An airfoil assembly (200) comprising: a central spar (202) extending along the first direction (R); a blade skin (210) positioned around the central spar (202) to define an airfoil (212) that has a pressure side (214) and a suction side (216) extending in the second direction (A) between a leading edge (218) and a trailing edge (220), wherein at least one cavity (230) is defined between the blade skin (210) and the central spar (202); and a support structure (232) positioned at least partially within the at least one cavity (230), the support structure (232) comprising: a foam (240); and a foam reinforcement structure (242) embedded within the foam (240).