John P. Crotty
If you think of the Beach Boys when someone mentions California, then an aerobie, which is a flying ring, is the beach toy for you. An aerobie is made of plastic and rubber. It has a diameter of thirteen inches and weighs four ounces. Alan Adler invented the shape in 1984 after studying and experimenting with frisbees for almost a decade.
An aerobie is thrown like a frisbee; only it goes farther. The world record for a frisbee is 550 feet; for an aerobie, it is 1,046 feet.
Adler says that what makes the aerobie go is a special rim around the ring’s outer edge. This allows the aerobie to be aerodynamically stable. In order to be stable, the front and back of a flying ring have to have an identical degree of lift. This is hard to achieve because the trailing edge of the ring is always flying in the downwash of the front. This reduces the lift on the back and that causes the flying ring to crash. Downwash is why the tail sections of conventional airplanes are always tilted down a bit. This provides the little extra lift for stability.
An aerobie is an airfoil that has to have one characteristic at the leading edge and another characteristic on the trailing edge. The aerobie’s airfoil has to have a higher lift flying backwards than it does flying forward. Adler finally designed an aerobie with a spoiler lip on the upper edge of the outer ring. This reduced the lift of the leading edge and increased the lift on the trailing edge making an extremely stable flying ring.
Adler uses a piece of cardboard to explain the problems in balancing a flying disc. Throw a piece of cardboard straight out like you were flying a paper plane. It will almost immediately fly at an upward angle. The reason is that the aerodynamic force is concentrated towards the front end. This inclines the cardboard a bit more creating more lift and suddenly the cardboard has flip-flopped.
Now, take the same piece of cardboard and flip it away from you like a frisbee. Instead of flipping over, it wants to roll over. Since this cardboard is spinning when the air hits its leading edge, the forces act near its side.
Therefore, the design problem for the aerobie was that lift had to act at the center of gravity. Just cutting out the center of the cardboard isn’t enough, because then you would be faced with the downwash problem.
Adler says that he nearly gave up his project several times. However, since Adler, who has lectured at Stanford University, likes to work on things that he enjoys using, he continued with his experiments. Prior to working with aerobies, Adler had experimented with sailboat design. The aerodynamics engineer has since founded his own company, Superflight. By 1986, the company had already sold over a million aerobies at $8.95 each.
This unit has been about that concept of enjoying what you’re doing. I have tried to show that having fun does not necessarily have to mean playing or being involved in frivolous activities. You can work and have fun. Unfortunately, I cannot promise that you will become a millionaire like Adler. I can promise that you will become more involved in an activity. The more involved you become, the better you will learn. The better you learn, the happier you will be. So although I can’t promise wealth, I do promise knowledge and happiness.
Time Aloft Model
Paper size: 8-1/2x11 Time: 8 seconds
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Distance Model
Paper size: 8-1/2x11 Distance: 68 feet, 10 inches
(figure available in print form)
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