US Patent 10407159 Reinforced blade and spar

A spar for a propeller blade comprises central structural member extending from a root to a tip of the spar. A first portion of the central structural member extends from the root of the spar and a second portion extends from the tip and adjoins the first portion. The central structural member includes a first plurality of plies of composite material on a pressure side thereof and a second plurality of plies of composite material on a suction side thereof wherein the first plurality of plies are in contact with the second plurality of plies in the second portion from a leading edge to a trailing edge thereof. A plurality of yarns extends through the central structural member in at least the second portion.