Effective weight =
Mass x g + tail downforce.
Tail downforce, which adds to actual weight to increase lift (and hence lift co-efficient) is affected by c of g (forward c of g requires more tail downforce).
Genghis can give the long complicated answer if required...........
(edit - I see he has, although in the original post load factor was separated out, and I think that book considers effective weight as lift required in straight and level flight).
Last edited by Fitter2; 17th May 2012 at 10:58.