making arrows
scp
You are correct. It should be "perpendicular to the annular rings."
I meant it that way. I misspoke probably thanks to the ambiguity of the
term 'grain'.
"Is primarily a strength thing":
Spine is basically a measure of the stiffness of an arrow shaft
and therefore "is primarily a strength thing."
That does not mean "they" knew about its function
concerning the way arrows bend in flight.
Instead of bogging down in semantics,
we can ask whether "they" knew about the way
spine affects the flight of arrows.
What would be good evidence for such knowledge?
scp
Believe it or not, IMHO it would be easier for the primitive people
to guess the comparative spine than to guess the comparative weight of
arrow shafts.
If you don't think so, just hold the ends of two or three shafts in one
hand
and bend them with the other hand, one by one.
scp
It appears that the original question of "cancelling out spine" might
have been asked in the context of light and weak spined cane or bamboo
arrows.
As the spine of such arrows vary a lot, it is not unreasonable to ask
what would be the most reasonable length to adopt
if we are going to disregard spine completely.
Even though I'm not sure why at the moment,
it also appear that such arrows can benefit from long draw length.
We are probably talking about the length between 33" to 43".
What would be the minimum length of light arrows that are reasonably
reliable,
if we were to completely disregard spine,
as we are supposed to do so up to quite recently?
scp
Bowyers Den, no. I tried to make arrows out of bamboo tomato stakes
without much success. I do make shootable arrows with split cedar, maple,
and occasionally even oak.
As I make bows and arrows for physical exercise, I don't bother to
measure the spine of shafts yet. I just use their weight and length and
occasionally flex them by hand. For a while I have been making my arrows
32" long, even though my normal draw length is 28". Now I'm thinking
about making them 36" long and gradually increasing my draw length to
match it. Probably I have to change my shooting form drastically. Whether
my whitewood selfbows can take it is another story.
I wonder whether I can just use weight and disregard spine. Of course I
can, so long as I can keep them within the 36" target at 30 yards.;-) Did
I mention that I do this just for exercise?
scp
If you ever straightened an arrow, you would know about the stiffness of
an arrow shaft. Do you think primitive people ever discarded a shaft for
being too bendy? Sure. Still they might have been thinking only in terms
of weight. That is, they might have misunderstood the relationship
between weight and bendiness(spine). It's about time for us to refine the
question.
Did they measure spine? Of course, by bending the shaft.
Did they use any unit of measurement? Probably not. No record.
Did they know about spine? Depends on what you mean by "knowing about
spine."
There must be many more interesting questions to ask.