The physics behind archery is truly fascinating. Many people believe that an arrow just launches forward from the bow in a straight line and never spins in flight. However, the arrow can spin in certain directions but many factors can determine the percentage at which they spin. These include the size of the arrow, the fletchings on it, and its overall length.
There is actually something known as “the archer’s paradox.” When an arrow is released to the right of a bow, it doesn’t follow a trajectory in which you would think. The paradox occurs due to the way the arrow spins in flight.
The force of the released bowstring pushes the arrow forward from its rear and then the arrow starts to wobble. As the bow continues forward, its fletchings interact with the air surrounding it. These work to steer the arrow towards the target. This steering occurs due to a spinning motion.
To know why an arrow spins, we need to follow it from the bow. As an arrow travels around halfway past its bow, the string begins to move back in the opposite direction of where it was going in the first place. In other terms, it moves to the left first while it slides off the fingers. Next, it will begin to move back to the resting position by moving to its right. At this point, the arrow wobbles both ways but it still hasn’t left the bowstring.
As the arrow leaves the bow completely, its first wobble is also completed. If the arrow’s spine is too thick, it will not wobble properly and will usually go off target. If it is too thin, it could wobble too much and fail to fly effectively.
With the right thickness, the fletching catches the air and tugs on the arrow. As the arrow tries to veer left, the fletching exerts a force on the arrow, making it spin to the right. The same goes for the right to left. This is the point where the arrow begins and continues to spin.
As it spins, the arrow creates a force that acts against another force that is trying to pull it off target. An arrow’s spin helps it increase its speed and straighten its trajectory.
Which way do most arrows spin?
The direction in which an arrow spins is determined by the construction of the arrow itself. When building an arrow, the feathers can be installed with a right or left helix. Some can even be made with no helix at all (a straight fletch). The term helix means “to turn around” or “something in spiral form.”
The fletching can help spin out any imbalances in an arrowhead or in the arrowhead itself. It is there to help stabilize the tail of the arrow as it continues on its intended trajectory.
A left spiral or helical fletch will see an arrow spin counter-clockwise and away from the bow. This is if the bow is held in the left hand. A right wing fletch will see the tail of the arrow spiral toward the bow when it is held in the left hand. The opposite would occur if holding the bow in your left hand.
It’s all down to physics. If you release an arrow with feathers that spin to the left when the bow is held in a left hand, then it will have less contact with the bow when compared to an arrow with feathers that spin to the right.
So, there is no common way in which arrows spin. It is often to do with the way you hold an arrow, how it is made, and whether you are left or right-handed.
How fast do arrows spin?
We are glad you have come here to find this out instead of trying to find out for yourself as this would be a very tricky task.
Arrows are fast! But, how fast an arrow travels depends on various factors. When shot from an archery bow, arrows can travel up to around 200mph. Arrows shot from a compound bow can also reach speeds of 200mph or 300 feet per second (fps). If an arrow is shot from a recurve bow, it can travel at 150mph and 225 fps. In other words, you do not want to get in the way of one!
As we mentioned, different factors can determine the speed of an arrow. Bows come in different draw weights which are measured in pounds. This refers to the amount of force in pounds that is produced in a bow’s limbs once a bow is at full draw. The higher this number is, the more powerful the bow will be and the faster the arrow.
If you use a 34-pound bow compared to a 30-pound model, the weight increase is 13.3% but the speed increases by 3.8%. While this isn’t a huge leap, it is still a faster speed. Interestingly, increasing your draw weight will not always see continuous increases in speed. For instance, a 30-pound bow was 8.3% faster than a 26-pound bow. The overall difference with some bows is minimal.
The fletching of an arrow can also have an impact on its speed. If these feathers get wet, your arrow will become heavier and, therefore, slower. The weather conditions can also have a say. If you shoot into a headwind, your arrow will slow down as it competes with an oncoming force. But, get the wind behind you, and the arrow can speed up significantly.
Whatever the conditions and arrow build, it will begin to slow down as it travels through the air. This is due to drag effects. While it starts with no rotation, the spin rate will start to accelerate as the arrow accelerates. As the arrow moves faster, the fletching moves faster as well at a right angle to the arrow’s shaft. The spin rate increases meaning the net airflow direction rotates at the same level of arrow speed. The arrow will then reach a terminal rpm and the spin will not go any faster.