How to Make a Hot Air Balloon?
Adapted from Science Toy Maker: http://www.youtube.com/watch?v=uM7WOHg-ZXU
Supplies needed
- 4 birthday wax candles per balloon
- 4-6 sticks of plastic straws per balloon (depends on the diameter of your bag)
- 1 plastic bag used for fruits/veggies at your local supermarket OR plastic trash liner
- Aluminum foil
- 1 pair of scissors
- 1 roll of Scotch tape
- 1 ruler
- Sharpie marker
- Matches
Steps
1.) Using the ruler and scissors, cut a square piece of aluminum foil that is 4 inches x 4 inches in
size.
2.) Using the ruler and marker, make a dot on one side of the aluminum foil (near the center) about 1
inch from the edge of the foil.
3.) Repeat step 2 for the remaining 3 sides of the piece of foil.
4.) Light the bottom of one candle briefly (so melts) and also heat the foil BENEATH one of the blue
dots. Hold the candle on top of the dot and push down until wax solidifies.
5.) Repeat step 4 for remaining 3 candles.
6.) Stretch out the plastic bag and measure the diameter/length of the opening. Multiply this number
by 0.7.
7.) The length of each straw that form the “X” must be equal to the number found in step 6. You may
need to use more than one straw for each part of the “X!”
a. Make a small cut at the ends of each straw so easy to overlap with the end of another straw.
8.) Tape the connected straws together at the edges to strengthen the connection.
9.) Make an “X” with your two straws and tape at the junction using tape.
10.) Using tape, connect each edge of the straw to the ends of the bag (get 4 ends). You can round
the edges to get a tighter fit!
11.) Tape the aluminum foil containing the candles to the straws (facing INSIDE THE BAG)!
12.)
a. Make sure the candles are NOT sitting on top of the straws!!! Why? They will burn your
straws and balloon down!
Light the candles one by one and…see what happens next!
How It Works?
- The flame heats the air (which is made up of gas molecules), causing it to expand inside the
bag.
- This causes the air inside the bag to become less dense than the air outside the bag!
- This difference in density of air causes the balloon to rise in the air.
- What would happen if you used a thick trash bag or a shopping bag?
o It wouldn’t fly because the bags weigh too much! Need 6 µm or less size bag.
ALTERNATIVE PLAN
Supplies needed
- 2 birthday, wax candles per balloon
- 2 sticks of Balsa wood per balloon
- 1 plastic bag used for fruits/veggies at your local supermarket
- 1 pair of scissors
- 1 roll of Scotch tape
- Matches
Steps
1.) Check the bag to make sure there are no holes in the bag (otherwise air will escape).
2.) Approximate the length of the Balsa wood stick needed to fit across the diameter of the bag.
Cut the second stick at the same length.
3.) Make an “X” with the two Balsa sticks and secure with a piece of tape.
4.) Cut 2 birthday candles in half.
5.) Remove a little bit of wax to ensure the wicks are exposed.
6.) Light up a match and glue the base of the wax candle (end opposite to the wick) to the Balsa
wood near the junction of the “X.”
7.) Re[eat step 6 until each section of wood has a candle (like a square).
8.) Tape the plastic bag to the four pieces of Balsa wood (candles facing in towards the bag!).
9.) Light the wicks of the four candles and check for holes in the plastic bag.
10.)
Launch your hot air balloon!