xcead

george: i've been following your forum for a while, and i can see you are quite an expert on aerodynamics

im an aeronautical engeneering student ( 2º year ), and i see in many pattern planes this wingtips that are not so "clean" ( thats how we call to an aerodynamic surface )....they are rounded, and both upper and lower flows match in the wingtip and generates a big vortex and drag

i've attached some pictures to see....in my opinion the best wingtip is a 45º angle, to simulate the winglets , so the vortex is smaller, lower drag, cleaner flight

what do you think ? could someone explain why this shape?

thanks and sorry for my english

xcead

for example

Tall Paul

The upturned wingtips have the aerodynamic quality of extending the wing span, making the wing more efficient due to the higher aspect ratio, without making the wing longer, which could cause parking problems at some airports.
The upturned tips are most effective at a single cruising speed, which has been determined to be the most efficient for the plane.
For models, which don't cruise for any extended periods, these tips create drag throughout the flight regime.
For long duration models which will fly at a single speed, these "winglets" can be useful.
Some 3D manuvering planes add them for the side area useful in knife edge and other wings vertical flight.
Following Tony Frackowiak's modifications to his full-bodied Tribute, I added verticals to my long-suffering profile Tribute.
The flight characteristics have changed a lot, and it will take some time for me to finger out what's going on.