Centre of gravity

Imagine you’re the pilot of this aircraft. As one of your pre-flight checks, you’re going to see if the centre of gravity of the loaded plane is within specification. Why? You can see for yourself using those paper gliders. Try the yellow one. Launch it gently.

Oh dear. Its centre of gravity is too far back. It stalls and crashes. Try the blue one. Good. That one has a ballast mass on the nose, to bring the centre of gravity forward under the wing. You can trim a paper aeroplane by trial and error, but not a real plane– you have to calculate it. That’s what you’ll do for the paper glider in this week’s design task. But first, we’ll do some experiments. We’ll use two measurement methods to find the centres of gravity of some basic shapes, and some combinations of shapes. The analysis will show you how to find centres of gravity by calculation. Then you’ll be ready to decide on the ballast for the paper aeroplane.