No need for classic "bearings" but you will need to allow for some flex in the system or it'll bind. For the pivot rod in this case I'd suggest a length of something like 1/4 OD carbon tube that has a nice slick outside finish. Then pass it through the wing ribs at a chord point that puts 25% of the wing area ahead of the hinge line. The root rib should be made from 1/16 plywood and at a point out near the end of the pivot tube the rib there should be also made from 1/16 plywood as well. Accurately mark and drill the holes for the pivot but go for 1/32 oversize. Then glue in short sections about 1/4 inch long of 1/4 ID aluminium tubing. Any ribs located between these two bearing ribs should be drilled with the same oversize drill or punched out using sharpened brass tubing to the same oversize fit. The only two spots you want touching are the short bearing tube segments. A thin wipe of the carbon rod with some sort of lube will be all you need for a nice fit and operation.

To hold the wings on you'll need some sort of pin that inserts through the wing and into the tube to retain the wing from sliding off.

Why only touch in two spots? The carbon pivot tube is going to flex. When it does you don't want it to try to flex inside a rigid tube. By only supporting it at two points it is free to flex without binding. The tubes will have enough play to still operate freely despite the slight flexing of the carbon tube.

At least that's how I'd do it for this sort of scale...