THE APPLICATION OF A THEORETICAL BLADE SAILING MODEL TO PREDICT THE BEHAVIOR OF ARTICULATED HELICOPTER ROTORS

A theoretical model had been previously developed to predict the behaviour of a semi-rigid helicopter rotor blade during rotor engagement and disengagement under high wind conditions. This has now been extended to cater for an articulated rotor by modelling the droop and anti-flap stop mechanisms by high rate linear springs. Much increased blade deflections are predicted, as anticipated, along with the possibility of blade tip/tail boom contact at a high enough wind speed. The importance of the higher modes in the description of the phenomenon is demonstrated. A comparison ot the theoretical model with an experiment using a full size Puma aircraft is presented.