TABLE OF CONTENTS As lifting devices go, rotary wings differ considerably from conventional fixed wings. Basically, rotary wings are devoid of the various cutouts associated with fixed wings and are principally designed to take the attendant tension loads and to have favorable frequency placements. Beyond these issues, the analysis of rotorcraft stability issues is seen to be highly dependent on the interactions of the blade kinematics and the resulting coupled blade responses. At the basic level, the calculation of blade stiffness and mass distributions is mandatory. Also, even for blades constructed of conventional (isotropic) materials we need to know where the various elastomechanical points of interest (e.g., mass center, shear center) are located on the blade sections. Finally, with the introduction of composite construction, additional couplings accruing from anisotropic properties become available, which are either detrimental or to be exploited for aeroelastic response enhancement. This chapter addresses all of these issues with a special emphasis on the use of composite material construction. In most of what is presented, the use of conventional (isotropic) materials can be considered as a special case of composites.
With the current availability of quality finite element tools, the temptation to restrict one's efforts solely to their use is quite persuasive. However, blind use of only one tool is often a prescription for a failed or, on a more positive note, a more expensive design. The material we will examine serves two functions: first, it will provide useful first cuts at any new blade design to identify...
