1. Introduction
2. The Basics
3. How the Wind Affects a Disc's Flight
4. Throwing Uphill/Downhill
5. Disc Basics
• Disc Weights
• Disc Wear
• Disc Plastic
• Disc Color
6. Disc Design
• Disc Flatness/Size
• Disc Edge
• Rim Design
• Distribution of Mass

My name is Roman Bednarek and my progression to disc golf began in 1991 with "Ultimate." I was typically picked to throw the "kick-off" throw because I could throw farther than most. I played "Ultimate" until 1997 and then began playing Frisbee golf with my 175 gram Ultimate Frisbee around the campus of Clemson University in SC. I bought my first set of discs the summer of 1998 at the Gold Rush golf course from a stock of old discs (the baskets at Green Lakes were purchased from Gold Rush after the course was converted into a short ball golf course). I bought a bunch of discs and began with these. I couldn't use them at Clemson for fear of destroying something or hurting someone. So I began playing the Green Lakes course with the newly installed baskets during my summer break. It wasn't until I returned to Syracuse in August 1999 that I really discovered disc golf and got my first set of new discs. I was obsessed with drivers so I researched and purchased a bunch to see which would go the farthest or fly the best for my type of throw. I ended up buying a Discraft Elite XL, a DX Innova Eagle (the KC Eagle hadn't been released yet), a Polaris LS, a KC Cheetah, a Stratus (more of a mid-range disc), and a few more, most in the 170+ gram range. Through throwing multiple discs at each hole, I was able to learn how the discs fly relative to each other. So I began to look at the design of the disc in order to determine how each design characteristic affected the flight of the disc. I also began researching disc golf on the Internet to gather as many tips as I could get. I try to buy a lot of new drivers just released by disc makers in order to see if I can find something better, but I wouldn't recommend this because it can really screw up your consistency with the discs that you are already accustomed to. I've also played at a lot more courses and in a lot of different weather conditions since then. So this is my attempt to consolidate all of the information that I have gathered over the last few years. You may disagree with some of my concepts, but I am writing based on my experience, it may be wrong and this document will require updating as my experience grows. As far as discs are concerned, I will mostly concentrate on discs made by Discraft and Innova, I haven't been convinced to try others and am very satisfied with the quality and performance of discs from these two companies. I have noticed that discs made by Innova are somewhat inconsistent and they are constantly changing which makes it hard to find a replacement that flies like the original. I recently ordered a CE Eagle, CE Tee-Bird, CE Valkyrie, Z Elite XL, Z Elite XS, and Z Elite MRV in order to try to find a replacement for my favorite 174g Special Edition T Teebird which is no longer made… they only made Special Edition Teebirds in the T mold during the first production run, now they only make them in the TL mold. I'll be reviewing a lot of these drivers throughout this document.

The information provided here includes disc golf terms, disc flight characteristics, disc design, and how the discs I own fly for me. Some of these may help you find a disc that suits you or give you a better idea of how and why discs fly the way they do. Some of this stuff you may already know, but the stuff you don't may help your game… it can't hurt it.

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In this section I will be discussing some of the terminology used by disc golfers. First I will talk about a few of the various types of throws that exist. The most common throw is the backhand shot. This is the typical Frisbee-type throw where the back of your hand faces towards the target as you swing across your body. For a right-handed person, this type of throw will generate a clockwise spin on the disc, which will affect the flight pattern of the disc. A sidearm or forehand shot starts from the other side of the body (the side of the throwing arm) and the palm of the hand faces the target during the swing. This type of shot will generate the opposite direction of rotational spin than the backhand, which will theoretically cause the disc to turn in the opposite direction based upon the speed and spin of the disc. The tomahawk is another common type of throw and is very useful for getting over tall obstacles. The tomahawk is similar to a baseball pitch with the disc held vertically. A typical tomahawk throw will cause the disc to flip and as it drops, the disc will fade to one side. The direction of the fade of the disc as it falls is determined by the way the disc is held. If the top of the disc is facing away from you (you have to put your thumb on the inside rim to grip the disc, this is often called a "thumber") the disc will generally fade to the right as it falls (for a right-handed thrower). If the disc is held with the top side facing you, the disc will generally fade to the left (for a right-handed thrower).

