Originally Posted by
Chesty Morgan
That's correct.
If, in your original question, you added the winglet on to the existing span of the wing you would have a wing producing the same amount of lift but with a increased L/D ratio.
So, winglets (unlike wing extensions) produce no wing bending moment because they produce no lift because they are at a right angle to the wing.
There are two directions at right angle to the wing. Why do winglets extend up from wingtip, not down?