Our newly spliced, double braid Dacron string managed a couple of shots (351.2 fps, 347.5 fps) before  deciding to part from this earth. It was a sad end for such a pretty string. However, much has been learned.  Having practised twenty odd eye splices, I find myself bordering on proficiency at the whole miserable business. It is ironic that it now seems these terrors from the world of cordage are not really all that ideal for our purposes anyway. The strings are not breaking near the ends. They are snapping more towards the middle. The reason for their failure popped into my head in the middle of the night.  Without exposing the reader to the horrors of my dreamworld (populated as it is with writhing eye splices), suffice it to say, the following was revealed with a bit of the old lucid dreaming :

“………The inswinger design puts much more stress on the bowstring than a conventional outswinger. Now, this is only true if you rig the string too tight. Put on a slack string and the blow from the limbs is transferred completely into the frame of the machine. A string that is loose enough, need never experience that awful snapping action that occurs by jerking a fast moving pair of limbs to a complete stop.  With an inswinger the limbs end their power stroke at a force vector that is in a direct line with the bowstring.  This puts much more tensile stress on a  tight string than the acute vector coming from an outswinger. Therefore, loose bowstrings are essential for inswingers………

Armed with this vital intelligence, I found myself embarked on an afternoon filled with bowlines.  Bowlines are far more friendly with this sort of experimentation because their length is so easily altered.  (Timber hitches are out because they would never fit into the nocks.)  After a dozen or so tries I managed to find the right length string and quickly installed it on the machine.  Somehow though, it didn’t feel quite right. The Gallwey string was always nice and twangy, even at rest.  Now the string felt like a slack dog leash rather than a well tuned musical instrument.  Still, I remembered the premonition from my dream and tried to keep an open mind about it all.   We were only able to manage one shot with the loose string because it was our last bolt and it shattered into pieces trying to plunge through the local phone book.  A decisive end for such a worthy projectile.  Before dying,  it generated a comforting 350.9 fps.  This is very close to the other two shots fired with the tight fitting string that had broken earlier in the morning. I had been careful to increase the draw length with the new loose string by a couple of inches to help compensate for its slackness. Doing this gave us 3400 lbs of draw weight, exactly the same as used with the first two shots. All of which seems to imply that a loose string does not much effect the power of the machine, other than perhaps by losing a couple of inches of draw length. Not much problem there, we have plenty to spare with an inswinger.

It is encouraging to note that we now have three more data points that seem to indicate a fairly constant velocity, (351.2 fps, 347.5 fps, and 350.9 fps). It is still not the set of twelve uninterrupted shots I want to see, but I am starting to sense an underlying stability to the machine’s behavior. Better limbs, better strings, more bolts. The answer is in there somewhere.

Seen against the white background and slowed down 4 times, it is possible to just make out the bolt’s flight path as it wallops into a few stacks of the Daily Chronicle:   streak2

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