A Method for the Stress Analysis of Helicopter Blades

The method of analysis presented herein is applicable to both fixed and hinged rotors. Although the equations developed apply directly to rectangular blades, the method may be extended to cover blades having other shapes. Up to this time, an exact general solution has been found for even the simplest form of the differential equation governing rotor bending moments, although solutions can be determined for certain combinations of constants these solutions are not general. Because of the lack of a general exact solution, various approximate methods such as series, perturbation methods, etc., were tried, but convergence was poor in most cases, necessitating the use of an unwieldy number of terms. The solution presented in this paper is based on the method of finite differences and depends on teh evaluation of a number of simultaneous linear equations. The method leads to a rapid determination of the bending moment at any point on the blade.