Experimental weapons, Recoiless cannons:
Gerät 104 Münchhausen.
With the objective to destroy the naval supremacy dsiplayed by the Royal Navy compared with the Kriegsmarine at the beginning of of the war a massive cannon was developed in 1939-40 with the target of attacking british battleships and other strongly armored objectives.
The "element 104" was a weapon with an impressive caliber of 356 mm, designed to attack the ships with an armor piercing explosive war head.
Obviously the enormous recoil forces of a conventional gun of that caliber made it inadequate for its aeronautical use. For that reason it use the principle of the recoilless weapons, in this case allowing to of escape to gases of the firing by behind and that as well dragged capsula of propellant with a counterbalance, this balanced the two forces annulling the recoil.
The barrel:
The tube was made of chromium nickel molybdenum steel, it had a right hand twist. A belt for reinforcement was located in the zone where the propellant was deflagrated. The overall length was more than 10 meters.
(drawing from:
'German Aircraft Guns: WWI - WWII', Edward J. Hoffschmidt, WE Inc. 1969)
The ammunition of 356 mm:
The projectile of 35,56 cm was an armor-piercing shot of chromium steel with an explosive charge of TNT in the base and slowed down fuze of impact to allow him to explode within the ship once obtained the penetration. The driving band of the projectile was pre-engraved and it match the grooves of the barrel. This diminished the amount stress of the tube in the firing and therefore allowed a tube of thinner walls but of smaller weight. In order to introduce the ammunition two halves of the G-104 were unscrewed. The weight of the projectile was of
700 kg and the initial speed about
320 meters per second. In order to prove if the weapon were really recoiless it was tested ffrst on a car over of narrow railroad.
The results were satisfactory (in some ocation the barrel moves slightly forwards after shot) The next stage was the probes in a fake aircraft body.
In tests with false nose and tail of Do-17, notice the ammunition load of 356mm down completes with propellant and counterbalance to the left.
After shooting the gases slightly damaged the covering of fuselage in spite of the gas baffle plates located in each end. Nevertheless this problem was not serious and the weapon and the test continues until 1941 even was teorically proposed its use in the Ju-88, and He-177.