11 November 2011
Hovering in a whiteye
A research team based in Taiwan has published a new PIV-study on the hovering aerodynamics in hovering Zosterops japonicus, which birdwatchers know as whiteyes. These 6-7 g birds are capable of hovering, i.e. flying at zero forward speed, which was studied in a special hovering chamber. Wing kinematics and induced vortex flows were monitored, which uncovered a new mechanism for enhancing lift force in hovering in birds - a ventral clap-and-fling. This mechanism is known from some insects already since the dane Torkel Weis-Fogh's pioneering work, but had not been observed in birds before. Interestingly some of the high-lift mechanism previously known from insect flight are now being observed in birds and bats, mainly due to the application of the PIV-technique to animal flight. We, the Lund crew, are happy to see this approach spreading to other labs studying animal flight. The paper can be found in Experiments in Fluids.