Errata for TBB volume one and two
scp
been corrected in the following volumes. As it is quite plausible that
some people buy only the first two volumes, it would be nice to collect
those corrections in one place. Possibly to be printed and inserted into
the volumes or at least posted online somewhere.
I can think of only a couple of them at the moment.
1. "Yet the Holmegaard bowyers made the bow backward even when there was
no clear benefit doing so." Vol.2 p90
2. "If bows are measured under conditions of routine use - if they are
pulled once or twice before being measured or shot - hysterisis usually
shrinks to insignificance." "[A]n average bow, regardless of wood type,
looses a very small percentage of stored energy to hysterisis. So small
that for all practical purposes it can be ignored." Vol.1 p72
Anyone willing to post the corrections?
scp
1. We don't have any evidence or reason to believe that "the Holmegaard
bowyers made the bow backward."
2. The test method used in the volume one to test hysteresis was faulty.
"The math and engineering explanation is complicated and lengthy, so to
save space and to avoid torturing fellow mathlectics, let engineers ...
agreeing tentative number ... being about 9%."
"The 9% figure will surely vary slightly due to species, moisture
content, degree of set, arrow weight, and more. The lab is beckoning ..."
TBB vol.4 p.142
9% of the stored energy is not insignificant.
But the real issue for selfbows would be the variation due to wood
species.
scp
3. "Give me any of your sinew-backed bows and let me make an all-wood
bow with the same reflex, draw weight, and draw length, and its cast will
be identical to your sinewed bow." TBB vol1 p.50
The stored energy might be identical but the cast might not be, due to
the difference in limb vibration and hysteresis of the material used.
Especially if the material used is either "fiberglass or dried pasta."
scp
On 3. It might not be fair to handicap the sinew backed bow to the same
reflex and draw length as the all wood bow. It would be fair enough if we
just stipulate that the arrow weight (but not the length) and the draw
weight (but not the length) should be same for both bows.
scp
If it matters, I only make selfbows from staves. I haven't backed any of
them with sinew yet. If backing with sinew makes more reflex possible,
it's the merit of the sinew backing. If it allows longer draw length,
same thing. I sincerely hope that unbacked selfbows shoot faster than
sinew backed bows within certain parameters. But I'm not willing to
artificially handicap sinew backed bows to accomplish that.
scp
I do this because I like TBB most out of several books I have read on
bowery. I do this in the spirit of correcting typos in a favorite book.
As I said earlier, the corrections I mentioned are mostly made by the
authors themselves. That does not mean there are no genuine issues
unresolved. But it would be better to discuss them in depth in their own
thread. I like to keep this thread open and simple, even to allow the
collection of typos in one place.
scp
The book says the "cast" would be same. Of course, the stored energy
would be same. But the cast might be different due to the difference in
the amount of limb vibration and hysteresis.
I suspect all wood bows would shoot faster than horn bows "with the same
reflex, draw weight, and draw length" at 50# and 28". But it's not fair
to handicap horn bows that way.
Bows do not shoot arrows themselves. The only major limiting factor for
human shooters is the draw weight. Requiring "the same reflex, draw
weight, and draw length" would not be fair to horn bows, Japanese yumis,
Egyptian deflex tip bows. People can adjust their draw length rather
easily. But they cannot increase the maximum draw weight that easily.
To be fair we should just ask how far or fast a bow can shoot a certain
weight arrow (regardless of how long it is) at a certain maximum draw
weight (regardless of how long the draw length is, within reason of
course).
