You guys need a copy of 'Flying Guns - World War 2: Development of Aircraft Guns, Ammunition and Installations 1933-45'
This is an extract:
"More unusual was a series of German weapons designed for upward (or, in one case, downward) firing and intended to be triggered by automatic sensors. These were known as the SG series (usually given as Sondergerät = special equipment, but other contemporary documents give Schiessgerät, or shooting equipment). They were late-war developments which were tested but did not enter service. The SG 117 consisted of seven MK 108 barrels, each loaded with a single 30x90RB round, which were clustered together for firing upwards at bombers. The total weight was 28 kg. The barrel block slid downwards out of the aircraft during firing, sequentially triggering the shots as it did so (at an effective rate of 10,000 rpm) and simultaneously absorbing the recoil. A more conventional recoilless approach was taken by the SG 116, which consisted of three 30 mm barrels (each weighing 30 kg) firing special combustible cardboard RCL cartridges (315 g at 860 m/s ), and the 50 mm SG 500 Jägerfaust (1 kg - containing 400 g of HE - at 400 m/s). In both cases, the recoil was balanced by firing a counterweight from the back of the gun, as originated in the Davis guns; in the Jägerfaust, the counterweight was the cartridge case which was also extended upwards to act as the barrel. The firing of all three types was by electro-optical sensors as they passed beneath the target aircraft. An even more ambitious project was the SG 113, which was intended for attacking tanks. It consisted of a 7.5 cm gun firing a 4.5 cm saboted projectile downwards at 650 m/s, once again balanced by a Davis-type counterweight. Total weight of one barrel was 48 kg. The gun was intended to be triggered by the electrical impulse caused by flying over a tank at low altitude, but this proved unreliable.
Even more unusual was the 2 cm Harfe (harp) which consisted of single-shot RCL barrels (using the gas jet principle) firing fin-stabilised 135 g shells at 320 m/s. The barrels weighed 2.3 kg each and were intended to be assembled fifteen or twenty at a time, pointing upwards for attacking bombers and arranged in a line to minimise aerodynamic drag (hence the name). This was as fruitless as all of the others."
Tony Williams: Military gun and ammunition
website and Discussion
forum
