Key Concepts
Gravity
Thrust
Lift
Drag
 
Introduction
Paper airplanes are fun to make and fly. Most designs resemble miniature planes—made of folded paper, with wings, stabilizers and sometimes even flaps. These creations look like they are ready to soar. There are some designs, like the one you can try in this activity, however, that look so awkward one might imagine they would not fly at all. Find out if it will really soar!
 
Background
Although there are many different paper airplane designs, almost all of them have a flat winglike structure, which, like a traditional plane, helps create lift to keep the plane in the air. The plane in this activity, which is reminiscent of Phillip Swift's design entered in Scientific American's International Paper Airplane Competition in 1967, gets the lift needed to glide from two rings, instead of wings. Normal wings have wing tips that generate vortices, adding drag (which isn't ideal for an object trying to stay aloft). The lift-providing rings have no wing tips and so they have less drag. The streamlined shape of the "hoopster" also makes it easy to throw accurately.
 
Materials

  • Scissors
  • Ruler
  • Pen or pencil (optional, for measuring out paper to cut)
  • 3-x-5-inch index card (or a file folder or some other stiff paper)
  • Piece of printer paper (or similar stiff paper)
  • Clear plastic tape
  • Stiff plastic straw (that does no have a bendy top)
  • Measuring tape (or long string)
  • Open space—indoors or out—where you can throw a paper airplane and measure the distance traveled. A long hallway or large room might work best indoors. Outdoors, try to find a time when and area where it is not too windy.

 
Preparation

  • Use the ruler (and pen or pencil) to measure one-inch increments along the short side of your index card.
  • Cut a file card the long way into three equal strips, generating three strips that are one inch wide and five inches long. (If you're using stiff paper, use a ruler to make three strips that are one inch wide and five inches long.)
  • Place one piece of tape on the short end of one strip. Curl the paper into a full loop and tape the two short ends together.
  • Place the other two strips end to end, so they overlap a little. Tape them together to make one long strip.
  • Place another piece of tape on one end. Curl the strip into a larger loop and tape the ends together.
  • Place one end of a straw onto the middle of a strip of tape. Place the big loop on top of the straw and fold the tape up the sides of the loop.
  • This part can be a little tricky: Place another strip of tape at the other end of the straw and press the small loop very gently onto the tape. Move it around until it lines up with the big loop then press the tape down firmly. Does this look like any aircraft that you have seen before? How well do you think it will glide? Why?
  • Use the other sheet of paper to construct your favorite standard paper airplane. (See the "More to explore" section's "Paper Airplanes" link for ideas.)

 
Procedure

  • Get ready to fly your "hoopster"! Hold the hoopster in the middle of the straw, with the small "hoop" in the front. Throw it like a spear. (It may take a little practice to get the throwing technique right). How did it glide?
  • Designate a "starting line" from where you can throw both planes.
  • Throw the hoopster. Measure from the starting line to where it landed. How far did it go?
  • Repeat this at least two more times. What is the average or the median distance it traveled? Do you think it will beat the paper airplane?
  • Practice throwing your standard paper airplane. How did it glide?
  • Now stand at your same starting line and throw the standard paper airplane. Measure from the starting line to where it landed. How far did it travel?
  • Repeat at least two more times with the standard paper airplane. What is the average or the median distance it traveled?
  • Which paper glider soared farthest? Were their flight patterns different? Did you need to throw them differently?
  • Extra: Try changing the dynamics of each plane with an addition. Put a paper clip at the bottom of the small hoop. What happens when your hoopster has cargo? If you add the same cargo to the standard airplane, does it have a similar effect?
  • Make a really long hoopster with two straws. Does it fly farther than the short one? To do this, cut a little slit at the end of one straw and pinch it so it fits inside the other straw, then tape them together.
  • Make a double hoopster. Use two index cards to create two little hoops side by side on one end and two big hoops side by side on the other. Do the extra hoops make a difference in how it flies?

Observations and results
The same principles are at work in all fliers. Gravity is puling them down but at the same time air helps hold them up. If you drop a flat sheet of paper, it flutters to the ground, wobbling this way and that. To reach the ground the paper has to push the air aside. Each time the paper wobbles it lets more air flow past it and it gets a little closer to the ground. Because a flat sheet of paper has to push a lot of air out of the way, it falls slowly. Crumple that same piece of paper into a ball and it will fall straight down without fluttering. The ball of paper has the same weight as before but air can flow around it easily and it falls quickly.
 
For something to glide through the air there must be a balance between the gravity that pulls the glider down and the lift produced as it glides through the air. A design must balance these forces so that the glider moves forward, propelled by the pull of gravity.
 
What works well? What doesn't work at all? Another part of fooling around scientifically is keeping track of your results. Keep track of alterations that you try. If you come up with a new design that you like, share it!

More to explore
What Makes Paper Airplanes Fly?, from Scholastic
Four Forces on an Airplane, from NASA
Paper Airplanes, from Exploratorium
Spinning Blimps, from Exploratorium
 
Loop-the-Loop with a Hoopster was developed by Exploratorium, and is featured on page 76 of Exploralab: 150 Ways to Investigate the Amazing Science All around You. Created by Exploratorium, Exploralab is a book that takes curious kid scientists, ages eight to 12, through 24 hours' worth of household investigations, experiments and discoveries.

This activity brought to you in partnership with Exploratorium

Exploratorium