I just cut from foam and go fly it to see if any of the theory is relevant to small models .
The textbook answer to most efficient wing always ends up as a great glider wing --and a lousy low speed aerobatic wing.
Lift is drag and drag is lift . call it whatever you like .
for some planes , the most efficient wing is one where you can trade off high lift for high drag - and still retain high maneuverability and transition from one to another.
For those who don't fly --I mean a setup that has lift at very low angles of attack and instant braking power (all drag )- if suddenly angled sharply
No good for full scale DC3 but GREAT for a high powered low wing loading model aerobat.
This may be a textbook somewhere - probably in Russian --
Dick,
Yes, the theory is relevant. The textbooks don't define efficiency as narrowly as you seem to think they do, and you are using the word "efficient" when you should be using the word "optimal", or "effective". Drag is not lift, and lift is not drag. The textbooks, the English ones, German ones, Russian ones, and all the others, teach theory that predicts and explains the behavior you see with your precious foamies. Sorry, you haven't discovered any new aerodynamic realities, you simply like to fly planes that have some unusual characteristics (efficiency not being among them). Evidently, you also hold some profound disdain for the discipline of aerodynamics. You can save the rant about closed-mindedness, I can go read it 10 other places if I want to see it again.
banktoturn