Concertina Folding/Gluing
One of the ways cardstock is used in this project to carry the flight loads is by using "Concertina Folds".
Basically they are just a combination of "mountain" & "valley" folds.
A line of glue is placed inside the valley folds, using a scrap piece of wood to press the folds flat. The wood has been sanded using 600 grit so that it slides back & forth without catching or wrinkling the cardstock.
Wood allows even pressure to be applied while the glue tacks/dries.
Photos show the size of wood , 45 degree angle used while sliding back/forth. What isn't shown is how hard I press down when gluing-lots of pressure is best...
Wing Spars, and Fuselage Longerons are built up this way.
Basically you are using lots of cardstock compressed into a smaller part-sort of how the cardstock is formed when being manufactured.
This construction mimics bals wood, except the cardstock "Skin" carries a major portion of the load. Hence the fewer longerons along the fuselage.
Best regards,
Mike Bauer
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