QF STAAG Mark II (40 mm)
The 40 mm QF STAAG Mark II is a naval anti-aircraft twin mounting that consists of two British-produced, water-cooled Bofors 40 mm L/60 gun with onboard radar and fire control systems (radar functionality is not present in-game). The Bofors 40 mm L/60, also known as the "Bofors L/60", the "Bofors gun", or simply "the Bofors", was a highly successful Swedish anti-aircraft gun design of the interwar period and was widely used during the Second World War by both sides and in all theatres and remained in service long after the end of WWII.
Vehicles equipped with this weapon
The QF STAAG Mark II has a barrel diameter of 40 mm and has a barrel length of 2.25 m. It has a magazine size of 4 rounds and has a rate of fire of 156 rounds per minute, though firing for too long will jam the gun.
There are three ammunition choices available:
- Universal: AP-T · HEFI-T
- 40 mm HE clips: HEFI-T · HEFI-T · HEFI-T · AP-T
- 40 mm AP clips: AP-T · AP-T · AP-T · HEFI-T
Comparison with analogues
All naval Bofors 40 mm L60 guns are virtually identical, the only difference between them being the rate of fire: all single mounts fire at 160 rpm, while twin and quadruple mounts fire at 156 rpm. They all fire the same ammunition from 4-round ammunition clips and have a short enough reload that they can sustain continuous fire as if there wasn't a reload at all. In other words, their cyclic rate of fire (mechanical rate of fire) is the same as their effective rate of fire (rate of fire with reload times taken into account). All naval Bofors 40 mm L60 guns can jam if fired for too long.
The only naval Bofors 40 mm L/70 currently present in the game is the MEL58, which is, by and large, superior with a much higher rate of fire of 240 rounds per minute. The only other difference is the HE round: the MEL58's HE round has less explosive mass (0.03625 kg TNT eq.), but it has a higher muzzle velocity (1030 m/s).
The 40 mm Bofors Flak 28 is the only naval Bofors gun in-game with access to a pure HE ammunition choice, at the cost of not having any AP options. Every other naval Bofors gun has ammunition choices comprised of a mix of HE and AP, in ratios of 1:1, 3:1, or 1:3.
Compared to other common guns of similar calibre:
- 3,7 cm SK C/30 (37 mm): The 3,7 cm SK C/30 has a higher muzzle velocity for both its AP and HE rounds (1,000 m/s) and has a stronger AP round (87 mm @ 10 m, 0°; 0.0374 kg TNT equivalence); but it has a much slower rate of fire (30 rpm), has a weaker HE round (0.0274 kg TNT equivalence), and has a lower projectile mass for both its AP round (0.82 kg) and HE round (0.75 kg). This gun is single-shot and cannot jam.
- 3,7 cm FlaK-Lafette C/36 (37 mm) and 3,7 cm FlaK-Lafette LM/42 (37 mm): These guns have a higher rate of fire (250 RPM); but they have a lower muzzle velocity for both their AP round (845 m/s) and HE round (815 m/s), have a weaker AP round (67 mm @ 10 m, 0°) and a weaker HE round (0.04403 kg TNT equivalent), and have a lower projectile mass for both their AP round (0.7 kg) and HE round (0.623 kg). These guns fire from a 5-round ammunition clip and have a very quick reload, so their cyclic rate of fire and effective rate of fire are practically identical. They cannot jam.
- 70-K (37 mm): The 70-K has a higher muzzle velocity for its HE round (880 m/s); but it has has a lower rate of fire (150 RPM), has a lower muzzle velocity for its AP round (880 m/s), has a weaker AP round (79 mm @ 10 m, 0°) and a weaker HE round ((0.05698 kg TNT equivalence), and has a lower projectile mass in both its AP round (0.758 kg) and HE round (0.72 kg). It fires from a 500-round magazine and can jam if fired for too long.
- 2pdr QF Mk.IIc (40 mm) and 2pdr QF Mk.VIII (40 mm): These guns have a higher rate of fire (200 rpm) and have a lower projectile mass in their AP round (0.91 kg); but they have a lower muzzle velocity for its AP and HE rounds (701 m/s), have a weaker AP round (60 mm @ 10 m, 0°) and a weaker HE round (0.071 kg TNT equivalence), and have a lower projectile mass in both their HE round (0.82 kg). They fire from a 56 round magazine and cannot jam.
Usage in battles
A twin mount of one of the best medium-range anti-aircraft cannons in the game, the QF STAAG Mark II provides very good AA coverage for any ships that it's mounted on. With a 0.0986 kg TNT equivalent explosive charge in each HE round, any hit on an enemy aircraft will usually result in critical damage, if not a kill. The rounds that these guns fire have an above-average muzzle velocity and projectile mass, resulting in a much further effective range than guns of a similar calibre: laterally (i.e. targeting surface targets), the maximum range is about 3.25 km.
