this was one general recipe and the key was: it was a general one [Ming's punctuation and emphasis]
Like the centipede that fell over when trying to work out which foot to put first Splash, use your own judgment on brown mate: no one knows what colour anything 'actually' was back then and the colours of models (the source of the colour info) look very different to real-size aircraft colours. Colours look different when they're in smaller or bigger patches, and also a colour changes depending on which colours surround colour-patches, nervous-system thing. Brown will be fine

74 pounds of pigments in the following proportions
40 pounds yellow ochre
30 pounds umber
2 pounds 8 ounces Red Ochre
1 pound 8 ounces Chinese Blue.
Their yellow ochre is not our yellow ochre, their Chinese Blue (Chinese Blue?) is not our Chinese Blue and so on
Yellow ochre (earth colour) plus red ochre (earth colour) equals orange ochre plus blue is khaki, umber (earth colour) just darkens the khaki so we're talking about dark brown depending on the strength of the umber
No green anywhere, these are purely secondary colours and mix down to the colour of the output of the digestive system, cacker. That's why they call it khak

Ming