This episode of our Video Guide Series features an ADVANCED explanation of disc golf disc Turn (high-speed stability) numbers, including how Turn affects flight, factors impacting Turn, and how to choose between Overstable and Understable discs (full video transcription provided at the bottom of this post).

Links to Resources Mentioned in this Video: Innova Discs Flight Rating System


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Full Video Transcription:

Warning: may contain minor transcription errors, and definitely containing the grammatical errors I use when speaking!

Welcome to Best Disc Golf Discs Video Guide Series. In this episode we’ll be covering “Understanding turn and choosing the right disc stability.”

In this video will cover:

  • What is turn?
  • How turn affects disc flight
  • Key factors that impact turn
  • and answer: Which level of turn should you use?

To ground everyone on the graphics we will be showing today, all of the flight models shown will be based on a right hand backhand (RHBH) or left-hand forehand (LFFH) motion, which means that the disc will be spinning clockwise after being thrown.

In this analysis, we will be basing our discussion on the popular four number flight rating system, of which the third number represents “turn.”

So what EXACTLY is “turn”?  

Turn is the measure of high-speed stability. This statement can be broken down into two parts:

  • The first of which is “high speed” which defines the initial part of your throw when the disc is traveling at the highest velocity
  • The second part is “stability.”  Stability is a sliding scale measuring turn from 1 to -5, with 1 representing the most overstable desks and -5 representing the most understable disks.

Understable Flight GraphicTo demonstrate the difference between overstable and understable discs,  an overstable disc at high speed is going to have a tendency to follow a natural arcing pattern to the left.  Understable discs, on the other hand, will have a much higher tendency to turn over in the high-speed portion of flight, actually bending off to the right before fading back to the left in the slow speed portion of the flight.

We defined turn as the overstable vs. understable tendency of a disk to turn over, but what we really mean is “velocity required,” because the reality is all drivers will turn over if they are thrown with enough velocity. This is the concept that many of you will recognize from our detailed video on Choosing Drivers for Maximum Distance.

Multiple Flight PatternsLet’s say for example we have two discs, one of them rated as understable the other rated as overstable. Both of these discs will produce understable and overstable flight patterns, the difference being the speed required for each disc to generate the different flight patterns. With the understable disc having a higher tendency to turn over it may provide the optimal flight pattern at a velocity of 60 miles per hour, where the overstable disc, on the other hand, may require a speed of 70 miles per hour to generate that same flight pattern.

So which do you choose?

There are really two variables to consider. The first of which is optimizing for distance when you’re throwing. The second of which is dialing-in consistent performance.  Unfortunately, these can sometimes be opposing concepts when selecting a turn rating for your disk and create a situation of “risk vs. reward.”

To illustrate, let’s say we have a disc golfer that has selected a disc that at his release speed provides the optimal flight pattern for maximum distance. Let’s say the player has an average throw speed of 60 miles per hour, and has selected disk that provides the ideal amount of turnover at 60 miles an hour — right at his average throw. While this combination does provide maximum distance when everything goes correctly, let’s say there is a strong headwind or the thrower has an unusually good throw with excellent release velocity. In that scenario, the disc is going to turn over much more than the player is normally used to,  creating a flight pattern to look something like this.

Disc Golf Disc Turn Youtube thumbConversely, let’s say the player has an unexpected tail wind or a poor release. In that scenario the disc will get a much more overstable flight pattern than expected, creating the opposite problem.

For the sake of comparison let’s say that this same player now selects a much more overstable just a disc that will not provide the ideal amount of turnover until it is thrown 80 miles an hour (much more quickly than this player is capable of releasing). Also let’s say the player adjusts his line of released to the right to compensate for the overstable flight pattern that he knows is coming.  With these three throws, even if variable conditions are experienced all three flight patterns are going to be very similar because the player is not even beginning to approach a speed at which the disc would begin to turn over in flight.

Comparing the landing positions of the three throws you can see that with the understable disc optimized for distance, the player did have a shot at making it all the way to the hole but fell victim to potential variable conditions.  With the overstable disc, while he unfortunately could not make it all the way to the hole he eliminated the risk of the trees, the risk of the water, and had three very consistent shots.

In summary:

When choosing understable vs. overstable did you want to take into account:

  • the wind conditions at the time
  • any hazards that may be in play
  • your personal consistency in terms of release velocity
  • as well as any scoring needs that you may have at the time of the round.

You’ll also want to take into account the projected end of flight Fade but that’s another video!


Thanks for Watching and Reading!

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5 thoughts on “Overstable vs. Understable Discs: How to Choose the Best Turn Rating

  1. mike holtzclaw says:

    I have a discraft elite xtreme overstable driver disc that was given to me. Has nothing (nor can I find anything online about it) on the disc other than that title. any idea of the numbers for it?

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