Reported in Scientific American, This Week in World War I: February 13, 1915
German Zeppelins (airships with rigid frames) bombed Liège, Belgium, on August 6, 1914, only a few days after the Great War broke out. Over the next few weeks, Zeppelins carried out raids throughout Europe on military and civilian targets. The actual damage caused by these raids was minimal, but at the time the idea of bombs raining down from the sky was new and frightening. The public clamored for a response: by the end of the war, quite a lot of resources had been diverted to air defense (and probably more than the threat warranted).
One possible solution was printed in the February 13, 1915, issue of Scientific American. An artillery shell had been developed by technicians of the English armaments firm of Armstrong, Whitworth & Co. Shot from an anti-aircraft gun on the ground, the shell carried three blades that would pop out of the shell body after it was fired. As the shell tore through the airship canvas sides of its intended target, a mechanism would detonate the shell within the body of the craft, “thus effectively destroying the craft, or at least compelling instant descent.” The author of the article did not know if the shell had been deployed yet, and wrote, “Whether these shells have been brought into service or not has not been announced.”
It is an appealing idea to have a shell that can rip into an airship and blow it out of the sky. And it looks like a clever design. Technically, though, in the days before mechanical (let alone electronic) computers, it would have been almost impossible to place a shell within the body of an airship flying at altitudes of up to 10,000 feet (usually at night). A shell flying through the air, with the blades out and acting as ailerons, would have been quite a challenge to shoot accurately. Yet there is no information about development hurdles, or test results, or where or when it would be used, or photographs of the shell. Perhaps censorship would have expunged that kind of information.
These shells do not seem likely to have been of much use. Were they a thought experiment as opposed to an actual engineering design? If so, it is likely the article on them was a propaganda ploy presented for public consumption as a response to public fear about Zeppelin attacks: engineering gobbledygook designed to assuage public concern.
As it happens, Zeppelins proved to be vulnerable to other hazards. They are kept aloft by hydrogen, a flammable gas. The development of incendiary bullets by John Buckingham in 1915, and their deployment in 1916 in the guns of airplanes guided by increasingly well-organized air-defense systems, led to high losses of Zeppelins, which were largely withdrawn from their attacking role as the war progressed.
Our full archive of the war, called Scientific American Chronicles: World War I, has many articles from 1914–1918 on airships and aviation warfare. It is available for purchase at www.ScientificAmerican.com/wwi