Hawkmoth flight performance in tornado-like whirlwind vortices

Area of Science:

• Aerospace Engineering
• Animal Flight Dynamics
• Fluid Dynamics

Background:

• Tornadoes and vertical vortex systems significantly impact aircraft stability.
• The effects of smaller-scale vortices on the flight control of animals and micro-air vehicles remain largely unexplored.

Purpose of the Study:

• To investigate the flapping kinematics and body dynamics of hawkmoths in controlled whirlwind environments.
• To understand how hawkmoths achieve flight control and stability when exposed to varying intensities of vertical vortex systems.

Main Methods:

• Hawkmoths were observed during hovering flights and while maintaining position within a vortex chamber generating three distinct whirlwind intensities (0.7, 0.9, and 1.2 m/s).
• Key parameters such as flapping frequency, wingbeat amplitude, stroke plane angle, angle of attack, yaw, pitch, and roll were measured and analyzed.

Main Results:

• Yaw and pitch variability increased, while their average values decreased in whirlwinds compared to normal hovering.
• Wingbeat amplitude decreased, and the stroke plane angle increased.
• Significant asymmetry in the angle of attack between wings was observed at medium and high vortex intensities.

Conclusions:

• Hawkmoths employ a combination of symmetric and asymmetric adjustments in wing kinematics to maintain flight control within tornado-like vortices.
• Changes in wingbeat amplitude, stroke plane angle, and particularly angle of attack are crucial for stabilizing flight in turbulent vortex conditions.