tubes: 20 (smooth bore)
Rocket: 7 in./178 mm x 32 in./813 mm fin stabilised rocket (3 in. / 76 mm motor)
Warhead: 8 oz / .14 kg aerial mine (CE)
Fuse: No. 700 and No. 720
Rate of Fire: Salvoes of 10
Maximum Altitude: @ 1,000 ft / 305 m
Elevation Angle (Max. / Min.): ? ° / @ 45°
Training: 360°
Comments: Hood was outfitted with 5 UP mounts which were added in 1940. One was atop "B" turret, and the remaining four on the Shelter Deck. In general, the UP (AKA "rocket-on-a-string") was a largely unsuccessful attempt at a low altitude anti-aircraft defence system. The basic concept was to create an aerial minefield: When hostile aircraft were detected, the UP "layer" (operator) would manually launch a salvo/spread of 10 rockets.

Upon reaching @1000ft, the rockets would detonate and expel mines attached to three parachutes by @400ft of cable. Aircraft flying through the aerial minefield would snag the cables and pull the mines into themselves. In reality, the system was slow & cumbersome.  The aerial minefields were clearly visible & easily avoidable.  This, coupled with other factors such as the volatile nature of the cordite/rockets & the risk of mines floating back onto the launching ship, doomed this weapon to mothballs. There are no records of UPs bringing down any aircraft. It's entirely possible that this system injured or killed more Britons than enemies due to accidents, fires, etc.

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0.5inch Vickers machine guns aboard H.M.S. Hood

0.5" / 62 Vickers Machine Gun

Type: Mark III
Calibre: 0.5" / 12.7mm
Number of Barrels: 4
Gun Length (Overall): 70" / 178 cm
Projectile Weight: 1.3oz / 0.37kg
Muzzle Velocity: 12520fps / 768.1 mps
Magazine Capacity: 200 rounds per gun (4 drums/800 rounds per mount)
Rate of Fire: 600 rounds per minute (maximum) / @180 (practical)
Max. Range: 1500yds / 1371.6m
Elevation (max. / min.): +80° / -10°
Training: 360°
Comments: This was a naval variant of the famous Vickers machine gun. Water-cooled and could be remotely controlled. The first two mounts, referred to as M1 (starboard) and M2 (port), were added near the Conning Tower in late 1933. These guns were known by the colourful nicknames of "Pip" (port) and "Squeak" (starboard). Two more were added abreast the Rear Superstructure in late 1937. These were M3 (starboard) and M4 (port). These were nicknamed "Simon" (starboard) and "Paul" (port). Hood's variants included shields and each had two nearby ready-use lockers.