For the harmonic analysis of periodic curves, machines as well as numerical methods are available. The machines are expensive and not generally available, and time is required to learn their operation. Therefore, an occasional analysis of a curve consumes even less time by the numerical method than by the machine. The best known numerical method is that of Runge (1) described in many places; a good account is found in Scarborough’s book (2). The principle is clear, but writers usually give the method for 6, 12, or 24 ordinates for the sake of simplicity, which is not sufficiently accurate for most applications. In this paper the 48-ordinate scheme is fully given in Tables 1, 2, and 3.
For the analysis of torsional vibrations the harmonic content of the torque curve of the disturbing engine is required. Such analyses have been published for the four-cycle Diesel engine (3) and for the four-cycle gasoline engine for aviation purposes (4). But to the author’s knowledge none have been published for the two-cycle Diesel engine. Such a spectrum is given herein.