PPRuNe Forums - CG TOW (B747-400)

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CG TOW (B747-400)

Hello all,

I am trying to determine the TOW CG in excel.
I have the following formula so far but it differs approx 1 with the manual trim sheet.

=(((H19-50)*300000/G19+1323,6)-1258)/327,8*100

H19 = TOW index (i.e. 63)
G19 = TOW (i.e. 257795)

The outocme of the above is 24.8
The outcome on a manual trim sheet is approx 25.8

Do you guys have any idea if I am doing something wrong

Can I see your trim sheet and the graph?

How thick is your pen??

Loadsheets Calculations

If you are doing weight and balance calculations mathematically and using the correct bay centrums from the applicable manual for that aircraft either pax or cargo, then your end result should be very accurate.
If you're doing a manual loadsheet using the same bay weights and interpolating the index from a list of weights, you will always find a slight difference, additionally it will depend on the accuracy of the ZFW/TOW graph and the thickness of the pencil you use. Either way, the mathematically produced loadsheet will always be more accurate. It's the final %MAC you need to be looking at, a difference of more than 2% at TOW should be considered too much.