When I started looking for an equation to match the template a few years ago, initially I just plotted the template angles in excel to try to match the curve, as I muddled about I found out that excel had a solver function which matches best fit equations to curves and I came up with this polynomial equation. I played with it for a while, but then got sidetracked with other ideas and it got left behind and forgotten, with this recent look into equations I dusted off the polynomial and had another look.
It just relates to the tail portion, but is much easier to manipulate and predict than the other 2, here is the overlay below:
It matches the template quite well, there's very little difference between the angles, the tail ratio comes out to 1.75 giving it a length of 3.49 as compared to 3.56 which is around 98% of specified length, although after this detailed study I do think an extension of the template drawing would come out a bit short of the 3.56 figure.
If you look hard you can see that the curve is just a fraction higher than template between 30-50%, but otherwise it's almost a perfect match.