I have noticed that many of the high performance 3fnc have a very similar fin shape (as seen with the mongoose,blackhawk, and shadowaero blackbird) I have done alot of research to try to find the reason for this shape and why it would be chosen over other shapes and I have been unable to ubderstand it. I read a piece in an apogee components book but it gave me no specific reason on why that shape would perform better than a swept parallelogram.