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How to Make a Small Paper Hot Air Balloon

The hot air balloon is one of the oldest methods of human flight. Using only super-heated air and a bit of clever design, a hot air balloon can traverse great distances, albeit at relatively low speeds. Explore the physics and design of the hot air balloon by building a small working model yourself, or with a class of students. You will not be able to hop in and go for a ride, but you will be able to see the physics principles at work.

Things You'll Need

Silk paper
Ruler
Scissors
Pencil
Glue
Paperclip
Cotton balls
Alcohol
Matches

Instructions

- 1
  Cut your silk paper into eight strips, all measuring 3 inches by 9 inches.
- 2
  Stack the strips on top of each other and ensure they all line up. Fold the strips lengthwise to create one long, narrow strip.
- 3
  Draw the shape of one side of a balloon on the top strip and use it as a guide to cut a balloon shape into all eight folded strips. Cut on the side of the paper that is not folded.
- 4
  Unfold the paper and lay the sheets out so they overlap one another by about a quarter of an inch.
- 5
  Apply glue to the second flap below the top layer. Fold this 1/4 flap over so that it glues to the top strip.
- 6
  Apply glue to the third strip and fold it over on top of the second. Continue this process until you reach the last flap, which should be folded around and glued to the first top flap.
- 7
  Unfold your glued creation once the glue dries to reveal a small paper balloon.
- 8
  Patch the hole in the top of the balloon with another piece of silk paper.
- 9
  Fold a paperclip into a hook shape and secure it to the bottom of your balloon with a dab of glue.
- 10
  Shove a couple of cotton balls onto the hook on your paperclip. Inflate the balloon with a quick exhale.
- 11
  Soak the cotton balls in alcohol and light them with a match. As the air inside the balloon heats up, it rises into the sky.

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