Why do some pack designers use framesheets instead of internal stays?
Definitions:
FRAMESHEETS> semi-rigid plastic and foam sheets used to stiffen a pack's back for light load transfer of pack weight to the hipbelt and to retain a pre-determined pack shape.
STAYS> aluminum rods, tubes or flat "bar stock or carbon fiber or engineering grade fiberglass reinforced plastic vertical pieces (or single piece) used to stiffen a pack's back for load transfer of weight to the hipbelt.
I own a large Camelbak daypack (2,800+ cu. in.plus 800 cu. in. of side pockets) that had a framesheet. I had to add 1" wide aluminum stays to the pack to get decent load transfer to the hipbelt with a fully loaded pack of day ski touring equipment.
In my experience a framesheet has very little support and ability to transfer a load much over 20 lbs. (9 kilos). So why are they used??? Can the weight savings really be that much?

