Fig. 8. Lateral view of a dove at the beginning of the downstroke in slow flight (1 m s^-1) with vectors showing the components of the induced velocity calculation (equation 3). The vertical induced airflow (W_iv) is calculated from equation 3, incident airflow (W_k+V_e) is measured via kinematics and wind-tunnel velocity, and horizontal induced airflow (W_ih) is calculated from W_ih=W_ivtan(/2-). Note that the vectors shown are not precisely to scale and that W_k acts opposite to the direction of wing motion. W_k, airflow generated by wing motion; V_e, effective wind-tunnel airflow; W_iv, vertical induced airflow (equation 3); W_it, total induced airflow perpendicular to W_k+V_e; W_ih, horizontal induced airflow; , angle between W_iv and W_k+V_e.