n I have heard that the development of
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new methods of windscreen cleaning offer advantages, including simplicity and lower cost, over the conventional type of windscreen wiper. Have you any information on such systems?
AA number of alternative methods of windscreen cleaning have been evaluated but we do not know whether they have been applied experimentally.
A blast of air could be used to clear a windscreen of moisture and mud—the air could be heated to defrost the screen. But the cost of the equipment would be high and it might be discovered that air consumption is excessive. Other methods that have been mentioned by research engineers include the use of electrostatic charging or ultrasonics, but no details of these systems are available.
The Boeing Rain Repellent system was described in our associated journal MOTOR (20 May 1967). This system, which has been used on a number of aircraft and on the 1967 Le Mans cars, involves the use of a special fluid that is squirted on to the windscreen from a pressurized bottle.
A conventional type of wiper system is employed to spread the fluid over the screen.
The fluid increases the surface tension of water with respect to the glass so that it forms globules that do not adhere to the screen. At present the cost of the Boeing fluid is about £8 for 500c.c., which rules it out for commercial use on road vehicles, and we understand that there are some practical limitations to its use on relatively slow vehicles.