Folding for The Keel Effect and Directional Stability

If you want to start making your own paper aeroplane designs, here’s one very useful, but also very simple, fold that you might want to incorporate.

It’s a fold that helps give paper aeroplanes lateral stability by shifting the centre of gravity down to the base of the fuselage – useful for enhancing the keel effect. It also shifts the centre of gravity to a position forward of the longitudinal centre of the plane, which gives the plane greater directional stability (as discussed in the earlier post here).

Here it is:

Once you’ve tried this out yourself, you might notice that there is now more paper mass concentrated towards the tip of the plane, especially at the on the triangle at the centre line. The next diagram shows the number of layers of paper by colour. White = 1; Pink = 2; Red = 4

This means, when you continue to make the other folds of your plane (whatever they may be), you’ll be starting from a position where the centre of gravity is shifted towards the nose of the plane and the base of the fuselage. This is just what you want if you want to use the keel effect for lateral stability and to increase the surface area of paper and (and the moment arm of the end of the fuselage and the fins) behind the centre of gravity along the longitudinal axis of the plane.

Straighter, more stable flight awaits!