Bofors Flak 28 (40 mm)

4 cm Bofors Flak 28

File:4 cm Bofors Flak 28.png

Information

Automatic CannonType

Germany County of Origin

General Characteristics

40 mmDiameter

2.25 mLength

4 roundsBelt Capacity

160 rpmRate of Fire

881 m/sMuzzle Velocity

80 mmMax Penetration

Production History

Bofors CompanyDesigner

Limited ProductionProduction Status

1940 - 1945Produced

Description

The 4 cm Bofors Flak 28 is a naval anti-aircraft single mounting fitted with either captured Bofors 40 mm L/60 guns, or those produced under German occupation during WWII. 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.

Other variants of the Bofors 40 mm gun within the game include:

• Bofors L/60 Mark 1: US-produced, water-cooled twin mount
• Bofors L/60 Mark 2: US-produced, water-cooled quad mount
• Bofors L/60 Mark 3: US-produced single mount
• QF Mark V: British-produced, water-cooled twin mount
• QF Mark VII: British-produced single mount
• QF STAAG Mark II: British-produced, water-cooled twin mount with onboard fire control systems
• Bofors (40 mm): Army version, mounted on various US and British anti-aircraft vehicles (SPAA)
• MEL58: Bofors 40 mm L/70 (increased barrel length and rate of fire), mounted on Jaguar-Klasse (140)
• M266: Army version Bofors 40 mm L/70 (increased barrel length and rate of fire), mounted on M247 Sergeant York

Vehicles equipped with this weapon

• Emden
• Nürnberg
• Prinz Eugen

General info

The 4 cm Bofors Flak 28 has a barrel diameter of 40 mm and has a barrel length of 2.25 m. It has a magazine size of 4 rounds per gun and has a rate of fire of 160 rounds per minute, though firing for too long will jam the gun.

Available ammunition

There is one ammunition choice available for this gun:

• Default: HEFI-T

Penetration Statistics
Ammunition	Penetration @ 0° Angle of Attack (mm)
	10 m	100 m	500 m	1,000 m	1,500 m	2,000 m
HEF-I	_	_	_	_	_	_
AP-T	80	77	66	57	50	45

Shell Details
Ammunition	Projectile Mass (kg)	Velocity (m/s)	Explosive Type	Explosive Mass (kg)	TNT Equivalent (kg)	Fuse Delay (m)	Fuse Sensitivity (mm)	Normalization at 30°	Ricochet
									0%	50%	100%
HEF-I	0.9	881	Tetryl	0.068	0.0986	0.0	0.1	_°	_°	_°	_°
AP-T	0.882	874	N/A	N/A	N/A	N/A	N/A	_°	_°	_°	_°

The AP-T round, though present in the game files, is currently not available for any ship mounted with this gun.

Tetryl is equivalent to 1.45x TNT.

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 practically 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 (40 mm), which is, by and large, superior with a much higher rate of fire of 240 rounds per minute. The only other difference between this gun and the other Bofors L/60 guns is the HE round. The MEL58's HE round has less explosive mass (0.03625 kg TNT eq.), but they have a higher muzzle velocity (1030 m/s).

It should be noted that 4 cm 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 (1000 m/s) and has a stronger AP round (87 mm @ 10 m, 0°; 0.0374 kg TNT eq.); but it has a much slower rate of fire (30 rpm), has a weaker HE round (0.0274 kg TNT eq.), 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 eq.), 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 eq.), 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 eq.), 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

One of the best medium-range anti-aircraft cannons in the game, the 4 cm Bofors Flak 28 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 longer effective range than guns of similar calibre: laterally (i.e. targeting surface targets), the maximum range is about 3.25 km.

Despite each gun's 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, they 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.

The 4 cm Bofors Flak 28 only has one choice of ammunition, the default clips, which are consists purely of high-explosive rounds, making it the only naval Bofors gun in the game with such an option. Other naval Bofors guns have mixed ammunition choices, at most having 3 rounds of HE for every 1 round of AP. Against aircraft, and small boats in certain situations, this effectively raises the gun's effectively 33% by getting rid of the "useless" AP round. However, this comes at the cost of not having any AP rounds. Given though that the 4 cm Bofors Flak 28 is only currently found on cruisers in-game, this isn't much of an issue, since any armoured targets can be more effectively dealt with using the cruiser's main armament, anyway.

