Among the physicists conducting this research was Sinitiro Tomonaga and by the end of World War II he and his team had produced a magnetron 8in (20cm) in diameter with an output rated at 100kW. Could this have been developed into a weapon? We cannot tell for sure, because the research papers were all methodically destroyed before the Allies invaded and occupied Japan, although there are reports of how effective it could have been in theory. The calculations suggest that, if properly focused, the beam available by the end of the war could have killed a rabbit over a distance of 1,000 yards (or metres) — but only if the rabbit stayed perfectly still for at least 5 minutes. Nothing more was heard of the Japanese death ray, though it would be wrong to regard Tomonaga as a forgotten scientist. After the war, Robert Oppenheimer invited him to carry on his research at Princeton University in the United States and Tomonaga was eventually awarded the Nobel Prize for physics — jointly with Richard Feynman.
It is August 2009. On BBC television from London is one of those pop-science shows, where the eager presenters are all hyperactive and hypnotically confident, and where any need for the viewer to think scientifically has been surgically excised. The set is rich in bright gadgets of every hue, the teeth dazzling, the smiles fixed. ‘Welcome to my world,’ says the presenter excitedly, this being the world of the vortex gun. ‘My prototype vortex cannon blew a bottle into a bin from twenty feet [about 6m],’ he reports. But he wants to go ‘a lot, lot further’. With a budget of £7,000 ($10,000) and the help of some technicians, the BBC have constructed a cannon in which acetylene and oxygen exploded to drive a spiralling plug of air, a cross between a smoke-ring and a whirlwind, for many yards across a disused quarry in rural England. First a pile of straw, then a wooden box, and finally a target made by piling bricks upon each other are knocked sideways by the blast of the high-speed vortex. It’s an excellent demonstration, and the script emphasizes its uniqueness. This, the viewer is told, has ‘never been seen before’ in this country.
It is an important codicil, for thousands of vortex guns have been built elsewhere (mostly in the United States). The British viewers had the impression that this was a leap in the dark, unprecedented and unique, and no mention was ever made of the thousands of earlier vortex cannons already in existence for over 100 years. In reality, this was not new at all. There are booklets, kits, magazine articles, demonstrations on YouTube; building a vortex cannon is a well established weekend hobby for enthusiasts, and has been done for decades. Although the show said nothing of the fact, this had an earlier history, as a secret German weapon of World War II.
The vortex cannon was constructed in early 1945 by an engineer named Dr Mario Zimmermayr at Lofer in the Austrian Tyrol. He came up with two designs, the Wirbelwind Kanone (Whirlwind Cannon) and the Turbulenz Kanone (Vortex Cannon). The design of the Vortex Cannon proved to be most promising. It was essentially that of a large mortar buried in the earth, which fired an explosive into a cloud of fine coal powder. The idea was to create a whirling tornado of air that would bring down enemy aircraft flying overhead. High-speed cine cameras were used to film the experiments, and they showed that a large and energetic vortex of exhaust gases was expelled from the device. It was reckoned that this could have an effective range of just over 300ft (100m) though it was never used in practice against enemy aircraft. There were reports of a similar vortex cannon being used against personnel in Poland although these have never been substantiated.
But the concept was not new, even in World War II. Vortex guns had been built in Italy since the late 1800s, where they were used to fire vortices into the clouds above the Italian vineyards, in the hope of encouraging rain to fall and to break up large hailstones that could decimate a crop. At the beginning of the twentieth century, an Australian government meteorologist named Clement Wragg saw these guns exhibited in Europe. An article from the Melbourne Argus newspaper dated 29 January 1902 says: ‘Sufficient funds have been collected to purchase a Stiger vortex battery for preventing hailstorms, and tenders are now being called for a battery of six guns.’ These vortex cannons were impressive, each with a barrel 10ft (3m) long, and they were installed at Charleville, an agricultural township 470 miles (760km) west of Brisbane. On 26 September 1902 the mayor ordered six of the guns to open fire, and ten shots were fired at the clouds from each barrel. A few drops of rain were felt, and several hours later there was a light shower. Nobody could be sure the vortex cannons had caused it, but the results were encouraging and eventually 13 more were built in Australia. Some have been preserved and stand in Charleville to this day.
A similar concept lay behind the Windkanone (Wind Cannon) that was manufactured in Stuttgart during World War II. This was a large angled cannon which could eject a high-speed mass of compressed air that was intended to bring down nearby aircraft. The device used a critical mixture of hydrogen and oxygen in the ratio of 2:1, obtained from electrolysis of water. The sharp explosion produced a bolus of highly compressed air that could cause damage at a distance. When experimentally demonstrated at Hillersleben in Saxony, it could break a wooden board 1in (25mm) thick at a distance up to almost 700ft (200m). It was recognized that it would be hard to aim and control the projectile, and so further tests were carried out using nitrogen dioxide, a brown gas which allowed the engineers to study the path it took. A prototype was installed to protect bridges over the river Elbe, though no hits on aircraft were ever recorded.
Plans were also drawn up to use the pressure of sound waves against personnel, rather than aircraft. The Schallkanone (Sound Cannon) was designed by Dr Richard Wallauschek and was first produced in 1944. It comprised two parabolic sound reflectors that projected a beam of intense sound waves against enemy troops. A pulse of intense sound waves was produced by detonating a critical mixture of oxygen and methane that was forced under pressure into the detonation chamber. The chamber was carefully calibrated to produce a resonance of the frequency that increased dramatically in intensity up to a pressure of an atmosphere (15psi or 1 bar) some 175ft (50m) away. This was calculated to be enough to incapacitate a soldier instantly. There were reports that experiments with it worked, for example a dog tethered over 125ft (40m) from the weapon was said to have been killed.
The device has re-emerged in more recent times. This kind of weapon appeared in the adventures of the boy detective Tintin, by the Belgian author Georges Prosper Remi (popularly known as Hergé), entitled L’Affair Tournesol which was published in English as The Calculus Affair. It has been used in fact, as well as fiction; ships are now being fitted with sound guns based on the same principle. The LRAD device, currently manufactured in the United States, is being fitted to ships around the world and is commonly brought out and primed for action as ships enter dangerous waters, or when they come into port where a raid might occur. The design initiated by the Nazis has found a peacetime application in keeping cruise passengers safe from modern-day pirates.
During the war there were several designs for modern and state-of-the-art tanks. Super-heavy tanks were soon on the drawing board, and there were also attempts to find a method of transportation that would provide better traction than the standard caterpillar tracks. Few were as bizarre as the Tsar tank that the Russians had first manufactured in World War I. Instead of having parallel tracks it was fitted with two spoked wheels some 27ft (8m) in diameter. A single trailing wheel at the rear was only 5ft (1.5m) in diameter. The idea was that the large wheels could overcome obstacles on the ground and it was tested before the Army High Commission in August 1915 near Moscow. The rear wheel was liable to sink into the ground, and the front wheels were too narrow, and so they sank into mud; the prototype was marooned where it stood for years, and was eventually broken up for scrap iron by the Bolsheviks in 1923.