Month in the Patent Office Available to Purchase

A biplane comprises upper and lower wings of substantially the same span and so arranged that the gap decreases to a relatively small value from the plane of symmetry toward the wing tips and that the trailing edge of the upper wing at its tip, viewed in plan, is located adjacent to the leading edge of the lower wing. Figs. 1 and 2 show an upper wing 1 with a straight leading edge and forwardly swept trailing edges 3 and a lower wing 5 of constant chord with forwardly swept leading and trailing edges, the planes being staggered so that the trailing edges of the upper wing at the tips are located slightly in advance of the leading edges of the lower wing. The two halves of the lower wing are given a positive dihedral and the upper wing may have a negative dihedral or a positive dihedral angle less than that of the lower wing. The lower wing may be tapered and may alternatively be formed with a sweep back or be without sweep in either direction. Ailerons 8 are fitted to the lower wing. According to the Provisional Specification the invention may be applied to multiplanes and the tips of the upper wing may be hinged about a transverse axis, a shield being optionally associated with the hinged part.