Dual-purpose gun
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Adual-purpose gunis anaval artillerymountingdesigned to engage both surface and air targets.
Description
[edit]Second World War-era capital ships had four classes of artillery: the heavy main battery, intended to engage opposing battleships and cruisers of 305 mm to 457 mm (12 inch to 18 inch); asecondary batteryfor use against enemy destroyers of 152 mm to 203 mm (6 inch to 8 inch); heavy anti-aircraft guns of 76 mm to 127 mm (3 inch to 5 inch), which could create barrages to knock out airplanes at a distance; finally, light rapid-fireanti-aircraft batteries(A/A) to track and bring down aircraft at close range. The light A/A was dispersed throughout the ship and included bothautomatic cannonsof 20 mm to 40 mm (.787 inch to 1.57 inch) andheavy machine gunsof 12.7 mm to 14.5 mm (.50 inch to.58 inch).
During World War II, theUS Navy,Royal Navy,theFrench Navy,and theImperial Japanese Navycombined the secondary battery with the heavy anti-aircraft guns, creating a dual-purpose secondary battery. They discarded the dedicated, anti-ship secondary batteries altogether, because a battle-line fleet would be screened against cruisers and destroyers most of the time. Also, it was deemed unlikely that a battleship would be simultaneously facing both rushing destroyers and aircraft, and it would take up too much space to have separate types of guns to deal with both threats. Rather, they replaced them with turret-mounted dual-purpose guns that could be used against both aircraft and ships. The space saved from combining the two types of guns added to simplification of supply, increased deck armour coverage, stowage of other equipment, a larger light anti-aircraft battery, and other needs. This arrangement was seen as more efficient, and was deemed adequate to meet anti-surface and anti-aircraft needs under most circumstances.
TheKriegsmarine,in a practice similar to the Italian and Soviet navies, adopted a mixed-calibre secondary battery, with dedicated anti-ship guns, coupled with smaller-calibre heavy anti-aircraft batteries, instead of adopting dual-purpose secondaries like the British or Americans. Both navies were concerned by possible close-range torpedo attacks from enemy (in particular, French) destroyers and torpedo boats, and considered the more powerful, larger calibre anti-ship secondaries a must. The French Navy used a mixed-calibre system, as well, but their secondary battery was dual-purpose. This tended to complicate ammunition supplies and render certain armament useless in some situations.
Dual-purpose guns are designed as a compromise between the heavy main armament of asurface combatantand dedicatedanti-aircraft guns.Usually of a mid-range caliber, the gun is heavy enough to prove useful against surface targets including ships, surfaced submarines, and land targets. However, it is compact enough to fit into a mounting capable of good traverse and high elevation, as well as being capable of a high rate of fire, allowing it to successfully engage air targets at all angles. For example, a Royal Navy battleship of theKing George Vclasshad sixteenQF Mark I5.25-inch (133 mm) guns that could engage either enemy ships or high level aircraft, as necessary.
Not all dual-purpose guns have high elevation. The determining factor was whether or not the mounting was provided with ananti-aircraft fire control systemand a method for setting the time fuze in the A.A. warhead, fired by the gun. Starting with theTribal class,the Royal Navy introduced a series of destroyer classes that had dual-purpose guns, but in4.7 inch QF Mark XII,twin CP Mk. XIX and later mountings limited to 40, 50 or 55 degrees elevation, however, the guns were controlled by anA.A. fire control systemand the mountings were provided with A.A. shell fuze setters. The USN had developed a similar class of destroyer, thePorterclasswith eightMk 12 5-inch/38-caliber (127 mm) gunsin four Mark 22 Single Purpose (surface action only) twin mounts, limited to 35 degrees elevation, but with no provision for A.A. fire control and no on-mount fuze setters.[1]The 40-degree elevation did limit the ability of theTribalclass[2]guns to engage dive and high altitude bombers but they were still effective in engaging low altitude, level, and torpedo bombers and could still provide barrage fire over other ships being attacked by dive bombers. AdmiralSir Philip Viandescribes the use of 4.7 inch Mark XII guns against aircraft during the 1940campaign in Norway:
"It became clear at once that in an attack from the air in narrow waters flanked by mountains, the cards were held by the aircraft. There was too little sea-room for full freedom of manoeuvre, and the aircraft's approach was screened by the rock walls. As often as not, when they did come into view it was at such an angle that our 4.7-inch guns, whose maximum elevation was only forty degrees, could not reach them...Aandalsnesis approached through theRomsdal Fiord,and lies forty miles from the entrance, off which we arrived on the 24th April. The daylight passage of the convoy and escort through this waterway, speed five knots, on a steady course and with mountains rising steeply either side, presented an alluring invitation to enemy aircraft.Junkersattacks persisted to the end, but the fire of the destroyers, although limited to an elevation of forty degrees, was enough to keep the enemy just too high for their standard of marksmanship. Not a ship received a direct hit, though some were damaged by the splinters from near misses. "[3]
Dual-purpose guns, often abbreviated toDP guns,were originally designed as a secondary armament for large surface ships such ascruisersandbattleshipsto complement their heavy main armaments. Later, such guns began to be added to smaller vessels as their primary gun armament, and with the progression of ship design away from heavy-caliber guns, today nearly all main gun armaments are of dual-purpose nature.
