About 400 years ago, Leonardo da Vinci wanted to fly… so he studied the only flying things around at that time: birds and insects. Then he did what any normal kid would do—he drew pictures of flying machines!
Centuries later, a toy company found his drawing for an ornithopter, a machine that flew by flapping its wings (unlike an airplane, which has non-moving wings). The problem (and secret to the toy’s popularity) was that with its wing-flapping design, the ornithopter could not be steered and was unpredictable: It zoomed, dipped, rolled, and looped through the sky. Sick bags, anyone?
Hot air balloons that took people into the air first lifted off the ground in the 1780s, shortly after Leonardo da Vinci’s plans for the ornithopter took flight. While limited seating and steering were still major problems to overcome, let’s get a feeling for what our scientific forefathers experienced as we make a balloon that can soar high into the morning sky.
Materials: A lightweight plastic garbage bag, duct or masking tape, a hand-held hair dryer. And a COLD morning.
Here’s what you do:
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Shake out a garbage bag to its maximum capacity. Using duct or masking tape, reduce the opening until it is almost-closed leaving only a small hole the size of the hair dryer nozzle. Use the hair dryer to inflate the bag, heating the air inside, but make sure you don’t melt the bag! When the air is at its warmest, release your hold on the bag while at the same time you switch off the hair dryer. The bag should float upwards and stay there for a while.
Troubleshooting: This experiment works best on cold, windless mornings. If it’s windy outside, try a cool room. The greater the temperature difference between the hot air inside the garbage bag versus the cold, still air, the faster the bag rises. The only other thing to watch for is that you’ve taped the mouth of the garbage bag securely so the hot air doesn’t seep out. Be sure the opening you leave is only the diameter of your hair dryer’s nozzle.
Want to go BIGGER? Then try the 60-foot solar tube!
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Yes, it sounds like your blow dryer is too hot, make sure it is on the lowest heat setting. Be sure the bag doesn’t sit right in from of the opening from the blow dryer by slightly inflating the bag before you insert the blow dryer. Also, be sure to remove any tie that may be built into the bag…that way the bag is as light as possible.
We did this in the garage so the bag wouldn’t float away because it was windy. However, our bag (a regular white kitchen trash bag) almost immediately began to melt and stick to itself. Hair dryer too hot, or wrong bag type?