Design, build and test hot air balloon.

This activity is designed for students to use a variety of skills including critical thinking and questioning, testing and redesign, researching balloon design, researching component designs and analysis of final classroom designs. Scientific terms used are air density and buoyancy. Students can use the scientific method to determine design features.

This lab activity should be successful for students in grades 7-12. Students can work in groups of 2, 3 or 4. Students in a group of 4 should work in pairs on different design elements. This lab will take a minimum of 2 hours but can be modified or extended in time. Hot glue guns and a hair dryer are the basic equipment needed. Students should have knowledge of buoyancy and density.

This lab activity should be successful for students in grades 7-12. Students can work in groups of 2, 3 or 4. Students in a group of 4 should work in pairs on different design elements. This lab will take a minimum of 2 hours but can be modified or extended in time. Hot glue guns and a hair dryer are the basic equipment needed. Students should have knowledge of buoyancy and density.

Activity Description:

Hot air balloons made from plastic bags are easy to build BUT success of flying is a challenge. There are numerous websites covering the history of hot air balloons and how to design and build a hot air balloon with plastic bags. Students will have to determine or formulate a hypothesis on how to build a hot air balloon. The best design will be the largest volume with the least mass, lightest system to hold the heat source and the lightest heat source which produces the greatest amount of heat.

You will provide students with a variety of plastic bags, construction materials, and heat sources.
A. Provide a variety of plastics bags including heavy garbage to light garbage bags plus any others you can find. However, make sure you ask your local dry cleaner for dress or wedding gown bags. These will be the least density considering the mass divided by volume. Please note dry cleaner bags have small holes on the top which students will have to seal in some way.
B. Students will have to provide some sort of framework to hold the heat source underneath the plastic bags. There are many different methods to do this but, again, the weight is a factor. You should provide students with plastic straws (case quantities available at Sam's Club), string, metal wire, thread, aluminum ash tray from local dollar store, popsicle sticks, and glue and anything else students could use to build their design.
C. Give students options for their choice of heat sources. Small birthday candles provide significant heat but burnout fast. I use a hair dryer to pre-heat the air in the plastic bag. You can put Vaseline on cotton balls, sterno, wooden matches, just for a few suggestions.

You should introduce the lesson with the history of hot air ballooning. Students can fill out a questionnaire on what they know about hot air balloon. How or why do they fly, how are they designed, and where have they been used in history (Civil War).

Now have students brainstorm about what are some key elements in a hot air balloon design. Have students build separate components of the hot air balloon. They should design and test:

A. The balloon structure looking for flaws and thinking about stability

B. Design and build different ways to hold the heat source under the balloon

C. Test different heat sources for maximum heat with minimum mass.

Now have students do research on the internet for other ideas and successful designs. How do the student designs compare? Emphasis can be on "Why reinvent the wheel if it has already has been done?" You can show students several pictures of flying hot air balloons to motivate and inspire them to continue but even with the new ideas, having a successful design that flies will be challenging.

Materials needed:

In addition to the materials listed above, you should have:

-Scissors

-Scotch tape

-Electric hair dryer

-Glue (different types)

-Hot glue guns

-An electric knife is very useful in cutting and sealing the plastic bag.

You should build your own prior to the activity and test-fly it. Once you have a successful flying design, you can show students the design features that made your hot air balloon a success.

Procedure:

Students are to design, test and redesign a flyable hot air balloon. This activity will require collaboration, testing and frustration. Review Thomas Edison's method of discovering the light bulb. Designs just don't happen, they evolve.

Conclude the activity by test flying all designs. Review the best design features of all balloons. If they don't fly maybe they are rugged. You can also review designs made from BLACK garbage bags and how they could be used to build a solar hot air balloon. Stress the positives and what modifications could be done to improve the design. Introduction Question Sheet (Microsoft Word 31kB Sep10 08) Elements of design worksheet (Microsoft Word 27kB Sep10 08) History, use and design of hot air balloons (Microsoft Word 211kB Sep10 08) One method: Step by step in building a hot air balloon (Microsoft Word 276kB Sep10 08)

Use the lightest materials possible. Large dry cleaner bag or purchase .35 mil (9 micron) bags from Home Depot. Use the electric knife to cut to size and seal the plastic bag. You can use the plastic straw frame work to hold the candles or a thin aluminum ash tray to hold the Vaseline soaked cotton ball. The aluminum is suspended from the plastic bag by three pieces of thread. Do not use string or wire because it just adds weight. Paper candle balloons are used annually in Thailand in their celebrations. It is a challenge to get it to fly but it is possible.

Review sheets can be handed out for students to assess student designs. This can be done prior to flight testing. On the sheets, students can predict if they see design elements that will allow the balloon to fly. They can look at the components, the parts, and critique each part. Students who designed the balloon can answer questions as to why they made certain choices. Their answers can be part of the assessment. I review the entire process in order to determine credit. I look for if they made significant changes from original to final design based on what they learned from research and testing. Finally, test flight: Did the balloon fly? I usually give extra credit for a successful flight. Student should have had success along the way but not all designs will fly. You can allow students to go back on their own time to redesign or change elements in order to get the extra credit. Many will do this after seeing other designs and ideas.

I.B. 1, 2 Design and complete sci exp using sci method.
II. C. 2 Differentiate between kinetic and potential energy