Whether throwing the Frisbee around at the beach or playing a riveting game of Kan Jam, I assume most people have used a Frisbee over the course of their lives. Thinking about it more deeply, I wondered to myself how these discs are able to fly so far, and more significantly to me, how are people able to throw them in straight lines?
While flying through the air, Frisbees are impacted by both drag and lift forces, similar to how a wing or propeller would be influenced. The most important factor in a Frisbee's flight is the spin of the disc. Without this, the Frisbee would simply flutter to the ground and make for an incredibly unexciting toy. The spin makes it so a Frisbee can be stable and travel long distances, similar to the analysis of a hockey puck that I did a while back. In that example, the spin made for the puck to be more stable and, in turn, more accurate in its flight. The Frisbee acts in a similar way. Generally, the lift on the front part of a Frisbee is greater than the lift on the back, which causes the Frisbee to reach greater heights, and causes a torque on the disc. The torque on the Frisbee is what causes it to drift to the left or right in flight, the main reason why most Frisbee flights aren't perfectly straight. If it is straight, the Frisbee was likely impacted with a great initial angular momentum, and the lift on the disc is insignificant. A phenomenon that you have probably noticed in your use of Frisbees is that when someone throws the Frisbee higher in the air, thus giving it more "lift", then the Frisbee is likely to have a large tail or hook within its flight. If a Frisbee is released at a higher angle, it will go much higher in the air but travel a much shorter distance, maybe even ending up behind the thrower, due to the drag force acting on the disc. This is what causes some Frisbee throws to be sort of like a boomerang. If you want the disc to travel further distances, then you'll want to apply a greater initial velocity to the Frisbee rather than a greater launch angle.