title: Multiple leading edge vortices of unexpected strength in freely flying hawkmoth.
abstract: The Leading Edge Vortex (LEV) is a universal mechanism enhancing lift in flying organisms. LEVs, generally illustrated as a single vortex attached to the wing throughout the downstroke, have not been studied quantitatively in freely flying insects. Previous findings are either qualitative or from flappers and tethered insects. We measure the flow above the wing of freely flying hawkmoths and find multiple simultaneous LEVs of varying strength and structure along the wingspan. At the inner wing there is a single, attached LEV, while at mid wing there are multiple LEVs, and towards the wingtip flow separates. At mid wing the LEV circulation is ~40% higher than in the wake, implying that the circulation unrelated to the LEV may reduce lift. The strong and complex LEV suggests relatively high flight power in hawmoths. The variable LEV structure may result in variable force production, influencing flight control in the animals.
authors.affiliation: Department of Biology, Lund University, Ecology building, SE-223 62 Lund, Sweden.
authors.forename: L Christoffer
authors.initials: LC
authors.lastname: Johansson
authors.forename: Sophia
authors.initials: S
authors.lastname: Engel
authors.forename: Almut
authors.initials: A
authors.lastname: Kelber
authors.forename: Marco Klein
authors.initials: MK
authors.lastname: Heerenbrink
authors.forename: Anders
authors.initials: A
authors.lastname: Hedenström
mesh_terms: D000818:Animals; D005426:Flight, Animal; D009036:Moths / Q000502:physiology*