Arrow shaft length (not including point) should be at least from the bottom of the nock grove to the button + 1". If the fraction of the length is over .5" use the next highest length. So for 27.6" to 28.5" use 28". Easton revised the recurve spine selections, the 2015 Easton catalogue has the old bow weights, the 2016 catalogue and their online selector have revised bow weights.
These charts are only a rough guide and can show some discrepancy depending on the individual archer. The data used here has been collect from various internet sites so may be incomplete, missing or wrong so check with the maker or supplier before buying. Please check you are allowed to use all carbon arrows before buying them as mixed use and school playing fields often prohibit them. Carbon fiber splinters being hard to remove from flesh because they snap easily and are not rejected by the body like wood and metal.
| Arrow Length: | |
| Peak Bow Weight: | |
| Bow type: | |
| Aluminium or Carbon: | |
| Current: |
The shafts listed in each column are ordered by weight (grains/inch), lightest at the top, heaviest at the bottom.
| Weaker Spine | Correct Spine | Stiffer Spine |
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Calculates the approximate arrow weight and FOC (Front of center).
FOC is the distance the balance point is from the center of the arrow.
This is an approximation for how far the center of mass is in front of the center of pressure.
Easton recommends an FOC of 7-9% for aluminium arrows, 9-11% for A/C/C arrows and
11-16% for others. However for aluminium arrows it's no longer easy or so important
to get the right FOC as they are usually only used at shorter distances with large fletchings.
| Shaft: |
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| Spine: |
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| Shaft Length (inches): |
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| Pile or Point (grains): |
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| Vanes: |
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| Wrap length: |
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| Nock: |
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| Total Weight (grains): |
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| FOC %: |
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| AMO Draw length (inches): | ||
| Bow Brace Height (inches): | ||
| Measured Draw weight (lbs): | ||
| Arrow weight (grains): | ||
| Launch angle (degrees): | ||
| Efficency (%): | ||
| Approximate Arrow Speed: | ||
| Approximate Distance: |
There are too many variables to calculate anything other than approximate values.
To calculate the approximate distance the average arrow speed is needed, the speed measured just after leaving the bow will be higher.
For a recurve 7 to 8 degrees is probably the maximum angle using a sight and try 38% for efficency.
For a compound try 50% for efficency, but the maximum angle using the sight may be only 5 degrees.
Approximate Speed = sqrt ( 2 x force x efficency x distance / mass )
this distance is the distance over which the arrow is accelerated, AMO draw length - 1.75" - brace height.
force is the force applied to the arrow in Newtons, peak draw weight in pounds x g / 2.204
efficency allows for the force not being the same over the whole draw length and other losses.
mass is the weight of the arrow in kg
Approximate Distance = speed2 x sin ( 2 x angle ) / g
where g is acceleration due to gravity 9.81 m/s/s.
ArcheryGB