Fig. 11. Drag coefficients as functions of time are plotted for five angles of attack for an Re of 128. For each simulation, the same angle of attack was used on the downstroke and upstroke. The angles of attack for the five simulations were 10°, 20°; 30°; 40° and 50°. The maximum translational velocity of the wing was 0.06 m s^-1. Drag coefficients increase with increasing angle of attack. Maximum drag forces occur during acceleration from rest at the beginning of the stroke and during rotation at the end of the downstroke and at the beginning of the upstroke. Drag forces are larger during rotation at lower angles of attack because the distance over which the wing moves and its angular velocity are larger.