Secret Weapons

by Brian Ford

  So, at last, the project was terminated. All the scientific and engineering data should have shown that it could not work. Even a cursory examination of the elementary physics involved would have shown that it was doomed from the start. The cost of the project is unknown, but was clearly considerable, and the wastage of time was immense. At the time, a financial saving, or the release of a few thousand man-hours, would have been of the greatest value to the war effort. Householders were giving up their kitchen saucepans in order to supply light alloy to the aircraft industry and railings were being torn up and melted down to make steel sheet for weapons manufacture. To have these resources diverted to the Panjandrum project was unjustifiable.

  This was not the last we heard of the wasteful Panjandrum fiasco, however. It has re-emerged in more recent times. A lightweight reconstruction featured in the BBC’s wartime comedy series Dad’s Army, first broadcast on 22 December 1972. This episode featured the many problems that befell the device, and paralleled the original trials in some ways. The only time a Panjandrum ran successfully was in 2009 when a 6ft (1.8m) diameter replica was constructed to mark the 65th anniversary of D-Day. Like their wartime predecessors, these designers also envisaged that it would speed along the beach, heedless of the problems caused by the question of torque and the backward pointing rockets. It was ignited in a ceremony for the Appledore Book Festival in Devon, and ran down a small ramp. Although it worked to a fashion, the model trundled for several yards, mostly moving at walking pace, before it slowed to a halt and its rockets burned out.

  And so attention turned to designing an explosive landing craft. It was planned that this could deliver a load of explosives to breach a protective Atlantic Wall of concrete and allow the Allied troops through to the plains of France. It was being argued privately, that — even if the Panjandrum had delivered its load of explosives — they would not have exerted the desired effect. To give full benefit, an explosive charge would have to be clamped firmly against the wall. The blast would otherwise be dispersed and dissipated as it produced a huge crater in the sand. The proposed landing craft were designed with hydraulic rams which would provide the desired result — they would extend to force the explosive charge firmly against a concrete wall, maximizing its effect.

  The vehicles chosen were Alligator landing craft made in the United States. They were based on the amphibious DUKWs vehicles but had caterpillar tracks instead of conventional wheels. Attached to the tracks were spoon-shaped paddles which propelled the craft through the choppy seas until it came to land, when it would rise from the water and proceed up the beach like a conventional tracked vehicle. The Directorate planned to fit each craft with a 1-ton bank of high explosive mounted on a mattress base; this — on contact with the concrete wall — would be firmly clamped in position by the hydraulic rams and automatically detonated.

  The Alligator itself was a formidable device. Each was 26ft (10m) long overall and more than 10ft (3m) wide, weighing about 11 tons. But once in the water they were cumbersome and slow, and under sea trials they ran into repeated problems of instability that are reminiscent of the Panjandrum tests. On one occasion the hydraulic ram mechanism was actuated while the craft was still at sea. Its 1-ton mattress of explosive, ballasted with sand, tilted the whole contraption upwards at a crazy angle and a serious accident was narrowly averted. The Alligator took with it more casualties than its fiery predecessor had done as it spiralled up the beach.

  As with the Panjandrum, eventually someone realized that they were unlikely so succeed with this project and the Alligator too was cancelled. It was just as well. Both devices were being specifically designed to blast through an impenetrable wall of concrete behind which the Germans would be hiding. But, as intelligence showed (and as the Allied landings would confirm), the concrete wall simply did not exist. The Germans had never thought to construct an impregnable wall, and the Allied strategists had been developing weapons against a target that had never even been built.

  There was one final attempt to use rockets as a secret device for the Normandy landings that would aid the Allies, and intimidate the Germans. This was a novel idea: to drop containers of vehicles and equipment from low-flying bombers, using retro-rockets to slow the descent and cushion their landing on the beaches of Normandy. The Army proposed this novel idea to the Admiralty’s Directorate of Miscellaneous Weapon Development, who had been working on parachuting equipment during the invasion. Using parachutes to drop heavy equipment was no problem, but the relatively heavy impact was causing damage. Surely a retro-rocket assembly could cushion the landing. The preliminary designs seemed perfectly satisfactory, and the device was code named Hajile.

  The idea was to set off a battery of rockets when the container was a few yards from the ground. Solid-fuel rockets could not be relied upon to ignite at exactly the same time, and early tests showed — when the smoke had cleared — that the container was often left crunched into the ground. It was decided that it would be safer to carry out some tests over the open sea, and the site chosen for the observers was the holiday pier at Weston-super-Mare, which was designated HMS Birnbeck during the war. It was decided to drop a large container, fitted with its retro-rockets, from a Lancaster bomber but the pilot’s aim was not accurate and the horrified technicians realized that it was heading straight towards the buildings. They ran back along the pier, just in time to avoid the container as it crashed through the roof and demolished the workshops.

  There were plenty of other tests. One of them involved dropping containers from a tall crane. On the second attempt, the container hit the ground just as the rockets fired with a massive roar — this propelled the container back up into the air, where it smashed into the jib and demolished the crane that had dropped it. Several of these containers were built for the D-Day landings, but the device was never formally commissioned and remains a peculiar sideline to the war effort. The only remaining secret was the strange name given to the device: Hajile. Unlike Panjandrum, it seems to have no meaning at all, but its roots lie in the Old Testament. Elijah is said to have ascended unto heaven in a pillar of fire, remember?

