INCREASE in the amount of night flying with the advent of airplanes into the commercial field makes more acute the need for proper lighting facilities, not only of airports and airways, but of the airplanes themselves. As only about one-half of the regularly used airways in this Country are lighted for night flying, and few airports are equipped with lighting facilities for night landings, it is necessary for airplanes to be provided with lighting equipment for flying and for emergency landing at night.
Besides the high-intensity lighting needed for following unlighted airways and for landing, airplanes need navigation lights and illumination for the instruments and the cabin.
Immediate study and direction should be given to the problems of meeting each of these requirements most effectively and economically before it becomes too difficult to standardize methods and equipment.
The authors divide the entire problem into (a) lighting requirements, (b) lighting equipment, and (c) energy supply and distribution; and each of these divisions of the subject is discussed.
Landing-lights are said to present the most difficult problem, because of the high intensity and large quantity of light required, and the stringent weight and space limitations imposed on the equipment. When tests have been made to determine what quantity and distribution of light are required, numerous other problems will face the equipment designer. Some of these are location of the units; reduction of wind resistance, vibration, weight and energy losses; accessibility; and protection against the elements.
With either a battery or a battery-generator system of energy supply, regulation of the voltage at the lamp socket to reduce to the minimum the voltage variation is important. From 40 to 50 per cent of commercial airplanes used in night flying are generator-equipped, as standard battery-equipment does not furnish sufficient current for continued use of one landing-light in bad weather for following natural landmarks between beacons. Standardization of batteries and lamps to provide a longer period of illumination for emergency landing in bad weather should not be difficult, according to the authors.
The designing of airplane landing-lamps in particular will be a greater problem than the designing of automobile lamps unless some standard of installation, wiring and operation can be worked out at the present stage of the industry. Therefore, investigation should be started at once to lead to standardization of the lighting equipment, its location, and the wiring. Recommended practice should also be established for the battery and generator systems and the sizes to be used for night flying.
The discussion emphasizes the need of ascertaining the lighting requirements of airplanes used in commercial service and of standardizing the units promptly so that manufacturers shall know what they will be expected to produce.