Thanks for that information, but the cost/benefit ratio comes down deep in the red. My fuselage shell is primarily bounded by the torsional and bending stiffness between the wing and the root of the vertical fin, for which any kind of core is pretty much immaterial. What little panel stiffness we need back there is easily provided by the ring stiffeners we apply in a secondary operation....
There is a new sandwich material called "3d core" (www.3d-core.com). You can get it in either XPS or PET and it can be easily infusioned (so done in one step). The honeycomb is adding significant weight, yet it is still way lighter than Soric. Another upside: the Epoxy within the structure is protecting against core failure. We want to test it for a safety cell which can be manufactured in a single step.
I thought this may be the solution for your fuselages if used in 3mm thickness.
As I've written before, my fuselage is optimized to meet its structural requirements when fabricated by one leader and a crew of total amateurs on their second day of composites experience. That demands a simplified layup schedule with lots of margin for minor inconsistencies in techniques and processes. And as it turns out, for a female-molded carbon fiber part, the weight penalties for doing it that way are rather modest. That, among other things, is why I still firmly believe that molded carbon fiber is among the most cost-effective way of fabricating even modest-performance airframes. Once you accept the value of collective action (or reject the exorbitant cost of rugged individualism) the necessary molds and infrastructure amortize themselves very quickly.
Going OT, we generally make our fuselages at our Akaflieg build sessions, and it takes a newbie crew of three a five-day week:
Monday: Cut carbon, consumables, and fin foam core. Wax and prep the mold, safety briefing for the crew.
Tuesday: Fabricate fuselage right half (the easy one) and the turtledeck.
Wednesday: Fabricate fuselage left half (the hard one because it has the bonding joggle).
Thursday: Install ring stiffeners and elevator push-pull tube guides.
Friday: Install plumbing, wires, and rudder cable tunnels. Prep all bondlines. Install bondline pressure rails. Mix and apply bonding paste, bond halves together.
Saturday morning: Separate fuselage molds, demold finished fuselage shell.
For a crew with two or more experienced members, we can lay up both fuselage shells on the same day, compressing the schedule by one day to catch up for a lost day or advance the demolding to Friday.
For a Canadian fuselage shell, we would omit the bonding operation, and instead temporarily join the shells with aluminum pop rivets 6" OC. The builder would then drill thru the rivets, have the shell interior inspected by TC, then field-close the shell using more pop rivets or clecos for bondline clamping.