Abstract: Disclosed herein is a collapsible wing assembly of an unmanned aerial vehicle (UAV) and a method of locking and unlocking the collapsible wing assembly of an unmanned aerial vehicle (UAV). The collapsible wing assembly comprising a centre wing adapted to be attached to the fuselage; and a pair of outboard wings, wherein each of the outboard edges of the centre wing comprises a first attachment structure, and each of the inboard edges of the outboard wings comprises a second attachment structure, wherein the first attachment structure is operable to engage with the second attachment structure and displace the second attachment structure to a captive position towards the trailing edge of the centre wing.

Abstract: A self-leveling apparatus, a tray table for use with a seat comprising such an apparatus, and a method of maintaining a horizontal level of a mounting member are provided. The self-leveling apparatus comprises: a gear train rotatable about a fixed reference point, the gear train comprising a first gear fixedly mounted to the reference point; a rotatable last gear, and an odd number of rotatable intermediate gears meshing between the first gear and the last gear; and a mounting member adapted to be coupled the last gear, the mounting member having a surface capable of being positioned horizontally; wherein the last gear is further adapted to rotate locally about its axis an equal and opposite amount to a system rotation by the gear train about the reference point, thereby maintaining the surface horizontal.