Despite the guns' small magazine size of only four rounds, the reload is short enough that there isn't any noticeable difference between its cyclic rate of fire (the rate of fire only considering the mechanical speed of the gun) and its effective rate of fire (the rate of fire accounting for reload times). In other words, it can sustain virtually continuous fire, as if there was no reloading at all. However, this comes at the cost that if fired for too long, the gun can jam. For this reason, it can be advantageous to set the AI gunners to only target aircraft. If allowed to target surface targets, the AI gunners will often waste ammunition on targets well outside of the gun's maximum range, leaving the guns jammed when actually needed.
Since the QF STAAG Mark II is currently only mounted on destroyers in-game, there is no reason to use any ammunition option other than 40 mm HE clips since it contains the highest ratio of HE to AP rounds. While the AP rounds do have a very gun penetration for its calibre, armoured targets are more effectively dealt with using the destroyer's main armament anyway. With the 40 mm HE clips, the QF STAAG Mark II will have the highest effectiveness against its intended targets, aircraft and small boats.
Pros and cons
- Large explosive mass in HE round
- High-penetration AP round
- Very quick reload
- Can jam if continuously fired for too long
In 1928, the Swedish Royal Navy contracted the Bofors Company to design a suitable replacement for their Vickers 2-pounder guns anti-aircraft guns (the Vickers "Pom-Poms"). Work on the design began right away and a prototype model was produced by mid-1930. The prototype had a vertical sliding breech block design and was automatic. Upon firing, the recoil of the gun would open the breech and eject the spent casing out its rear whilst an autoloading mechanism would insert the next round into the empty breech, after which the action of the gun sliding back into place would close the breech once again, leaving the gun ready to fire once more.
While proving the potential of the design, the prototype failed to meet the specified rate of fire requirement of 130 rounds per minute. It wasn't until 1934 that a production model, 40 mm L/60 Model 1934, was ready. In the following years, minor improvements led to the development of 40 mm L/60 Model 1936, which would finally be accepted into Swedish service as 40 mm/60 Model 1936. Despite its name, the barrel length of the 40 mm L/60 Model 1936 was actually 2250 mm (56.25 calibres).
The British Army first purchased 100 Bofors guns in 1937 for examination and testing which were found to show satisfactory performance. However, many parts of the gun as originally designed were intended to be fashioned or fitted by hand, limiting the rate of production to a pace that couldn't possibly meet British demand. Thus, Britain acquired a licence to produce the gun domestically. Changes were made to the design to streamline mass production, including the conversion of measurements from metric to imperial. These changes not only vastly improved production efficiency, but they also lowered production costs.
The Stabilised Tachometric Anti-Aircraft Gun (STAAG) Mark II mounting was a post-war twin mounting with two mirrored OQF 40 mm Mark X guns mounted side-by-side. Weighing in at a total of 17.8 tonnes, the STAAG Mark II was one of the most complex anti-aircraft mounts of its time. The mount had its own stabilization systems and was triaxially stabilized, but not in the traditional sense; the mount itself was on stabilized on two axes, while the third came from lateral deflection of the guns themselves. Mounted to the rear and left of the guns, the STAAG Mark II carried the Type 262 radar, as well as a separate tracking radar and rangefinder, that provided onboard computers with target information, allowing the system to predict the target's movements. In this aspect, the STAAG Mark II was considered very accurate. The Mark X guns of the STAAG Mark II were water-cooled, and the STAAG Mark II had its own pumps to circulate water through the guns' water jackets. Additionally, the STAAG Mark II was hydraulically powered, able to elevate and train the guns at a rate of 35°/s both ways, and had an onboard backup generator in case power was cut to the system.
Sitting behind the gunshield and to the left of the guns was the gunner. Behind him was radar cabinet, just behind which sat the radar operator. Standing on a platform behind both of the guns was the commander, who had his own displays and controls. SAP, AP, and HE rounds were produced for the British Bofors guns, each weighing 0.894 kg (1.97 lbs.). Both SAP and AP were painted black with white tips, with AP being distinguished by a white ring painted on the body. HE, painted buff, had 0.068 kg (0.15 lbs.) of TNT and self-destroyed after travelling for approximately 3,200 m (3,500 yds). Rounds with tracer were indicated by an additional red ring. To either side of the commander at the rear of the firing platform were two ammunition hoists. Crewmen on the deck loaded ammunition into the hoists. Ammunition from the hoists was loaded by the crew on the firing platform through the top of the guns into ammunition "hoppers", from which the automatic loaders pulled the ammunition from. Spent cartridges were ejected out of the rear of the gun, down chutes redirecting them under the guns towards the front where they can be ejected safely away from the crew.
The STAAG Mark II replaced many of the older, yet similar Mark IV "Hazemeyer" mountings. Despite its technological advantages, the STAAG Mark II suffered from many of its own problems. The first of these problems was its weight of 17.8 tonnes, which was significantly heavier than mounts of its type, especially for a twin mount. Another problem was the complexity of the STAAG Mark II, which needlessly complicated maintenance and lowered reliability without showing enough improvements over other mounting designs to warrant it. A third issue was that the radar and other electrical equipment were carried directly on the mount itself, which put them under stress from the STAAG Mark II's movements and the vibrations from firing the guns. For these reasons, the STAAG Mark II did not remain in service for very long, soon replaced by the much simpler and more reliable Mark V twin mount.
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