The vortex shedding characteristics of finite aspect ratio plunging wings, set to a zero geometric angle of attack, have been examined using force, particle image velocimetry and volumetric velocimetry measurements. Dual mode deflected jets have so far only been observed for two-dimensional airfoils. In this study, we investigate whether one can observe this phenomenon with finite aspect ratio wings, to significantly improve the time-averaged lift by exploiting the proper deflection mode. A gradual transition between the existence of these deflection modes in the 2D case and its absence on a finite aspect ratio wing is observed by gradually increasing the spacing between the tip of the wing and endplate. We believe that tip vortices may be preventing the formation of these deflected jets. Volumetric measurements illustrate that intertwined vortex loops are formed downstream of the wing, consisting of trailing edge and tip vortices. A double helix structure is observed within the trailing edge vortex, allowing the two consecutive loops to remain interconnected.
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