Why do multiple parachutes have stable spacing rather than bunching together?

i.sstatic.net/1KtMaQ53.pngcommons.wikimedia.org/wiki/File:Apollo_17_Splashdown.jpgi.sstatic.net/7oWkG2re.pngavitec.pl/wp-content/uploads/2023/01/G-11B-cargo-parachute_1.jpg

Since the riser can only generate tension along its axis and drag can only be in the axis of motion, a simple vector diagram implies all parachutes should experience a resultant which moves them towards their common vertical.

In addition, the venturi effect of air flowing between adjacent parachutes should generate a force to draw the parachutes together. This is the same effect which “sucks ships together” when they are steaming in close parallel formation (as in when replenishing underway) .youtube.com/watch

Obviously this problem has been solved, but how?i.sstatic.net/8M5rLu0T.png