RE: why are wing tips UP , Down , or flat ?
All depends on what the designer thought looked good. Wing tips on our models do very little. Different story on full scale as tip shape can be used for stall control and effeciency increases, not so much for our models. I'm sure all the full scale theorists will come in and argue my point of veiw. If anyone is willing to test some different tips on a telemetry equipped airplane and report the results, it would be interesting.