Build y4b

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  Here are some of the materials that you can use

  • 1 balloon (12–16 in. [30–41 cm]) 
  • balloon pump (found at craft supply stores)
  • cardboard tubes
  • 2 Mylar balloons with a ribbon (helium-filled) (you can find these at party stores, florists, dollar stores, drug stores, or supermarkets)
  • paper clips (small)
  • rubber bands
  • scissors
  • sheet of copier paper
  • straw
  • tape (clear and duct)
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  Prepare ahead of time

  • Have paper and a pencil ready to write down ideas and sketches as you design.
  • Work in an area away from windows or doors that might have drafts or breezes.
  • Think about things that are streamlined, or longer rather than wider, to go through the water or the air like a blimp. (Airplanes, birds, fish, submarines)
  • Explore how an object falls when dropped from different a position. Hold a sheet of paper so the flat side is perpendicular to the floor. Drop it. Then drop it with the flat side parallel to the floor. Which way does the paper fall more slowly to the floor? 
  • TIP: An object will fall more slowly when its flat or wide side is parallel to the floor because the object has more drag, or force, that that is resisting its movement. 
  • Make the jet. Fit a straw into the balloon’s neck. Seal it tightly with tape. Blow into the straw to test that the seal is tight. It is tight if the air stays in the balloon.
• 3
  

  Think about the challenge

  • Why is a blimp’s shape streamlined like a football?
  • How will you connect the balloons?
  • Why do blimps need to move around? (Film sporting events or news broadcasts, search-and-rescue missions, observe wildlife or wild fires in an area, perform search-and-rescue missions)
  • TIP: An object that has to travel long distances through the air has to be longer than it is wide so it can slice through the air.
  • TIP: Point the straw in the opposite direction that you want your blimp to travel. If you make very small adjustments to where the straw points, it will have a noticeable effect on how the blimp travels. 
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  Think about and write down your ideas

  • How will you control the direction the blimp moves in?
  • How will you use the jet to provide thrust, or a pushing force, to your blimp?
  • How will you control how fast air escapes from your balloon?
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  Look at the materials

  • How will you make your blimp fly in a straight path?
  • What materials will you use to make your blimp?
  • What will you use to attach the jet to your blimp?
  • What materials will you use to power the blimp?
  • TIP: Blowing up a balloon stretches the rubber, which stores energy as potential energy. When the pressurized air inside the balloon rushes out, the potential energy changes to motion energy (kinetic energy), making the blimp move.
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  Design and build the blimp

  • Decide how long you want to make the axis of rotation (distance between the balloons) on your blimp.
  • Think about how you will attach the two Mylar balloons.
  • Build your blimp.
  • TIP: To help your blimp travel in a straight path, lengthen the axis of rotation. If the axis of rotation is short, the blimp is more likely to spin and get off track.
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  Test the blimp

  • Test the weight and balance of your blimp.
  • Make it hover, or float, in one place.
  • TIP: If you want your balloon to hover, it needs to have neutral buoyancy. This means the force pulling down (gravity) has to be equal to the force floating up (lift).
  • TIP: Air is denser, or heavier, than the helium gas inside the balloons. The air pushes the helium aside and makes an upward force, or pressure, called a buoyant force. This pushes the balloon up. A balloon will stop rising when it reaches a point where the density of the air outside the balloon is equal to the density of the helium inside the balloon.
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  Test the blimp (continued)

  • Modify your blimp if it doesn’t hover in place.
  • Add or take away weight if the blimp rises or falls.
  • Retest your design.
  • TIP: Add or remove materials such as clips, ribbon, or tape to balance the weight of the balloon. Add or remove one weight at a time to find the neutrally buoyant point when your balloon hovers in one place.
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  Attach the jet propulsion system

  • Think about where to place the jet on your blimp.
  • Decide how you are going to attach the jet.
  • Choose your materials and attach the jet to the blimp.
  • TIP: If your blimp is top-heavy, it won’t stay level. Try attaching the balloon jet toward the bottom of the blimp.
  • TIP: If your balloon jet wiggles on the blimp, try taping it in two places to anchor it better and keep it steady.
  • TIP: If your blimp is not neutrally buoyant after you add the jet, try removing some of the tape or extra materials on the blimp.
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  Test the jet propulsion system

  • Decide how much power you will use to set the blimp in motion.
  • Inflate the balloon.
  • TIP: If you don’t have a balloon pump, you can inflate the balloon by carefully blowing into the straw.
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  Launch your blimp

  • Choose a clear area to launch your blimp. Send it flying!
  • Modify and adjust the rate of escaping air if your blimp doesn’t fly. 
  • Retest your design.
  • TIP: If air escapes from your jet too quickly, the initial thrust, or push, will be powerful, but it will quickly die out. 
  • TIP: If air escapes from your jet too slowly, there is too little thrust to push it forward.
  • TIP: If you overfill your balloon, chances are it might pop. More air is not always the answer!
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  Did you know?

  • It’s a Blimp! It’s a Jet! It’s Both!
    Robert Rist is a natural engineer (not a trained one). One day, as he was building a model blimp airship with his son, he wondered what would happen if it had wings on it. He took his idea to a friend, and together they turned the idea into Ohio Airships, Inc.—an aircraft manufacturing company.
    
    The company created a 120-foot (37-m) long prototype of a half-blimp, half-jet airship called the Dynalifter. The airship is kept up in the sky with balloon-like cells filled with helium and is equipped with wings that help provide lift. In 2013, the prototype ed tests and got the go-ahead to be turned into the real thing. The real Dynalifter will be over three times bigger than the prototype. Now all Ohio Airships has to do is raise about $40 million so they can get the job done!
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  Try this next!

  • Race against yourself. Modify your blimp by making a longer or short axis of rotation, or add decorations to your blimp to see how the decoration’s weight effects the distance your blimp flies.