Abstract: A foldable, multisectional air foil with apparatus enabling it to fold or curl up or down about the body of a craft; and to a system to maintain air foil rigidity during flight. This system includes three separate assemblages which may be used in combination: sliding spar, continuous strap and cable pressure. The former includes apparatus for a sliding segmented spar within a segmented spar built into the air foil sections, which allows the air foil to fold when the joints of both spars are aligned yet provides sufficient rigidity when said joints are offset. The continuous strap assemblage provides for the air foil to be encircled by continuous yet segmented straps, each section of which contains hinging and locking mechanisms allowing the air foil sections to fold and unfold yet which--when locked into place as a continuous strap--provide structural strength to the air foil whole.