Fig. 3. Performance of theoretical wings generated with the five shape equations versus the proportion of area in the outer one-fifth of the wing. Each point represents the performance of one theoretical wing shape. The area of each wing tested is 0.0069m² (multiplied by 2 to give the total performance of an animal). U=0.15ms^-1, c=0.3ms^-1, H=0.058m and f=2.27s^-1. Wing area was fixed, and span was adjusted to create wings with the four specified aspect ratios (AR). (A) Thrust versus the proportion of area in the outer one-fifth of the wing. (B) Efficiency versus the proportion of area in the outer one-fifth of the wing. U, velocity; c, wave speed; H, fin tip amplitude; f, flapping frequency; l_avg, average chord length.