The angle that the disc is released at during a throw is very critical in determining the direction that the disc will fly. A flat throw is parallel to the ground and will typically lead to a straight throw for the beginning of the disc's flight, a lot depends on the type of disc thrown. When the far edge of the disc faces towards the ground during the throw, the disc will begin its flight in the direction that the edge of the disc faces and this is known as a hyzer throw. An anhyzer throw is the opposite of a hyzer, the far edge of the disc will face upwards and the disc will start out in the opposite direction.

Now I will discuss some of the basic terms that are used to characterize a golf disc's flight. Golf discs are characterized by their stability. Discs can be generalized into three main categories: understable, stable, and overstable. I will define the flight characteristics that each of these terms describe based on a right-handed backhand throw which generates a clockwise spin on the disc. An understable disc will have a tendency to curve to the right relative to the initial angle of release. A stable disc should maintain the angle of release throughout its flight. An overstable disc will tend to curve to the left relative to the angle of release. In other words, if the disc is released parallel to the ground, an understable disc will turn right, a stable disc will fly straight, and an overstable disc will hook left. These are the basic terms, however, the amount of speed and spin on a disc has a big effect on the stability of a disc. The more speed and spin on the disc, the less stable the disc becomes. Hence, a disc that flies understable for a "big arm" will often be overstable for a novice. Also, discs are often characterized by high-speed and low-speed stability. Most, if not all, discs tend to be overstable at low speeds during the tail end of their flight. There is not a disc in existence that is more understable at low speeds than at high speeds and if there was it would be an extremely popular disc. Some other terms that are used to describe a disc's flight include the disc's speed and glide. There is typically a trade-off between speed and glide for most discs on the market. Usually, the slower the disc, the more glide it will have, while a faster disc will tend to have less glide. Disc's that glide well tend to be slower because some of the energy is being absorbed in order to produce the aerodynamic lift that allows a disc to glide. When there are less aerodynamic interactions slowing down the disc, the disc will not slowdown as fast after release, hence it will be a faster disc with less glide. I tend to prefer a balance of speed and glide to get the most consistent results. Faster discs have a tendency to exaggerate any errors made during the throw/release of the disc.

There are three main categories of golf discs which are based upon the length of shot. While ball golfers have a putter for putts on the green, drivers for tee shots, and irons for everything in between, disc golfers use putters, long-range drivers, and mid-range discs. Most disc golf putters are stable and fly slowly to prevent a long comeback putt. Putters are typically used for shots under 100 feet from the basket, however I've seen many people use them for shots over 200 feet. Some examples of putters include the Aviar, Birdie, Polecat, Omega SS, Magnet, Softie 86, APX, and many others. Mid-range discs are usually faster than putters, but much slower than drivers. Mid-range discs are used for shots that are too far for the putter, but too short for a driver. Most players tend to be more accurate if they throw a mid-range disc with more power than throw a long-range driver with less power. Some of the more popular mid-range discs include the Roc, Hawk, Stratus, MRV, and MRX. Finally, the long-range drivers are typically the fastest discs and are obviously designed for the longest shots. Drivers also tend to be more overstable than other discs and beginners often have difficulty starting out with a driver because most beginners are accustomed to throwing Frisbees, which are much slower and more understable than golf discs. Most players use drivers for shots over 250 feet and the world record distance for a golf disc was recently set at a distance over 700 feet with a Discraft XS model disc. Most experienced disc golfers are capable of distances between 300 and 400 feet with a long-range driver. Some examples of long-range drivers include the Leopard, Cheetah, Gazelle, Teebird, Eagle, Valkyrie, Firebird, Banshee, Whippet, Xpress, XL, XS, X2, Xtreme, Cyclone, Cyclone2, X-Clone, and JLS. My favorite is the Teebird, however that is a very general statement since there are so many different variations of the Teebird available between two different types of molds and four different types of plastic.

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The wind plays a big role in determining how a disc will fly. It is easy to determine how a disc will fly if the wind is in the same direction that you are throwing. The wind essentially changes the relative speed of the disc with the air speed. The disc's aerodynamics are not determined by how fast it is going compared to the ground, but are based on how fast the air is hitting the disc. Thus, a headwind will increase the disc's speed, which will cause the disc's flight to be more understable. The disc speed increase is exactly proportional to the wind speed. For a downwind shot, the disc will see a slower relative air speed and will tend to fly more overstable. The angle of the disc is important when encountering side winds. If the wind hits the bottom of the disc, the disc will rise and float in the direction of the wind. If the wind hits the top of the disc, the disc will fall down in the direction of the wind. The best wind in order to obtain greater distance for a right-handed backhand thrower is one that comes from the left and behind. Throw a slightly high anhyzer with a stable to overstable long range driver and aim to the left of the target. The disc will initially be carried from the left to the right as it travels and it will finally curve back and glide to the ground when it loses speed. I was able to throw over 400' with that throw at Chili on a windy day.

