Solving the Aquatic Equation
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WITH Europe freed, and the last W river barriers crossed, more can be revealed of the development of waterproofing for army vehicles,. and the parallel achievements for ships' lifeboat engines. The problem that had to be solved might be termed the aquatic equation—how to make the modern vehicle and internal-combustion engine capable of operating while deeply immersed, or actually right under water.
That this problem has been most successfully solved is shown by the _following review of waterproofing developments by the Austin Motor Co., Ltd., which has been largely responsible for, the processing work in this direction.
At the outset the Army possessed many thousands of perfectly standardtype vehicle, constructed for use on roads or very rough and steep ground. Time would not permit of a special vehicle of amphibious characteristics being designed and built in sufficient quantities to meet the needs of fl-Day in Europe, quite apart from the requirements of the Sicily landings. The per
fectly standard vehicle, therefore, had to be adapted.
Naturally, as most people would expect, the high-tension circuit, with its exposed sparking plug and other terminals, was a big problem, but, as experimentg were continued, it was found that the ignition difficulty could be overcome, but other problems cropped up which had been considered to be of only a minor character and easy of solution.
A Many-sided Probleni
The question of keeping water out of the crankcase, the clutch housing,. the starter and dynamo, the gearbox and the axles—all had to be dealt with from some special and different angle. The petrol tanks, on the majority of vehicles, were almost certain
to be under water, and this,, was another item to be catered for.
The solution came in the form of a plastic compound, which could be applied to those .parts from which water had to be excluded, and this played a large part in the general waterproofing
schenie. The properties of this compound cannot—for obvious reasons—as yet be given, but it is sufficient to say that not only had it to be capable of preventing high-tension currents, in the order of several thousand volts, leaking to earth, hut it was required also to
• stand up and maintain its insulation and form, when in position on a very hot cylinder head.
Obviously, there were many items such as air vents, or " air escapes," 'which could not be:satisfactorily dealt with by the plistie method, and for these points simple covers, such as could be made up by a soldier in the field if necessary, were designed, In fact, the scheme for waterproofing generally adopted by the Austin concern was one of a simple character which any member of the fighting forces could easily carry out, if given the materials and explicit instructions, and both of these were provided,
Normally, water splashed up from the road on to a dynamo rarely presents
trouble of a Serious nature. It is a fact that low-tension electrical equipment, such as a dynamo or starter motor, will function quite well in •a watersplash, but salt water is an entirely .different problem, and the serious results of such immersion have to be seen to be realized.
Long hours of testing on the beaches made 'it perfectly clear that much had still to be learned—even by the most experienced—regarding the corrosive effects of salt water on live electrical terminals, and the resulting electrical resistance build-up. It became neces• sary completely to waterproof 'both dynamo and starter motor.
Then came ventilation problems. For instance, to apply a plastic compound to keep out water _from the distributor was found to be insufficient. That unit had to be ventilated by a vent pipe brought. well above the expected water level.
The need for this ventilation arises from the fact that the electrical discharge from the rotor to the electrodes for each plug creates a nitrous gas which will quickly blacken -the electrodes and the contact-breaker points. Unless this can be prevented, there will, • in quite a short time, be no current flow through the ignition circuit and, therefore, no spark available at the plug points.
Similarly, venting had to be carried out on the other components for other than electrical reasons. Air must tie allowed to enter fuel tanks in order to maintain the flow. Then, in respect of valve covers, and the engine crankcase generally, it was found important to ensure a sutwly of clean air so soon as practicable after being rendered watertight for immersion, so that condensation would not occur to bring in its train such evils as rust and other corrosion.
48 Instructions for Drivers Consequently, the earlier task books, giving the army. driver, information as to how to make his vehicle waterproof, contained no fewer than 48 instructions; some of them simple,. but all together representing a number of hours of work. .
All the experience enabling these instructions to be 'passed en was gained by immersing the individual components in special tanks for long periods, and by testing the complete vehicle on beaches and in rivers: For instance, at a certain point in the River Severn, Austin army. vehicles . might. often be seen, milling around in deep ' water, as if their drivers had mistaken the river for a normal road.
Austin lifeboat engines also received thorough treatment for waterproofing. In this case, the scheme is of an even more permanent nature, the electrical leads being fully screened and the magneto completely enclosed in a watertight case. One marine engine model, for use in an airborne lifeboat, even runs completely enclosed in a' large
rubber bag. Altogether, about 3,000 Of these lifeboat engines were supplied during the war.
To-day, waterproofing, either of complete Austin vehicles or lifeboat engines. has-ceased to be a matter of adaptation . and experiment. Subject to the maximum wading depths or other conditions to be encountered being fully established, vehicles and engines for war service are equipped to be easily waterproofed so that their aquatic _abilities Can, at any time, be brought into full -play at short notice.