Fig.8. Sample instantaneous forces for various combinations of stroke deviation and tip trajectory. All other kinematic variables were constant (amplitude =180°, angle of attack =45°, flip duration =0.5, flip timing _f=-0.05). The format for each panel is that described for Fig.3 and Fig.6, except for an additional panel showing the instantaneous radial forces (green). (A) Forces generated with a large oval deviation in which the downstroke starts with upward motion and the upstroke starts with downward motion D_dev=+25°, U_dev=-25°, where D_dev is equal to the maximum angle of downstroke deviation and U_dev indicates maximum angle of upstroke deviation. Both lift and drag transients are higher at the start of the upstroke when the wing travels downwards than at the start of the downstroke. The absolute average radial forces are also correspondingly large. (B) Reversed condition compared with A, the downstroke starts with downward motion and the upstroke starts with upward motion (D_dev=-25°, U_dev=+25°). Lift and drag transients are now much larger at the start of the downstroke. (C) Forces generated with a figure-of-eight deviation in which both strokes start with upward motion (U_dev=D_dev=+25°). Both lift and drag are low at the start of each stroke, but reach elevated values at midstroke. (D) Reversed condition compared with C, both strokes start with downward motion (U_dev=D_dev=-25°). Both strokes now start with large transients in both lift and drag. (E) Forces generated by comparable kinematic pattern to those in A–D but with no stroke deviation.

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