AIRFOIL WITH RADIALLY-SPACED RIBS AND INTERLOCKING TABS, AND GAS TURBINE ENGINE

An airfoil (60) incudes an airfoil section (64) that defines an internal cavity (70). The airfoil section (64) is formed of a fiber-reinforced composite (62) that is comprised of fiber plies (72). The fiber plies (72) include core fiber plies (74/76) and an overwrap fiber ply (78) that wraps around the core fiber plies (74/76). The core fiber plies (74/76) are arranged as first and second tubes (80/82). each of the first and second tubes (80/82) defines a plurality of windows (80a/82a) therein. The windows (80a) of the first tube (80) align with the windows (82a) of the second tube (82) so as to form radially-spaced ribs (84) that extend across the internal cavity (70). At least one of the first or second tubes (80/82) has at least one tab (86) that is radially between the radially-spaced ribs (84). The at least one tab (86) interlocks the first and second tubes (80/82).