[Both packs are sold.]
The pre-K2 buyout, Bozeman-made Dana Design packs have achieved cult status. Some of this is the mythology of rarity, but a lot of it is based in fact. They’re heavy, and lack a few refinements considered mandatory today, but nothing subsequently made has been both as durable and had as good a load carry.
Shown below is a size small Arcflex Terraplane, with small straps and belt, and a size large ArcFlex Astralplane with large straps and belt. The Astralplane was larger than the Terra, and came with full side-access zips. My parents bought these for an Alaska trip back in 1996 or 7. They’re in really good shape. I’m selling them on their behalf. Anyone interested? Leave a comment and I’ll email you.
Several things make these packs what they are. Above all else is the construction quality, which is better than anything I’ve seen from any manufacturer (cottage or mainstream) in the last five years. The stitching is immaculate, and all stress point are anticipated and reinforced by design, rather than just an extra bit of stitching and/or material. The shoulder strap attachments are one example. Stout webbing backed with velcro is sewn into the main seam, and the straps themselves velcro and buckle on. This gives them some adjustment, as well as requiring only two layers of webbing be sewn to the pack body.
The second thing which makes these packs work so well is the suspension. A single 1″ by 1/8″ 2024-T4 aluminum stay runs from the haul loop down into the lumbar pad (i.e. in front of the hipbelt). A stout plastic sheet runs wall-to-wall within the lumbar, and the same piece continues into the main back, and then up to the load lifters. There is a large triangular cutout above the haul loop, which in concert with the internal compression strap creates headroom, even when the pack is stuffed. Lastly, fiberglass rods run from the outside corners (reinforcement pockets shown above) to the load lifter buckles. These flexible rods do an excellent job of augmenting vertical stiffness without being excessively stiff. The alu stay is unyielding for support, while the rest of the frame is just stiff enough.
The hipbelt is also worth noting. There’s a stiff plastic cradle which is structurally separate from the pads, which attach via velcro and a buckle. This gives the padding enough flexibility that there is no gap between the belt and lumbar pad, a common symptom on packs designed for heavy loads.
So why sell these? For most users they are just too heavy. I need a new scale, but I’d guess around 7 for the Terra and close to 9 pounds for the Astral. Unless you’re a guide, wilderness ranger, or trail crew worker you simply do not need the durability built into these packs. If you are one, or know one, get in touch.
Weight savings in a pack designed for abominable loads is an interesting problem. Cutting weight with lighter fabrics beyond the harness area is low hanging fruit, but in addition to durability problems being exacerbated with heavy loads (i.e. seam retention), this doesn’t get you too far. The multi-layered hipbelt which works so well here adds four layers of fabric, and results in a belt which weighs as much as modern UL packs. The belt on the Paradox packs evolution is an interesting solution to this problem. It uses the external frame to remove any force other then downward from the belt, which is thus saved from needing any sort of rigid structure, and thus weighs a fraction of what the Arcflex belt does.
The Paradox Evolution load transfer system is one continuous piece of webbing per side. Simple and strong.
Bedrock & Paradox 
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