Data from: Efficiency of lift production in flapping and gliding flight of swifts ...

• Main Authors: Henningsson, Per, Hedenström, Anders, Bomphrey, Richard J.
• Format: Dataset
• Language: English
• Published: Dryad 2015
• Subjects: gliding; efficiency; Aerodynamics; wind tunnel; flapping; Apus apus; particle image velocimetry
• Online Access: https://dx.doi.org/10.5061/dryad.cn252; https://datadryad.org/stash/dataset/doi:10.5061/dryad.cn252

Many flying animals use both flapping and gliding flight as part of their routine behaviour. These two kinematic patterns impose conflicting requirements on wing design for aerodynamic efficiency and, in the absence of extreme morphing, wings cannot be optimised for both flight modes. In gliding flight, the wing experiences uniform incident flow and the optimal shape is a high aspect ratio wing with an elliptical planform. In flapping flight, on the other hand, the wing tip travels faster than the root, creating a spanwise velocity gradient. To compensate, the optimal wing shape should taper towards the tip (reducing the local chord) and/or twist from root to tip (reducing local angle of attack). We hypothesised that, if a bird is limited in its ability to morph its wings and adapt its wing shape to suit both flight modes, then a preference towards flapping flight optimization will be expected since this is the most energetically demanding flight mode. We tested this by studying a well-known flap-gliding ... : Vector fields of flapping and gliding swiftsFlow measurements behind swifts (Apus apus) in flapping and gliding flight in the Lund University wind tunnel. The data are in the form of vector fields in DaVis VC7-format. The zipped file contains two folders, one holding all the sequences from the flapping flight experiments and one all the sequences from the gliding flight experiments. Each of these folders contains sub-folders with names corresponding to the flight speed examined during measurements. Inside these subfolders sequences are located and the names of each of them show time and date of acquisition and the major processing steps performed in DaVis. Only sections within these sequences corresponding to steady flight where the complete semi wake span is present were used for analysis.Vector_fields_Swifts.zip ...