  Suddenly, all is clear: Hajile in simply Elijah in reverse.

  CHAPTER 8

  ELECTRONIC SECRETS

  Detecting the enemy at a distance has long been an aim of any warring nation. The first distant detection system relied upon the sound of the enemy, and methods of picking up and amplifying faint noise are more than a century old. In 1880, the pages of Scientific American featured the topophone, invented by Professor A. M. Mayer, which was intended to amplify a distant noise and make it possible for the user to detect the direction from where it originated. The use of sound reflectors to concentrate distant engine noise from enemy aircraft dates from World War I when Professor F. C. Mather dug a parabolic reflector into the cliff near Maidstone, Kent. This was in 1916 and the reflector was used to detect incoming aircraft or Zeppelin airships. An observer would be stationed at the focal point of the acoustic reflector, listening for distant sounds. The experiments worked well, and a similar reflector was then dug out in Baharic-Cahaq on the Mediterranean island state of Malta. Further examples were planned for Aden, Gibraltar, Hong Kong and Singapore.

  A British parabolic concrete sound collector 20ft (6m) in diameter was erected near Dungeness, Kent, in 1928. A larger reflector 30ft (9m) across was built two years later, together with a large concave concrete reflector 200ft (60m) from end to end. During the 1930s, portable and steerable reflectors were designed. They could detect faint sounds over large distances, and the position of the sound source could be confirmed by the direction in which the reflectors were pointed to collect the loudest sound. By the beginning of World War II, as an alternative to the fixed parabolic reflectors, conical sound collectors had been built in Britain and were being successfully tested. Some were in the form of directional funnels that could be moved from place to place and could indicate the position of incoming planes. This was, though, a doomed technology. Det
ecting the sounds of aircraft engines was relegated to the sidelines when radar began to emerge.

  RADAR ARRIVES ON THE SCENE

  It is hard to imagine contemporary transportation without radar. All the airliners in the world are tracked by operators using real-time images of where they are in the sky. Every liner and container ship is watched intently from the shore; and they see each other with an unblinking eye. Even little yachts can carry a radar device to survey the surrounding seas, and they have a radar reflector at the masthead to ensure they are seen by the rest of the community. Radar is taken for granted, and — were it to vanish overnight — global transportation would be finished. It is clear that the modern world relies on radar to a great degree, but this important technological development has a long and interesting history.

  Origins of radar

  Many of the resonances between the secret weapons of World War II and today’s high-tech world will have come as a surprise. Radar, by contrast, is something with which we all feel more comfortable. It is widely believed that it was the urgency of World War II which led to the invention of radar, and that is was the brainchild of Robert Watson-Watt, the brilliant British electronics engineer and visionary. It may come as a surprise to many, then, to hear that radar was in existence prior even to World War I.

  It arose from the grief of a radio engineer named Christian Hülsmeyer from Düsseldorf, Germany. One of his closest friends lost his mother at sea when two ships collided in fog. Hülsmeyer was greatly saddened by the death of someone so close, and began to speculate on a means of trying to prevent a recurrence. He had been studying radio waves, which had been examined since 1887 by Heinrich Hertz, who is now commemorated by the use of the term ‘Hertz’ to describe the frequency of a radio beam. Hertz made many observations that were of interest to science — and one of them was that radio waves could be reflected from a metallic object. This caught Hülsmeyer’s attention and he began to carry out experiments to see whether the metallic object might be a ship at sea, and whether the nature of the reflection could tell you where it was. In the 1890s Hülsmeyer was a school teacher and devoted his spare time to these experiments; he later joined the Siemens Company. In 1902 he met a successful businessman from Cologne who agreed to speculate on the invention and advanced funds for the work. They called it the Telemobiloscope and together they launched a company called Telemobiloscop-Gesellschaft Hülsmeyer und Mannheim. A public exhibition took place on 18 May 1904 in Cologne. Hülsmeyer set up his apparatus on the Hohenzollern Bridge, and as soon as a ship sailed into the forward-facing beam a warning bell sounded loudly. Then, as the ship sailed away from the beam, the ringing stopped. Hülsmeyer had demonstrated the remote detection of a ship — it could have saved the life of his friend’s mother. There were rounds of applause from the spectators, and positive reports in the press.

  They took out patents on this remarkable new device, and in June 1904 the detector was demonstrated at a shipping conference in Rotterdam. The Telemobiloscope used a spark transmitter operating on a wavelength of 15.7–19.7in (40–50cm). The spark gap was submerged in oil to prevent it from burning away and the radio beam was emitted from a reflector shaped like a cone. To prevent a stray signal from some other transmitter from triggering the alarm bell, there was a time delay built into the circuitry so that the bell did not ring when the first signal was detected, but only when a second pulse was registered. This reduced the likelihood of a false alarm. Using this device, ships could be detected by simply aiming the beam in a given direction. Although there was no timing device to detect the delay between sending and receiving the signal (which would have given an immediate indication of the range) Hülsmeyer managed to show how to obtain a rough idea of the distance of the ship. The beam could be moved up and down, and — once you knew the height of the transmitter above the surface of the water — it was easy to work out the range.

