12.8 cm FlaK 40

The 12.8 cm FlaK 40 was a German World War II anti-aircraft gun. Although it was not produced in great numbers, it was one of the most effective heavy AA guns of its era.

Development of the gun began in 1936, with the contract being awarded to Rheinmetall Borsig. The first prototype gun was delivered for testing in late 1937 and completed testing successfully. 

The gun weighed nearly 12 tonnes in its firing position, with the result that its barrel had to be removed for transport. Limited service testing showed this was impractical, so in 1938 other solutions were considered.

12.8 cm Flak 40
A static mounted 12.8 cm Flak 40.
Type	Anti-aircraft gun
Place of origin	Nazi Germany
Service history
In service	1942–45
Used by	Nazi Germany
Wars	World War II
Production history
Designer	Rheinmetall-Borsig
Designed	1936
Manufacturer	Rheinmetall-Borsig
Produced	1942
No. built	Total 1,125
Variants	12.8 cm FlaK 40 12.8 cm FlaK 40 Zwilling
Specifications
Weight	17,000 kg
Length	7.835 m
Barrel length	61 calibers
Shell	26 kilograms
Caliber	128 mm
Breech	Horizontal sliding
Recoil	Hydropneumatic
Carriage	Static or railcar mounted.
Elevation	-3 to +88 degrees
Traverse	360 degrees
Muzzle velocity	880 m/s
Maximum firing range	10,675 m
Feed system	Power rammer

The eventual solution was to simplify the firing platform, based on the assumption it would always be securely bolted into concrete. The total weight of the Flakzwilling twin-gun mount system reached 26.5 tonnes, making it practically impossible to tow cross-country. In the end, this mattered little since by the time the gun entered production in 1942, it was used in primary static defensive applications. 

There were four twin mounts on the fortified anti-aircraft Zoo Tower, and they were also on other flak towers protecting Berlin, Hamburg, and Vienna. During the Battle of Berlin, the guns on the Zoo Tower were used successfully to support ground forces, where the heavy 128mm shells obliterated Soviet armor, especially when hit from the side. The rush to capture the Reichstag led to dozens of tanks being destroyed. Approximately 200 were mounted on railcars, providing limited mobility.

The gun fired a 27.9 kg  shell at 880 m/s to a maximum ceiling of 14,800 m. Compared with the 88mm FlaK 18 & 36, the 128 used a powder charge four times as great.

Variants
12,8-cm-Flak on a Flak tower.

12.8 cm FlaK 40 -12.8 cm Flakzwilling 40/2 The 12.8 cm Flak 40 ordnance on a static dual mounting with a total weight of 26 tonnes, capable of firing 20 rounds per minute. Used mainly on flak towers. Production started in 1942 with 10 twin sets produced, another eight in 1943, and in February 1945 a total of 34 were available.

12.8 cm PaK 40 A derivative anti-tank gun, rejected in favour of the Krupp 12.8 cm Pak 44, used to arm the Sturer Emil prototypes