Vibration of Crankshaft-Propeller Systems. New Method of Calculation

Abstract

The calculation of torsional oscillations in crankshaft-propeller systems is carried out by a new method which reduces con- siderably the numerical work in the case of in-line engines. The theory is briefly outlined and the reader is referred to another publication of the author for further details. Three applications follow. In the first, all six natural frequencies and the corre- sponding modes are calculated for a V-12 engine. In the second 'example the method is adapted to the direct determination of the fundamental frequency. The third example deals with a la-cylinder flat opposed engine coupled to a blower and through gears to a propeller; all eight natural frequencies are determined. The natural frequencies are determined by plotting a simple curve generally close to a straight line and the corresponding modes of oscillation in the crank are expressed in terms of a sine function. The amount of numerical work involved in the pro- cedure is independent of the number of cylinders of the engine.