In a nutshell - your chart is not very representative of any models we have ever seen.
discuss this info with guys who actually fly various types of models.
Then plug in some numbers --and catagories.
As you have already guessed - I am just a plain ol country boy - --so I am more influenced by results
Calculations are fine but should be representative of real world data -
I thought that was the reason for the "cubic " scaling---
So far I don't see the correlation.
BTW - the 37 lb setup would hardly fly .