  Hülsmeyer and Mannheim were delighted with their success and felt that their time had come. Details of the invention were sent to the Naval office and also to commercial shipping companies, but nobody seemed interested. Their hopes were dashed, and the Telemobiloscope remained a mere curiosity. A similar device, which detected radio beams bounced back from the surface of the ground, was invented by R. C. Newhouse at the Bell Laboratories in the United States. This was patented in 1920, and it later gave rise to an altimeter worked by radio (rather than air pressure). The first British patent for what was called radio location was taken out by L. S. Alder for His Majesty’s Signal School in 1928, and the Italian wireless pioneer Guglielmo Marconi — who knew that one could use radio to detect a moving object — demonstrated a device that could detect distant objects in 1933.

  This was the year when Hitler swept to power over Germany, and the emergent German Navy began to investigate harnessing the power of radio detection or Funkmesstechnik. In the following year, research started in Russia and successfully detected aircraft up to 55 miles (88km) distant. Nothing further happened at the time, though a French vessel in 1935 demonstrated a radio beam as a method of avoiding collisions, and this Barrage Electronique system was used early in World War II.

  Seeing the invisible

  And so, by the mid-1930s, there had been a range of different developments that allowed observers to penetrate fog or to detect ships in the darkness of night. Italian, German, British and American research had all played their part in harnessing the effects first observed by Hertz in the Victorian era. Even before World War I it had been possible to detect an otherwise invisible ship, using marine radar, even though few were interested in the idea. And since the time of World War I the directional use of sound detection had been used to give warning of distant aircraft. A combination of the two — detection funding from a transmitted pulse of sound — gave rise to sonar, which was developed by separate Canadian, British and American researchers starting in 1912.

  As war began to loom, increasing efforts were directed to defending Britain from attack. Robert Watson-Watt was a meteorologist who had studied the detection of lightning through the radio interference that was caused by the discharge, and he was approached about stories that were beginning to filter out from Germany. The Nazis, it was said, had a death ray. They could beam a radio transmission and wipe out populations at a considerable distance. Britain needed one too, it was agreed, and Watson-Watt must be the person to approach. It did not take him long to calculate that it was impossible, and he wrote a report to defuse the concern felt in official circuits. At the end, he added a note on a different problem that was ‘less unpromising’ than a death ray. This was the detection of objects by reflected radio waves. A report on that, he said, will be ‘submitted when required’.

  Aircraft and radar

  Watson-Watt did not invent the idea of detecting objects by reflected radio signals. This had long been established as a way of detecting shipping, where the metallic mass reflected the beam, but what about using this approach on aeroplanes? They were not heavy steel objects, and were often made of cloth and wood, but could they still reflect a radio beam? In February 1935 Watson-Watt wrote a top secret memorandum for the Air Ministry in London. He entitled it Detection and Location of Aircraft by Radio Methods. This was a radical new departure, and the Air Ministry asked for a demonstration. Within weeks, an experiment was set up at Litchborough, near the BBC shortwave transmitters at Daventry. Two transmitters were set up so that their signals cancelled each other out. Anything that interfered with the signal would deflect a spot on an oscilloscope screen. Only three people were involved: Watson-Watt and his assistant Arnold Wilkins, with a representative of the Ministry, A. P. Rowe. A Handley Page Heyford bomber was chosen as the first target. The Heyford was a biplane built in 1930, and was the last heavy biplane to be used by the Royal Air Force. Its wing-span was also exactly one-quarter that of the wavelength of the radio beam, which would maximize the chances of generating a positive echo in the signal. Flight-Lieutenant R. S. Blucke was the pilot that day, and he took o
ff from the airfield at Farnborough and climbed slowly to 6,000ft (1,830m).

  When he reached Daventry, the team on the ground saw the oscilloscope signal suddenly begin to flicker. The three men watched until the signal returned to normal when the aircraft was 8 miles (13km) distant. The principle was proved — not only heavy steel ships, but even lightweight aircraft, could be detected by the reflections of a radio beam. Within four short years, the system was refined until planes could be detected at a distance of 100 miles (160km) and work began on erecting a series of detector stations. This became the Chain Home network, known as CH for short, and it was fully operational in 1937, long before World War II broke out. This was the first radar system detecting aircraft in the world. When the war began in 1939, many nations were harnessing the same effect: France, Germany, Hungary, Italy, Japan, Netherlands, Russia, Switzerland and the United States were all investigating radar systems of their own.

  The true value of radar was recognized during the Battle of Britain in 1940–41, when the system gave advance warning of attacks, and knowing the direction of incoming German aircraft enabled fighters to be dispatched in good time. Reports of planes being detected by the CH stations scattered across the south of England and the Isle of Wight, were sent by telephone to ‘filter rooms’ which brought all the results together. Orders were then issued to the airfields to coordinate a response by British fighters. The Germans failed to grasp the way the CH system worked, and did not investigate how to jam the transmissions.