Hi, the coloured dots are a typical worked example.
Starting with Empty at 27 tonnes, you then add 10 tonnes of passengers and freight, to bring ZFW up to 37 tonnes. Then you can add the 6 tonnes of fuel, to bring the Gross Weight up to 43 tonnes.
As this Magenta spot lies within the envelope, you are within W+B. Then you can set the Trim to the take-off position.
As for % MAC the diagram does not contain MAC dimensions... You would need to know the width of the MAC.
The vertical axis is well marked in Tons. The horizontal axis I presume is in Inches (or centimetres.?).aft of datum position.
There is no simple %MAC that suites all (such as 20 to 35%.) or that would give an envelope with straight vertical edges..
Last edited by scifi; 25th Mar 2019 at 11:43.