A wing box having an outboard section and a center section, the wing box comprising: a composite skin; outboard planked stringers that are laterally oriented within the outboard section and are co-cured with the composite skin at the outboard section; and center planked stringers that are laterally oriented within the center section and are co-cured with composite skin at the center section, wherein: each outboard planked stringer has a quadrilateral cross section and includes planar layers of Carbon Fiber Reinforced Polymer (CFRP) that are parallel with the composite skin at the outboard section, have fiber orientations aligned to bear tension and compression applied to the wing box, and each extend a different distance along the composite skin at the outboard section towards the center section of the wing box so that neighboring planar layers of the outboard planked stringer each extend further towards the center section, and some layers of the composite skin extend different lengths along the outboard planked stringer in order to account for the increase in thickness caused by overlapping layers of the outboard planked stringer, without substantially increasing the thickness of the composite skin and the outboard planked stringer; and each center planked stringer includes planar layers of CFRP that are parallel with the composite skin at the center section, have fiber orientations aligned to bear tension and compression applied to the wing box, and each extend a different distance along the composite skin at the center section towards the outboard section, and some layers of the composite skin extend different lengths along the center planked stringer in order to account for the increase in thickness caused by overlapping layers of the center planked stringer, without substantially increasing the thickness of the composite skin and the center planked stringer. a composite skin; outboard planked stringers that are laterally oriented within the outboard section and are co-cured with the composite skin at the outboard section; and center planked stringers that are laterally oriented within the center section and are co-cured with composite skin at the center section, each outboard planked stringer has a quadrilateral cross section and includes planar layers of Carbon Fiber Reinforced Polymer (CFRP) that are parallel with the composite skin at the outboard section, have fiber orientations aligned to bear tension and compression applied to the wing box, and each extend a different distance along the composite skin at the outboard section towards the center section of the wing box so that neighboring planar layers of the outboard planked stringer each extend further towards the center section, and some layers of the composite skin extend different lengths along the outboard planked stringer in order to account for the increase in thickness caused by overlapping layers of the outboard planked stringer, without substantially increasing the thickness of the composite skin and the outboard planked stringer; and each center planked stringer includes planar layers of CFRP that are parallel with the composite skin at the center section, have fiber orientations aligned to bear tension and compression applied to the wing box, and each extend a different distance along the composite skin at the center section towards the outboard section, and some layers of the composite skin extend different lengths along the center planked stringer in order to account for the increase in thickness caused by overlapping layers of the center planked stringer, without substantially increasing the thickness of the composite skin and the center planked stringer.