Fig.3. Sample instantaneous forces for various combinations of total stroke amplitude and mid-stroke angle of attack . In each case, the wing rotation parameters were kept constant (flip duration =0.16, flip start ₀=-0.08, flip timing _f=0). Each panel (A–H) shows a plot of measured drag (solid red line), the quasi-steady estimate of drag (broken red line), measured lift (solid blue line) and the quasi-steady lift (broken blue line). Since the radial forces were zero for all these kinematic patterns, they are not plotted. A two-dimensional diagram of the wing kinematics is plotted above each set of traces using the convention described in Fig.1C. The wing chord is shown in light blue, and the superimposed black vector indicates the magnitude and direction of the instantaneous aerodynamic force. For convenience, the kinematic values of stroke amplitude and angle of attack used in each trial are printed in the upper left of each panel. Values for the measured mean force coefficients (_D and _L) are printed adjacent to each set of traces. Axis labels given in A apply to all panels. (A,B) Forces generated at a 90° angle of attack with no wing rotation (=90°) for a short stroke amplitude (A, =60°) and a long stroke amplitude (B, =180°). Note the enormous transients in drag at the start of each stroke due to wake capture. (C,D) Forces generated at a 50° angle of attack for a short stroke amplitude (C, =60°) and a long stroke amplitude (D, =180°). The contribution of rotational circulation is apparent at the end of each stroke. (E,F) Forces generated at a 30° angle of attack for a short stroke amplitude (D, =60°) and a long stroke amplitude (F, =180°). (G,H) Forces generated at a 0° angle of attack for a short stroke amplitude (G, =60°) and a long stroke amplitude (H, =180°).