Wing-kinematics measurement and aerodynamics in a small insect in hovering flight.

ABSTRACT: Wing-motion of hovering small fly Liriomyza sativae was measured using high-speed video and flows of the wings calculated numerically. The fly used high wingbeat frequency (?265?Hz) and large stroke amplitude (?182°); therefore, even if its wing-length (R) was small (R???1.4?mm), the mean velocity of wing reached ?1.5?m/s, the same as that of an average-size insect (R???3?mm). But the Reynolds number (Re) of wing was still low (?40), owing to the small wing-size. In increasing the stroke amplitude, the outer parts of the wings had a "clap and fling" motion. The mean-lift coefficient was high, ?1.85, several times larger than that of a cruising airplane. The partial "clap and fling" motion increased the lift by ?7%, compared with the case of no aerodynamic interaction between the wings. The fly mainly used the delayed stall mechanism to generate the high-lift. The lift-to-drag ratio is only 0.7 (for larger insects, Re being about 100 or higher, the ratio is 1-1.2); that is, although the small fly can produce enough lift to support its weight, it needs to overcome a larger drag to do so.

SUBMITTER: Cheng X 

PROVIDER: S-EPMC4863373 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature