Teach Engineering: Rubberband Helicopters

The rubberband-powered helicopter is a favorite of my students because of the ease of construction and the exciting end product. 

Students will investigate the ideas of lift, drag, and stored energy as they each build their own helicopter. Furthermore, students will learn how the aforementioned ideas work together to create a successful flying machine. Promoting the process of learning physics through direct experience and experimentation is the ultimate goal of this project.

Materials and Tools:

6" hook nose propellers
Craft sticks
Paperclips
Contest rubberband
Colored construction paper (or other rigid yet light material)
Masking tape
Scissors

The cost per helicopter is around $0.65 when 50+ propellers are purchased for the bulk discount.

The Lesson Plan:
Total time from start of lesson to end of cleanup is approximately 40-60 minutes, depending on age level and how the project is conducted.

Show students how the helicopter works right away to quickly get their attention. Explain how the helicopter works and the function of each part as you demonstrate it.

How It Works:
1. Energy is stored in the sport rubber by winding the propeller.
2. When flown, the sport rubber rapidly releases its energy by unwinding, which turns both the propeller blade and the paper cutout.
3. The paper cutout pushes against the surrounding air, which creates horizontal air resistance, or drag. This makes it harder for the cutout to spin. Because the cutout does not spin as easily, more energy from the sport rubber is released into the propeller, which is much easier to turn. In this way, the paper acts like the rear rotor of a real helicopter
4. As the propeller spins rapidly, it begins to create lift by pushing air downward. With enough energy, the helicopter will fly in whatever direction it is pointing.

Step by step, construct a helicopter in front of the students. When you're finished, show students the proper technique to flying the helicopter. Tell your students that flying the helicopter takes practice. Hand out materials and allow students to begin building.

Take the students outside (or to a gymnasium) to fly their helicopters after everyone has finished. Bring scissors, extra paper, tape and sport rubber with you. Remind the students how to fly the helicopter upon arrival.

Adapt this lesson to fit your class. Middle school students will find more challenge in figuring out how to build a helicopter without guided practice. Perhaps you prefer to build first, then follow up with a Q+A to understand the theory. Do what works for you.

Encourage the students to experiment, be willing to fail in the pursuit of the perfection. When everything is done you're students will have a first-hand understanding of how helicopters work and a fun new toy!

Tips and Troubleshooting:

- Try it at home at least three times before bringing it to class!
- The number one reason helicopters fail to fly is due to simply not winding the rubberband enough.
- The second biggest reason is caused by letting go of the whole helicopter at once. When I show students how to fly the helicopter, I say, "Let go - let go," as I release the top and bottom. Tell your students that verbalizing "Let go - let go" in one's head or out loud can help coordinate one's hands.
- You may want to tie the sport rubber for younger students during your prep time.
- Try making templates of bird wings or a helicopter silhouette. For one Halloween, I made cardboard templates of bats. For added flair, the project was renamed "Baticopters."
- In my experience, a long rectangle approximately 6" x 1.5" made out of cardstock is the most efficient shape and material.
- Cutouts which span less than 3" typically do not perform well.
- With a little practice, students can throw the helicopter as it is being released for additional height
- Spinning propellers can get caught in long hair.
- Stay far away from buildings, trees and fences!

Here's to you!

Thanks for taking a look at my Instructable. I would love to hear about your experiences with this project, as well as your comments and criticisms. Enjoy teaching!