Author Renato Vesco revived the wartime theory that the foo fighters were a new Nazi secret weapon in his non-fiction work 'Intercept UFO', reprinted in a revised English edition as 'Man-Made UFOs: 50 Years Of Suppression' in 1994. Vesco alleges that the foo fighters were in fact a form of ground-launched automatically-guided jet-propelled
flak mine called the
Feuerball (Fireball). The device, operated by special
SS units, apparently resembled a
tortoise shell in shape, and flew by means of gas jets that spun like a
Catherine wheel around the fuselage. Miniature
klystron tubes inside the device, in combination with the gas jets, created the foo fighters' characteristic glowing spheroid appearance. A crude form of collision avoidance radar ensured the craft would not crash into another airborne object, and an onboard sensor mechanism would even instruct the machine to depart swiftly if it was fired upon. The purpose of the
Feuerball, according to Vesco, was two-fold. The appearance of this weird device inside a bomber stream would (and indeed did) have a distracting and disruptive effect on the bomber pilots; and Vesco alleges that the devices were also intended to have an
offensive capability.
Electrostatic discharges from the klystron tubes would, he states, interfere with the ignition systems of the bombers' engines, causing the planes to crash. Although there is no hard evidence to support the reality of the
Feuerball drone, this theory has been taken up by other aviation/ufology authors, and has even been cited as the most likely explanation for the phenomena in at least one recent television documentary on Nazi secret weapons.
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