Fig. 4. Lift (A) and drag (B) coefficients for four sinusoidal strokes. The green lines show the results of the immersed boundary simulation, the blue lines represent numerical data for a two-dimensional elliptic wing (Wang et al., 2004), and the red lines describe the experimental data for a three-dimensional model wing (Wang et al., 2004). In all cases, the leading edge vortex did not appear to separate during translation. The wing in each case flaps in a sinusoidal motion with =0, ß=/2, and A_o/c=2.8, as defined in Eqns 17 and 18, at Re=75. This represents a 2.8 chord translation and a minimum angle of attack of 45°.