US Patent 9488056 Propeller blade with modified spar layup

According to one embodiment, a propeller blade includes a foam core and a structural layer formed of multiple layers that surrounds at least a portion of the foam core. The structural layer includes a mid-thickness location defined between the foam core and an outer edge of the structural layer and the multiple layers include at least one unidirectional layer and at least one biased layer disposed asymmetrically about the mid-thickness location.