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Rifled spin (Read 17276 times)
David Morningstar
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Re: Rifled spin
Reply #15 - May 17th, 2010 at 12:34pm
 

Rat Man, are you throwing with your knuckles in vertical line, as if you are hitting with a hammer? This would put the cords one above the other at the moment of release which will align the pouch correctly for a rifled release.
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Rat Man
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Re: Rifled spin
Reply #16 - May 17th, 2010 at 2:33pm
 
I believe so, David.  I know I finish up that way.  I'll have to check to be sure that's how my hand is positioned at the moment of release but I suppose it would have to be.  My projectiles will usually start out pointing straight up and down, then tip forward into the spiral.  It's something that serendipidously happened to my shot.  If I'd set out to do it I'd probably still be trying.
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Re: Rifled spin
Reply #17 - May 18th, 2010 at 6:53am
 
This is, of course, anecdotal...but the other day I cast an oblong, almost-cylindrical river stone--and took note that it definitely appeared to be spinning along its main axis as it sailed over the Delaware River.  I tell this because I've read here previously of "rifled spin" of sling projectiles; but thought this was a sort of wishful thinking.  I guess those Romans were right in shaping their lead like an American football!
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Re: Rifled spin
Reply #18 - May 18th, 2010 at 7:15am
 
mrdeadpt wrote on May 18th, 2010 at 6:53am:
This is, of course, anecdotal...but the other day I cast an oblong, almost-cylindrical river stone--and took note that it definitely appeared to be spinning along its main axis as it sailed over the Delaware River.  I tell this because I've read here previously of "rifled spin" of sling projectiles; but thought this was a sort of wishful thinking.  I guess those Romans were right in shaping their lead like an American football!

If you look back to the early days of this forum, you'll see a lot of questioning about whether consistent rifle spin was ever possible. I think it's one of the things we have all learnt now - that it is. And the technique almost certainly goes back into the stone age, the Romans didn't invent it, nor even (for once!) the Greeks Wink.

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Re: Rifled spin
Reply #19 - May 18th, 2010 at 5:04pm
 
If I want a rifle spin I use a straight underhand or a figure 8. These two style are practically mirror images of eachother on release. When using the fig8 and throwing oblong stones I can get enough rifle spin that when the stone hits the water at 70yds out it will sometimes make quick jump to the right. When I skipp stones on purpose using a very low and fast sidearm the rocks spin in the same way as a top. This is easy to see because as the stone skips it usually curves with each skip. I only use a one finger spacing narrow grip.
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Rat Man
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Re: Rifled spin
Reply #20 - Jun 2nd, 2010 at 8:54am
 
I want to word this correctly;  I don't consider myself the best slinger here.   There are many here who make better looking slings, are more accurate, and/or can shoot farther.  I consider myself very average.  One thing I can do though is get a perfect rifled spin on my overhand style shots as many times as I want, as long as the projectile is somewhat oval shaped.  If I take one hundred shots, one hundred of them will be spirals.  In that the rifled spin is desired and not being achieved by some forum members it's a little disappointing to see that no one has tried what I suggested.  I generally use three styles of overhand shot:  Helicopter, Byzantine, and an overhand sidearmed style.  (I'll try it with Apache soon) With all three of these styles if I modify my release as described earlier in this thread I have no problem getting a nice, even spiral.. every time.  It's simply a matter of 1) loading your projectile perpendicular to the pouch and cords and  2) following   through with your palm facing down and 3) your throwing arm placed like Snidley throwing his cape across his face.  If you're a right hander then you want to finish with your right elbow bent inward, near your nose. 
    Granted, we all have our little throwing quirks and idiosyncrasies.  Possibly there's some unique hitch in my style that allows the above method to work for me and not someone else.  We won't know for sure until someone tries it and shuts me up.  Thanks.
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Re: Rifled spin
Reply #21 - Jun 2nd, 2010 at 6:28pm
 
R-M old mate, it works for me too. With overhead Fig.8 I always get rifle spin same as you. Even with sidearm variation it's still mainly rifle but with a bit of sidespin so the ball curves gently to the right.

