Aircraft Electric Power-Supply System

An ever increasing demand for electric power in aircraft has been felt for some time. The necessity of using an electric storage battery started the practice of accompanying it with a d-c generator, first of low current and voltage capacity, later of 50-ampere 12-volt rating, and for the past few years of 200-ampere 24-volt output. In the largest four-engine aircraft, even four generators of maximum capacity do not furnish ample electric energy. Experiments have proved so far that generation of a-c power and application of lightweight transformers, together with its conversion to direct current by means of selenium rectifiers, is entirely a reliable and practical way of attaining large, trouble-free electric plant capacity in aircraft. The subsequent pages and illustrations portray the current progress made with lightweight power transformers and rectifiers in the a-c-d-c aircraft systems. They also represent at least a partial answer to the questions raised by Lieutenant Colonel Holliday¹ when he discussed problems of applications of electric power in aircraft two years ago.