12.8 cm FlaK 40

• Name — 12.8 cm Flak 40 • Origin — Nazi Germany • Type — Anti-aircraft gun • Is Ranged — yes • Is Artillery — yes • Service — 1942–45 • Used By — Nazi Germany • Wars — World War II • Designer — Rheinmetall-Borsig • Design Date — 1936 • Manufacturer — Rheinmetall-Borsig • Unit Cost — 12,000 man-hours • Production Date — 1942 • Number — 1,125 • Variants — 12.8 cm Flak 40 12.8 cm Flak 40 Zwilling • Weight — 17,000 kg • Length — 7.835 m • Part Length — 7.8 m 61 calibers • Cartridge — 128 x 958mm R • Cartridge Weight — 26 kg • Caliber — 128 mm (5.03 in) • Rate — 10 to 12 rounds per minute • Velocity — 880 m/s • Max Range — 14,800 m • Feed — Power rammer • Breech — Horizontal sliding-block • Recoil — Hydro-pneumatic • Carriage — Static or railcar mounted. • Elevation — -3 to +88 degrees • Traverse — 360 degrees

Development of the 12.8 cm Flak 40 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. Ultimately the firing platform was simplified, based on the assumption it would always be securely bolted into concrete. Approximately 200 guns were also mounted on railcars, providing limited mobility. 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 primarily 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. It is claimed that during the Battle of Berlin the guns on the Zoo Tower were used successfully to support ground forces. The rush to capture the Reichstag led to dozens of tanks being destroyed. The gun fired a 27.9 kg shell at 880 m/s to a maximum ceiling of 14,800 m. Compared with the 88 mm Flak 18 & 36, the Flak 40 used a powder charge four times as great. The Bundeswehr Museum of German Defense Technology in Koblenz has one of these cannons in its collection.

• 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 tandems 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, though rejected in favour of the Krupp 12.8 cm Pak 44 for mass production, but two pieces used to arm the Sturer Emil prototypes.

• 120 mm M1 gun, a US gun of almost identical performance. • QF 4.5-inch gun: British 113 mm heavy anti-aircraft gun firing a slightly lighter shell. • QF 5.25-inch gun: British 133 mm heavy anti-aircraft gun firing a heavier shell. • 5"/38 caliber gun: US Navy single/dual purpose shipboard 127 mm heavy anti-aircraft gun firing a slightly lighter shell, used on many U.S. Navy ships built during World War II