Abstract: A method of unmanned aerial vehicle (UAV) flight includes providing horizontal thrust in-line with the direction of forward flight of the UAV using at least one electric motor, providing primary vertical lift for the UAV during the forward flight using a fixed and non-rotating wing, repositioning the at least one electric motor to provide vertical thrust during transition of the UAV to vertical flight for descent, landing the UAV on a surface using a vertical approach after the motor repositioning, and deploying an anchor to secure the UAV to a surface.

Abstract: A composite arch structure and method of making it are taught. The composite arch structure comprises a pair of retaining wall portions and a top arch portion extending therebetween. A stiffening and load distributing member is structurally affixed to the top arch portion and extends longitudinally of the composite arch structure for the majority of the length of the structure. The composite arch structure preferably also includes longitudinally extending, load spreading buttress means on either side of the vertical axis of the structure at positions where a radial force acting on the structure forms an angle of about 45.degree. or more to the horizontal.

Abstract: In a composite arch structure of the type comprising an arched liner with compacted fill material or dense soil thereagainst to form a soil arch thereabout, means and a method to permit controlled settling of the liner so as to achieve load relief on the liner and a soil arch with improved load supporting capabilities. A foundation is provided for the liner comprising yielding footer means. The yielding of the footer means is controlled so that the liner settles at a desired rate relative to the adjacent compacted and consolidated fill material when a predetermined load on the liner is exceeded.