Here's some pics of more experiments to try to use less balsa wood.

The total tailplane area is 150 sq.in. and, as it stands, weighs 78g.

The elevator weighs 25g and is from 6mm Depron, vacuum bagged with 48g cloth and carbon tows top and bottom. The elevator has a 3x6mm balsa LE.

The stab at 53g has a lightweight minimal 6mm balsa frame with flat composite skins, top and bottom.  The skins are made from 2mm wallpaper foam, vac. bagged with 48g cloth on the outer surface and 25g cloth on the inner. Integral with the skins are spar caps of 100g cloth about 20mm wide.  When epoxying the skins to the balsa frame, carbon tows were also added to the spar.

These items are already fuel-proof apart from around the edges and are very stiff.

Steve

Looks nice.  I googled "wallpaper foam" to see what it is and all I came up with was foam wallpaper, almost all of it with embossed textures ....  Can you explain the materials more ??   I'm all for alternatives to balsa, but I also don't want to learn and perfect new skills such as vacuum bagging and a whole lot of fiberglass work ...

This is the product I use.  It is an insulating wallpaper liner. Is it not commonly found in the US?
https://www.erfurtmav.com/erfurt-mav-wallpaper-products/insulating-wall-coverings/heatsaver-2mm-wall-underliner#hikashop_show_tabular_description

I've found vac-bagging dead easy to master, also vac-bagging gives a nice finish with minimal weight gain and adds strength.

I use a diy vac bagging system that cost me less than £30.  A compressor from a scrap fridge and a diy electronic vacuum switch. For the vacuum bag, I use heavyweight polythene sheet, the sort used for damp-proofing buildings.

Steve

David,
Just to clarify, the individual stab skins, top and bottom, are vac formed. Then the skins and balsa frame are then glued under weights.

The elevator carbon tow pattern is drawn on the outside of the mylars. individual tows are placed by hand, dry, on top of the wetted cloth. Works very well.

I use a Sharpie to draw on the outside of the mylars. Can be wiped off with some meths.

Steve

Steve,
Very nice work. Do you make up the FG as a sheet then apply it to the frame like you would do with a balsa skin? Seems one could wet out the glass flat then after it gets fairly firm apply it to the frame.

Best,    DennisT