E13 Wing beat mechanics

Topic

The mechanics of this wing-beating action model the insect's wing—specifically the wing acting as a forced torsional oscillator—upon which the insect's direct or indirect musculature exerts a specific periodic torque.

The insect's system operates preferentially near its resonant frequency; here, the elastic energy stored in the wing's cuticle and specific wing ligaments is efficiently exchanged with the wing's kinetic energy, thereby reducing the metabolic cost—defined as the difference between flight metabolism and basal metabolism.

This mechanical resonance is particularly critical in insects with indirect flight mechanisms—such as the fly—where the insect's thorax acts as an elastic resonator.

The wing's aerodynamic torque provides feedback to the oscillator's dynamics, effectively modifying the system's overall damping. A more intense aerodynamic torque results in a correspondingly greater modification of the oscillator system's damping due to this feedback. Thus, this model—featuring the forced torsional oscillator introduced at the outset—enables the insect to modulate the final amplitude of its wingbeat by varying its active muscle stiffness, without needing to alter the neural firing frequency established elsewhere in the model; this affords the insect precise control over its lift. The insect's ability to modulate the wing's active muscle stiffness with even greater precision results in a correspondingly more precise final wingbeat amplitude—again, without ever requiring a change to the neural firing frequency.

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