Because of the relatively simple kinematics of their linkage to the swashplate, the blades will be forced to change pitch as they rotate. People often mistake helicopter control as tilting the rotor disc. While this may make for simple explanation and visualization, it is more accurate to think of helicopter control as the tilting and lifting of the swashplate. Blades Originally, helicopter blades were fabricated from wood, with perhaps some aluminum bonded to them to form the aerodynamic section of a lighter material. Eventually, blade construction changed to metal spars with the aerodynamic section fabricated from metal, and later, from composites.
Current technology uses blades fabricated almost completely of composites.
The weights permit the designer to better tailor the blade's flight characteristics and control feedback forces. They also allow the blades to be balanced with respect to each other at installation on a given aircraft. The abrasion strip is often replaceable, so that the whole blade does not need to be replaced because of its most obvious sign of wear. If hydraulic powered controls are used, control force is less important, and non-symmetrical airfoils are often employed to maximize lifting efficiency. Some blades also employ twisting along their length, again to optimize lifting efficiency.