Patent ID: 7682682

Claim:
A stiffened composite aircraft panel with at least one stiffener secured thereto, the stiffener comprising: a longitudinal core having a first longitudinal edge directly secured to an outer base skin of the composite aircraft panel substantially along an entirety of the first longitudinal edge, an opposed second edge having a height with respect to the first edge, and opposed side surfaces extending between said first edge and said second edge substantially along an entirety of the core, said core having two opposed longitudinal end portions wherein the longitudinal end portions form longitudinal stiffener stops of the stiffener, wherein at least one of said longitudinal stiffener stops comprises first and second slopes separated by a plateau, said first slope starting at the second edge at a first height and descending to a first intermediate point on the second edge at a second height less than the first height, the plateau extending from the first intermediate point to a second intermediate point on the second edge, and the second slope descending from the second intermediate point to the base skin.