It is important to compensate for wind when putting. If you are putting into the wind, be sure not to aim too high because the headwind will produce an additional lift which often causes the disc to overshoot the target. I typically try to aim low and use less power. The opposite is true for a tail wind. You should aim higher and put more power into your putt, because there will be less aerodynamic lift to propel the disc to the basket. Sidewinds are a little bit tricky, just remember that if the wind hits the top of the disc it will drop and if the wind hits the bottom of the disc it will tend to rise. Sometimes you just have to trust your putter and drill it in there.

A little tip that I have found helpful is to pay attention to the other players' shots in your group to see how the wind affects their throws in order to try to determine how to set up your shot. Some courses can be tricky however, because wind patterns can be constantly changing which makes it very difficult to judge what direction the wind is blowing or even if it is blowing at all.

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When throwing uphill or downhill you obviously have to aim higher or lower depending on the situation. Most beginners have problems throwing downhill since they will often throw straight out rather than throwing downward on a line parallel to the ground. The problem with throwing straight out is that the disc loses speed at a point where it is still well above the ground plane and the result is a severe hook due to the low speed overstability of the disc. When the disc is thrown parallel to the ground on a downhill shot, the disc will actually have extra accelleration causing it to seem more understable or turn-over more easily. When the disc finally does lose speed due to wind resistance, the disc will be closer to the ground and will hit the ground before it has a chance to fall and hook as it would have if thrown straight out. When throwing downhill, I often choose a point on the ground in the distance to aim at and then throw towards that target. Throwing lower also reduce the effects that the wind might have on the disc as well. When throwing uphill, you must obviously throw upwards. In this situation you are throwing against the force of gravity and the disc will tend to deccellerate faster than when thrown on a flat surface. Since the disc will slow down quicker, it will seem more overstable and won't turn-over as easily. The height that the disc is thrown at relative to the ground will determine the amount of overstable hook the disc will have, because if the disc hits the hillside before losing speed it will not hook as severely. Most people tend to use a more understable disc when throwing uphill or put more of an anhyzer on the throw to compensate for the added overstability caused by gravity. For downhill throws, a disc that would typically fly stable, or straight, on a flat throw might have a tendency to turn-over if thrown at a downward angle. Thus, it is often wise to choose a slightly more overstable disc, but beware of the low speed overstability characteristics if the disc is thrown too high from the ground plane.

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Some of the basic characteristics of golf discs will be discussed in th is section. These characteristics include the effects of disc weight, wear, plastic, and color.

Golf discs come in a variety of weights, typically ranging from 140g to 180g. The maximum weight limit for a disc is specified as 200 grams by the PDGA. A disc's design plays a role in determining the maximum weight of a particular disc and larger diameter discs tend to have higher weight limits. Just about any disc is available in weights below 175g. However, a lot of the discs in the special, more durable plastics are molded in a limited weight range. Innova Special Edition and Ken Climo Edition plastics are only available in weights from 165g-175g. Discs under 150g grams are considered "150 class" discs. A lot of beginners prefer these lighter discs because they tend to fly with less stability (turnover with less power/speed) and require less force to throw. F=MA : Mass- goes down, Force- constant, Acceleration goes up. I started out with a 175 gram Ultimate Frisbee and only bought discs that were over 170 grams. I recently began trying some 165 gram discs and always release the disc too late, too far right. I get most of my distance and accuracy with a one-step throw which requires a lot of acceleration on the disc. My release is based upon the timing in my swing from the point of acceleration. Based upon the above formula, if the force on the disc is constant (the power of my arm is the same regardless of the disc), the mass of the disc goes down by 10 grams or 10/175 which is about 6%, the acceleration of the disc will go up by 6%. Since my throw is based upon acceleration for a fraction of a second, which is a timing that I am accustomed to, the lighter disc will have accelerated faster and traveled farther before release and since the natural swing/follow through of my right-hand backhand throw continues around to the right, I pull the disc right. Heavier discs are better for compensating for disc flutter upon release of the throw. Any flutter is a bad thing in general since it is energy that is being wasted that could and should have been employed in propelling the disc forward. A final statement about disc weight involves wind conditions. Heavier discs are less susceptible to winds and lighter disc are more susceptible to the wind. If you are trying to use the wind to help increase your distance you might want to use a lighter disc. For putting, I typically like to use the heaviest putter possible, which is a 175 gram Aviar . The heavier weight makes it less susceptible to the wind and also makes it more consistent for the pendulum type putting style. I'm not sure if this is good advice of not, but I seem to like to stick to one weight for all of the discs that I carry in order to have some kind of consistency in my throw. I find it to be much easier to judge my timing during my release and I have just recently discovered this when I tried to throw some 165g discs after only throwing 170+ gram discs. Some people say that you can get more distance out of lighter discs. This may be true, but distance doesn't mean anything if you can't keep the disc on the fairway! Well, that's enough about disc weight, time to move on to something else.

