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HISTORY
Big wheels & little wheels – the story of UK-born Australian Sir Laurence John Hartnett (1898 – 1986) Australia’s “Father of the Holden” and much more
PART 43
TORBEERDOES!
WW2, Dec.1941: Encouraged by the British Admiralty, a decision was made by the Australian War Cabinet to manufacture torpedoes in Australia, committing Australia’s precision engineering to a difficult undertaking. The latest methods of torpedo-manufacture in Britain and the US were studied, and British specialists were brought to Australia. However many local manufacturing problems did not need the help of these specialists, and to investigate these, the Directorate of Ordnance Production formed a team of production engineers under the guidance of Laurence Hartnett and Francis Daley. One idea came from a beer-brewery mechanic!
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ome of the best ideas came to us (at the Australian Army Inventions Directorate) from people in the most unlikely occupations. One of the brightest, one which had the Americans and British very excited, was for a “self-seeking” (or “wake-following”) torpedo. This torpedo would snuffle along in the wake of a ship, like a dog on the scent, until it found its target, hit and blew up. The idea was based on the fact that water in the wake of a ship, having been stirred up by the propeller, is aerated. Its specific gravity is not as great as unaerated water, and the mechanism of the torpedo was designed to make the weapon seek out the lighter, aerated water and stay in it. My CEO Dr Richard Woolley was most enthusiastic: ''This is a good one, Hartnett. My technical men can't toss it. It works on a basic principle, and it could be a winner.'' We made up an experimental torpedo, and it worked. The invention was put on the super-secrecy list and, as was our custom when anything really promising came along, we told the Americans and the British.
Valuable intelligence was obtained from captured Japanese midget submarines. (navy.gov.au)
They both flew high-ranking naval officers to Australia to study the torpedo. The inventor watched all the demonstrations, but he was told not to say who he was, or what he was. The visitors were very keen. They flew home with all the information we could give them - all the information except one little item: the man who thought up the idea was a brewery mechanic from Brisbane, and beer had given him his brain-wave. He had noticed when he was pumping beer that if it had a head on it - if it was aerated - it took much less energy to move than when it was flat and unaerated. Would the Americans and the British have shown so much enthusiasm if we'd told them a keg of frothy beer had given a man an idea? I wonder. Australia’s southerly cities felt more secure from Japanese invasion than those in the north. That feeling was shattered in May and June of 1942 when three Japanese midget subs sneaked into Sydney Harbour - causing chaos and deaths. Two were detected and attacked; the third attempted to torpedo the Allied heavy cruiser – the USS Chicago. The importance of precision engineering in torpedo-manufacture is well illustrated by this attack on the USS Chicago which was anchored off Garden Island in Sydney Harbour. The Japanese midget submarine lay 1000 yards away. With quiet harbour water and a close, stationary target, a direct hit by the Japanese sub should have been a certainty; yet the torpedo veered to starboard, missing the Chicago by a few yards, and finishing its run unexploded on the shore of Garden Island. Examination of the gyroscope revealed what appeared to be the source of the Chicago's good fortune: The Japanese had, astonishingly, been careless in the choice of the material used in the bearings of the gyroscope wheel. They had used a steel which was not adequately resistant to corrosion, and slight rusting had caused the torpedo's gyroscope to deviate and so turn the torpedo from its set path. The firm of H.A. Chivers in Melbourne, was chosen by the Ordnance Production Directorate to manufacture gyroscopes because it had similar experience with aircraft.
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However specs for a torpedo gyro were far more stringent. In order to keep the diameter of the balls used in bearings to within plus or minus five-millionths of an inch, it was necessary to grade them individually by means of an optical method based on the interference of light waves. Without procedures such as these, it was impossible to produce a gyroscope wheel with perfect static and dynamic balance. It took some time to reach the desired high degree of accuracy, but at length it was achieved. The manufacturer commented that "this gyroscope could never have been made by any firm in Australia without the unfailing assistance given by navy officers and inspectors and the technical staff of the Ordnance Production Directorate". The Role of Science and Industry, Australia in the War of 19391945 (AWM) *AMT was delighted to discover that HA Chivers (started by watchmaker HA Chivers in 1920 and now known as Preslite Drive Technologies, Reservoir, Melb.), was still in existence after 100 years! Congratulations for your success and a belated thank you for your contribution to the war effort. The manufacture of precision instruments such as tachometer equipment and gyroscopes was no mean feat in Australia in the 1940s.
This is an extract from ‘Big Wheels & Little Wheels’, by Sir Laurence Hartnett as told to John Veitch, 1964. © Deirdre Barnett.
AMT JUN/JUL 2021
To be continued…
