〈 Berger | Dillon 〉

Are they, though? They look more like they're plotted over an elliptical domain fairly smaller than the cross section of the can. IMO the advantage over flat ellipses is the traction created by contact between curved surfaces preventing the stack from collapsing inside the can

Yes, more elliptical than circular. https://en.wikipedia.org/wiki/Pringles#/media/File:Pringles_chips.JPG …

You would get the same traction regardless if a circular or elliptical region .. at least i don't see any difference between the two in terms of traction

Right, but I was comparing flat ellipses with curved surfaces plotted over elliptical regions, i.e. if the region is elliptical and doesn't fill the cross section of the can, that means the stack has room to collapse and the curved shape makes that less likely to happen,

whereas with a circular region that fills the cross section of the can there's not much reason to have a curved shape instead of a flat one since there's no space for it to collapse anyway.