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Over time a disc will tend to wear down which can change the flight characteristics of that disc. The amount of wear typically determines the extent that the flight changes. The type of plastic that the disc consists of determines how much of a "beating" the disc can withstand before its flight changes. Trees and pavement are the most common culprits for disc damage and a bad hit can take a chunk out of the edge or can bend down the edge of the disc. The latter is often referred to as a "taco." If a disc is severely tacoed, some people have suggested soaking discs in 150 degree water for some time which allows the disc to reform to its original molded shape. As discs wear, they tend to become more understable. In other words, they tend to "turn-over" more easily. There are a few scientific principles that can be applied in order to explain this hypothesis. First of all, as a disc becomes more worn, there is more aerodynamic wind resistance in the outer rim of the disc which causes the disc to be less stable. This explains how the rough edges in the rim of the disc affect the disc's flight. The "taco" effect causes the disc to have more of an aerodynamic dome which may cause the disc to have more lift and less speed. If you refer to what I wrote earlier on the tradeoff between speed and glide, a domier disc will have more glide and less speed. Furthermore, a domier disc will tend to be more understable and fly slower. I may be wrong about the above theories and I am always welcome to any suggestions as to any corrections or inaccuracies previously stated.

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Discs are available in a variety of plastics, each with its own advantage and price range. I will concentrate on plastics from Innova and Discraft. Innova offers four different types of plastic including: DX (regular baseline quality plastic), SE (Special Edition plastic), KC (Ken Climo plastic), and CE (Champion Edition plastic). All of Innova's discs are available in the DX plastics and these are the least expensive and least durable discs that Innova offers. Innova offers the Super Roc, Rhyno, and Teebird in the Special Edition plastic which is more durable and expensive than the DX plastic, but is a little bit smoother and flexible. Special Edition discs are only available in weights in the 165 to 175 gram weight range and tend to be more overstable than the similar model in the DX mold. There are numerous discs available in the Ken Climo plastic which to the best of my knowledge are limited to weights above 165 grams as well. I've heard that the most recent production runs have incorporated blends of plastics which included KC and Champion Edition plastics. The KC plastic discs tend to be less flexible than the Special Edition discs and more durable. They also tend to be more overstable than the SE and DX discs. The latest plastic that has been released by Innova is the Champion Edition plastic which is the most durable plastic they offer. This plastic is pretty slippery however and Innova seems to be having some problems with molding consistency between production runs. The most common problems involve the amount of "dominess" or "flatness" that the top of the disc has after coming out of the mold. I've received quite a few "flat-top" discs that fly very-fast and have a severe low-speed overstability which causes the disc to hook at the end of it's flight. Okay, back to the plastic, the Champion Edition plastic is the most expensive plastic that Innova offers and is very durable. It is also very overstable relative to the other types of plastics. For example, I've got a CE Leopard that is almost impossible to turnover whereas my SE or DX Leopards turnover very easily. I am under the impression that some of this extra stability has to do to the fact that the CE plastic is much smoother than the other plastics, but perhaps that is just a guess. Current discs that are available in the CE plastic include: Valkyrie, Leopard, Teebird , Eagle, Firebird.

Now I will discuss some of the types of plastic's that Discraft offers. I am under the impression that Discraft's baseline plastic is a little more durable than Innova's DX plastic. Discraft offers an Elite line of discs which is similar in durability to the SE or KC line of Innova's discs. Discraft also offers the Hawk in a HD (High Durability) plastic which is similar to the Elite plastic and is also pretty durable. Similar to Innova's CE plastic, Discraft has recently introduced a line of discs molded in Z plastic which is a highly durable, translucent plastic.

