Friday 2 October 2009

Fire Balloons

Inspired by Roald Dahl's 'Danny Champion of the World', we've decided that our current project is to make a fire balloon. In the book, Danny and his father make a balloon out of tissue paper, wire and a cotton wool ball soaked in meths. Our first attempt copied this pattern. We used fuse wire to hold the wool and made a cylindrical envelope out of tissue paper. Unfortunately on an attempted launch we had a spectacular, if predictable failure with the tissue paper going up in flames.
There has been many discussions about the causes of the failure. The key problem seems to have been that the fuse wire was rigid enough to support a dry ball of cotton wool but the weight of the meths caused the wire to bend. Design efforts are now focusing on the fuel-holding mechanism. One theory is that we can use wooden cocktail sticks. The objection is that the wood will burn through before the meths has run out. We think we're going to try an experiment to find out. That should be fun!

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