This design is adapted from an old tin toy that featured a monkey that climbed a string. This dragon fly variation is simpler and it still demonstrates an extreme application of mechanical advantage to do exactly the opposite of what it seems it should do--pull down but it goes up. The fast spinning wings add a nice touch. It is the perfect reincarnation for half-gallon milk cartons.
This was one of the first projects I wrote up. Unfortunately, the strings tend to jump off the pulleys and it's a huge hassle getting them back on. The pulleys/shaft can also get jammed and require careful observation to see where they're stuck. I now consider this project too difficult for any but the bravest and most skilled people. It's a shame because it's another way to look at mechanical advantage, pulleys and leverage. It's also counterintuitive so it really makes you think. If you make it, let me know and please share your suggestions for improvement.
|For illustrated instructions for building a dragonfly with mechanical advantage click here or on the picture.|
|For explanations, activities and cool links related to the dragonfly click here or on the picture.|