HI, I want to know how to interpre the mc kee formula, for example: Thruster Tail fin for M5 multisystem at 8.4 cms from tail. This means from the end of the fin, or from the fin box? Im using FCS system.
Another question is, If I have a swallowtail, I have to measure from the tips or by the short part (the crack)
I can't speak for McKee; but measurement is usually to the back edge(trailing edge) of the fin. So your box or plug is placed in such a way that when installed will put the trailing edge of your fin on that measurement.