Arrows for a 100lb bow?

[HoorayHorace]

Picked up a self hickory Heavy English longbow of ebay for not many bucks. 100lb@30 



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?

[Badger]

  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.

[PatM]

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.

[HoorayHorace]

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. 

[HoorayHorace]

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 

[Buck67]

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.

[PatM]

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.

[Badger]

   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"

[steve b.]

I've got fir shafts from surewood that are 11/32 100#.

[HoorayHorace]

So why did the English use shafts of 1/2 inch? Surely those bows must have been 200lb plus?

[steve b.]

Probably because the bows were 200 lbs. plus......?

[dylanholderman]

weight

[Pat B]

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).

[Del the cat]

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

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
Most of the Mary Rose arrows were Poplar which isn't particularly stiff.
Del