The current study was aimed at identifying wing planform
geometries which favours low induced drag. The
geometries were defined by mathematical functions and
following a subsequent parametric study, with a focus
on sweep angle and taper ratio, inspired by birds wings
and aquatic animals flukes or caudal fins planforms. The
parametric studies were carried out using a vortex lattice
method (VLM) which was validated with experimental
data from literature. The main finding is a confirmation
of the fact that the maximum Oswald efficiency factor, e
is not exclusive to an elliptical wing planform. Despite
its apparent simplicity, in fact a swept-back-tapered wing
with a linear chord distribution can reach e = 1, the limit
or minimum induced drag established from elliptical lift
distribution. Moreover, the crescent wing geometry, such
as the one displayed by the swift, can even surpass this
limit
