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cute dimples (Read 7122 times)
JeffH
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cute dimples
Dec 10th, 2003 at 9:50pm
 
I asked a golf playing buddy of mine about the speed of a golf ball when it leaves the club head.  He said the big guys are sending the balls away at about 175 mph +/-.  This is over 250 fps.

To achieve this velocity, you would have to sling about an 8' diameter circle at 10 revolutions per second.  I find it hard to believe that anyone could achieve this velocity within any reasonable style or level of practice.

Indeed, I think most of us probably attain to about half that with some practice.

So, maybe the dimples would get us something, but It would be, I strongly believe, immeasurable.  My calculations on bullets with greatly differing ballistic coefficients shows that at velocities 10 times the 10 rps above there is no appreciable difference when fired at the same velocity.

So, I think that dimpling a stone or glande would be a waste of time.

jeff <><
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So David triumphed over the Philistine with a sling and a stone. (1 Samuel 17:50)
 
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David_T
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Re: cute dimples
Reply #1 - Dec 10th, 2003 at 10:56pm
 
This may be a dumb question but, Do we not get our speed and velocity from the "whip" or "snap" of the sling? We can not really figure our speed by the "RPMs"  m e t h o d can we?? Undecided Undecided
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JeffH
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Re: cute dimples
Reply #2 - Dec 11th, 2003 at 12:20am
 
Correct, David, but it is still hard to believe we can achieve the equivalent of over 250 fps, snap or other accelerating technique notwithstanding.

I did not mean to imply that rps is the only or even the actual way we should/can measure our velocities.  It was conveinient for the discussion at hand though and is relavent for discussion.

Did I mention that I find it hard to believe that we can achieve the velocities that golfers do with the club/ball combos?

jeff <><
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So David triumphed over the Philistine with a sling and a stone. (1 Samuel 17:50)
 
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Chris
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Re: cute dimples
Reply #3 - Dec 11th, 2003 at 2:01am
 
The dimples aren't making the balls fly any faster, just travel longer.  The mechanics of a golf club and sling arn't that different.  It's just the power of the circular motion of the pouch or club.  I think such speeds are possible with a 50 inch sling.  Thats a 157 inch circumference.  The final snap of the wrist might accelerate it to 15 rpm.  Thats 2356 inches a second, or about 200 fps. 

You have to keep in mind that a pitcher can throw a baseball at 100 mph.  Think of a pitcher with a 6 foot arm.  Speeds of 200 mph don't seem so impossible. 

Chris
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JeffH
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Re: cute dimples
Reply #4 - Dec 11th, 2003 at 12:28pm
 
I think that I am not so much arguing theory here as I am reality.  Certainly, slings of greater length would generate greater velocity.  That is if you could swing it that fast.  There is a limit to how fast I can sling with any given weight and length of sling.  I think that at some point the increase in length would begin to show up as a decreas in rotational velocity.  This is because of the dynamics of the sling itself and that old gremlin conservation of energy.

For instance, when I swing one of my bullroarers it is obvious that it slows down as I let the string out longer and speeds up as I pull it in.  We only have so much energy and speed built into our shoulders.  Overcoming the longer sling to get more velocity would not be as easiy as it seems.  Besides, a 57" sling would require me to hold my sling hand above my shoulder just to keep the stone off the ground prior to slinging.  Now, the human ergonomic comes into play in another way.

In practical terms I think the sling works like a bow or gun in that there are limits that can't easily be exceeded; even with increased x, y or z ellements of the device.  An 80 lb bow does not shoot faster than a 50 lb bow of similar design by any appreciable amount, it just shoots heavier arrows at the same velocity.  All cartridges based on the 30-06 shoot bullets of similar sectional densities at similar velocities. But, if you shoot the same weight bullet in all of them you get very different velocities or sometimes dangerous pressures.  With both the bow and gun you can increase the velocity only so far.  Then you begin to risk either damage to the gun/bow or wasted energy that cannot be applied to the projectile.

This probably seems irrellavent, but in reality it is not.  The dimples may increase the range of a golf ball but a stone from a sling is a different matter.  In fact, a stone thrown overhand would actually hit the ground faster if the dimples had such a great affect, since that stone would have top rather than bottom spin.  We can't expect to get consistent direction of spin like a golfer.  And besides, even if we could, we still have to ask how much would the dimples increase the useful range of the sling.  Without great study it is probably not to be known, but still seems like a moot point due to the likely small improvement for the effort invlolved in making dimpled projectiles.

