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Harnessing the Power of Air
Harnessing the Power of Air
BAG BALLOONS ~ BUILDING A HOT AIR BALLOON ~ WINDSOCK
Hot Air on the Rise
Hot Air on the Rise
Hot air balloons are one of four different types of aircraft falling under the category of "lighter than aircraft."
There are two ways a balloon can rise:
A balloon can be filled with a gas that is lighter than air. Helium would be an example of this type of gas. Helium is the second lightest element and is much lighter than air allowing a balloon filled with helium to float. The main sources of helium are natural gas fields that can be found in Texas, Oklahoma, and Kansas.
A balloon will also rise if it is inflated with air that is heated sufficiently to make it “lighter” than the air outside the balloon. Heating air makes it less dense, causing it to become essentially “lighter”. Gas balloons and hot air balloons float because they are lighter than the air they displace.
In this activity you will have the chance to investigate how heat can change the observable characteristics of air through constructing a working model of a hot air balloon.
What you will need:
Plastic bag (at least the size of a 4-gal trash bag; can substitute with a plastic grocery bag)
Paper clips
Stickers or miscellaneous decorations
String
Hair dryer
ACTIVITY: Bag Balloons
ACTIVITY: Bag Balloons
Get your supplies ready.
Decorate the outside of the plastic bag which will become your hot air balloon. NOTE: The decorations you choose should be small and light because they will add weight. Stickers work pretty well. You could also use markers to decorate your bag.
Tie a string around the top of your hot air balloon. (See the picture example on the right.)
Now, add paperclips to the bottom of the hot air balloon. Try to make them evenly spaced to help with balance. This will help you get the right shape to your bag when filling with hot air.
Hold your hot air balloon over the hair dryer and turn it on the high setting. This definitely requires more than one set of hands. Get some help if you can from your family or friends.
When you feel the hot air balloon tugging you should release the balloon. The hot air balloon has become buoyant. The hot air inside the balloon is lighter than the air in the room and so it will begin to float.
Key Events in the History of Ballooning:
Key Events in the History of Ballooning:
September 19, 1783 – The Montgolfier brothers launches an unmanned hot air balloon from Versailles with a duck, sheep, and rooster as the first air travelers
January 19, 1784 – Joseph Montgolfier made his only recorded flight in Le Fleusselles. This balloon is believed to have had the ability to carry more than 30 people!
January 7, 1785 – Blanchard and Jefferies made the first crossing of the English Chanel by balloon. This flight included the first letter delivered by air mail.
July 1785 – Jean-Francois de Rozier attempted to cross the English Chanel in a hybrid gas/hot air balloon. Tragically, this was also the first recorded aviation accident.
January 9, 1793 – Blanchard moved to America where he piloted the 1st known balloon flight in North America. It's believed this 1st flight was witnessed by George Washington.
This second activity (Building a Hot Air Balloon) will require assistance from your family. If you choose to do this project, be prepared that it will take a few days to complete. If you test launch your paper hot air balloon outside, please be aware and steer clear of power lines and do not launch within the vicinity of an airport.
Building a Hot Air Balloon
Building a Hot Air Balloon
There is something truly magical about a hot air balloon and the opportunity it provides a person to soar above the ground simply through utilizing the basic scientific principle that warmer air rises in cooler air. Hot air is less dense than cold air, which is why hot air rises and cold air sinks. Another way to envision this is that hot air rises because sinking cold air drops below it, filling up that space and pushing the hot air up.
How is hot air less dense? Well, as molecules of air heat up there is a transfer of energy that makes the molecules move faster and expand outward. The original amount (or mass) of air molecules now takes up much more space within the balloon. With more space now between each molecule, it becomes less dense than the colder air molecules which are not moving as fast and, as a result, are located closer together.
To keep a hot air balloon rising, you need to continuously reheat the air inside the balloon envelope. In real life hot air balloons, pilots do this by firing a burner that is positioned under the balloon skirt burning the propane that is stored in lightweight containers inside the basket. It then has an intake hose that runs to the bottom of the cylinder to draw the liquid out.
In this activity, you will learn more about the design and heating of a hot air balloon. You will definitely need to ask for some help. Don't be discouraged if it doesn't work out the first time...second or even third time. Use the engineering process to think about why you think it may not have worked and then make some adjustments to your design to see if you can make it work. Watch the first video from Drew as she steps you through the changes and adaptations she tried. The instructions for what she tried can be found below.
The remaining videos include step-by-step instructions to give you another example of how to create a tissue paper hot air balloon. In this second example, the teacher uses what looks like a camping stove with a long cylinder over it to serve as a vent to funnel the super heated air up into the balloon. If you notice, only the teacher uses this heating method and not his students. This type of heating method really needs to be done by an adult. Good luck!!!
Exploring Meteorology
Exploring Meteorology
A wind sock is a type of kite used to detect wind direction. It is a tapered tube of cloth that is held open at one end by a stiff ring. Wind is directed down the tube, causing the narrow end to point in the same direction the wind is blowing. It's like an arrow pointing out the way the air current is flowing.
Brightly colored wind socks are used at airports to help pilots determine the wind direction along the ground. Pilots preparing for takeoff or landing observe wind socks to determine wind direction and speed, because they want to land and takeoff facing the wind to reduce the takeoff and landing distance.
Meteorologists use wind socks to help forecast the weather. Some factories that must regulate the amount emissions they may put into the atmosphere use wind socks monitor wind conditions, wind speed and direction will have an effect upon the distance and direction the emissions will travel.
In this activity you will construct and use a simple wind sock to measure wind direction and speed.
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