Magne

Todd:
I used 2 layers of 49 gram/m2 (approx. 1.45 oz/sq yd.) on the outside, and one layer on the inside.
This gives a surface which is quite dent-proof, and is more than is actually required for flying loads.
I know that people successfully have used one layer of 49 gram/m2 (1,45 oz) on the outside, and one layer of 25 gram/m2 (3/4 oz) on the inside.
I opted for the extra strength, because my model is "light enough" for my requirements anyway.

If I make an other model, I will experiment with thin slices/sheets of white polystyrene foam, approx. 1.5-2mm thick. This is what a lot of manufacturers use (I think e.g. ZN and former PL used this material.) I have made some test pieces, and it is possible to lay this down in the mold after the outer skin, and make it stick to the surface, without the use of vacuum. It should thus be possible to join the two fuselage halves wet, all in one process.
But I would like to carry out a few more tests, before I commit myself to a full fuselage.

Tom:
The layers of fiberglass mentioned above, make up a sandwich panel consisting of 0.108mm (2 x 0,054mm) thick fiberglass - 1/16" balsa - 0.054mm fiberglass. The total fiberglass thickness used is therefore only 0.016mm thick. (0.0006" ) Each layer of fiberglass weighs approx. 90 -100 gram/m2 when laminated, and the balsa weighs approx. 150 gram/m2. Total weight is therefore 420 - 450 gram/m2.
If you made a panel of fiberglass only, which weighed 420 - 450 gram/m2, it would be MUCH softer / more flexible than the sandwich panel.
However, the pure tensile/compressive strength ALONG THE FIBRES would probably be higher, as glass is stronger than balsa. But our models don't fail in tensile/compression along the fibres, but more probably in compression perpendicular to the laminate, or in buckling.

Regards,
Magne