Within aerospace engineering, the span efficiency factor is a very important flight performance metric, describing how efficient lift is produced. Here we have developed a method to empirically determine the span efficiency in flapping animal flight, based on PIV data. We used this model to estimate span efficiency for both bat species studied in the Lund wind tunnel. The results show that the flying bats are more efficient that a similarly sized airplane wing.
Four views of the wake behind a flying bat, consisting of vortices (green) and downwash (color surface) . The downwash distribution was used to estimate span efficiency.
Last modified 16 Oct 2012