There's been a bit of discussion on fancy twists and sweep in swept wings from bell distribution to elliptical. The consensus is that building in the twist and getting the sweep, washout and taper correct is quite hard with a narrow range of workable solutions. But what about untwisted designs that rely on the elevons? Don Mitchel did it successfully with a range of Mitchel wings from the B10 on, using detached slotted elevons. He used a pretty constant foil across the span with no significant twist. He got pretty bad adverse yaw by all accounts and the spin could be nasty if the CG was aft. But it definitely worked with a reasonable LD at about 16:1 at the time. And he used sweep platform well under the ideal 20 degrees - that looked to be about 10 or 15. Later modification increased the elevon size and set them up further and eliminated the adverse yaw by all reports. So rather than designing in a difficult twist - or using the hassles of a detached elevon, needing mass balancing etc, is there any reason why an elevon that's maybe 70% of the tip chord at the tip and tapers to zero at the mid span can't be used to induce the twist at the tips without twisting the foil? This way you can tailor in the required "twist" by adjusting the elevon settings and CG. I know of quite a few RC wings that do this (Paiole, Zaggi etc). Is there any compelling reason it won't work full scale?