How many have tried wing-tip plates, and did you think they were worthwhile?

Some years ago I flew a Midwest "Sweet Stick" with "tipletts," as I called them, which were made of 1/8-inch balsa. They were attached with two machine screws (2-56 size), into blind nuts in the outer-most rib, which was double thickness. The plate had only one hole near the leading edge, but three different holes for the second screw. This allowed the plates to be attached so that the area of the plate was totally above, totally below, and half-and-half (half above and half below).

As you might expect, they were most effective when positioned below the wing. Above the wing probably reduced the vortex somewhat, but the increased efficiency of the ailerons was most apparent with the plates all below the wing. Roll-rate was obviously increased.

Attached is a photo of my newest design for electric power, with tip plates.

These add to the efficiency of a wing (improving lift/drag ratio), especially at low airspeeds, by reducing the wing-tip vortex. It does this by restricting the flow of high-pressure air from the underside of the wing, which wants to roll up to the top of the wing where there is a nice low-pressure area. The circular flow that results is called a vortex, and it spoils the lift near the wing tip as well as creating additional drag.

Try 'em; you'll like 'em.