A method that uses the added mass of vortex sheets was developed to estimat
e induced power in flapping Right for birds and insects. This new method ha
s advantages over existing methods. First, it is valid for flights with any
forward velocity. Second, this method can be used to determine the effects
of most kinematic parameters of flapping wings on induced power, like the
inclination of the stroke plane, amplitude of the flapping angle, and the m
ean flapping angle. For hovering flight this method has the same accuracy a
s methods based on the Rankine-Froude momentum theory or on vortex ring the
ory. When the forward velocity is large, this method agrees with the moment
um theory for a fixed wing.