Fig. 5. Performance of theoretical wings at varying flapping frequencies with S_p=0.0069m², U=0.15ms^-1, c=0.3ms^-1 and H=0.058m. All wings were generated with first-degree polynomials. (A,B) Thrust and efficiency versus average chord length for triangular wings that have 4% of the wing area in the outer one-fifth of the wing. (C,D) Thrust and efficiency versus average chord length for wings that have 12% of the wing area in the outer one-fifth of the wing. (E,F) Thrust and efficiency versus average chord length for rectangular wings that have 20% of the wing area in the outer one-fifth of the wing. S_p, total area of one pectoral fin; U, velocity; c, wave speed; H, fin tip amplitude; f, flapping frequency.