We recently got foam discs for spin up. After some testing, it became apparent that these are not frisbees. They are symmetrical discs, which seem to generate zero lift when tossed through the air. We came to this conclusion through a few tests as well as some research.
We compared different throwing methods, and different objects to figure it out. We threw the discs in three different orientations: like a frisbee, vertically, and like a catapult. We compared these throwing methods to a tennis ball and frisbee. When comparing different objects we tried our best to throw them in the same way and took some notes on the movement of the objects.
The same person at approximately the same power for each throw.
- We threw a disc and a tennis ball in the way you would throw a frisbee, and they approximately traveled the same distance. The disc was stable while it was spinning, but did arc, while the tennis ball traveled in a straight path.
- Throwing a frisbee and a disc with a frisbee throw resulted in the frisbee going MUCH farther than the disc.
- Comparing the disc to a ball in an overhand throw(see fig 2) resulted in the disc being slow and not traveling very far while the ball moved in a parabolic trajectory.
- Throwing a disc in a vertical orientation(see fig 3) in an overhand throw results in the ball going further than the disc. I think that the way we through this one compared to the ball is a bit different because it’s weird to try to flick a ball.
- Throwing the disc underhand while flicking the wrist(fig 4) made the disc go further than the ball, but this might just be the fact that the flick of the wrist is easier for the disc than the ball.
- Throwing a disc and a ring like a frisbee resulted in them going approximately the same distance.
Figure 1: All thrown objects.
Figure 2: overhand throw orientation disc horizontal.
Figure 3: overhand throw orientation disc vertical.
Figure 4: underhand throw with flick of the wrist.
An airplane wing (and a frisbee / Nerf gun disc) generate lift through the air by forcing the air to travel a longer distance over the top than the bottom, as the frisbee is traveling through the air. These are symmetrical, thus they cannot generate lift while traveling through the air and do not “fly” like a frisbee.
One might bring up the question of stunt planes, and ask “how do the stunt planes fly upside down?” These planes have symmetrical wings and instead rely on the engine to pull them up when they are flying upside down. In this case, the angle of the wing is facing upwards and the air is being pulled underneath the wing, by the power of the engine. Without the engine pulling the plane forward, there would be no lift and the plane would fall. An extreme example of this is when the airplane is flying straight up into the air, just on the power of the engines.
The rotation of the discs does have a gyroscopic effect in “conserving” angular momentum. I.E. a disc tossed parallel to the ground, will tend to stay parallel to the ground while it is spinning – much like someone at the circus spinning plates on the ends of sticks.
Bottom line, the dynamics of these discs will more closely resemble those of a tennis ball than they do a frisbee, but key aspects of the discs, gyroscopic stability, resemble the movement of a frisbee.
I would like to learn more about the dynamics of these discs and how they fly, so I might do more tests with less human error at some point.
This started with us looking at the kinematics graphing tool topic that @TheRichDarth. @LastMinuteFix brought up a paper on the physics of frisbee which brought about our debate if discs are frisbees.