As any verteran disc golfer knows, the flight characteristics of a disc are sensitive to many different parameters. One good tree hit and your favorite driver might never be the same. Accurately modeling disc flights begins with getting out and capturing data of real discs doing their thing.
We capture the behavior of a disc mold using a special video camera setup. Multiple video cameras are placed around the tee. These special cameras capture high def footage at high frame rates. Through a special calibration process, the 3D position and orientation of the disc can be calculated from the pixel position of the disc in the videos.
For each disc, multiple throws are captured to cover a variety of speeds and release angles. Multiple discs from the same mold are thrown as well to cover the variation in flight characteristics. Check out the video below for an example of data collection.
Modeling Disc Flight
In combination with the real disc data collected by video, we've developed a computer model of how discs fly. The model needs release parameters for the throw like disc speed, hyzer angle, and nose angle. With these parameters, the model calculates the forces on the disc throughout the flight to get a realistic flight shape.
The aerodynamic signature of a particular disc is unknown and needs to be set based on data of actual disc flights. Once the aerodynamic signature of a disc is determined, the computer model can be used to predict a disc flight for a range of conditions including speed, hyzer angle, nose angle, wind, temperature, and elevation. The plot below is an example disc thrown in the exact same way except that the hyzer angle is varied. Press the Animate button to see them fly!
Putting It All Together
With the combined powers of the actual disc flight data and the computer model, we have all we need to simulate realistic disc flight. Using a guess and check procedure, our software guesses the aerodynamic signature of a particular disc and checks to see how well that signature matches the actual data of the disc flight path. This process is repeated over and over again until the software finds the aerodynamic signature that best matches the disc flight data.
With a good match for the aerodynamic signature, the computer model has the information it needs to predict the flight of that particular disc for a variety of arm speeds, angles of release, and environmental conditions. The plot below shows the flight paths of three actual disc throws compared to the simulated disc throws for the same conditions. The simulations are spot on!