Abstract:
This report is based upon the first application of the torsiograph described in Reference I, the observations being made in the course of development of the instrument. Subsequent applications have been to Merlin 61 and Sabre engines, with results which are given elsewhere. The torsiograph pick-up unit was fixed into the pinion-driving shaft of a Merlin II engine on a hangar test-bed and records were obtained at various crankshaft speeds from 900 r.p.m. to 3,000 r.p.m., and with blade settings ; 16.5 deg., 20.5 deg., 22.5 deg., 25.5 deg. and 29 deg., measured from tile propeller disc at 42 inches from the shaft axis. The observed cyclical torque oscillations have been analysed into harmonic components and the causes of the corresponding modes of vibration are examined in the report. To assist this examination, some vibrograph observations were made and also a mathematical analysis, which is given in the Appendix.
