The Problem of Flapping Flight

Extract

It is only within the last few decades that it has been possible to conceive of a flying machine operating on the flapping system which would be consistent with mechanical principles. The development of gliding or “ wedge ” flight through the medium of the screw-propelled aeroplane has largely contributed to this result, but it must not be overlooked that as far back as 1899 Prof. Maurice Fitzgerald (Trans. Roy. Soc., Vol. LXIV., p. 420, and also (A) Vol. LXXXIII., p. 72, 1909) and Rayleigh (Manchester Lit. and Phil. Soc., Vol. XLIV., Pt. 2, No. 5, pp. 1-26—see Appendix III. hereto) enunciated certain of the most important factors of the problem. Whether the mechanical action should be the same as that of a bird is a matter for discussion, but anyway it is certain that a moving surface having a periodic vertical motion and a periodic change of “ attitude ” can efficiently produce lift and propulsion. The success of several rotary feathering lifting wheels (e.g., Clarkson's and Pichou's, concerning the latter see “ L'Aerophile,” March 1st, 1912) in producing appreciable lifts per horse-power is significant, but it is probable that the inventors have not sufficiently realised :—