K.H. Heron

This paper describes an experimental method for the identification of the structure-borne path by which the vibrational energy from a helicopter gearbox is transmitted to the cabin. The method involves taking detailed measurements of the gearbox/cabin interface vibration field as well as of the internal noise field; typically 24 accelerometers and 12 microphones are used. The method also involves calculating the statistical accuracy of the various predictions and thus being able to display the results as confidence intervals. In many ways this statistical approach is vital since it is necessary to know the quality of any result as well as its numerical value. The heart of the method lies in the way these statistical results are calculated as well as the way statistical confidence tests are used to drive and steer the necessary data fitting processes. This paper also describes the results from a full scale laboratory validation trial using a grounded Lynx helicopter. A series of known "flight" conditions were measured and then the method applied. The known results were indeed reproduced; and furthermore the statistics were validated in the sense that a 90% confidence interval for a given result was indeed wrong about 10% of the time! The method can now be considered to be an engineering tool of proven quality, able to accurately diagnose and quantitatively identify the different paths.

17th European Rotorcraft Forum 1991, Berlin

Conference Paper

englisch

21,0 x 29,7 cm, 12 Seiten

DGLR-Bericht, 1991, 1991-08, 17th European Rotorcraft Forum Proceedings; S.495-506; 1991; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

helicopters, vibration, gearbox

Bestellbar

1991