By mid-1944, Nazis were so desperate to stop the murderous Allied bombings that they were ready to pursue just about any project, no matter how “unconventional” (i.e. bizarre) that promised to solve this crucial problem.
One such project was the “whirlwind cannon” proposed by Dr. Mario Zippermeyer, an Austrian inventor The cannon worked by generating explosions in a combustion chamber, which would be released through special nozzles, and finally directed towards Allied aircraft.
A scale model was built which proved to be successful, as these “whirlwind” blasts supposedly shattered wooden planks at a range of 600 feet. Despite having a working scale model, the project was scrapped after a full sized version could not replicate the same effect at high altitude targets (reportedly in an actual combat situation – in defense of a bridge over the Elbe River in 1945).
The actual “Whirlwind Cannon” itself was found rusting and abandoned by puzzled Allied forces on the Artillery Proving Ground at Hillersleben in April 1945. The second cannon was destroyed at the end of war during its transportation to Frankfurt.
A variation of the “whirlwind cannon” was the “Turbulenz Kanone”. It was a large caliber mortar sunk into the ground with fired coal dust and slow burning explosive shells to create an artificial vortex.
This also worked well on the ground but again the problem was the same – how to generate a large enough effect to reach the aircraft. And again, this problem turned out to be impossible to solve.