The structural finite element modelling and the finite element analysis of linear buckling characteristics of the composite by pass duct case of aeroengine are carried out.

The shroud at high speed is modeled as an elliptic wing in order to construct a momentum theory method to investigate the aerodynamic characteristics of ducted tail rotor in hover and forward flight.

Then the equation of helicopter pendulum is derived from the nonlinear differential equation and linear differential equation, with the principle of helicopter aerodynamics.