TIP Russian patent published in 2021 - IPC B64C23/06 

FIELD: aerodynamic tip.

SUBSTANCE: tip of the aerodynamic surface contains the upper and lower sides, mating with each other to form the leading and trailing edges, as well as a working curved edge consisting of incoming and outgoing sections adjacent to the leading and trailing edges and mating at a point corresponding to the maximum span of the aerodynamic surface in this way that the projection of the working edge onto the chord plane has the form of an outward-facing arc of constant or variable radius. The tip additionally contains two boundary layer drains arranged in a row on the outgoing section of the working edge with the possibility of crushing the end vortex core into vortex bundles of co-directional rotation. Each of the drains is made in the form of a triangular structural element formed by the upper and lower surfaces, which are a continuation of the upper and lower surfaces and mate with each other to form the outer and rear edges, which are an integral part of the working edge. The outer edge of each of the drains is twice as long as the rear edge and mates with it at an acute angle to form a backward-facing apex. The drains are displaced relative to each other in such a way that the projection of the outgoing section of the working edge onto the chord plane has the shape of steps, where the next step in the direction of flow is displaced inward relative to the previous one.

EFFECT: bottom resistance reduction by eliminating accumulation and local instability of the boundary layer near the outgoing section of the working edge.

11 cl, 26 dwg