Most modern dual-purpose guns are in the 76 mm to 127 mm (3-inch to 5-inch) medium-caliber range.
In British service the termHA/LAfor "High Angle/Low Angle" was used.
List of dual-purpose guns
[edit]Calibre | Weapon name | Country of origin | Period |
---|---|---|---|
40 millimetres (1.6 in) | Bofors 40 mm L/60 gun | ![]() |
1930s–present |
40 millimetres (1.6 in) | Bofors 40 mm Automatic Gun L/70 | ![]() |
1940s–present |
57 millimetres (2.2 in) | Finspång 57 mm QF naval gun L/55 model 1889 | ![]() |
1890s–present |
57 millimetres (2.2 in) | Bofors 57 mm naval gun L/21 model 1916 | ![]() |
1910s–Cold War |
57 millimetres (2.2 in) | Bofors 57 mm Naval Automatic Gun L/60 | ![]() |
1952–1990 |
57 millimetres (2.2 in) | Bofors 57 mm Naval Automatic Gun L/70 | ![]() |
1970–present |
76.2 millimetres (3 in) | 76 mm/62 Allargato | ![]() |
1962–present |
76.2 millimetres (3 in) | OTO Melara 76 mm | ![]() |
1964–present |
76.2 millimetres (3 in) | AK-176 | ![]() |
1976–present |
100 millimetres (3.9 in) | 10 cm/65 Type 98 naval gun | ![]() |
World War II |
100 millimetres (3.9 in) | Type 79 100 mm naval gun | ![]() |
1973–present |
100 millimetres (3.9 in) | 100 mm naval gun | ![]() |
1961–present |
100 millimetres (3.9 in) | AK-100 naval gun | ![]() |
1978–present |
4 inches (101.6 mm) | QF 4 inch Mk V naval gun | ![]() |
1914–1940s |
4 inches (101.6 mm) | QF 4 inch Mk XVI naval gun | ![]() |
1936–1950s |
4 inches (101.6 mm) | QF 4 inch Mk XIX naval gun | ![]() |
World War II |
4.45 inches (113 mm) | QF 4.5-inch Mk I – V naval gun | ![]() |
1938–Cold War |
4.45 inches (113 mm) | 4.5-inch Mk 8 naval gun | ![]() |
1972–present |
120 millimetres (4.7 in) | Bofors 120 mm Naval Automatic Gun L/50 | ![]() |
1952–1985 |
4.7 inches (119 mm) | QF 4.7-inch Mk IX & XII | ![]() |
1928–1970 |
4.7 inches (119 mm) | QF 4.7 inch Mark XI gun | ![]() |
1941–1970 |
127 millimetres (5 in) | Otobreda 127mm/54 compact gun | ![]() |
Cold War–present |
127 millimetres (5 in) | Otobreda 127mm/64 gun | ![]() |
2012–present |
127 millimetres (5 in) | 12.7 cm/50 Type 3 naval gun | ![]() |
1928–1966 |
127 millimetres (5.0 in) | 12.7 cm/40 Type 89 naval gun | ![]() |
1932-1945 |
5 inches (127 mm) | 5 "/38-caliber gun | ![]() |
1934–1990s |
5 inches (127 mm) | 5 "/54-caliber Mk 16 gun | ![]() |
1945–1993 |
5 inches (127 mm) | 5 "/54-caliber Mark 42 gun | ![]() |
1953–present |
5 inches (127 mm) | 5 "/54-caliber Mk 45 gun | ![]() |
1971–present |
5 inches (127 mm) | 5 "/62-caliber Mk 45 gun | ![]() |
2000–present |
130 millimetres (5.1 in) | Type H/PJ38 130 mm naval gun | ![]() |
2014–present |
130 millimetres (5.1 in) | Canon de 130 mm Modèle 1932 et 1935 | ![]() |
1935-1942 |
5.25 inches (133 mm) | QF 5.25-inch Mk 1 gun | ![]() |
1940–1966 |
135 millimetres (5.3 in) | 135mm/45 gun | ![]() |
1940–1972 |
138.6 millimetres (5.46 in) | Canon de 138 mm Modèle 1929 | ![]() |
1934–1954 |
6 inches (152 mm) | 6 "/47-caliber Mk 16 gun | ![]() |
1937–1992 |
Notes
[edit]- ^Hodges,Tribal Class Destroyers,Almark Publishing Co. Ltd, 1971,ISBN0-85524-047-4,p.32: Diagram of High Level Bomber Attack: A 240mph target, at 12 thousand feet altitude could expect to be under for fire about 75 seconds, from the time it enters the effective range of theHACSuntil it flies to within the minimum range of a 5.25 gun elevated to 70 degrees. A Tribal class destroyer would be able to engage the same target for about 37 seconds.
- ^Vian, Philip,Action This Day,London, 1960, p.40 and 44.