Sunday, 3 July 2011

Candle powered hot air balloon

Build a candle powered hot air balloon using painter's plastic, balsa wood, and birthday candles.

Step 1

Cut the plastic and heat-seal the edges. 

Layout your materials on a large sheet cardboard. 

Pull out approximately 6 feet of the painter's plastic and cut it forming a sheet 9 x 6 ft. It's important to have plastic that is 1/2 mil (12 microns) or thinner. Thicker plastic is too heavy to fly. 

Fold the sheet in half along the 9 ft side forming a two-ply sheet 4.5 x 6 ft. Use a hot knife to seal the two 4.5 ft edges. An electric hot knife makes this really easy, but it can also be done with an old metal knife heated over a flame. 

Check your edges and correct any large holes. A few small holes won't cause problems.

Step 2

Melt candles together and attach them to balsa. Again, an electric hot knife makes this step a breeze. A heated fork can achieve the same results. Make sure to do both sides. 

Once the candles are attached together, melt them to the middle of a piece of balsa wood 3/16 x 1/8 x 36 inches.

Step 3

Assemble the balsa frame.

Make an "H" with the 36 in balsa and candle piece and two 3/16 x 1/8 x 30 in balsa sticks. Make the joints with a small piece of clear tape.

Step 4

Tape the balloon to the balsa frame.

Step 5

Use a stick inside the balloon to hold the plastic away from the candles and light them. Keep holding the plastic up until enough hot air has filled the balloon to inflate it.

Step 6

It's an amazing feeling when your creation first gets lift and starts to take off. 

At this stage, there's about ten thousand things that could go wrong. Carefully think everything through before you actually do it. 

I tied some thread to mine so I could fly it inside our warehouse without it getting away and setting the place on fire. 

It will drip a lot of hot wax, so keep it over the cardboard if possible. Also, if you let the candles burn all the way down, the balsa will catch on fire. I am currently experimenting with other types of candles to prevent this. 

Fly safe!

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