DESIGN AND TEST EVALUATION OF A SUPERCRITICAL SPEED SHAFT
BOEING CO MORTON PA VERTOL DIV
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The report describes the research, evaluation, experimental procedures, and conclusions from a study of the feasibility of the use of a supercritical speed interconnecting shaft in helicopters and other aircraft that require interconnecting drive shafts. The program was centered around the design, construction, and test of a full-scale supercritical speed shaft with dimensions compatible with the Boeing-Vertol CH-47A helicopter. Particular emphasis was placed on the design and development of suitable dampers for supercritical speed shaft installations, and on the development of shaft balancing procedures suitable for production application. The test shaft was operated successfully through a speed range from 0 to 9500 revolutions per minute, and subsequent analysis showed that the supercritical speed shaft offers a number of advantages over the subcritical speed shafts that are now used. All methods, procedures, and results are thoroughly documented with substantiating data, and firm conclusions and recommendations are presented. Four mathematical appendixes are provided.