I felt a little more ambitious this morning so I added some typical empty motor weights. Of course there’s a certain degree of variability here depending on motor choices; I tried to use one of the larger recommended motors in each case. The result is still fairly linear, I’d sayand the comparison between actual and “fit” chute size is much the same.
Again the fit gives a larger chute size than the stock chute for the smallest rockets and mixed results for the rest, and again the Mustang “wants” to be around 19″ compared to the stock 16″, but is not an outlier. The linear fit here is
I also tried using a model where area is proportional to weight (with empty motor). That doesn’t seem fruitful. The area/weight ratio varies from around 60 in^2/oz for the smallest model rockets to around 15 in^2/oz for the high power rockets; there’s no way to get a good fit of area vs. weight with a straight line through the origin. And again, this makes some sense in that the big rockets will be more strongly built, and will fly higher, than the little models, so you’d want them coming down faster.