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Dry Fire Speed

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adb:
I understand the concept of DFS, but can someone explain how to determine it?

bubbles:
I seem to remember reading something about shooting lighter and lighter arrows through an chrony. As you approach the DFS for your bow, you will stop getting gains in FPS by dropping arrow weight.   

Badger:
    I think dry fire speed is just another word for efficiency. I have never shot anything under 100 grain from a bow but from what I have found lighter arrows keep getting faster. I don't see where the term has a useful application even though a few years ago we used this term quite a bit. Inefficient bows will show less gains as arrow weights go down, very efficient bows tend to show large gains. Kvillo recently posted a bow showing various speeds with various weight arrows. It gave a clear illustration of how lighter arrows will gain a lot of speed with small drops in arrow weight.


193 grain arrow: 299 fps
236 grain arrow: 252 fps
323 grain arrow: 216 fps
545 grain arrow: 174 fps

Kviljo:
I think you are right, Steve. I never thought about it this way, but when I plotted a graph of the same numbers, and made a hypothetical line of what the dry loose speed of a slow bow would look like in theory, it does not seem to make much sense. It would be interesting to test a slower bow and see what the graph looks like. I think there would be a flattening out at some point, or that's what I have thought before. Perhaps there is not, and that lighter arrows beyond the DLS fool us with their low capacity to overcome the air resistance.

Perhaps we have been fooled by the fact that light arrows will not go far because they take with them too little energy.

In any case, with normal target bows there is nothing to gain in distance by using lighter arrows below a certain point.

bubbles:
I think this is what I was remembering TBB4 pg 162:
1) Maximum dry fire arrow weight : the point where arrow velocity gains from reducing the arrows weight drop off to where they are no longer of benefit.
- I guess I just assumed that guys were testing out their bows to find this point.

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