737 Centre of Gravity

[The African Dude]

Hi folks,

Quick Q on the 737-300: could anybody advise roughly where the CoG range limits lie, from the nose? I understand it's normally calculated by loading/dispatch in reference to the MAC but I don't have that info.

Cheers

[ANOTHER ton?]

The African Dude,

This question is not as simple as that. First, CofG is expressed in %MAC, so if that's not what you want, how would you like it described? Station numbers or inches from the nose can probably be derived from %MAC...

Secondly, the CofG limits depend entirely on the take off weight of the aircraft.

I just happen to have a 747-400 balance chart to hand, and for example, if very light, the %MAC range is 18% - 28% (i.e.10%), but at 360,000kg the range is 10.5% - 31% (20.5% - double the range of light weight).

I may be able to get a 737-300 balance chart to read off the numbers for you, but I need a weight and how you would like it expressed.

Regards..

[The African Dude]

Hi AT,

I'm looking for the range for the 733 at MTOW (56,473 - 61,236 kgs? or something similar, for the standard CFM56-3B1 engines?)

I'm ultimately going to use these limits as a distance from the nose, so if the values were in %MAC I'd need some guidance on how to work out the conversion.

If you were able to find the most forward / most aft locations of CoG, in terms of distance from nose, and the corresponding weight, that would be really fantastic - otherwise any info at all.

Thanks alot - very much appreciated!
Andy

[ANOTHER ton?]

Andy,

I am off work for the next three days, but will endeavour to get the chart for you when I'm next in, if you can wait that long..

regards..

[ANOTHER ton?]

Right, paperwork acquired, here we go:

For a max take off weight of 61,234kg, %MAC range is 13% - 25%, which correlates to 593.08" - 609.23" from the nose.

The largest range (most fwd and most aft) occurs at 40,823kg, and is 5% - 31%, which is 582.33" - 617.29" from the nose.

The above is for take off and landing, the inflight fwd most limit is 4%, or 580.98" at the same weight. (Aft remains the same)

For info, to work out distance from nose: ((%MAC x 134.5)/100)+625.6-50

Above values and equations are valid for the B737-300 only

[The African Dude]

Thanks,

Absolutely spot-on information.. I do like dealing with to-the-point technical people despite being a blithering idiot myself most of the time!