DTIC AD0772569: CH-53A Flexible Frame Vibration Analysis/Test Correlation

by: Defense Technical Information Center

Publication date: 1973-03-28

Topics: DTIC Archive, Keningsberg, Irwin J, UNITED TECHNOLOGIES CORP STRATFORD CT SIKORSKY AIRCRAFT DIV, *HELICOPTERS, *AIRFRAMES, MATHEMATICAL MODELS, VIBRATION, SHAKING, FUSELAGES, DEGREES OF FREEDOM, RESONANT FREQUENCY,

Collection: dticarchive; additional_collections

Language: English

The Sikorsky Finite Element Airframe Vibration Analysis (Fran/Vibration Analysis) has been found to correlate well with data taken in shake tests of the CH-53A. The frequencies of fundamental fuselage bending and transmission modes were predicted by the FRAN/Vibration Analyses to an average accuracy of three percent. In addition, the mode shapes were defined accurately. The modeling techniques and analysis used in the study can be applied during helicopter design and during evaluation of growth versions of current aircraft. These techniques, in combination with an accurate definition of the vehicle's structural characteristics, will enable accurate prediction of all transmission and fuselage modes for a vehicle without a cargo ramp.