Wind dispersal of seeds is an essential mechanism for plants to proliferate and to invade new territories. In this paper we present a methodology that combines 3D-printing, a minimal theoretical model, and experiments to determine how the curvature along the length of the wings of autorotating seeds, fruits and other diaspores provides them with an optimal wind dispersion potential, i.e., minimal terminal descent velocity. Experiments are performed on 3D-printed double winged synthetic fruits for a wide range of wing fold angles (obtained from normalized curvature along the wing length), base wing angles and wing loadings to determine how these affect the flight. Our experimental and theoretical models find an optimal wing fold angle that minimizes the descent velocity, where the curved wings must be sufficiently long to have horizontal segments, but also sufficiently short to ensure that their tip segments are primarily aligned along the horizontal direction. The curved shape of the wings of double winged autorotating diaspores may be an important parameter that improves the fitness of these plants in an ecological strategy.Autogyrating motion is also widely observed in multiwinged diaspores and seeds. These are commonly known as whirling fruits or helicopter fruits, which can be found in plant families such as Dipterocarpaceae [28,30,32], Hernandiaceae, Rubiaceae [34] and Polygonaceae, occurring in Asia, Africa and the Americas. These fruits are equipped with a leaf like structure (persistent and enlarged sepals), which acts as wings in their rotary descent, illustrated in their Greek name, i.e., di = two, pteron = wing and karpos = fruit. Compared to the single bladed maple fruits, these have a more complex wing shape which curves upwards and outwards [35]. Only a limited sub-set of tropical whirling fruits are described in terms of their terminal descent velocity as illustrated by the data from 34 neotropical trees [7], 53 recodings by [8] and recently extended by 16 entries of Paleotropic trees [32], which clearly limits predictions of dispersal distance. These flight recordings [7,32] suggest that the arXiv:1811.12221v2 [physics.flu-dyn]