As we can see from the preceding discussion, a good tip geometry is an advancing tip with a sharpened outer edge. The cross section of the tip should progress from rounded near the leading edge as it transitions off the nose of the airfoil to sharp farther aft. The sharpened portion of the outer edge should be highly swept so that once the sweep of the tip planform exceeds 45�o 60�the transition from round to sharp cross section should be complete. The aft portion of the outer edge should remain sharp all the way back to the trailing edge of the wing.

https://www.kitplanes.com/design-process-wingtips/