Mark,
based on those measurements, I calculate a MAC = 10.88". A simple area calculation would then be 65" x MAC = 707.2 sq in.
If the MAC was rounded off to 11" then the area would have been ~715 sq in and a 720 square wing would really require a MAC = Area/Span = 720/65 = 11.077"
The geometric area, tips included, gives me 678.9 sq in.
So it looks like you are right and the actual T720 wing area is less than 720 squares. It doesn't surprise me as I've come across that in just about every other plan that I've measured. Who knows how areas where calculated or, rather, specified 35 years ago but I'm sure being
generous with their figures was not uncommon.
David
Originally Posted by
mmattockx
David,
Root is 13.1", tip is 8.3", span is 65" with a 1.25" thick tip block (ie - each core is 31.25" span and has a root chord of 13.1" and a tip chord of 8.3") and TE forward sweep is 1.375" as per the notes on the plans. The airfoil is an odd one, it is almost like a sharp nosed NACA 00XX series or a combination of a NACA 630XXA and the 00XX series. Very thick, too, at close to 17%. The stab airfoil looks a lot more typical, being quite close to a NACA 63012A.
Mark