We’ve been experimenting with zip line racers in the Maker Space this week, trying out different body size configurations, wings, flaps and rubber bands. To conserve materials (yay environment!) we kept this a make and take-apart program, but we’ve had lots of “how-to” requests from visitors and since we aim to please. Just a note, this activity was inspired by the fine work of Lance from the Young Engineers Workshop. You can learn more on instructables, as well as check out his other great projects.

First, you’ll need to gather your materials. The “standard” zip line racer body that Lance designed uses five popsicle sticks, but you can add more or try less as you get comfortable with designing. You’ll also need a rubber band powered propeller which you can easily find online and in hobby shops, 1 paper clip (the kind without the notches in them), 2 small or medium binder clips, a rubber band, masking tape, hot glue, some paper or cardstock and cord for the zip line (we used nylon but fishing line or any other monofilament type cord will do).

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Materials:
  • Popsicle sticks (as few as 3 would work, these instructions use 5)
  • Rubber band powered propeller
  • 2 small or medium binder clips
  • 1 Paper clip
  • Rubber Band
  • Hot Glue
  • Tape
  • Scrap Paper
  • Cord for the zip line (we used about 20 feet)

You’ll want to start by making the body of your zip line racer. Lay out two popsicle sticks end to end on a protected work surface.

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Apply a strip of hot glue down the length of the third popsicle stick and center it as best you can on the two sticks on the table. This will make sure your body is nice and strong and can withstand the torque from the rubber band.

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Next you need to partially unfold the paper clip. The easiest way to do this is to hold the big part between your thumb and index finger on one hand, and pinch the little inside part with your thumb and index finger on the other and pull down slightly until you’ve made an “L” shape out of the bend.

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Add some glue to one end of your racer’s body and place one half of the paper clip firmly on top of it. Add another dab of glue over the metal, just to make sure it’s really secure. This will be the hook that holds your rubber band taught.

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While that’s drying add a small dot of hot glue to either side of the center support stick. This is where you’ll glue your racer uprights.

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Place one popsicle stick on each glue dot, trying to keep them as straight as possible (you want them perpendicular to the body).

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After all the hot glue is dry you need to apply some masking tape to the paper clip/hot glue joint. This keeps the paper clip secure and stops the rubber band from ripping the hook off the end of your racer. A small three inch piece will do. Just wrap it around your paperclip and the popsicle stick, making sure not to accidentally tape the paperclip closed.

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Next, you need to add the propeller and the rubberband. Attach the propeller at the end opposite the paper clip, making sure the little metal loop is hanging down away from the uprights.

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Hook your rubber band on the propeller and stretch it back to the paperclip hook and attach it there as well. You’re almost done!

Finally, you’re going to need some drag in order to get your racer going. Use your piece of paper to create wings or some interesting shape (give it some flair!) or, just cut it into a rectangle like I did. Span it between the two uprights and tape it on.

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Add the two small binder clips to the tops of the uprights, these will be the “hooks” that grab on to the line.

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You’re now ready to race!

Place your zip line somewhere high enough that it’s relatively safely out of the way, but low enough that you can still reach it (even if that means you’re using a stepstool). You want your line to be tight so your racer doesn’t have to fight the slack. Ours is about twenty feet long but you can make yours as long as you’d like.

To get your racer to fly you need to wind up the band. With the propeller facing you, wind it clockwise (to the right) until you have a double coil on the band. You can see the difference between a single and double coil in the images below.

 
Single Coil
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Double Coil
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Hang your racer on the line using the two binder clips. You’ll want to hold the propeller with one hand while you open the clips over the line and clip them onto the uprights.

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Give it a little slide to make sure your racer is hanging freely. When you’re ready to race, hold it by the propeller between your thumb and index finger. Then, just open up your fingers (without pulling down on the racer) and watch it fly!

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Now that you know the basics you can experiment with different body sizes, rubber bands, wing/drag configurations and anything else you can really think of.

We hung two zip lines (one over the other) to set up a race track type environment. In order to keep this fair, the lines need to be at the same angle, and the racers have to be started evenly. Build one with a friend or a family member and see whose goes further or faster!

 

Other challenges to try

Add a load! Create a device to carry a load (a basket or a tray, or even just a seat) and add someone/thing to go along for the ride. I’m partial to plastic dinosaurs, but you can be as creative as you like with this. Can your racer carry its passenger to the other end safely? Will it have enough momentum? Try it out and see!

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Try putting your zip line at an angle and see what type of racer is able to go the highest. (Note: this will be much harder to do if you’re using fishing line as the friction between the clips and the line will be next to nil and the racers will want to slide back down. Hooray for gravity!)

Try smaller and larger racer bodies and see what works best.

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Reverse engineer! Try a racer with the propeller in back instead of in front. Does this make a difference? How would you have to change your design to make this work as well as the front facing propeller?

Check out what our visitors have made on our Instagram @makerspace and add your creations too! Let us know if you come up with any other creative challenges and keep making!

Until next time, happy flying!

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– Annalise