Abstract: This method controls the drone in order to flip through a complete turn about its roll axis or its pitching axis. It comprises the steps of: a) controlling its motors simultaneously so as to impart a prior upward vertical thrust impulse to the drone; b) applying different and non-servo-controlled commands to the motors so as to produce rotation of the drone about the axis of rotation of the flip, from an initial angular position to a predetermined intermediate angular position; and then c) applying individual control to the motors, servo-controlled to a reference target trajectory, so as to finish off the rotation of the drone through one complete turn about the axis of rotation, progressively from the intermediate angular position with a non-zero angular velocity to a final angular position with a zero angular velocity.

Abstract: A dam structure for retaining water in a reservoir includes precast concrete panel assembly forming the face or upstream side. A bonded impervious liner means, such as polyvinylchloride sheet, is provided on the downstream face of the precast concrete panels assembly. The liner means includes individual membranes bonded to adjacent panels, and heat welded impervious strips are provided along the joints between the panels. A poured concrete curtain wall is provided adjacent the liner means of the precast concrete panel assembly. Roller compacted concrete (RCC) is then provided in layers on the downstream side of the poured concrete curtain wall. An elongated, substantially horizontal blocking sheet of polyvinylchloride membrane is also provided at least adjacent the base of the dam to prevent water migrating upward through the dam between the precast concrete panels and the poured concrete curtain wall.