The acute string angle at the 49″ draw can be seen in the following video.  The fins on this bolt probably need a touch more trimming to clear the string.

Click here.   20100622105903o

This particular shot got an error reading from the chronograph.  However, no reason not to think it wasn’t in the same 325 fps range as yesterday.  The kamarion is noticeably less jiggly now that it has gone and got a case of the muscles.     …… The Rebecca informs  I  might consider it a  worthy role model.

One Response to “Acute video”

  1. Joel says:

    What I find most interesting after many views is what happens to the string after the shot. (Hope this is the right vid) After the limbs have ceased movement, there seems to be an apparent slack of a couple inches that takes about 2.5 seconds to retrack completely so that it lies straight with tension on it.

    I dont know how long it stayed in shooting position before trigger was released, but suspect not long. If this is a regular occurance then it means you able to inroduce a certain amount of pretension in the string without fear of snapping it.

    It is my thinking that the string should absorb a certain amount of force as it changes the major stress point in the limb regarding arresting movement upon release.

    Without the string to arrest tip movement, it is my theory that the stanchion then becomes a simple fulcrum with the bundle itself arresting movement. This would result in a wobbling of the limbs after impact and bundle movement. As a result there must be tremendous side to side strain on the bundle as it is designed to be twisted rather then absorb impact forces.

    If your tremendously fast moving limbs weigh 15 lbs, then that weight is multiplied relative to the position of the fulcrum to the lever which in turn will strike one side (or half) of the bundle like a big sledgehammer.

    I could be wrong about the matter of the stanchion becoming a fulcrum but that is how it pictures out in my head.

    On another note, I just re-read over a years worth of your blog, and it is nice to see the steady progress you have made. I am afraid that what ever ballista thoughts I have these days mostly concern YOUR machine LOL. Somehow you have me mentally engineering rope bundle tech, AND a non-compounding to boot.

    There are certain rewards to my pestering you with lengthly comments. Most notable is the absence of the 2855 grain durabolt in favor of 7000 grain harpoons. Who knows? In another year or so I will have you up 10,000 grains or more, hopefully at 400fps plus!

    For now, Im pretty sure that without the brass stanchion inserts them big logs you call limbs should be able to get you verrrry close to that should you tighten it up again and make use of that 63 inch draw your machine has.

    BTW – I figured out what might be a simple fix regarding the stretching of the bundle and the “huddling” on Philon spoke of.

    The answer I came up with is really too simple to actually work. Once the springs have stretched out a lot and huddling occurs, simply back-off the tension and insert a wider bar supporting the bundle. The “ears” or slot in which it sits will certainly accomadate it. Slack taken out, bundles properly stretched and “settled”, the huddling from excessive twist should once again be kept at check or at the least not “excessive”. Performance restored.
    Again just another brain fart and no doubt there is a logical and simple reason it isnt already so.

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