Wrathall Mark wrote:

Snip>>Usually a reference point is chosen at the tip of the tractor spinner
so

 > all the
 > >moments are of the same sign

On most production aircraft, the refence point is normally located on the
jig. It will normally be some way ahead of the firewall, but not neccesarily
ahead of the spinner. If you want to see a station location nightmare, try
doing a weight and balance on something like a 737-900 which is third
generation stretch of a stretch. You get into kind of bonus station
locations at the inserted frames, while the basic station numbering was
kept. This means that you might have station 300 60 inches behind station
299, at 420 inches south of the datum
Mark Wrathall

 
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