Design considerations for D-C aircraft generators

J. E. Mulheim (nonmember; Westinghouse Electric and Manufacturing Company, Lima, Ohio.): Calculated frequency-amplitude curves such as that shown in Figure 10 of Mr. Miner´s paper serve several useful purposes. Qualitatively, they indicate the critical frequencies of the generator structure at which any appreciable excitation will produce destructive amplitudes of the various structural components. Quantitatively, in regions other than those where the structure is resonant, they can be expected to give reasonable estimates of the forces acting on the different members when used in conjunction with engine-vibration curves.¹ Their principal disadvantage is that they are not applicable in the three regions of resonance because the effects of damping are not considered. The calculations required to incorporate the effects of damping are very arduous. However, it is possible to determine the more or less exact shape of such curvesby an electrical-analogy method.²