Higher-voltage D-C aircraft electric systems

CURRENT discussion of large aircraft electric systems has been carried on mainly in terms of commercial power distribution experience. There has been a tendency in such discussions to make blanket statements concerning the superiority of a-c systems without due consideration of direct current or aircraft-design requirements. Extrapolation of commercial practice and experience out of the field of its origin into aircraft design remains to be proved. The airplane presents a very special electrical design problem. Only when a-c systems are applied to actual aircraft designs, and after a careful competitive check made of both a-c and d-c results, are valid conclusions possible. A few facts learned from one such study on an actual airplane will be presented in this paper.