A4 practical: Rubber powered motor
I haven't tried this idea yet but I have tested it with my 10 research questions in 10 minutes principle and managed it easily. When I was a boy I used to make model air planes out of balsa wood, I never got to the level of building planes with petrol motors so all of my models were powered by elastic bands. Actually that's not quite true I once made a rocket powered plane using a jetex solid fuel rocket motor but it...