Studying Biology & Wildlife at Salford
Dr Jamie Gundry – Teaching Fellow, Biology & Wildlife 2
Hoverfly Flight Remarkable flight control: maybe the most aerobatically gifted flying animals that have ever lived. 3
High Speed Digital Video Setup Stereo high speed digital video camera setup, silhouetting the subject to maximise light levels, and capturing 4800 images per second in each camera. 2 species: Eristalis (approx. 110mg) and Episyrphus (approx. 25 mg). 4
What Did I Find Out? 1. Wingbeat amplitude can drop by 40% in only 10 wingbeats, suggesting a decline in aerodynamic force of 60 to 65%. 2. Delaying the wing supination and pronation by 5% or 10% of a wingbeat cycle (0.25 to 0.5 milliseconds) greatly reduces vertical thrust. 3. Mixing early supinations with late pronations helps to generate considerable backwards thrust. 4. Altering the strokeplane angle shifts the forces generated by the whole wingbeat cycle forwards or backwards, with changes of 5 o having marked effects. 5. Fine control of angle of attack is remarkable, especially given flies’ main flight muscles are unresponsive to high frequency nervous stimuli. 5
What Did I Find Out? 6. If hovering using high strokeplane angle (31.3 o in this example), the fly depends on downstroke for most of its lift (i.e. 0.16 vs. 0.83 vertical force units) and uses the upstroke to exactly cancel out the backward thrust generated by the downstroke (i.e. 0.44 vs. -0.45 horizontal force units). What remarkable animals they are! 6
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