Overstable vs Understable

The flight of a disc is one of the most important factors we consider when buying a disc. The feel of the disc in our hand would be a close second. But, how the disc actually flies for us tops the list of factors. One of the most important aspects of the flight of a disc is its stability.

Disc Stability

 

The stability of a given disc is how the disc flies immediately out of our hand, and how it behaves as it slows down. I talked about those disc qualities in my blog about flight numbers, HERE. For this blog, we’ll explore the terms ‘overstable’, ‘stable’, and ‘understable’. We will also looks at the weakness in using those terms to describe the flight of a disc. So, let’s get right to it!

For the sake of this blog post, I’ll look at each of the three terms mentioned above and establish a definition for each of them, so we can be consistent in our description about the flight of the disc. I’ll start with the term ‘overstable’.

Overstable

 

Let’s define ‘overstable’ as a discs ability to resist turning during the first part of the flight, and its hard fade as the disc slows down. The ‘turn’ of a disc, for a right-hand back-hand throw (RHBH) is its movement to the right immediately after the disc is thrown. The ‘fade’ is its movement to the left as the disc slows down. As players improve their technique and skill, their ability to throw the disc at high speeds increases. As the speed of the throw increases, so does the need for more overstable discs to prevent the flight from turning too much.

 

Understable

 

Now let’s consider the term ‘understable’. We consider a disc as being understable if it has a tendency to turn a significant amount right out of the hand. A disc that is very understable typically doesn’t have very much fade at the end. An understable disc is great for newer players who lack the arm speed to throw more overstable discs, since they can’t generate enough speed for the overstable discs to fly right. If the necessary speed can’t be achieved, nearly every disc becomes overstable to a beginner.

One of the ways the manufacturers can offer more molds to beginners is to offer overstable molds in lighter weights. Due to the disc having less mass to get up to speed, newer players can ‘cheat’ the system and still throw molds that would be too overstable in heavier weights.

 

Stable

 

Now let’s talk about the term that has a little more flexible definition: ‘stable’. When I hear people calling a disc ‘stable’, they typically mean that the disc doesn’t have a lot of turn, nor does it fade hard. When I hear it in reference to another disc, it can either mean more overstable or more understable, depending on the situation. If you say that you are throwing a Slab (12, 3, 0, 4), but want something a little more stable, you are saying that you want a disc that is not so overstable.

If you are throwing a Kon Tiki (4, 5, -3, 0) and say you want something a little more stable, you mean that you want something that is less understable. Basically, in both examples you are saying that you want something that flies a little less extreme and a little closer to a neutral flight.

Occasionally, I’ll hear someone refer to a disc being more stable than another, when they mean more overstable. That is an inconsistent use of the term, and may lead to a follow-up question to clarify the meaning. To eliminate any ambiguity, I recommend referring to discs as being more or less overstable or understable.

Flight Numbers

 

 

The flight numbers of a disc help us know the basic flight of a disc, assuming we can throw the disc at the proper speed. If we can meet the speed requirements of a disc, we can then look at the last two rating in the flight rating to determine the overstability or understability of a disc. Let’s look at some examples.

Disc Examples

 

The Scepter and the Sphinx are speed nine discs from Infinite. The Scepter’s flight numbers are 9, 4, 0, 4. The ‘0, 4’ are the last two numbers, and tell you that this mold would resist turning, even at high speeds (the 0), and will finish strong to the left (the 4). It is an example of an overstable fairway driver.

 

The flight numbers for the Sphinx are 9, 6, -3, 1. The -3 is the amount of turn that the Sphinx exhibits when thrown at the necessary speed. That means it will turn to the right quite a bit at high speeds. Add a little headwind into the situation and the Sphinx could end up as a roller. Plus, the last number, ‘1’, indicates that the Sphinx isn’t going to fade very much to the left. It is an understable fairway driver.

The more negative the turn number means the more turn to the right the disc will move during the high-speed portion of the flight. A disc with a -5 turn number will turn more to the right than one with a -1 turn number. Discs with a turn of 0 or positive 1 won’t turn to the right very much at all, and are great for headwind shots.

The fade number tells you how much a disc will move to the left at the end of the flight. The higher the number, the more it will travel to the left as it slows down. In our examples above, the Scepter (fade number is 4) moves a lot more left than the Sphinx (fade number is 1).

Using The Numbers

Knowing the stability of a disc helps up choose discs that work for our needs. Keep in mind that the weight and plastic type also affect the stability of a disc. Check out Infinites flight ratings for each disc, for a more accurate depiction of a discs actual flight. Click HERE to see the blog mentioned previously, which talks about the Infinite Flight Rating.