QF 4.5 inch naval gun

. All British 4.5 inch guns actually have a calibre of 4.45 inches (113 mm).

History

From the BL Mark I of 1916, the 4.7 inch gun (119 mm) was the mid-calibre weapon of choice for the Royal Navy, used particularly on destroyers. Apart from some ships armed with 4 inch guns due to supply problems, it remained the standard weapon for destroyers up to the W class destroyers of 1943. However, its usefulness as an anti-aircraft weapon had been limited by the failure to develop a mounting with elevation over 55°, the lack of a predictive fire control system (see HACS) and the setting of fuzes by hand.

The QF 4.5 inch L/45 (114 mm) was developed originally as a dual-purpose weapon with which to arm aircraft carriers and reconstructed battleships and battlecruisers. It was later developed as a new dual-purpose weapon with which to arm destroyers, supplanting the ubiquitous 4.7 inch gun. Despite the lower calibre, it actually had a heavier shell, resulting in a more powerful weapon.

Variants

The nomenclature system for guns used by the Royal Navy can be somewhat confusing. The gun and mounting each have their own Mark number and a letter(s) giving additional information. QF stands for "quick firing", UD for "upper deck", BD for "between decks" and CP for "central pivot".

* QF Mark I - adopted after failure of a 5" gun project and used a fixed round, which proved to be somewhat heavy for the loaders to keep up the intended firing rate. Was fitted in twin mountings UD Mark III.
* QF Mark II - used by the British Army as an anti-aircraft gun, with the barrel lined down to 3.7 inches to use the same ammunition as existing weapons.
* QF Mark III - same as Mark I, except for firing mechanism. Was fitted in twin mountings BD Mark II, BD Mark II** and BD Mark IV.
* QF Mark IV - used a two part (charge and shell) ammunition system. Designed specifically for use by small warships. Fitted in mountings BD Mark IV, CP Mark V and UD Mark VI.
* QF Mark V - a further development of the Mark IV, designed from the outset for anti-aircraft use with remote power control (RPC, where the guns automatically train and elevate the target) and a high rate-of-fire assisted by automatic ramming. Carried in the mounting UD Mark VI, with separate high-angle and low-angle hoists for the two types of ammunition (AA and SAP/HE) and a third for the cartridges

Some 800 naval 4.5" guns of various marks were built.

During the 1950s, a change was made in designating the weapons systems which focussed on the gun mount rather than the gun itself. Together with a change from Roman numerals, the Gun QF Mark V on mounting BD Mark VI became simply the Mark 6. The Mark 7 was never produced as the planned "Malta" class aircraft carriers they would have been used on were never built.

The majority of new escort vessels built for the Royal Navy in the 1950s and 1960s carried at least one Mark 6 mounting, with two in the "Leopard" class frigate and County class destroyer and three in the "Daring" class destroyer. This gave these ships a level of firepower unprecedented only 15 years earlier. The Type 81 Tribal class frigates were an exception, using reconditioned Mark V mounts from scrapped C class destroyers that were fitted with RPC and known as the Mark 5* Mod 1.

The evolution of the 4.5 inch gun family ended with the Mark V gun / Mark 6 mounting. It has been replaced by a new weapon of original design, the 4.5 inch Mark 8.

Use

Ships with 4.5 inch guns QF Mark I in twin mounting UD Mark III
* aircraft carrier "Ark Royal"
* Dido class cruisers "Scylla" and "Charybdis"
* naval auxiliaries

Ships with 4.5 inch guns QF Mark III in twin mounting BD Mark II
* reconstructed "Queen Elizabeth" class battleships "Queen Elizabeth" and "Valiant"
* reconstruced "Renown" class battlecruiser "Renown"
* "Illustrious" class aircraft carrier
* aircraft carrier "Indomitable"
* "Implacable" class aircraft carrier

Ships with 4.5 inch guns QF Mark III in twin mounting BD Mark II**
*"Audacious" class aircraft carrier, "Eagle" and "Ark Royal"

Ships with 4.5 inch guns QF Mark III in twin mounting BD Mark IV
*Battle class destroyer
*Nueva Esparta Class Destroyer "D-11 Nueva Esparta", "D-21 Zulia" and "D-31 Aragua"

Ships with 4.5 inch guns QF Mark IV in single mounting CP Mark V
*Z class destroyer
*Ca, Ch, Co and Cr class destroyer
*"1944" Battle class destroyer

Ships with 4.5 inch guns Mark 5* (rebuilt mounting CP Mark V).
*rebuilt Ca class destroyer (Mark 5* Mod 1)
*Type 81 Tribal class frigate (Mark 5* Mod 2)

Ships with 4.5 inch guns QF Mark V in twin mounting UD Mark VI (later renamed gun Mark 6)
*"Daring" class destroyer
*County class destroyer
*Type 12 "Whitby" class frigate
*Type 12I "Rothessay" class frigate
*Type 12M "Leander" class frigate
*Type 41 "Leopard class frigate
*Type 61 "Salisbury" class frigate
*Nueva Esparta Class Destroyer "D-11 Nueva Esparta", "D-21 Zulia" and "D-31 Aragua"

ee also

* 4.5 inch (114 mm) Mark 8 naval gun The Royal Navy's current, but unrelated, 4.5" gun
* 5"/54 caliber Mark 45 gun, the US Navy equivalent of the 4.5" gun.

References

* [http://www.navweaps.com/Weapons/WNBR_45-45_mk1.htm Page from Navweapons on Mk 2, 3, 4 and 5]
* [http://www.navweaps.com/Weapons/WNBR_45-45_mk5.htm Page from Navweapons on Mk5, Mk 6 and Mk7]