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Permissible Amplitudes of Torsional Vibration in Aircraft Engines
ISSN: 0148-7191, e-ISSN: 2688-3627
Published January 01, 1939 by SAE International in United States
Annotation ability available
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.
CitationMasi, F., "Permissible Amplitudes of Torsional Vibration in Aircraft Engines," SAE Technical Paper 390160, 1939, https://doi.org/10.4271/390160.
- See SAE Transactions, Vol. 33, August, 1938, pp. 335-341: “Torsional Vibration of In-Line Aircraft Engines,” By Hazen R. M. and Montieth O. V..
- See “Vibration Problems in Engineering,” by Timoshenko S., D. Van Nostrand Co., 1928.
- See “Strength of Materials,” Vols. I and II, by Timoshenko S., D. Van Nostrand Co., 1930.
- See Air Service Information Circular No. 421, April 1, 1923: “Standard Method of Engine Calculations.”
- See “Handbook of Aeronautics,” Vol. II, by Swan A., Pitman Publishing Corp., 1938.
- See “The Fatigue of Metals,” by Moore H. F. and Kommers J. B., McGraw-Hill Book Co., 1927.
- See SAE Transactions, Vol. 30, November, 1935, pp. 412-418, 421: “An Analysis of Critical Stresses in Aircraft-Engine Parts,” by Taylor C. F..
- See “Formulas for Stress and Strain,” by Roark R. J., McGraw-Hill Book Co., 1938.
- See Zeitschrift des Vereines Deutscher Ingenieure, Oct. 26, 1935, pp. 1303-1306: “Zur Frage der Formziffer,” by Thum A. and Bautz W..
- See NACA Technical Memorandum No. 743, 1934: “Fatigue Strength of Airplane and Engine Materials.” by Matthaes Kurt.