I'm designing an R/C plane with interchangeable winglets and I've so far calculated the taper ratio to be .246 (aspect ratio 9.5 if that helps). I'm taking some design/geometry cues from the A320. How does taper ratio affect aerodynamics?
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Taper ratio is mainly used to control how lift is distributed spanwise with the goal of having an elliptical distribution in order to reduce induced drag. The following plot represents how lift changes spanwise according to the taper ratio (source):
As a rule of thumb, taper ratios of 0.25 and 0.45 are the optimal for swept and unswept wings respectively.
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$\begingroup$ The lift distribution and the effect of taper is also strongly influenced by the sweep on the wing. This figure appears to be for an un-swept wing, so use caution when applying to something with the ~35deg of sweep of a commercial transport. $\endgroup$ Commented Jul 8 at 15:25
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$\begingroup$ Actually, two questions are asked here and a third is what are your requirements, really? Sounds like you want the aesthetics of a 'real' short/medium commercial a/c but it will be operated at low speed and be of small scale. $\endgroup$– AeroAndyCommented Jul 8 at 23:56
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$\begingroup$ @AeroAndy I'm looking to replicate the aesthetics of a commercial airliner as a testbed for most categories of winglets out there. (honestly this sounds kinda dumb now since most winglet effects are realized in cruise) but anyway $\endgroup$– ageek245Commented Jul 9 at 15:41
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$\begingroup$ Don't be hard on yourself. :) A low-speed comparison of different winglet geometries would be interesting and relevant. That said, it begs the question of the ability to discern configuration differences from your flight test data. Also, be aware of Reynolds # effects. For example, depending on the scale & speed of your R/C platform, the winglet may have extensive laminar flow whereas full-scale will have a predominantly turbulent boundary layer (in the absence of specific attempts otherwise). There are methods to mitigate this. $\endgroup$– AeroAndyCommented Jul 9 at 19:16
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$\begingroup$ In addition to aerodynamic performance, I'm betting structural dynamics, loads, mass properties and producibility are some other key areas driving winglet design. $\endgroup$– AeroAndyCommented Jul 9 at 19:19