The effects of three centres

i.e. aerodynamic centre

centre of gravity and centre of torsion

of blade on fluttering have been studied. A structural model of the coupling between bending and torsion is presented in the theoretical analysis.According to their dependence of the displacements of the blade vibration

the aerodynamic loads are considered as a function of the velocities of the blade vibration. The complex eigenvalue equations are resolved by iteration approach .The conclusions drawn from the study are as follows: the blade with the forward centre of torsion is less stable than the blade with the backward one; the blade with the forward centre of gravity is more stable than the blade with the backward one. In the case of the blade with the foreward torsion centre

its stability is improved when the aerodynamic centre takes place between the gravity centre and the torsion centre. As far as the blade with backward torsion centre is concerned

the blade will be unstable when the aerodynamic centre is located between the gravity centre and the torsion centre. The analysis of these three different kinds of blades demonstrates that the blade with the aerodynamic centre located at the leading edge of the blade is the best one.