Secret Weapons (29 page)

Gerk’s proposals from that time look very like the later magazine illustrations that Geoffrey Pyke promoted. What is more, Pyke was not even the inventor of what became known as Pykrete. The secret story behind this curious idea began when Pyke was shown a paper written, many years earlier, by Professor Herman Mark in Austria. Mark was a former professor of physical chemistry at the University of Vienna and an expert on the structure of plastic materials. For many years he studied X-ray diffraction, a technique in which the effect of a material on a beam of X-rays can be used to work out the molecular structure that lay hidden within the material. In 1926 he joined the chemical company IG Farben and worked on the development plastics that we now take for granted – PVC, polystyrene, polyvinyl alcohol and synthetic rubber.

Mark laid plans to leave Germany as Hitler was preparing for war. He had a huge store of platinum wire that he wished to take with him because it is a catalyst that is crucially important for his research. He knew the authorities would not permit him to remove such an important element from Germany, so Mark conceived a way of smuggling the wire with him. He bent the platinum wire into the shape of coat hangers, and his wife knitted neat covers for them all. When his suitcases were checked for contraband, the coat hangers did not even attract a second glance. The Canadian International Pulp and Paper Company in Dresden had asked Mark to come and organize research at their research headquarters in Canada, but the Gestapo arrested him, confiscated his passport, and gave him an official order not to contact any Jews. By bribing an official with a payment equal to his annual salary he secretly retrieved his passport, and – with the help of the paper company – he managed to obtain a visa to enter Canada. In April 1938 he mounted a Nazi pennant on the front of the family car, tied their skis to the roof of the vehicle, and drove across the frontier to Zurich, Switzerland, with the clothes (on their coat hangers) safely concealed in suitcases. From here they set off to reach London, England, where Mark boarded a transatlantic vessel to sail to Montreal.

He ended up carrying out research on paper pulp not in Canada, but in the United States at the Brooklyn Polytechnic where he set up the first course in the world for students of polymers and plastics. Mark was convinced that there was an important future for composite materials made from fibres held together in a mass by a plastic bonding agent. He was right, of course; the new Boeing Dreamliner is largely constructed from just such composite plastic materials. One of Mark’s early trials was an investigation of a wood pulp composite that was bonded, not with plastic, but with ice. The resulting material had properties rather like present-day fibreglass and was very strong.

In 1942, Mark sent a paper on his research to one of his former students, Max Perutz, who had escaped from Germany to England. Perutz is the scientist who coined the term ‘molecular biology’. I knew him later at Cambridge. When Perutz passed the papers to Geoffrey Pyke, it was Mark’s research on which Pyke set out to base his proposals for a floating mid-Atlantic airfield. His plan was for a top-secret ‘aircraft carrier’ made of ice and pulp that floated in the middle of the Atlantic; it would allow planes to stop and refuel, thus bringing Europe within easy flying distance of the United States. But would it work? Several practical trials were carried out in the summer of 1943, and a small prototype was constructed at Patricia Lake, Alberta, Canada. It measured 60ft (18m) by 30ft (9m) and was thought to weigh 1,000 tons. A 1hp (0.75kW) engine drove the freezer unit to keep the ice solid. Pyke himself was not permitted to join these trials, as he had already caused problems when the Weasel idea was being investigated in America, but he remained a persistent advocate of the concept.

Pykrete proved to be a solid material; buoyant, slow to melt, low in density and floating high in the water. In recent years television documentary producers have recreated Pykrete and there is no doubt that it works. But Pyke was not easy to work with, the scaling-up of the project would have cost prodigious amounts of money, and the sheer size of the project meant it was never tried on a larger scale. As a result, Pyke’s private experiments continued and he is, to this day, firmly associated with the strange saga of the aircraft carrier to be made of ice; but both the concept, and the material, had already been published years before. The secret origin of Pykrete was nothing to do with Pyke, and Professor Mark surely deserves his own place in the history of World War II.

