by Ann Hinds

Created on: November 15, 2009   Last Updated: November 16, 2009

The field across the street has become the new favorite place for recreational ballooning. This has become a teachable moment for our child and friends who sleep over. When it is 36 degrees Fahrenheit outside, teaching them how hot air rises is more graphic.

We constructed a hot air balloon once. It is a wonderful science project but monitor it carefully. The very first step is to insure the balloon is tethered. Do not allow the project to proceed without some way to insure that it will not go up more than a few feet.

The best bag for the balloon itself is a dry cleaning garment bag. It is flammable so care must be taken. The rest of the items needed are two straws, four candles, string and the all-important tether.

Start with the straws. Cross them and tie them together in the middle. That makes four outer points to add the candles and the strings to hold the bag. Attach the strings to the end of the straws. They should be about eight inches. Attach the other end to the garment bag, securing it tightly.

Lay the bag on its side and attach the candles. The easiest way is to melt the bottom of the candle to the straws. The candles should be mounted about two inches from the center, one on each straw. One the wax has set, have someone hold the bag up and over the candles. Light the candles and the bag will fill with hot air. One there is enough warm air, the bag will lift. The air outside the bag needs to be cooler than the heat that the candles can produce.

There are a few things to keep in mind while doing the science project. If the bag is not tethered, it can rise higher than the sixty-foot sycamore tree next door. The wind can catch it and move it down the street at sixty-feet. The bag can continue rising until it is at the end of the street and catches on fire. Once the bag catches on fire, the plastic dripping can be dangerous. At that point, another thing you will need is binoculars. That way, you will be able to track the progress while inwardly screaming that you did not expect it to work and that you gave candles and matches to children. What were you thinking?

In a controlled science project, making a hot air balloon is great for teaching. When our child is an adult, he will be able to try it on his own. In the meantime, we are grateful that they launch across the street. We discuss how the burner works and we point out that the balloons are tethered. We watch the people climb in with parachutes and gracefully float into the air. They wave, we wave and there is no need for binoculars.

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