Intro

The mission of this project, sponsored by Hooligan Discs, is to apply a rigorous engineering design process to develop the “farthest flying disc on the market.” The project entails the creation of two distinct driver discs: one that conforms to the technical standards of the Professional Disc Golf Association (PDGA) for competitive use, and a second, unconstrained experimental disc designed for maximum possible distance. My role was the design and development of the PDGA regulations “constrained” disc.

Our team followed traditional requirements, ConOps, and basically that whole systems “V.” However, my goal always remained simple: I needed to make the farthest flying PDGA-legal disc on the market.

Design and Analysis

Initial exploration involved materials, manufacturing, and design trade studies. The aerodynamic theory for the disc golf driver disc was an interesting problem.

Modeling the disk in a stream tube helped me to understand key lift generation characteristics applying Bernoulli’s. Moreover, coupled with rotation, these observations allowed me to understand how to make the disc fly farther for a standard right-hand back hand throw.

The primary tool I used to measure aerodynamic performance of a design before manufacturing and flight test was ANSYS Fluent. These simulations were conducted at a translational velocity of 35 m/s, a rotational velocity of 119.15 rad/s, and SST k-ω turbulence modeling for accurate boundary layer modeling. The values for the velocities were determined based on average professional throw speeds from disc golf players’ forums. From the start, there was a clear understanding that CFD is simply a tool and would require validation, so a wind tunnel testing plan was created before leaning more heavily on CFD to improve designs. Temporarily, though, initial values were compared to similar studies on disc golf discs from research on similar geometry. My initial values for the disc’s C_L and C_D were within 7% of the previously referenced research.
Following the completion of the wind tunnel testing, there was a tight timeline to iterate the design for manufacturing and flight testing, so design studies were conducted based on feedback from players and flight test data.
Initial feedback focused on iteration 1’s over-stability due to its relatively flat flight plate. Disc stability falls into three categories: overstable, stable, and understable. For further distance, an understable disc is better at resisting the natural right-handed
backhand throw’s tendency to curve left for a longer distance. This behavior means, though, that an understable disc can still eventually fade to the left.

Hooligan’s current competitor to the market leader was the Yeet, and I was able to compare its flight path data to the market-leading Innova Destroyer.

So, to improve the design, naturally I first looked to the market leader—the Innova Destroyer.

I whipped out the dremel and calipers to find a few surprising observations. One path to achieving understability and better flight is to increase the “dome” of the disc; however, the destroyer did not utilize a high % of dome. Moreover, this helped point me in the correct direction of disc diameters to start at. After setting up a parametric model, I conducted a few studies in CFD.

The domage study helped me to confirm there is a drop off past a certain ratio of domed diameter to flat diameter of the disc. Moreover, the AOA study shows that the more-domed Iteration 5 disc clearly has better stall characteristics across commonly seen AOA ranges than a flat-top disc (Iteration 1).

The dome design changes were great, but the corresponding manufactured discs still fell 6ft short of the market leader. So, to make the disc more understable, I looked at increasing dome again and lowering the leading edge height of the disc. This is also where the parting line is located for injection molded discs.

This change ultimately led to the best aerodynamically performing disc in CFD and professional flight testing.

Build and Test

Wind tunnel testing data was awful and compliance in the model made it worse. I could have CNC disc out of aluminum or something stiffer for better results.

For prototype design, hand-feel and target weight were essential for better comparisons with the existing injection-molded market leaders.

I initially prototyped using Silk TPU 98A to best match disc material as PETG was rough to hold/throw for the flight test. We then proceeded to test iterations with the TAMU professional disc golf team (best in the nation) against market leading discs.

As my designs improved, the final designs were actually CNC’d out of injection molded blanks. I reached out to a company called ProtoFlyte that has dialed in the process for CNC with higher deflection materials.

Specifically, for testing, we used a weather station to record wind conditions alongside a range finder to measure disc performance. Another critical factor was player feedback and ratings of iterations through google forms and live flight test days.

The pink disc is actually the 4th fully tested iteration (6th CNC disc design iteration), and consistently flew the farthest. This disc averaged 30 ft more of flight than the market leader, and a later iteration I designed was great at rolling on the ground and went even further. These two farthest flying PDGA constrained discs were my final designs I delivered to our stakeholder: Hooligan Discs.