The second airfoil was constructed using the heavier 24” x 48” 200 lb cardboard sheet. A 10” chord was chosen arbitrarily because this airfoil was only for experimental purposes to learn how to work with the material.

Experiment 1: Scoring the Cardboard to Create a Curve

The cardboard was still too stiff to achieve the desired radius of curvature. Next, the length of the airfoil was divided into two to test the behavior with a) just one layer of paper removed and b) with both a layer of paper and the corrugated layer removed.

Experiment 2: Removing Inner Paper Layer

This worked very well but the number and distribution of scores along the cardboard needed to be increased.

Cardboard airfoil opened to show ribs, scoring and removed paper

Experiment 2: Profile of the airfoil with a layer of paper removed around the main curve

Experiment 3: Removing Inner Paper Layer + Corrugated Layer

The airfoil curve was too flexible without the corrugated layer along the curve. It would need to be reinforced, defeating the purpose of removing the corrugated layer.

Experiment 4: Creating the Control Surface

The excess cardboard strip along the trailing edge of the airfoil was scored to allow it to bend, however, it would only bend in one direction. To allow it to bend in the opposite direction, a small strip of the corrugated layer was removed along with the score. A demonstration of the range of motion of the control surface is shown below.

Gif of cardboard airfoil control surface demonstrating the range of motion