Sikorsky Aircraft Corporation

Jacob A Fehrman

Francis E Byrnes

A composite spar for a helicopter blade includes two or more layers of unidirectional laminate material. One or more upper plies of bi-directional laminate extend from an upper airfoil portion of the spar disposed between adjacent layers of the two or more layers of unidirectional laminate material. One or more lower plies of bi-directional laminate material extend from a lower airfoil portion of the spar disposed between adjacent layers of the two or more layers of unidirectional material. The upper plies and the lower plies overlap defining a crackstopper layer configured to prevent propagation of defects in the spar.

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Lexington, KY, United States of America

Jacob A Fehrman