• Thickness of shaft
• Weight of the pile
• Size of the fletchings
• Overall weight
• Ideal combination
  
  Thickness of the shaft
  
  There is essentially a choice between 5/16 and 11/32 inches. The larger the diameter the heavier and stronger the arrow will be. Therefore I choose 11/32 for indoor target archery and field archery and 5/16 for outdoors target archery and clout. Remember, the heavier the arrow the stiffer it gets.
  
  Weight of the pile
  
  This is very much trial and error and I have not come across any formula for the selection of piles. They are usually sold by weight in grains. The heavier piles are longer. There are two things to consider. A heavier pile increases the overall weight of the arrow and  tends to decrease its apparent spineage. So, a heavier pile will make the arrow whippier and make it fly to the right. A lighter pile will make the arrow stiffer and fly to the left. (The opposite ways for a left handed archer).  Chris Mussolini wrote to me to explain that increasing the point weight will make the dynamic spine of the arrow weaker. Increasing the point weight by 25 grains will make the dynamic spine of the arrow weaker by approx 3.5lbs.

The second issue is that the centre of gravity or balancing point of the arrow will be further forward of centre with a heavier pile and (though I have not seen this recorded) the arrow will fly off the bow higher and then dip down sooner that a comparable arrow with a lighter pile. The net effect is that it will not reach as far as a lighter arrow. The advice I have seen agrees that the balancing point should be as much as 2" in front of the centre of the arrow length. Tests have shown that as the centre of gravity moves towards the rear of the arrow the range of the arrow diminishes.

Size of the fletchings

The profile of a fletching has less effect on the flight of the arrow than its overall size. However a shield fletching will have more drag than a parabolic shape. See http://www.longbow-archers.com/arrows.htm

For clout you will want the smallest feathers that you can find. For target archery you will see a wide range of sizes as many longbow archers prefer the look of larger fletchings. But if you are shooting at 100 yards you will want to have as little drag as possible and you dont need large fletchings as there is plenty of time for the arrow to straighten out. Indoors or in field archery where the distances are shorter, you can legitimately argue for large flashy feathers.

Overall weight

It is common sense that a heavy arrow will fly a shorter distance than a heavy one. However, the science of flight contradicts common sense! Although a lighter arrow will leave a bow with greater velocity- the retarding effect of the air means that it slows more quickly and hence will travel a shorter distance.

What is the ideal combination?

I will have to leave it to you to find the combination that works best for you. It is trial and error, but when you find that magic combination, keep a record and make the next set exactly the same.

Whilst you are waiting for the perfect match to your bow, your best plan is to get each arrow in your set to match each other. My priorities in order are: a. spine within one or two pounds; balancing point within half an inch: and finally overall weight. Of course, even if all three were a perfect match, there is not guarantee that the arrows would behave in the same way when shot, even if you could replicate each shot perfectly each time. The wood is a natural material. The moisture content will differ from arrow to arrow, as will the wood grain, the thickness of the varnish, the cresting and so on. If you want perfect arrows you would not have chosen to shoot the longbow!