Just as the Russians had contrived methods of propelling tanks though mud and snow, the British worked in secret on designs that would allow conventional vehicles to operate in difficult conditions. The Bedford Giraffe was a modified van intended for beach landings. The important items – cab, instruments, engine, etc – were raised on a frame for working in water. The engine was 7ft (2.13m) and the driver’s seat 10ft (3.05m) above the water’s surface. Tests proved satisfactory and the first orders were placed but, at the last minute, it was discovered that the vehicle was not reliably waterproof in choppy seas and the problems could not be solved. The project was abandoned.

The Vickers Company produced an amphibious tank during the 1930s. It was not put into production by the British during World War II, though a later model, designated the Vickers-Carden-Loyd M1931 Light Amphibious Tank, was sold in some quantity to the Chinese Nationalist Forces in the years leading up to the war.

At the other end of the scale came the gigantic
Maus
(Mouse) tank. A mock-up made from wood was shown to Hitler in May 1943. The final version of the tank would weigh a colossal 190 tons. The Führer immediately ordered that 150 be manufactured and by November 1943 the first prototype was ready for demonstration. Despite being powered by a modified aircraft engine by Daimler-Benz the tank’s vast weight made it difficult to move. Even when that was overcome, and the tank could crawl along at a maximum velocity of 8mph (13km/h), it was soon realized that it could not cross any existing bridge in Germany without bringing it down. The Maus was therefore fitted with a snorkel system so that it could pass underwater through rivers up to 26ft (8m) deep. It thus became the largest amphibious vehicle in history. But it remained over-engineered, too heavy and too slow. Hitler, once more, changed his personal preferences and so the entire order was dropped.

More successful was the
Landwasserschlepper
(Land-Water-Tractor) that was commissioned by the Heereswaffenamt in 1935. It was intended for use as a light tug that could also travel on land. The vehicle was designed by the Rheinmetall-Borsig Company in Düsseldorf and looked like a boat mounted on tracks. Its original function was to work on rivers where the bridges had been destroyed, but with the plans advancing for the German invasion of Britain under Operation
Sealion
, it was envisaged as hauling assault barges onto the shore. It entered service after considerable testing and modification in 1942 and saw service in North Africa and on the Russian Front. Towards the end of the war, a new design was introduced which featured a protected cockpit for the driver and was manufactured on a Panzer Mark IV tank chassis. Even though it was beset with problems, this bizarre Landwasserschlepper was still in operation at the end of the war.

Britain’s greatest mistake was one of the most spectacular follies of the entire war. It was a secret weapon that was doomed to fail from the start – the giant Panjandrum. This was to be a large explosive wheel that could roll up the beaches and destroy German fortifications on the coast of Normandy, France. The unlikely name came from the theatrical writings in London of Samuel Foote in 1754: ‘The grand Panjandrum himself … playing the game of catch-as-catch-can till the gunpowder ran out at the heels of their boots.’

In construction it was to be a pair of large wheels, each some 10ft (3m) in diameter and with a tread around the periphery about 1ft (30cm) in width. In the middle, at the hub, there was to be a substantial explosive charge fitted with a fuse that would detonate on impact. Around the rim of the two wheels would be cordite rocket charges that would spin the whole device up the beaches of northern France during the Allied invasion. In use, it would look like a pair of Catherine wheel fireworks.

The original idea was approved by the British Royal Navy’s Directorate of Miscellaneous Weapon Development based on rough sketches prepared by a Combined Operations group-captain. In August 1943, at Leytonstone in East London, construction of a prototype began. Within a month it was ready for testing. Let us step back and examine the idea in principle. At once a serious defect in the design becomes apparent. If the wheels were propelled forwards by rockets that burned only when facing to the rear, it would be driven along at increasing speed like any other reaction-propelled vehicle. This dramatic concept of the rocket-propelled weapon was no doubt what immediately appealed to the designers. But think about it: the Panjandrum was not a reaction-propelled vehicle at all. The rockets burning around the periphery were going to exert their effects in turning the wheel – in creating torque, as an engineer would say – and it was the torque, rather than the backward thrusting rockets, which was going to drive the device forward.

