Extremely large sweep amplitude enables high wing loading in giant hovering insects.

Area of Science:

• * Biomechanics and Insect Flight
• * Robotics and Bio-inspired Design

Background:

• * The Japanese rhinoceros beetle (Allomyrina dichotoma) is a large insect with significant hovering flight capabilities.
• * Its large wing loading presents a challenge for aerial locomotion, necessitating unique flight strategies.

Purpose of the Study:

• * To investigate the hindwing morphology and kinematics of Allomyrina dichotoma to understand its flight performance.
• * To determine the effect of hindwing sweep amplitude on the beetle's flight efficiency and power requirements.

Main Methods:

• * Measurement of hindwing morphology and kinematics in Allomyrina dichotoma.
• * Utilized the unsteady blade element model to estimate power requirements for vertical force production at various sweep amplitudes.
• * Investigated power loadings under constant vertical force, mean wing tip speed, and flapping frequency, including wing surface area effects.

Main Results:

• * Allomyrina dichotoma exhibits a large hindwing sweep amplitude (approx. 191°) at high flapping frequencies (36-41 Hz).
• * A high sweep amplitude of ~190° is more power-efficient for generating lift compared to smaller amplitudes, which require higher frequencies and incur greater inertial power.
• * The study provides insights into the biomechanical strategies enabling flight in large insects and informs the design of flapping-wing robots.

Conclusions:

• * A large hindwing sweep amplitude is a key biological strategy for Allomyrina dichotoma to achieve efficient flight despite its substantial body mass and wing loading.
• * Understanding these flight mechanics can guide the development of advanced insect-inspired aerial robots.