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Permissible Amplitudes of Torsional Vibration in Aircraft Engines
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English
Abstract
ACTUAL computation of the vibratory crankshaft stresses, although a laborious process beset with many difficulties, should offer the best chance for an intelligent evaluation of the crankshaft torsional-vibration characteristics in aircraft engines and of whether the amplitudes are dangerous or within safe limits, Mr. Masi concludes. In a discussion of the various methods used, their relative merits, and allied problems, he shows that the simple expediency of using fixed allowable amplitude limits, for certain classes of engines, determined from experience, is likely to lead to erroneous conclusions.
A novel method, which has been used on numerous engines by the Naval Bureau of Aeronautics, is suggested by Mr. Masi. It consists of determining the twist of the crankshaft with the application of rated engine torque and basing the allowable vibration amplitude on the amount of the twist. This method, he reports, lends itself to rapid routine check of a variety of engines and gives reliable data for conventional designs.
In the light of present knowledge, he concludes, propeller vibration must be considered a separate and distinct problem peculiar to each engine-propeller combination, and requires separate and individual consideration.
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Citation
Masi, F., "Permissible Amplitudes of Torsional Vibration in Aircraft Engines," SAE Technical Paper 390160, 1939, https://doi.org/10.4271/390160.Also In
References
- SAE Transactions 33 August 1938 335 341 “Torsional Vibration of In-Line Aircraft Engines,” Hazen R. M. Montieth O. V.
- “Vibration Problems in Engineering,” Timoshenko S. D. Van Nostrand Co. 1928
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- “Handbook of Aeronautics,” II Swan A. Pitman Publishing Corp. 1938
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- “Formulas for Stress and Strain,” Roark R. J. McGraw-Hill Book Co. 1938
- Zeitschrift des Vereines Deutscher Ingenieure Oct. 26 1935 1303 1306 “Zur Frage der Formziffer,” Thum A. Bautz W.
- NACA Technical Memorandum No. 743 1934 “Fatigue Strength of Airplane and Engine Materials.” Matthaes Kurt