Efficiency

Why a quasi airfoil wing creates lift with both minimal front and induced drag.

Upper surface camber of a conventional airfoil wing is the curve of the top of the airfoil that is typically more pronounced than the lower surface camber. But both convex surfaces create drag. A quasi airfoil wing is thin with non-convex surfaces. The upper surface is smooth and causes friction only skin drag.

The upper surface boundary airflow passes with maximal possible speed and air pressure is minimal according to Bernoulli principle. At the same time, the speed of the airflow that passes the lower wing surface is smaller because of under wing dimples.

Those wing dimples create higher pressure because of the under wing turbulence and drag. But if created under the flat wing, the drag is smaller than the drag created by convex surfaces of a conventional wing. The described pressure difference creates quasi wing lift force.

At zero angle of attack, the lift generated by the quasi wing is positive. A small increase in the angle of attack results in an increased lift without any stall. A smaller quasi wing angle of attack creates a smaller induced drag.

Low span DRONEs with annular tip-less ring wings (e.g. oval, triangle, elliptical, box e.t.c.) avoided wingtip vortices that cause induced drag.