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got some thinking to do on luggage sizes

here is a handy list of airline carry-on sizes, unfortunately in inches. they summerize the situation well below, we’ve got a 550x400x200 mm group and a 22x14x9 inch (558.8x355.6x228.6 mm) group. and then a bunch of outliers. 550x350x200 appears to fit almost everything they list for carry-ons. they don’t really do much analysis on personal items, and many airlines don’t seem to give information about them. but of the airlines whose restrictions are collected there 350x250x100 mm fits within most of them, and 330x200x100 fits within all of them.

mass limits are also concerning - many airlines restrict carry-ons (sometimes including personal items) to 5kg. that’s ultralight backpacking level restrictions. if we only consider airlines that grant 10 kg (normal backpacking), we still get 550x350x200 mm as a good size, and 350x250x150 starts looking more reasonable.

ideally i’d have a luggage with either large enough wheels to handle significant terrain (gravel roads and flat trails, not proper hiking) and a day pack that i wear or a luggage that can be a comfortable backpack (with a waist band) when combined with the day pack. in either case, i have this vision of interchangable compartments, where the luggage and day pack are both just frames that accept variously-sized containers.

a critical component of both the day pack and the luggage is the ability to haul them around - straps and pulling mechanism. lets say that and other fixed features eats up 50mm of our depth, so we have 550x350x150 and 350x250x100. needing to tuck decently large wheels away into the sides would probably shave off another 100mm from the width of the bottom of the luggage. turning it into perhaps, a 300x250x150 section and a 250x350x150 section.

if we shrink the depth of the luggage by 50mm more, we have a compatible unit size of 50x250x100.

digging into the details on these sizes a bit more, for personal items the base size is mostly 300x100, 300x150, 250x200 or larger. this means that if we can interchange some width and depth (perhaps in attachment), we may at least be able to manage 300x150 interchanging with 250x200 (more likely 250x175).

this implies something like 250x125x{50,100} stacked containers, which does leave 75mm of depth in the luggage for structure and perminant compartments, as well as two vertically slotted 250x125x50 containers… well that’s tidy.

obviously they need to be a bit smaller to accomdate the framing. 240x120x40 would fit nicely with the openstructures grid.