Fig. 10. Principle of the Willoughby Delta design.

CROSS-SECTION

Diagram showing different aerofoil shapes and aspect ratios (A.R.).

Fig. 3. A simple experiment in annular aerofoils.

Fig. 4. Principle of the Huth annular-biplane system.

Fig. 6. Huth annular biplane of 1909.

Fig. 7.-Cedric Lee Monoplane No. 1 of Tilghman Richards, 1912.

Fig. 8. Project by Warren and Young for a light twin-engined two-seater of 90 h.p. (1937). The elevator is fitted between fin and fuselage. There is no tailplane.

Fig. 9. Model of the "annular wing" of Antes, 1933.