That is, do it by means of the thoughts in solving statically indeterminate problems.

In this paper, the stability of compressive rod and structure (statically indeterminate structure) is analyzed.

By using the boundary conditions of the statically indeterminate shaft with three fulcrums,the deflection curve square of the shaft is got;By utilizing the energy method to improve the calculation formula, the accurate first order critical speed of the statically indeterminate shaft with three fulcrums is obtained quickly.

Compared with general aeroplane,tailless aeroplane has static instability in longitudinal mode.

With introducing the ACT to overall design of an Air to Air Missile(AAM), this thesis analyses the capability improving of the AAM because of using the RRS design, and sets forward the stability criteria for static instability missile body.

The active control technology(ACT) which had been used widely in the field of plane design is introduced to overall design of air to air missiles, and the judge criterion of stability for static instability missile body is brought forward.

After a thorough investigation of the bifurcation behaviors of the nonlinear model of an inherently static unsteady aircraft at high angles of attack,eigenstructure assignment was applied to design the longitudinal control law and gain scheduled lateral control law.

Bifurcation Analysis and Catastrophe Theory Method (BACTM) was applied to a nonlinear dynamics model of an inherently static unsteady aircraft to calculate the equilibrium curve while regular control surfaces deflected.