The 3D printed semi scale external fuel tank is the heart of this turbine conversion and is what made it so easy since there was very little foam carving needed to fit in the fuel near the CG. This was my first time to do an external tank so I basically followed Keith's lead and advice.
The tank comes out of the printer in 5 pieces. Front, rear, 2 baffles, and a fuel tube holder (not shown here). The tank is printed out of clear PETG filament which Keith says is fuel proof. It is later sealed with a coat of epoxy resin inside and out.
The rear section has a flat front face that forms the rear wall of the tank when the rear section is joined to the front section. The rear section is hollow and is the FOD shield for the turbine. Only the front section holds fuel. We estimate it holds 40oz of fuel. With the 14oz header tank inside the fuse the total fuel capacity is about 54oz plus air trap fuel.
The rear section plugs into the front section with about a 3mm overlap and forms the back of the tank
The two baffles are indexed on small tabs inside the front section
This shows baffles tacked in position with CA