Are winglets taxed under the cost/ complexity formula? What about aerodynamic biplane struts and wing braces or multi-surface wings?
A winglet (or tip sail) is included in the projected area of the wing as if it was folded down flat and added to the span of the wing, but is not treated as a separate surface (i.e. a wing plus winglet will be computed as only one “wing”, but with a larger total span). Interplane struts are included in the same manor. Multi-surface wings are treated as multiple wings with the exception that slats/flaps are considered part of the main wing. The projected wing area is the projected area of each “wing” taken individually. For example, a biplane will have 2 wings, each with it’s own projected area. For wings or wing panels with any type of extensible high-lift device (Slat, FCK, VCK, Flap etc.) the wing projected area used will be at the high-lift device setting which causes the greatest projected area.
