Unconventional lift-generating mechanisms in free-flying butterflies

• Published in: Nature (London) Vol. 420; no. 6916; pp. 660 - 664
• Main Authors: Thomas, A. L. R, Srygley, R. B
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 12.12.2002; Nature Publishing Group
• Subjects: Aerodynamics; Air flow; Air Movements; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Autoecology; Biological and medical sciences; Butterflies & moths; Butterflies - physiology; Flight, Animal - physiology; Flowers; Fundamental and applied biological sciences. Psychology; Insects; Protozoa. Invertebrata; Smoke; Vanessa atalanta; Wind tunnels; Wings, Animal - physiology; Arthropoda; Insecta; Flight; Lepidoptera; Aerodynamics; Invertebrata; Experimental study; Mechanism of action
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature01223

Flying insects generate forces that are too large to be accounted for by conventional steady-state aerodynamics. To investigate these mechanisms of force generation, we trained red admiral butterflies, Vanessa atalanta, to fly freely to and from artificial flowers in a wind tunnel, and used high-resolution, smoke-wire flow visualizations to obtain qualitative, high-speed digital images of the air flow around their wings. The images show that free-flying butterflies use a variety of unconventional aerodynamic mechanisms to generate force: wake capture, two different types of leading-edge vortex, active and inactive upstrokes, in addition to the use of rotational mechanisms and the Weis-Fogh 'clap-and-fling' mechanism. Free-flying butterflies often used different aerodynamic mechanisms in successive strokes. There seems to be no one 'key' to insect flight, instead insects rely on a wide array of aerodynamic mechanisms to take off, manoeuvre, maintain steady flight, and for landing.