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Disc color can make a difference for a variety of reasons. You wouldn't want to use a white disc in the winter when there is snow on the ground. You wouldn't want to use a dark colored disc in Texas on a 100 degree day because it would really heat up and become really flexible. Also, some people believe that some colors tend to mold better than others and some people are just comfortable with certain colors. I like to have variety myself so I don't get confused and grab the wrong disc by mistake. I like the "fly-dye" discs a lot, but sometimes those can be difficult to find depending on the type of dye coloration on the disc.

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In this section I will discuss how to get a general idea how a disc will fly by observing the physical characteristics of the disc. The information given here is based strictly on experience and my knowledge of physics, some of the information may be misleading due to the many different possible combinations of the following characteristics: disc flatness/size, disc edge, rim design, and distribution of mass. I will discuss each of these individually, but the combination of each property will determine the disc's flight characteristics.

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Most discs on the market are molded in a small diameter size around 21 cm. Larger discs are available and can typically be found in heavier weights than smaller discs due to PDGA golf disc regulations. The larger discs that I am familiar with include the Lynx, Jaguar, and Phenix. These discs tend to be slower and tend to float better or in other words have a better glide. Smaller discs are usually faster, but they can also have good disc due to the contour of the top which determine some of the aerodynamics of the disc. The flatter the disc, the faster the disc will be, the more overstable it will be, and it will have less glide. This is due to the fact that a flat disc has less aerodynamic wind resistance which makes it faster and also reduces glide due to less of an airfoil lift characteristic. Energy is mostly going into the speed of the disc and not the lift which is the trade-off that exists due to the physics principle of conservation of energy. I have also heard that a faster disc can be more difficult to control because any error in the release will be accentuated due to the speed of the disc, but I cannot prove this as fact or not.

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The shape of the outer edge of the disc has an effect on the flight characteristics of a disc. If the edge of the disc is blunt then the disc will tend to fly slower and typically not as far. Many midrange discs have blunt edges which make them slower, more predictable, and fly shorter. If the leading edge of the disc is very sharp, the disc will tend to be faster and fly farther because there is less wind resistance. Most long-range drivers have sharp leading edges which allows them to fly faster and farther.

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The design of the underside rim of a disc is very critical to the flight of the disc and there are many different configurations to consider. These different characteristics must be considered together for each one individually will have an effect that contributes to the overall flight of the disc when all aspects are considered. First of all, we will discuss the depth of the rim which I consider to be the distance from the outer edge of the disc to the center of the disc that the rim occupies. Typically, the wider the rim depth, the more overstable the disc will be. The next characteristic is the rim height which is the rim distance from the top of the disc to the bottom of the disc that the rim occupies. Typically, the greater this distance is, the more understable the disc will be. In other words, a shallower, flatter rim will tend to fly more overstable. The final characteristic to consider is the shape of the underside of the rim. Most discs have a concave rim that curves inward. The extent of this concavity usually plays a part in determining the stability of the disc. A disc that has a deeper curve or is more concave will tend to be more understable. The straighter this edge is, from the rim to the center portion of the disc, the more overstable the disc will be. In summary, the most overstable discs will tend to have the widest rims from the outside to the center, the shallowest rims from the top to the bottom, and the flattest slope along the bottom side of the disc. An Innova Firebird is a good example of these principles. On the contrary, the most understable discs will tend to have the narrowest rim from the outside to t the center, the deepest rim from the top to the bottom, and the most curvature in the underside of the rim. Some good examples of discs with these understable characteristics are the Innova Stingray and Cobra, and the Discraft Stratus. It can get quite confusing when a disc has a mixture of both overstable and understable characteristics. One good example of this is the difference between the T and TL mold variations of the Teebird. The original T mold is more overstable, however this disc has more concavity in the underside of the rim. The main reason that it is more overstable is because it has a shallower rim depth than the TL mold which has a deeper rim and a straighter edge. Also, remember that the other characteristics mentioned in this section also play a part in determining the overall stability of a disc.

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The final characteristic that contributes to a disc's flight characteristics is the distribution of weight between the center of the disc and the outer edge. The more weight on the outer rim of the disc, the disc will tend to be more overstable. Thus, the more weight in the center of the disc and less weight in the outer rim, the disc will tend to be more understable. This relates to the rim width from the outside to center of the disc discussed in the previous section since wider rims will tend to have more plastic in them and more mass will be located on the outside of the disc. Once again, remember that these are just general guidelines and many combinations of these different characteristics will generate different results. You must consider all of these characteristics as a whole in estimating how a disc will fly just by looking at it and there may be combinations that seem to defy these guidelines.

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