I have heard mixed feelings on mounting battery on foot well or aft to get
a more aft CG.
I ground some numbers tonight.
I used:
****a 62 inch CG, then calculated upset from this point
****used both a PC 545 (12 pounds)and PC680 (15.4 pounds)
****Considered the cables from the footwell to buss and motor needed on
all three scenarios so did not penalize footwell mount
****used three positions on each battery: 1) top of right footwell, 2)
right rear baggage bay, 3) right just aft of baggage bay bulkhead
****weight of wire used was for #4 copper clad aluminium wire, but under
no scenario if #4 pure copper wire was used would it add more than 1 pound
(less actual) The #4 copper clad aluminium wire is larger in diameter than
copper #4:
http://www.periheliondesign.com./fatwires.htm
Bottom line, battery on right footwell and adding lead to forward lower
front face of sternpost to achieve same aft CG as rear mounted battery
adds between 7 and 9 extra pounds for a given CG!
Range from 7 pounds first to 9 pounds:
545 / right rear baggage bay (~ 7 pounds lighter overall)
545 / right just aft of baggage bay bulkhead
680 / right rear baggage bay
680 / right just aft of baggage bay bulkhead ( ~ 9 pounds lighter overall)
Above includes the added weight and longer run of 2 cables and its effect
on CG.
I did not include weight of lugs or battery mounting, if I did it would
make case for aft mounted battery only look better.
Comments please.
Ron Parigoris
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