Hot Air Balloons

power point

handout

After learnning the history of hot air balloons and a few key principles, students design and construct a model hot air balloon using only tissue paper and glue.

Balloons work on the very simple principle called the Law of Buoyancy. That is, hot air rises is less dense than cold air; thus, hot air rises. A balloon has a set of burners to heat the air, which is then trapped by the envelope. As the air is heated, the lifting force eventually overcomes the force of gravity and causes the balloon to rise. The balloon will not rise forever though since the air in the envelope will cool and the balloon start to fall. As the balloon rises the air pressure also decreases. This means that there is less cool air to support the balloon so it will begin to drop again. By varying the temperature of the air in the envelope the balloon's altitude can be controlled.

Construction

Launching Balloons

Hot Air Balloon Design Challenge

Objective- Design and engineer a hot-air balloon to fly as high as possible.

Construction :
1. The hot-air balloon must be made using only tissue paper and glue.
2. The hot-air balloon must be at least 2 feet tall when inflated but no more than 9 feet tall when inflated.
3. The hot-air balloon can be of any shape desired.

Competition :
1. The competition should be held on a calm, cool morning. Temper-atures of 40 to 50 degrees are ideal.
2. The competition should be held in an area clear of buildings, wires, trees, and so on.
3. Students will draw to determine order of launch. The earlier balloons may have an advantage due to slightly cooler temperatures.
4. The hot-air balloons will be inflated using the Pitsco Hot-Air Balloon Launcher using propane gas.
5. Students may ask for a helper when inflating the balloon. This is especially necessary for larger balloons.
6. Students may release the balloon when they feel it is ready. However, there will be a four-minute time limit on inflation.
7. The altitude gained by the balloon will be determined by the teacher using trigonometric triangulation. An Estes altitude finder is recommended.
8. The hot-air balloon that goes the highest wins.

Variations :
~In case of rain, do the activity in the gym or a tall auditorium, and time how fast the balloons rise to the ceiling. The fastest time wins.
~Compete to see which hot-air balloon stays in the air the longest. This may be done inside or outside.
~Have a competition to create differently shaped hot-air balloons. Have the art teacher help judge these balloons.