After a long hiatus (likely influenced by the current stay in place mandate this year) — I am posting the mean diameter of the SP-D images from the supplemental figure in the manuscript by Arroyo et al. Diameters calculated by the same two methods mentioned countless times in this blog before: diameter and segmented (node or cusp)-arm length).
Specifics are:
n=196 (three measures per dodecamer with a rare SP-D molecule with five arms, or three arms included)

Sum, Σx: 26012.577
Mean, μ: 132.7172296
Variance, σ2:  108.7097499
sd 10.426

BTW, SP-D becomes a hot topic in todays coronavirus pandemic. THough retired, I am anxious to do some work on whether SP-D might behave with this SARS Cov-2 virus as it does with SARS Cov-1

I had two sets of 3 measures each from two images in Figures 3 and 6a in the original article which I compared to identical images found in Figure 4 of the supplement. So this is a duplicate measure, two different times (half a year apart) but using the same techniques (which is to use the authors micron bar marker to determine the diameters of the SP-D molecules using two methods (1) an actual diameter measurement — where the circumference touches at least three of the four CRD in a single molecule, and 2) vector lines from tip of the CRD to the other CRD for each hexamer) sugjected to a t test which did not turn up a significant difference in the measurements made: (The t-value is -0.30062. The p-value is .769863. The result is not significant at p < .05.) That is encouraging as the values include any errors in the bar marker and any of my errors in translating the bar markers into nm in my image measurements. That give a little more credence to the methodology, however I still will compare Figure to figure and especially the cover to the other figures in that paper.) That there are differences in the size of the SP-D images from one figure image (with bar marker) and others seems likely to show up