A braided composite spar or preform for a braided composite spar, comprising a plurality of tubular plies of braided fibers, wherein the spar or preform has a center line which extends lengthwise from a root to a tip, and at least part of the center line follows a curved path which does not lie in a single plane. The spar or preform can be used to provide a tubular main spar for a winglet. The winglet also has a front spar with a front spar web, an upper front spar cap, and a lower front spar cap. An upper skin of the winglet is joined to the braided spar and the upper front spar cap. A lower skin of the winglet is joined to the braided spar and the lower front spar cap.