Flybike,

As I understand it, the main reason to taper a wing is to tailor the distribution of lift along the span of the wing, to reduce induced drag. At high speed, induced drag is not important, so the spanwise lift distibution is not a big deal from that perspective. The other consequence of taper, if it is excessive, is to make tip stall more likely. For a plane that must turn hard, as in pylon racing, induced drag is a bit more important, although it remains much less important than parasite drag.

Most of the reasons to sweep a wing have to do with airspeeds which approach Mach 1. For a purely subsonic aircraft, the only reason I can think of, besides looks, to sweep a wing would be to generate vortex lift at high angles of attack. This could be to enhance maneuvering or to allow lower take-off and landing speeds for a plane with a small wing. Apart from that, sweep generally makes a subsonic wing less efficient.

Apart from truly well-designed winglets, which tend to be effective only for very specific flight regimes, there does not appear to be any significant drag benefit to any of the various wing tip designs. Aesthetics and ease of construction may be the best reasons to choose one wing tip over another.

banktoturn