Primitive Archer
Main Discussion Area => Arrows => Topic started by: HoorayHorace on December 20, 2014, 08:45:09 am
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Picked up a self hickory Heavy English longbow of ebay for not many bucks. 100lb@30 :D
I want to shoot trad arrows obviously, but not sure what diameter and spine I'm going to need. ???
Take it I'm going to need 1000g arrow?
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I recently bought some western larch that were 11/32 at 100# + spine. Raw shaft weight at 32" long is 750 grains on the average, that would wrok fine with a 125 grain tips.
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Wait and see how much thrust the bow actually has before buying broom handles. 100 pounds is not that heavy and the grip is no doubt a bit wider. You won't need arrows that are that stiff.
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11/32 seems quite a small shaft diameter for a 100lb longbow?
Didn't they use 1/2 shafts in the past?
I intend just to launch the arrows rather than target, so a little over spined for safety would not be an issue.
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I have some 1/2 inch ash dowels that I selected myself with no grain runoff :)
Now I'm thinking they might require a 200lb bow ???
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Both Hickory and Tonkin Bamboo make arrows with a high spline weight but are smaller than 3/8". You could probably start by trying to make some Lowe's tomato stake bamboo arrows.
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I have shot 3/8 Ramin from 100 pound plus bows for years. The grain selection is more important than the thickness of the arrow material.
7/16 "Poplar" is also fine.
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The diameter of the shaft is not of much concern, it is the spine that needs to be right. 100# 11/32 shaft that is 32" long is actually a 70# spine if you are using a 125 grain tip. They wouldproably shoot pretty well if you cut them down to about 30" or 31"
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I've got fir shafts from surewood that are 11/32 100#.
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So why did the English use shafts of 1/2 inch? Surely those bows must have been 200lb plus?
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Probably because the bows were 200 lbs. plus......?
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weight
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That early artillery(English War Bows) were meant to penetrate armor so a heavier physical weight arrow was desired. Those war arrows weighed about 3 times what a good hunting arrow weighs(1500 grains or more).
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That early artillery(English War Bows) were meant to penetrate armor so a heavier physical weight arrow was desired. Those war arrows weighed about 3 times what a good hunting arrow weighs(1500 grains or more).
+1
The arrow weight is more important than range or velocity (for penetration) despite the formula for energy having a 'velocity squared' term.
I't a bit counter intuitive, but the heavier arrow is more efficient as it takes more energy from the bow.
As a sort of rough and ready explanation:- (it ignores all sorts of stuff, but just gives an idea...)
If the arrow weighs the same as the effective weight of the bow limbs then it share the energy 50/50 between arrow and bow limbs+string etc.
A lighter arrow say half the weight of the limbs would take 33% of the energy leaving 66% in the bow.
This post from my blog shows that maximum velocity and maximum energy aren't the same thing...
http://bowyersdiary.blogspot.co.uk/2011/11/mass-velocity-and-energy.html (http://bowyersdiary.blogspot.co.uk/2011/11/mass-velocity-and-energy.html)
Back on topic, I've shot everything from 5/16" to 1/2" from 100#
11/32 or 3/8 is fine. The spine doesn't need to be as stiff as you might think! A 70 spine was too stiff for a flight arrow and I ended up using about 40 spine... mind that wouldn't have worked with a heavier point.
I've seen video of 1/2" Ash arrows leaving a bow almost sideways because they were too stiff :o
Most of the Mary Rose arrows were Poplar which isn't particularly stiff.
Del