Rotary‐Wing Aircraft: The Sixth Article of a Series Summarizin the Current State of knowledge Available to Purchase

ONE of the most troublesome problems associated with the development of rotary‐wing systems in which flapping hinges are utilized to compensate for the aero‐dynamic dissymmetry of forward flight has been the rotational oscillation of the blades. To accommodate the horizontal plane dissymmetry (Fig. 4, Ref. 42) due to flapping, vertical “drag hinges” are usually provided, but an alternating bending moment is produced at the blade root due partly to the displacement of the blade about its drag hinge being out of phase with the displacing moment and partly to the necessity for some form of restraint to prevent instability of the oscillating motion of the blade about this hinge.