This article is an excerpt from our Discs Explained series where we give in-depth information on the properties and uses of putters, midranges, fairway drivers, and distance drivers.
Every disc is manufactured with a specific flight pattern in mind. When thrown flat with a backhand by a right-handed player, some should go straight as an arrow (stable) while others should turn right (understable) or fade left (overstable). Discs with these intended flight patterns exist in every disc category: putters, midranges, fairway drivers, and distance drivers.
For those interested, we have a post that goes into the scientific reasons discs fly in certain ways.
One way some manufacturers have attempted to concretely define the differences in discs is by using flight numbers. These are a set of four numbers that describe a disc's speed, glide, turn, and fade. We have an in-depth article on flight numbers, but it's most important to understand what's meant by "speed."
Speed, which is largely governed by shape, is the only thing that truly separates most disc types, with putters having the slowest speed numbers and distance drivers the highest.
Discs are made to follow their intended flight paths when thrown at specific speeds. If you throw a disc with too much speed (or improper technique), it will tend to turn over and sometimes even roll. If a right-handed player throws a disc backhand with too little speed, it will just fade left and not travel very far.
Unfortunately, there is no standard speed scale all manufacturers use. The one most widely used in disc golf ranges from 1-15, with discs that fly true at higher speeds having higher numbers.
The maximum speed a disc can reach also affects the distance it can potentially travel. If you compared two discs whose weights were the same and whose flight numbers only differed in the speed category, the one with the higher speed rating should theoretically be capable of more distance.
Beware! You shouldn't take this to mean that because a disc is a higher speed, it will automatically fly farther. Most players need lots of practice and training to throw a high speed disc correctly. In fact, many beginners will find that slower speed discs fly farther for them than higher speed discs.