Sind elektrisch angetriebene Flugzeuge effizient und leise(r)?

Abstract

The noise of electrically driven aircraft is discussed including efficiency aspects. The presentation provides a survey over all sources of sound on aircraft and identifies those which directly or indirectly depend on the driving system of the propulsor. It is shown that little benefit may be expected by replacing conventional drive systems by electric ones. However, potential for noise benefits is seen in three concepts specific to electric drives: i) distributed propulsors, ii) non-uniform rotation, synchro phasing of propellers. Considerably noise reduction in line with a slight improvement of the efficiency is shown for distributed propellers. Noticeable benefit is projected for the use of controlled oscialltory non-uniformity of the rotation. The concept of synchrophasing (many propellers) may reduce noise in defined (and choosable) directions, while leaving noise increase elsewere, at the same time being acompanied by high system complexity.