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Fig. 12. Drag coefficients as functions of time are plotted for five angles of
attack for an Re of 8. 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 0.00375 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.