Storyboard

Beat kinematics describe the geometry of wing motion: how the position, speed, and orientation of each point on the wing changes throughout the beat cycle. It is the module that explains how the oscillatory movement of the wing driven by the muscles (E4) through the kinematics of the bone chain (E3) simultaneously generates lift (to support the weight) and thrust (to advance against drag).

The dimensionless Strouhal parameter (St = f·A/V) is the key to the propulsive efficiency of churning: swimming and flying animals tend to operate in the range St = 0.2-0.4 where the conversion efficiency of muscle power into propulsive force is maximum. This convergence in the Strouhal number between dolphins, tunas, butterflies, hummingbirds and seagulls is one of the most surprising results of comparative biomechanics.



Central physical principle: Wing tip speed has two components: the forward speed V_flight (horizontal) and the beating speed v_tip = 2f·A (vertical). The resulting velocity vector has an angle with respect to the horizontal. The aerodynamic force is perpendicular to this vector it has both vertical (lift) and horizontal (thrust) components. The feather pronation angle (E2) optimizes the direction of the resulting force to maximize thrust.

>Model

ID:('ky', 288)

Description

ID:(0, 288)