ABSTRACT
Consider a four-bladed rotor system supported on a platform (Figure 11.1), which can have longitudinal and lateral translational perturbation motions.
The blades are assumed to have only lag motion. The mass of the platform is MF; the stiffness along the x-direction is Kx and along the y-direction is Ky; and the damping along x,y directions, assumed to be of viscous type, are Cx and Cy, respectively. The rotor blade can be idealized as a uniform rigid blade having a root offset with a root spring Kς and a root damper Cς, as shown in Figure 11.2. Following the mathematical procedure given in section on
Isolated Lag Dynamics in Chapter 6 and using hub translational motions in longitudinal and lateral directions, the equations of motion of the coupled rotor lag and fuselage dynamics can be derived.
