Primitive Archer
Main Discussion Area => Bows => Flight Bows => Topic started by: DC on October 05, 2020, 12:32:24 pm
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In my shop I can get a sheet of paper set up about 8' from the bow. Is this far enough to tell me much about release and flight?
And is paper testing a decent option in liu of spine testing? If it's not cutting a great slash across the paper it must have come around the bow properly, right?
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A good paper test would trump a spine calculation. Can't help you on the distance but I think about 8ft would be pretty good. Allen does a lot of paper testing I am pretty sure he will chime in.
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I tried a couple of shots that showed the arrow was going sideways but I was using newspaper and it has a grain. Maybe I should use different paper?
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A good starting point for spine on a 50# bow. Test your arrow on 22" centers instead of 26". You are looking for 1" deflection with a 2# weight. Very little spine is needed with no weight up front and light arrows.
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Oh, very light, I'll try that. The paper training is saying that I need a stiffer arrow I think. I'm getting a 3" tear to the left. Since the bow is held horizontally in my machine left is actually up. I put the top to the right. Having the bow horizontal shouldn't have a big effect on this should it? I'm not sure what gravity would do in this case.
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A good starting point for spine on a 50# bow. Test your arrow on 22" centers instead of 26". You are looking for 1" deflection with a 2# weight. Very little spine is needed with no weight up front and light arrows.
Yikes,, I have to double check this. I don't have any boo this light. A regular 30# spine arrow(from my grandson's quiver) shows .5" (1/2") this way. What length arrows would be spined this way or does it matter? I think I'll put a longer pull rope on my shooting machine ;D ;D
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What length arrows would be spined this way?
@22 in centers, 1" deflection with 2#?
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I must be doing something wrong. I'm a coward so I'm using my 35#@25" bow and I'm drawing it to 20" where it's about 20#. If I use a 50-60#(26" centers)arrow it makes a 1" vertical tear. If I use the 1" deflection@22" (no fletching) it cuts the paper in half(8" tear) to the left. Could that be something to do with my machine. I'm reporting the direction if the tear as if the bow was vertical. Make it easier to think about. The paper is 7' from the bow.
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I must be doing something wrong. I'm a coward so I'm using my 35#@25" bow and I'm drawing it to 20" where it's about 20#. If I use a 50-60#(26" centers)arrow it makes a 1" vertical tear. If I use the 1" deflection@22" (no fletching) it cuts the paper in half(8" tear) to the left. Could that be something to do with my machine. I'm reporting the direction if the tear as if the bow was vertical. Make it easier to think about. The paper is 7' from the bow.
I was going by what Ivar Mald had told me at the flight shoots, 24" arrow that weighs about 160 grains, no point weight and tapered tip. If you have any weight at all up front it would change that formula drastically. Ivar had tremendous success with his arrows.
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I tried it once with no weight but it was 28" or better long. I'll try again at 24" no weight. Thanks :)
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I tried it once with no weight but it was 28" or better long. I'll try again at 24" no weight. Thanks :)
You will also need to taper the front 2" to get some more weight off the front
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Not a lot better but I did get 204fps from a 20#@20" bow ;D ;D. The arrow is 170 grains. I'm just throwing these arrows together so there may be a problem there but I think it's because I'm so close to the bow. I don't think the arrow can straighten out in 7'. I think I'll have to build a bigger paper frame that I can try outside.
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I don't think the arrow can straighten out in 7'
are you working on what it takes to straighten the arrow flight, or to see how straight it can leave the bow?
Perhaps a release from the string as close to a good finger shot as you can duplicate would be something to establish first.
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I have a rolling block release. I can't think of anything except maybe a spring to add some resistance to the release and I'm having trouble finding room or attachment points for that. I have a stop on the rolling block so that it doesn't flatten right out but leaves the "fingers" up slightly. Actually all the shooting machine releases I've seen(not many) have a compound bow type release which doesn't supply any sideways kick.
PS I just went and looked at Del's release and it's very much like mine.
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guess thats as close as it comes,
it would be nice to see some trend, ie the softer the spine, the further (or lesser) an arrow seems be knock left. I wonder if you are changing too many variables at once, only drawing 20"
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I did try varying the draw length. When I increased the draw length the arrow hit a little more to the left but the tear stayed the same length. I'm converting the machine from holding the bow horizontal to holding it vertical. See if gravity is messing with me. There's quite a bit to it. I don't use an arrow shelf so I've had to add one to the machine. I'm probably going to have to reposition the chrono lights. I can't use the chrono facing up like normal because the paradox(I know, wrong use) causes the arrow to fly in an arc and it misses the sensor windows so I just get errors. Especially with two chronos. Outside you can stand further away and give the arrow time to settle. I'm thinking more and more that it's the cramped quarters that's messing me up.
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I was just about to say you really need to mount your bow vertically or at least close to 'real life' orientation. You know gravity is just a theory right?! :)
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Vertical or horizontal doesn't seem to make much difference and it will be a bunch of work to move the lights so the chrono will work that way. The tears in the paper are very similar although turned 90°. If I have it horizontal I can set it up and take it down if a moment. Not so easy when it's vertical. Like you say," gravity is a theory."
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I am starting to think the slo-mo Video features on these smart phones is better than paper tuning. I can really see what is happening with the arrow if the background provides good contrast and the lighting and angle is right.
I was pretty impressed at how well Ivar’s arrows performed. They were very light and the spine very low. I think he Chrono tested his bow at around 380-something feet per second. The force on nock of the arrow seems like it should have caused the arrow to buckle and explode. I’m sure it would have exploded with a finger release. The hook & loop release he used makes a big difference.
Alan
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I've used slo-mo footage with phones and it sure is really good in seeing how the arrows do. And its so fast. Take a new bow, shoot bunch of arrows through it and film all. Then pick the one that flies best, easy.
I haven't tried it with flight shooting gear yet, but i'm looking forward to it.
The angle i think is best is of course straight behind the archer aligned with the arrow. There you can immediately see if the nock goes left or right.
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I have some video taken from a perfect angle and lighting behind me of shooting my footbow and I could clearly see the arrow make a horizontal slot in the paper. The next several frames showed the arrow continuing on its way with the nock left and point to the right, which was exactly what the hole in the paper would have told me. Each frame captured nearly three feet of travel, but it was good enough even at vey high arrow speeds.
The angle the video is taken from is important. It has to be taken directly from behind the bow. There is a rastering effect even with the high speed video frames where the image is usually scanned top to bottom. This made the arrow appear a little shorter in flight than it actually was. But it was good enough. There is another video where it shows a perfect hole punched in the paper and the next several frames show the arrow maintaining a perfectly aligned path. That arrow was one we didn’t find....
Alan