Hello, Goooooooooal (I think)
I found equation on AHM 560 of airlingus, in fact In this doc I found equation to compute Index and % Mac, I have explaination about almost constant.
as I thought it, each company for his each aircraft give LEMAC
Index =W*(Sta - Ref.Sta)/C + K
% MAC =( 100*C.(I-K) )/(MAC*W) + 100*(Ref.Sta - LEMAC)/(MAC)
W = Weight, actual
Sta. = Station, horizontal distance from station zero to the location
Ref.Sta. = Reference Station/axis. Selected station for calculation purpose
K = Constant used as a plus value to avoid negative index figures
C = Constant used as a denominator to convert moment values into
index values
I = Index value corresponding to respective weight
MAC = Length of Mean Aerodynamic Chord
LEMAC = Horizontal distance from the station zero to location of the
Leading Edge of the MAC
Now I nead found LEMAC for each aircraft which use in my software, because it's the only variable which move from aircraft to an onther aircraft
I made some test, and i ma on good way
PS: As i tell you in my previous posts, my english is poor and sometimes I don't understand all what you write, but I try to translate et I want thank you for all your help
See you later
Best regards