Vanes: deep dive
Adrian Tippins explains what and why
Introduction
Whether we're shopping online or in store we are affronted by hundreds of vanes of all sizes and shapes. This can often lead to option paralysis. The confusion leads a lot of archers of all levels to make poor decisions when it comes to making a purchase. Having a basic grasp of a few key facts and physics principles will put you in a position where you'll be able to short list your new vane candidates.
Incidentally, you might prefer to call them fletchings - and that's fine too. Fletchings is a much older word and is more commonly used in Britain, whereas vanes is the universal term in North America and much of the rest of the world. North America is where a lot of them are made these days, and we've decided to call them vanes throughout this article for consistency.
Before considering the merits of vanes it's essential to understand what their function actually is. Vanes stabilise, steer, spin and dampen the oscillation of the arrow. Just like the tail section of an aircraft, the vanes are flight control surfaces that control yaw (side to side) and pitch (up and down) of the arrow in order to produce stabilised level flight. These are just a few of the terms that will get bundled together to form the subject of aerodynamics. Although this is a very complex subject we can distil everything down into a few elements that are easy to understand and remember.
The faster an arrow travels the less stabilisation it needs. The slower it goes, the more surface area is needed to maintain stabilised flight due to the loss of forward
The parabolic shape has a rounded rear and a smooth curve from front to back. The type of vane gets it's name from the shape being a section of a parabola which is symmetrical curve. As parabolic vanes get longer the height tends to increase. A very popular example of these vanes are the Elite Plastifletch from AAE or Easton Diamond. The parabolic shape gives really good arrow speeds as the shape has very smooth airflow.
PARABOLIC VANES
momentum.
The larger the flight control surfaces are the more stability and steering they offer. This sounds all well and good but it comes at a price. More surface area means a higher drag coefficient. Drag will slow the arrow down and effect sight marks and trajectory of the shot.
An arrow is more stable when it's spinning. This is why most long distance projectiles are “rifled” to increased long distance accuracy. Many archers achieve this with the use of spin wings, which is an entire article in itself. Nevertheless, it is important to understand the principles of regular parabolic or shield vanes on arrows, before you complicate things any further.
Before we move on a look at the differences between types we should take a moment to understand the differences between indoor and outdoor shooting and what demands the two disciplines place on vanes.
Outdoor shooting requires low drag vane options as the distances are up to five times greater then those indoor. Good down range arrow speed is essential for long range accuracy. Weather is a factor outdoors and the distance means that the arrow will be airborne for a long time. This increases the chance of the weather factors interfering with the flight course. Outdoor vanes need to be able to deal with air currents efficiently.
In a complete reversal, indoor shooting requires the maximum amount of possible steering and stability. The difficulty with indoor shooting is that there is very little if no time for an arrow to get settled before hitting the target due to lack of distance. Therefore, we need to do everything we can to slow the arrow down and stabilise the arrow as quickly as possible. To do this we need to utilise a very high drag configuration. Obviously sight marks and weather are of no concern to us indoors.
Size, shape and profile.
We can now see that the smaller/shorter vanes are going to be more suited to outdoor shooting and the longer/taller vanes are going to be of benefit for indoor shooting. Taking arrow speed into account we can deduce that vanes on an outdoor compound arrow will normally be quite short. A typical length for a compound vane would normally be 1.87” to 2.00”. Such lengths are designed to allow the vanes have a nice “S” curve when fletched in helical format These vanes are also very low profile at just over a ¼ of an inch in height to mitigate cross wind drift. Recurve arrows lack the speed produced by their compound counterparts so their arrows need a bit more stabilisation. Plastic vanes for recurve shooting tend to be slightly shorter than compound vanes, at 1.75”, but taller in height. When shooting indoors it's always good to have the largest and longest vane possible to increase stabilisation. It's not uncommon to see recurve arrows sporting 3.00” and compound arrows using 4.00” vanes. You do need to be careful not to encounter bow clearance issues. This can be especially problematic for recurve shooters but can still affect compound shooting depending on the type of launcher used. Most vanes can be made to give a little more stability by placing them in helical or offset format as this increases drag and rotation. As arrows can drastically differ in length from one archer to another it's really important to
"OUTDOOR SHOOTING REQUIRES LOW DRAG VANE OPTIONS AS THE DISTANCES ARE UP TO FIVE TIMES GREATER THEN THOSE INDOOR."
remember that what suits one might not suit another. When I'm talking with customers I'm always thing about proportional stabilisation too. For example a 1.75” vane may well be fine for a 28” arrow but it might be unable to successfully stabilise a 31” arrow.
A long arrow may well benefit from a vane of increased length. A rule of thumb is the longer the vane, the more stable, but the longer the vane the more it will cost you in feet per second speed. It comes down to whether you want a more stable shooting shaft with a certain amount of 'wiggle room' or a faster shaft with less wiggle room. In situations where the draw length can vary, such as with trad and barebow shooters, stability of the arrow may become more important.
Whilst plastic vanes come in many shapes, broadly speaking they can split them into two major aerodynamic groups: shield and parabolic. A simple summation is that shield-cut vanes provide slightly more stability, and perhaps a accurate arrow, at the cost of a small amount of speed. (See the boxouts for more details on parabolas and shield).
Blazin' Squad
Some vanes such as the Blazer by Bohning are worth mentioning. Although these were developed primarily for compound hunting arrows, they do have a place in target archery especially in the Field Archery discipline. Blazer vanes employ Delta Wing shape that has a steep leading edge. This shape is used on most jet fighter aircraft. These vanes are designed to make an arrow shoot at the flattest possible trajectory for the longest amount of time. This is an advantage if you're not totally sure of the target distance like on an unmarked field round.
check the feet
There are a few important considerations that don't immediately spring to mind when choosing vanes. Firstly, you should take a little bit of time to think about the design of the foot of the vane. There is a massive difference in dimensions and shapes. Some types can make for some really awkward application problems. For example, a wide foot with lots of surface area will be great for getting a good bond, but it may be difficult to get the foot properly seated when fletching helical or offset on a thin shaft. Some brands
Shield: The shield shaped vane is essentially a parabolic vane with the rounded rear taken away in a left to right slope. This shape offers the arrow a greater degree of stability than the parabolic as it disperses divergent air currents more efficiently. The arrow speed however, is slightly lower. A super popular example of this shape of vane are the X-vanes from Bohning.
SHIELD VANES