Blimp on a String

Have you ever ridden in an aerial tram? a ski lift? They both ride on a cable through the air. We're making a blimp that rides through the air on a string. Once you've finished your blimp you can use it to move things from one side of the room to the other and conduct experiments to how the string's angle and the weight of the cargo change the blimp's speed. The blimp is made out of a paper balloon so you'll have to be careful when playing with it not to crush the balloon. For younger makers see our Airplane on a String tutorial.

• Straw
• Paper
• Scissors
• Tape
• Writing Utensil
• Glue
• String

The blimp's balloon will be built around a the straw. The string will be threaded through the straw and the blimp will travel by zipping along the string. The straw will have to remain clear on both ends so make sure no paper or tape gets in the way of the openings.

You will need to cut out 8 leaf (or lanceolate) shapes that are the same length as your straw and about 1"-1.5" wide. Glue two lanceolates to each other in the middle, overlapping slightly. (photo 2) Once the glue is dry you need to attach the ends of the two laneolates together with glue or tape. As you do this the shapes will bend to form a boat shape. (photos 3 & 4).

Once you have one pair of laneolates attached into a boat shape make another. Now attach your two boats together with either tape or glue. (photo 5). Do this a second time so that you have two boats made of 4 lanceolates each.

Now you need to attach the boat shapes to the straw. You want to only attach the tips of the boats so you don't need much tape. Tear off a piece of tape and use your scissors to cut it in half. (photo 2) Leave a bit of the straw sticking out from the balloon so that it's a bit easier to thread your string through and add your details later.

Attach the second boat shape to the straws the same way as the first. Now tape the two boat shapes together to make your full balloon.

You blimp will need a way to fly through the air. We choose a propeller on the back of it. You can make whatever propulsion you'd like: propeller, jet engines, rockets...

Now's the time to add details to your blimp. You can add fins, ropes, sensors or other instruments. It's up to you.

The gondola is where the passengers on a blimp sit. You can make it look however you choose. Keep in mind that a larger gondola will fit more passengers. You can attach your gondola to the blimp with some tape and string. It may be easier to do this while your blimp is suspended on the string.

Cut a length of string just a bit longer that the distance your blimp will travel, that way you'll have room to tie it or tape it onto things. Thread it through the straw on your blimp. Test it out. Does the blimp fly when the string is level? Does the blimp fly up the incline in the string without help?

Find passengers for your blimp. Add your passengers. How do they effect the speed of your blimp? Do they stay in the whole trip? Have fun experimenting.