Traditional contracting rucksak mouth and modern clamshell zippered pack entrance – both have tradeoffs. Pack entrance shown below combines them and therefore inherits their advantages and disadvantages.
Details are somehow explained below but would be much more obvious in prototype.
– less loaded zipper;
– less long zipper;
– no drawstring needed, no protracting efforts, no crumpled fabric;
– still wide opening from top;
– relatively tightly closed, preventing the loss of belongins.
– more complexity;
– needs a flap over entrance for rain-proofing;
– does not allow full opening of pack;
– elastic cord needed to spread corners.