Radio in the Air

Radio Record, Volume IV, Issue 48, 12 June 1931, Page 18

Radio in the Air

Ensuring Safety of Travellers

ERHAPS the most important aid in the safety of air travel is the modern radio outfit with which the aeroplane is equipped. Indeed, "just as wireless has ensured the safety of ships at sea, so it is now safeguarding planes in the air. We have become so accustomed to the use of radio for all manner of communication that we may not perhaps realise that each application of radio communication has its own peculiar difficulties, and this is especially so in the case of radio communica-

tion between an aeroplane and the ground or between one aeroplane and another. Probably the most comprehensive radio equipment carried on commercial] aeroplanes at the present day is that fitted to each plane flying over the famous air routes between Chicago, Oakland and San Francisco and between Seattle and Los Angeles. The Boeing Company, which controls these services, has carried out over a number of years its own special radio experiments and has developed an aeroplane radio equipment which meets all the requirements of these particular routes. The Pilot’s Enemy. prLots on these routes can now carry on direct conversation with ground operators from an altitude up to 12,000 feet and at a distance of 200 miles. Ground stations for transmission and reception have been established at every 100 miles along the routes and in this way all pilots are kept constantly informed as to weather conditions and other’ matters of importance. Bveryone knows that bad weather is the great enemy of the aeroplane pilot; in fact it is now alniost his only serious enemy. ‘The pilot’s task is made much simpler, however, if he can be kept constantly informed of weather conditions ahead of him and be given precise instructions with regard to the position of the landing ground, and how he is to make his landing. All this and much more is now posgible by means of the very much simplified radio equipment available for aeroplanes. The equipment used in the machines, on the routes mentioned above, weighs about 100 pounds and is practically automatic in operation; it requires no adjustment on the part of the pilot, whose full attention therefore may be given to the flying of the machine. Before the final form of the radio equipment was settled, a large number of experiments were carried out in order to determine the most suitable wavelength; eventually it was found that a wavelength of 90 metres was suitable for all required altitudes and also for day and night operations. Some Special Problems. Sosua of the special technical problems encountered are extremely interesting. It is found necessary, for instance, to "bound" the aeroplane completely; that is, to connect electrically together all metallic parts. The bonding of the aeroplane is necessary not only in order to reduce interference, but also to prevent the possibility of the aeroplane catching fire, since an insulated piece of metal, if of proper size and character and in a certain position, may pick up a sufficient electrical charge to produce sparks. The ignition of the aeroplane engine must be very carefully shielded, otherwise the interference from it will render radio communication impossible. {ff you were to listen with a radio receiver in an aeroplane, in which the motor had not been properly shielded.

all you would hear would be a eo storm of crashes, these, of cours. originating at the make-and-break cor}. tacts in the distributor, from the magneto and from the actual sparks in the sparking plugs. This type of interference is overcome by encasis all the spark leads in flexible copper armour, and even this apparently simple operation must be earried out in such a way as not ta interfere with the efficient working of the motor and of the aeroplane. In the equipment used on the abovementioned routes the radio apparatus is mounted behind the pilot.