Underarm styles are more unpredictable in terms of spin, especially if doing more than two preliminary rotations. Often there is distance destroying topspin which causes the ball to dive sharply at the end of its trajectory.
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Re: Rifled spin
Reply #22 - Jun 2nd, 2010 at 8:25pm
 
  I actually tried your method with the helicopter style with good success.  Took me a minute to get right, but sure enough away they spun.  Sorry I forgot to tell you about that!
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Re: Rifled spin
Reply #23 - Jun 2nd, 2010 at 8:38pm
 
Thanks, guys.  My underhanded shots do exactly that, Aussie.  I get a lot of top spin which gives them a low to the ground trajectory with a nose dive at the end.  For close shots I find underhanded very accurate but for anything over eighty or ninety yards it's useless for me.  Does anyone know if a rifled spin gives you more distance than back spin?  My guess would be yes, but I haven't measured one against the other yet.
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Re: Rifled spin
Reply #24 - Jun 2nd, 2010 at 8:39pm
 
  With golf balls I seem to get better range with backspin... but with egg shaped projectiles (which is what I use most of the time) the rifled is the way to go.
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Re: Rifled spin
Reply #25 - Jun 3rd, 2010 at 1:50am
 
My usual ammunition is golf balls, so of course I have seen that spin imparted by a throw can and does affect the flight of the projectile. Golf balls often fly straight when I sling them -- but they also often curve.

What I want to ask is, with rocks as ammo, is there a need for rifled spin? Does random spin affect rock flight as much as it can affect golf ball flight? Does rifled spin aid rock flight, or is it unnecessary?

I ask because I recently discovered that the local railroad bed is a supply of abundant golf-ball-sized chunks of granite (or something) and they have much better weight than my golf balls, so I "harvested" some the other night and slung two of them tonight across my fully empty work parking lot and I liked how they felt so I'll be using them more.
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Rat Man
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Re: Rifled spin
Reply #26 - Jun 3rd, 2010 at 11:06am
 
I sometimes use those black railroad type rocks.. there are a lot of them at a park where I walk the dogs and sling.  In my opinion they are much more accurate when shot with a rifled spin and I believe, though I haven't measured yet, that they travel farther too.  I try to select railroad rocks that are as close to oval shaped as possible.  Often the imperfections on one side cancel out the those on the other and it flies very true, like a perfect oval shaped stone would.  Other times the imperfections cause the rock to do interesting things in the air, like fly in an "S" curve pattern, where it cuts left then right then left etc...  Overall I'd say that, even with their varried shapes, railroad rocks fly truer and farther with rifled spin than without. 
   I agree with Brian.. golf balls fly the farthest with backspin.  Golf balls are my favorite ammo.  They fly noticably father... like around 30% or so..than any stone.  Often I don't see them land.
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Re: Rifled spin
Reply #27 - Jun 3rd, 2010 at 6:12pm
 
Rat Man wrote on Jun 2nd, 2010 at 8:38pm:
 Does anyone know if a rifled spin gives you more distance than back spin?  My guess would be yes, but I haven't measured one against the other yet.  


As Brian says, with a spherical projectile, especially a golf ball, backspin will give better range. Golf balls are specifically designed that way with the dimples and backspin deflecting the air flow around the ball and giving lift. (look it up on Wiki for a detailed explanation of how it all works.)

As P-J says, golf balls will also curve in flight. If you impart side spin the same principles as apply with backspin will now deflect the ball sideways, making accuracy difficult. However this sidespin does not increase range, only backspin does.

But with an elongated projectile it is important to keep it orientated point forward as this greatly reduces air drag by presenting the smallest possible frontal area, effectively increasing sectional density. Rifle spin gives a sling projectile gyroscopic stability, just as rifling does a rifle bullet, and keeps it flying efficiently, ie. with as little air drag as possible. If an elongated projectile flies with backspin it just presents a larger area to the opposing air and loses velocity more quickly.


Quote:
What I want to ask is, with rocks as ammo, is there a need for rifled spin? Does random spin affect rock flight as much as it can affect golf ball flight? Does rifled spin aid rock flight, or is it unnecessary?


Generally rifled or any spin does not affect a stone as much as a golf ball because stones are much denser (SG typically around 3 or higher) than golf balls which are only just denser than water (SG approx. 1.1) This means the side forces generated by spin are not as noticeable because of the greater mass, especially true of nice smooth rounded stones. However railway ballast stones are often very jagged and angular; these stones can have very unpredictable flight. Any stone which makes a loud whirring sound as it flies will give poor performance. An additional downside to irregular jagged stones is that they tend to hang up in the pouch, giving unpredictable release. No acident that in the DvG story David selects smooth river stones before battling Goliath.


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Re: Rifled spin
Reply #28 - Jun 3rd, 2010 at 7:38pm
 
does anyone know why a sling projectile sometimes twists and spirals? i find this on byzantine style. i'm posting it here because i think it has to do wit what type of spin it's generating.
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Re: Rifled spin
Reply #29 - Jun 4th, 2010 at 3:52am
 
Every sling projectile spins in flight; it's an inevitable by product of the way it comes out of the pouch on release. However the direction of spin varies a lot depending on style, hand posiion, width of the grip and so on. So if you have an irregular shaped projectile which catches the air a lot it can sometimes spiral in flight or at least veer off in some unwanted direction. Good evenly rounded stones usually fly much straighter.
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