Fred Morrison died on Tuesday at the age of 90, one of those people you may never have heard of, but really should have.
Morrison invented the Frisbee.
Since millions of these and other flying discs have been sold since the 1950s, it’s perhaps a bit humbling to discover, though, that even though throwing a Frisbee well is a skill that can be acquired, nobody has pinned down all the details of the science involved.
Morrison, born in Richfield, Utah, said the inspiration for the Frisbee went back to a Thanksgiving Day picnic in 1937 when he and his girlfriend (and future wife), Lu Nay, began throwing the lid of a popcorn tin back and forth.
They soon found that a tin cake pan flew even better, and shortly after that started selling “Flyin’ Cake Pans” on the beach at Santa Monica, California, for 25 cents each.
Morrison flew P-47 Thunderbolts during the Second World War, no doubt developing a new appreciation of aerodynamics, and shortly after the War, in 1946, created his first flying disc, the Whirlo-Way. In 1948, with backing from another former pilot, Warren Franscioni, he began molding what he then called the “Flyin’ Saucer” in plastic.
In 1955 he and his wife began producing their own discs with a deeper, thicker rim, calling them “Pluto Platters.” Wham-O bought the rights in 1957, and changed the name to Frisbee (which Morrison didn’t like), the name apparently based on the pie tins from the Frisbie Pie Company that students from East Coast colleges had long been flying.
A Wham-O designer, Ed Headrick, added the flight ridges to the top of the disc in 1964, improving its stability and speed.
So…how does a Frisbee fly, exactly?
Like an airplane wing: it generates lift by creating a difference in air pressure between its top and bottom sides. The top of a Frisbee is slightly convex, and the bottom is flat. That forces the air flowing over the top of the disc to move faster than the air flowing beneath it. Faster-flowing air has a lower air pressure, and so the higher-pressure air underneath forces the disc up. This is known as Bernoulli’s principle.
But a Frisbee is also very different from an airplane wing. Its curved rim disrupts the airflow on the bottom of the disk, creating turbulence. This means the airstream at the back of the disc tends to move much more slowly than the airstream at the front, creating an imbalance in pressure…which is why Frisbees often turn over in flight.
The other big difference between a Frisbee and an airplane wing is that the Frisbee is spinning. This is why the Frisbee, when it does turn over, tends to turn onto its side, rather than flipping front to back: spinning objects, through something called gyroscopic progression, tend to show the effect of a force in a spot perpendicular to where the force is applied.
At the same time, though, spinning helps the Frisbee stay stable. A spinning object resists being tipped. This “angular momentum” is why a moving bicycle, with its spinning wheels, is stable, but a stopped bicycle is not.
Some of the subtleties of a Frisbee’s flight, such as why it can make slight turns at the end of its flight, are still not well-understood. In the past few years, researchers have put Frisbees on a motorized rod and spun them in a wind tunnel to try to learn more, and have discovered that how fast a Frisbee tips over in its flight depends on the angle of attack (you want to tip it slightly upward as you throw it) and how fast it spins relative to its airspeed. A really dedicated and mathematically minded Frisbee thrower could, using the results of this study, figure out exactly what angle the Frisbee should be thrown at to make it go as far as possible or stay in the air as long as possible.
This kind of work has more “practical” applications: space probes, for instance, are often spun to improve stability, and Frisbee studies have figured into work on their design.
But who cares? Morrison’s invention has brought more happiness to more people over the years than any number of “practical” inventions. And for that, he deserves your thanks next time you spend a sunny afternoon on the grass with a Frisbee.
Actually, he deserves your thanks twice: once for yourself, and once for your dog.