Pros and cons

Pros:

• Large explosive mass in HE round
• High-penetration AP round
• Very quick reload

Cons:

• Can jam if fired for too long

History

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 breach and eject the spent casing out its rear whilst an autoloading mechanism would insert the next round into the empty breach, after which the action of the gun sliding back into place would close the breach 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).

Germany first acquired the Bofors gun near the start of WWII at the defeat of Poland, the Netherlands, and France, as well as during the Norway Campaign, capturing many Polish, Dutch, and British models. Eventually, these were put into service by the Wehrmacht as the 4 cm/56 Flak 28, for use in the Heer (the German army) as a towed anti-aircraft gun and in the Kriegsmarine (the German navy) as a medium anti-aircraft gun on the heavy cruisers Admiral Hipper and Prinz Eugen, and for use as stationary AAA installations in coastal fortifications.

The guns supplied to Admiral Hipper and Prinz Eugen were manufactured in Norway at Waffenfabrik Kongsberg (Norwegian: Kongsberg Våpenfabrikk), which had obtained a license to produce the gun prior to WWII but had to halt production during the invasion of Norway by Germany in early 1940. Several months later, with Norwegian capitulation in June 1940 marking the end of the Norway Campaign, Waffenfabrik Kongsberg started production again, this time under German occupation, producing a small amount of Bofors guns, as well as ammunition and spare parts, most of which would be supplied to Admiral Hipper and Prinz Eugen. Several hundred guns were also purchased from Hungarian arms manufacturer MAVAG in 1941. On Kriegsmarine ships, in addition to Admiral Hipper and Prinz Eugen, the 4 cm Flak 28 was also fitted to Schnellboote in 1942, and at least one example was fitted to the light cruiser Nürnberg in 1944, and possibly other cruisers as well.

During WWII, the Kriegsmarine only ever utilized the Bofors guns in single mountings. Being a captured design, the 4 cm/56 Flak 28 under German use was operated in much the same way as its Allied counterparts. The turret was hand operated by two crewmen, one sitting on each side of the gun. The crewman on the right-hand side of the gun was the gun trainer, who traversed the turret horizontally by turning a handcrank. Opposite him was the gunlayer, who elevated the gun in the same manner, with elevation limits of -6°/+90°. Ammunition for Bofors guns was manufactured in 4-round clips. Although the Allies had created HE, SAP, AP, and other types of rounds, Germany only ever produced high-explosive ammunition for the gun, which were preset to self-destroy after 10.5 seconds of flight time. Ammunition, in the clips, was placed by other crewmen directly into a "hopper", letting the gun's automatic loading mechanism do the rest of the work. So long as there was ammunition in the mechanism, the gunlayer could fire the gun by pressing a foot pedal. Spent casings were ejected out the rear of the gun and guided by chutes directed towards the front of the gun, where they could be discarded safely away from the crew.

By the end of WWII, the Kriegsmarine had 825 4 cm/56 Flak 28 guns in service. With the unconditional surrender of Germany in May 1945 and the subsequent dissolution of the Wehrmacht, the 4 cm Flak 28 ended German production and service. Nevertheless, the Bofors gun, proving its effectiveness during WWII, continued to see use throughout NATO nations. Now split into East and West, rising tensions between NATO and the USSR pushed West Germany to create a new military, the Bundeswehr, in November 1955, including a new navy, the Deutsche Marine, founding in January 1956. Here, the Bofors gun once again entered German service. The 40 mm Bofors L/60 remained in use on Deutsche Marine ships well into the 1980s, a true testament to the effectiveness of a gun which has its origins leading back nearly 90 years ago.

Media

An excellent addition to the article would be a video guide, as well as screenshots from the game and photos.

See also

• 3,7 cm FlaK-Lafette C/36 (37 mm)
• 3,7 cm FlaK-Lafette LM/42 (37 mm)
• 3,7 cm SK C/30 (37 mm)
• Bofors L/60 Mark 1 (40 mm)

External links

• Lone Sentry - 4 cm Flak 28 (Bofors): Antiaircraft Gun (Ex-Swedish) - Originally Catalog of Enemy Ordnance Material, United States Office of the Chief of Ordnance, 1945, p. 129
• NavWeaps - USA Bofors 40 mm L/60 Model 1936
• Wikipedia - Bofors 40 mm gun