The flapping flight of birds: Analysis and application

It was thought that the aerodynamics of flapping flight in birds is fully understood for quite some time, but recent studies have shown that this is not the case. Bird flight uses aerodynamic mechanisms to generate lift and thrust that differ significantly from conventional aircraft.
In slow speed situations, the aerodynamics of bird flight becomes very similar to the highly manoeuvrable flapping flight of insects: Some particular vortices develop on top of the wings while they flap through the air. These vortices (“leading-edge vortices”) enable insects and birds to generate very high and robust forces. Such forces are required for the amazing slow-speed capabilities and the excellent manoeuvrability of birds.
This thesis uses time-resolved, three-dimensional measurements of the flow around flapping model wings to determine in detail why these vortices develop and how they can be controlled.
These new insights on bird aerodynamics are very promising for an application to small unmanned aircraft: Due to the special aerodynamics of their flapping flight, birds can combine the manoeuvrability of helicopters with the efficiency of sailplanes. A prototype of a flapping wing device was developed to demonstrate that bird flight inspired unmanned aircraft have the potential for combining an exceptional manoeuvrability with outstanding aerodynamic efficiency – just like birds. Such a combination greatly enhances the applicability of small unmanned aircraft.