EXPERIMENTAL RESEARCH ON HELICOPTER TAIL SHAKE PHENOMENON

Abstract

Helicopter tail shake phenomenon is still remained as a long dragged issue that adversely affected the overall performance, occupants’ comfort and handling qualities of helicopter. The objective of this research is to improve basic understanding of the viscous unsteady flow phenomenon observed behind the helicopter tail part. For this, a wind tunnel test had been conducted with a rigid 14% generic model of Eurocopter 350Z helicopter in the Universiti Teknologi Malaysia- Low Speed Tunnel (UTM-LST) with a test section size of 2m x 1.5m x 5.8m and 288 km/hr maximum test wind speed. The model, supplied by Eurocopter France, is equipped with a motor that can rotate the main rotor up to 900 rpm during wind-on condition. As the induced wake, which consequently causing tail to shake, differs with angle of attack and yaw angle, the wind tunnel test was performed in a range angle of -10o to +10o , respectively. The selected test wind speed was 40 m/s, which corresponds to a Reynolds number of 3.7 x 106 . To investigate the characteristics of the induced wake, velocity fluctuation mapping using hotwire was done at 3 different planes behind the model with each plane consists of 4 measurement points. Results obtained later depict some interesting facts of this wake phenomenon.