Why Do Flying Rings Go So Much Further Than Frisbees?

Developing a Hypothesis

1. Do your background research and learn about the forces on flying disks and rings in flight. How do the forces differ between the two? How do you think this will affect flight distance?
2. Carefully examine commercial flying ring and flying disk products and note differences between them. For each of the differences, think about the forces acting on these objects as they fly, and try to predict the aerodynamic consequences.
3. For example, an obvious difference between the disks and rings is the open space in the center of the ring. What aerodynamic effect(s) result from opening up the center of a disk?
4. Test your hypothesis by building a series of rings (3–5), which systematically vary the design element of interest. To continue with the example above, you could build a series of rings with successively smaller open diameters in the center.

Construction Tips for Paper Rings and Disks

1. You can use Bristol board (recommended) or paper plates to make your flying rings/disks. (If you use paper plates, see the Bibliography for a way to find the center of a circle, so you'll know where to put your compass point.)
2. Use your compass to draw circles for your rings. Building up your rings from multiple layers will make them stiffer, and they will fly better (see below).
3. If you want to add weight to your rings, try extra laminations of the appropriate diameter, or glue pennies or washers in between layers. (Sobey, 2000, 55)
4. When building your flying models, change only one design variable at a time. For example, if you are investigating the effect of the diameter of the open center, all of the rings should have the same outer diameter, mass, edge curvature, etc. Only the size of the center opening should change.
5. How can you keep the mass constant but still have more material covering the center opening? The key is to build your rings out of more than one layer of paper (laminated construction). Laminated construction has multiple advantages.
   1. Your design can redistribute the material between different layers to keep the mass constant. For example, as you add material in the center of one layer (to decrease the open diameter), you remove an equal area of material from another layer (or layers). (It's easy to calculate how much mass you are adding. Since the paper has uniform thickness, the mass will be proportional to the area. The area of a ring is just the area of the outer circle minus the area of the inner circle.)
   2. You can explore how the distribution of mass (e.g., more mass towards edge vs. more mass towards center) affects flight performance.
   3. By gluing together two or more layers (laminated construction), you will end up with a stiffer ring or disk, which will fly better.
   4. A way to further increase stiffness is to compensate for the "grain" of the paper by rotating the disks relative to the original orientation before gluing them. Most papers bend more easily in one direction than the other (usually there is more resistance to bending in the long axis of the paper). If you systematically rotate the strong axis of the separate layers, your finished ring will be stronger. For example, with a two-layer ring, rotate one layer 180°/2 = 90° before gluing. For a three-layer ring, rotate each layer 180°/3 = 60° relative to the previous layer.
6. Glue the layers together carefully with white glue. Spread the glue evenly and make sure all edges are glued down tight.
7. Wait for the glue to dry (overnight is best) before test-flying.
8. If you want to curve the edges of your flying rings/disks, you can use the a piece of silverware (like the curve on a spoon where the bowl meets the stem). Work at the edge of a table, with the edge of your disk sticking out. Carefully bend the rim of your ring with the spoon. Rotate the ring and bend a uniform curve all around the edge. (Sobey, 2000, 57–58) Alternatively, make a curve-forming tool by cutting a plastic lid in the desired shape.

Test-Flying and Measurement

1. For measuring your flights, you'll need a tape measure and a helper.
2. If your tape measure is not as long as your typical throw, make a longer tape measure using a piece of string. Mark off regular intervals with tape labels and a marker, and you're in business.
3. Do your best to keep the conditions for all of your test flights constant. Try to throw with the same arm motion and speed for each ring.
4. Do at least 10 test flights for each ring. Record the results in your lab notebook.
5. Make one or more graphs to show your results. In this example, you could graph flight distance vs. center open diameter.