Lightweight propulsor blade with internal spars and rigid base members

A propulsor blade comprising:

• a. an external shell having a leading edge, a trailing edge, a tip end, a root end, a first airfoil pressure surface extending on one side of the blade in a chordwise direction between the leading edge and the trailing edge and in a spanwise direction between the tip end and the root end, and a second airfoil suction surface extending on the other side of the blade in a chordwise direction between the leading edge and the trailing edge and in a spanwise direction between the tip end and the root end, each of said airfoil surfaces having an interior surface enveloping a hollow interior cavity defined within said shell;
• b. a load bearing spar extending from a tip end disposed within the hollow interior cavity of said shell in a spanwise direction to a root end adapted for mounting to a blade retention means, said spar having at least a forward spanwisely elongated torsion box member and a rearward spanwisely elongated torsion box member spaced chordwisely aft of said forward torsion box member, a leading edge chordwise shear web projecting chordwisely forward from said forward torsion box member, a trailing edge shear web projecting chordwisely aft from said rearward torsion box member, and an intermediate chordwise shear web disposed between said forward and rearward torsion box members, each of said forward and rearward torsion box members defining a hollow internal cavity portion within said spar and having spanwisely extending side portions bonded to the interior surfaces of said shell;
• and
• c. a rigid base member disposed within the root portion of said spar and filling the hollow internal cavity portions defined within said spar.