Medium weight tissue is a much better option than polyspan on a built-up fuselage. I would think that this is true for a profile as well. The all-time easiest and most likely the strongest, is glass cloth, and a good finishing resin. An alternative to epoxy resin is of course, good old dope. Nitrate dope on glass cloth is probably also more rigid that with epoxy resin, and has the advantage of being a lot less messy as well. It sure dries quicker than epoxy, so this is another option.
For the last few years I've been making models out of mostly extruded foam, similar to Depron. Here in Darkest Africa, we get Isoboard which is used for ceiling insulation. I made my own cnc foam cutter and successfully made quite a few trainers and WW2 combat models. I covered them with medium weight tissue and white wood glue mixed with water, and they come out quite nicely. Then I tried some lightweight glass cloth (25 grams/sq.metre) and of course, I could not use dope so I resorted to aliphatic resin instead of the PVA white glue because it dries to a hard surface and sands nicely. This is a lot stronger and more ding-resistant than using the tissue option. On balsa however, I would stick to dope, and you can also do that trick that Phil Granderson does, and that is to add some talcum power to the dope for the last coat or two and then it fills the grain of the cloth very well.
Topic: PolySpan on the fuse? (Read 926 times)