BI781 Flakzwilling 40
Visit to the Aberdeen Proving Grounds Ordnance Museum, 23 Oct 2004.
"The 12.8 cm FlaK 40, was a German World War II anti-aircraft built as the successor to the 88 mm gun. Although it was not produced in high 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.
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 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 the production of mobile guns larger than 105 mm was prohibited. In August 1944 there were 450 such cannons available. As a result only a few were built and used, amongst other places, in the anti-aircraft flak towers protecting Berlin, Hamburg, and Vienna. Approximately 200 were mounted on railcars, providing limited mobility.
The gun fired a 27.9 kg (57.2-pound) shell at 880 m/s (2,890 ft/s) to a maximum ceiling of 10,700 m (35,000 ft). Compared with the 88, the 128 used a powder charge four times as great which resulted in a shell flight time only one-third as long. This made aim against fast-moving targets much easier."