The "book" figure for the pilot/passenger lever arm is 55" from datum. This
is some 7" forward from the bottom of the seatback. No doubt this has been
calculated from an average statistic for the human frame in the slightly
reclining position ,but it is obvious that the weight of the legs acts much
further forward from the nominal c.of g than the torso. So your personal
c.of g. arm will depend on how heavy your legs are relative the body (not
incidentally on their length, as everybody has to fold them into the distance
remaining to the rudder pedals). You can obtain this figure in a number of
ways e.g. Archimedes principle next time you are in the bath, but if you
can't wait, there two more direct methods , a) sit on a plank, with legs in
the necessary position and find the balance point on a (low) fence, or b)
the serious method --when the aircraft is weighed, do it also with yourself
in the cockpit. These will produce the accurate figures you need to use,
allowing for your personal statistics. I await with interest how your
figures compare with 55", particularly from women pilots.
Graham C.
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