I've never been interested in owning/riding a planetary hub since for me the limited range/large steps and loss of efficiency compared to derailleurs are not acceptable compromises. That said, I find them fascinating technically. My dad was into overhauling them when I was a kid, and there were certainly many bikes around in the neighborhood with the ubiquitous SA three speed hub. I think several bikes in the family had that setup; my dad's, my mom's (not that either of them rode much) and maybe one of my sister's bikes at one point. But I went straight from a coaster brake to a 10 speed.
So, anyway, can you SA planetary hub geeks direct me to a site with detailed design info? I'd be interested to learn details about how the different ratios are effected (I've studied planetary gears in the past, and have a general understanding of the different ways they can be implemented - for instance, lepelletier gearsets; I've even fully overhauled a ZF 4HP18 automatic transmission; so I'm looking for really detailed info, not a general overview or how to.