There are clear differences between a reaction-propelled rocket vehicle and one driven by torque. For instance, if the number or power of the rockets on a reaction-driven trolley (where all the rockets point backwards) is increased, then the contrivance will go correspondingly faster. This is not, however, the case with the Panjandrum. In this case, more rockets, or an increase in their power, could well lead to an increase in torque but that might just as well manifest itself as wheel-spin, rather than forward movement. Half the rockets are pointing backwards, true; but half are directing their thrust forwards, against the direction of movement. This is what the experimenters were to find. If the number of the rockets was too low, the device would not be able to overcome the rolling resistance of the sandy beach. However, if the number and power of the rockets were substantially increased, then wheel-spin could set in. There was no means, as it were, of slipping the clutch as the giant wheels slowly gained forward velocity.

There was an added problem: the device was not a carriage fitted with wheels – rather, it was a large pair of wheels. It would have only to run over a relatively small object (like a rock) to tilt sideways and substantially change course. One or two such perturbations could cause it to change direction several times, with possibly drastic results.

The mathematics of all this is involved, though not obscure; and even common sense would show that the Panjandrum was unlikely to succeed. A wheeled mine, driven by rear-mounted rockets, might well have been practicable. It would have no problems of torque, and would tend to maintain its straight course, as any four-wheeled vehicle would tend to do. Furthermore the manufacturing technology, being more conventional, would have posed fewer problems. I can see several alternatives. One would be the trolley, as I have already said. If the wheels were really necessary, then it might have been feasible to mount the rockets near the hub, on gimbals fitted with weights that caused them always to point to the rear. Another design that could have worked would be to have had the rockets mounted around the edge of smaller wheels that were geared to drive the larger, outer wheels. That way, the drive wheels would be spinning round at speed, and reduction gears would have transmitted their energy to the main wheels, turning more slowly as they gathered momentum.

But to the minds of the Directorate, the uncomplicated image of a vast, rotating, fiery wheel spewing its way up towards the enemy fortifications was romantic, bizarre, frightening even; the practical problems did not commend themselves to anyone on the team. The prototype was constructed under conditions of the greatest secrecy. When it was finished, it was transported under the closest security to the West Country with a police guard, moving only under cover of complete darkness. Once it arrived safely at the seaside town of Westward Ho! in Devon the security measures were forgotten about and the Panjandrum was unveiled, ready for the tests. Local residents, even people on holiday, crowded round the device with bemused interest.

On its first run it was clearly underpowered. Had anyone calculated thrust values (assuming that the complication of torque did not exist) they would have seen that the rolling resistance of such a vast, heavy object against sand was going to be considerable. But they did not take this into account, and the first test run came to an ignominious end as the ‘secret weapon’ trundled down a ramp with its rockets feebly firing and rolled steadily to a dead stop. The plans had been for the Panjandrum to storm across the beach at up to 60mph (almost 100km/h) and the depressing exhibition the device gave of itself must have been profoundly disappointing. So the number of rockets was increased; and they were clamped to the inside edges of the wheels, as well as the outside. The next firing was a failure because of the excessive torque. Not only that, but one of the wheels sank into the sand which threw the vehicle off course, and several of the rockets broke free and zoomed crazily across the beach. The spectators looked on in astonishment and not a little fear.

To correct the instability was the next priority. But how could this be achieved? It was decided to try fitting a third, central wheel. It is fairly obvious that, on even slightly rough terrain, this would add to the instability rather than correcting it. The test that followed proved the point. The huge contraption ran a little way up the beach, powered by a total of 70 rockets instead of the original 18. It lurched to one side, then turned back on itself, ran back into the sea and fell on its side, the rockets boiling the water around. Other rockets became detached and flew off low across the sands. Clearly, the middle third wheel was not an improvement. It was found to have been bent and buckled after this test run, and was abandoned.