Stacked one after the other, 16 plates x 1/4”ea = 4”. The photo clearly shows space between each plate so that’s more than the 4” purported by the article. The key to any armor system’s performance is the changing material characteristics in the armor “sandwich.”
It was poorly written, but I think the author meant 16 one-quarter-inch steel sheets spaced at four inches apart.
“The photo clearly shows space between each plate so that’s more than the 4” purported by the article”
Let’s assume you walked into Abby Sciuto’s lab with this picture, she’d probably give a spiel something like this:
The photo does show the spacing, but the photography leaves much to be desired. Nonetheless, the photo can be imported into a CAD program and using simple photogrammetry, the distance between the plates can be measured.
Plates 7 & 8 are the best subjects to use as their position in the optical field of view gives less distortion.
Assuming they are 1/4 inch plates, the spacing calculates to 3.39”. However the poor lighting distorts the actual thickness of the plates, so it 3.39” may not be accurate.
The spacers appear to be 2x6’s standing on edge. The nominal thickness of the “two” by six is 1.5”. Two side by side would be 3”, which is quite close to 3.39”.
Therefore, the safest assumption with this poor photography, when imported into a CAD program and measured, is a spacing of 3”.
(sorry, not picking on you on purpose, photogrammetry is something I do, and thought of it before reading your post)