Disc Flight Characteristics – What They Really Mean.
Discs in flight are commonly described as “fast” or “slow” and often given numerical ratings to describe their relative flight speed to those of other discs. The general impulse for a fast disc is that it should automatically be longer. However, it becomes more complicated if this is measured in terms of raw distance, consistent distance, or consistent accurate distance.
I generally look at a speed rating and see it more as a sign at an amusement park saying “you must be this tall to ride this ride.” That is, for a high disc speed, “you must be able to throw this fast to throw control this disc.” Fast discs will always fly faster than slow discs, but for players throwing discs that require speeds falling in or beyond the upper boundaries that they can consistently generate, the chance that they will regularly throw those discs well is fairly small.
Yes, it is true that the longest disc on the market today will likely yield the longest raw distance throws for nearly all players vs. throwing the longest disc from ten years ago. But keeping in mind that this is golf, it is a fair bet that lower powered players will have better consistent distance (lower variance) and much better consistent accurate distance with the older disc.
From my experiences with discs, I have found that the majority of drivers developed since 2002 require at least 300’ of power to be thrown with a great deal of consistency and accuracy without extensive compensation through technique, disc weight, or disc break in. While most players are/will be reluctant to put away the ultra-fast plastic, it may be the key to reaching your potential and speed up the development of your game. Only highly skilled ball golfers hit 1-Woods well, and I feel the same to be true of golf discs that are the 1-Woods of our sport.
When it comes to disc flight, there is lots of talk about glide, but very little talk about what glide really is. All discs will “glide” in a sense that they behave somewhat like a wing and ride on top of the air better than say, a large chunk of rock, but what exactly is “glide” in disc golf terms?
There has been a lot of discussion on the subject, and it seems a good number of people equate glide to the disc’s lift characteristic at lower speeds. To explain it further, it is the disc’s ability/tendency to stay in the air. While there are various factors caused by both the disc design and a player’s throw that will contribute to or detract from glide, certain discs will exert greater glide/lift characteristics than others.
High Speed Stability
There are three basic ways to describe a disc’s high-speed stability (stability during the first half of a disc’s flight):
1) High-Speed Stable – Flies straight at high speeds.
2) High-Speed Overstable – Exerts overstable fade properties at high speeds.
3) High-Speed Understable – Turns over at high speeds.
Since high-speed overstable and understable are fairly self-explanatory, I will focus on the idea of discs that fly stable at high speeds.
As drivers have become faster and designs have become more wing-like, the idea of high-speed stability is not as easy to describe as it once was. A disc’s design will yield its relative stability but in this era of disc two types of high-speed stability have been achieved.
The first type of stability (which is most common amongst the newer drivers) I call, for lack of a better term, “speed stable.” These are discs that have a high-speed stability that varies based upon how much power it is thrown with. Many of these discs will fly stable or overstable at high speeds for lower powered players and understable for upper powered players. For example, it will fly high-speed stable for someone that throws 200’ but very high-speed understable for someone that throws 450’.
The second type of stability (rare amongst newer drivers but more common from designs in the 1990’s and before) I call “true stable.” True stable discs are discs that will fly with similar high-speed stability for players of nearly all power levels. For example, the disc’s high-speed behavior will be the same (straight flying) for someone throwing 200’ as someone throwing 450’. These discs are becoming increasingly rare but are often held in high regard amongst big throwing players.
Low-speed overstability describes a disc’s fade characteristics during the second half of its flight. Discs of this era are harder to describe with general flight terminology and this characteristic is no exception. Two main disc factors determine the majority how much a disc will fade: rim design and mass distribution.
Certain discs will naturally be more overstable at low speeds due to their design. These discs I describe with the name, again for lack of a better term, “true overstable.”
Other discs will not have rim design characteristics that yield great low-speed overstability but will have a lot of natural gyroscopic fade based upon the disc’s mass distribution and/or disc diameter. Larger diameter discs and discs with a high percentage of mass on the rim will fade more at low speeds due to the gyroscopic effect. These discs I describe as “gyroscopically overstable.”
As for what this means in terms of disc flight, some discs will have a lot of true overstability while others will have a lot of gyroscopic overstability, and some will have both. It is fairly easy to tell which type of overstability is occurring by watching the disc fly.
Assuming a throw is a line drive trajectory with the nose down, a true overstable disc will bank into an increasing and fairly pronounced manner into its fade, changing in angle towards vertical as it fades. As this bank increases, the surface area keeping the disc in the air decreases and the disc will fall more quickly towards the ground (the most truly overstable discs are often described as “lawn darts” for their bank and crash flight path).
Under the same assumptions, a disc that exerts only gyroscopic overstability will generally change angle only slightly during its fade and as a result and will stay in the air much longer at low speeds than a true overstable disc. As a result, gyroscopic discs will generally have lower tendencies to fade, but they will often cover more geographic distance during their fade than a true overstable disc.