I gather some NASA vehicles were based on the width of a railway track which was determined by the spacing of charriot wheels that was based on the width of a horse's arse.
SRBs. Bollox, of course, as the US rail gauge is same as here; 4' 8.5". But their trains are much bigger. So the chariot wheel / horse's arse theory doesn't follow, as there's no direct relationship between rail gauge and loading gauge.
Back to aviation - why do aeroplane captains sit on the left, and whirlybird ones on the right?