All that said, I would happily throw anything handy fromo my sling, cute dimples or no.

jeff <><
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So David triumphed over the Philistine with a sling and a stone. (1 Samuel 17:50)
 
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Chris
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Re: cute dimples
Reply #5 - Dec 11th, 2003 at 3:06pm
 
Golf balls have dimples because they are beneficial to the balls flight path.  However, adding dimples to a mass produced object isn't such a big deal.  It would be an enormous undertaking for any slinger to do so with their projectiles, and the actual effectiveness might not be noticeable.  Plus, golf balls aren't cheap.  I certainly wouldn't pay that much just to sling em' into the woods.  Rocks are good enough for me.

I know what your saying about diminished rotational velocity with longer sling length.  It's because the longer cords increase the drag and slow it down.  Although a 5' sling might rotate slower than a 1' sling doesn't mean it's going slower.  The greater circumference of the 5' sling probably means the projectile is traveling much faster. 

I can use a 4' sling pretty well and get some good ranges.  We know that people are achieving ranges over 1000 feet (over 1500?). Think about how long 4 foot ball fields are and how long the projectile would be in the air, maybe 6 seconds (which is a pretty long time).  That’s 1200 feet in 6 seconds, or about 200 feet per second horizontally.  You’d need to fire it close to 45 degrees to hope to get that range.   So you’d need a vertical component to the velocity too.  That’s a combined muzzle velocity of about 280 fps.  These figures aren’t so unreasonable.  How else could slingers achieve such great distances?

Chris
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JeffH
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Re: cute dimples
Reply #6 - Dec 11th, 2003 at 7:55pm
 
Well, they just throw a really long way.  How else could they get the rock so far? Grin Grin Grin Grin Grin Grin Grin

I could not resist that.

Chris and David,  sorry if my posts have seemed obtuse or argumentative.  Not intentional at all.  I really don't know how much velocity is produced, I am just naturally skeptical about large numbers without proof.  I have no problem believing that a stone has been thrown in excess of 1000 feet.  This obviously happens and takes a lot of velocity.

My contention is with the supposed effect of dimples.  Sure, they are great on the smiling faces of  4 year olds and get your attention every time.  But on stones from slings?  I just can't see the return on the investment of making them (just as Chris said.)

So, just ignore the previous posts and suffice it to say that I am a believer in the mighty power of the sling.

jeff <><
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So David triumphed over the Philistine with a sling and a stone. (1 Samuel 17:50)
 
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Chris
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Re: cute dimples
Reply #7 - Dec 11th, 2003 at 8:36pm
 
I think we can all agree on that last line.

For that fact, I think we all agree with each other on everything in this thread.  We're just arguing for the sake of it.  Tongue
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David_T
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Re: cute dimples
Reply #8 - Dec 12th, 2003 at 8:52am
 
My wife asked that State Trooper who brings his child to our daycare if he thought his radar gun would work on slingstones. Cheesy  He told her that he just got one of the new high tech ones but could not really say. I need to set a definate time to meet him an see Grin He is willing and interested.

Then all we have to do is "FEDEX" Yurek in a box to SC, USA from Poland so he can sling the stones or lead glands while we try to get a reading on them. I wonder if "lead" would record easier than a stone on the radar?? Hey, while we are at it, we could test for a Stylth?, stelth?,  shape for our glandes 8)

Got to run but I will ask my wife to ask the trooper for a time. Then we wil at least know how fast this old ex-baseball player can sling a stone. Then you science guys can try to extrapolate my arm mass and length to Yurek's arm and mass --taking into consideration that he has a beard and I do not, of course we Americans have bad jokes  Grin Grinabout those from Poland so you would have to consider that factor. One thing that may help is that I too have Polish in my family on may mothers side so that my equalize other factors. Roll Eyes Grin

Seriously though I will try to get with this guy before the years end.
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Chris
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Re: cute dimples
Reply #9 - Dec 12th, 2003 at 8:07pm
 
LOL!   Grin

I can just see Yurek packing himself in a box at a FedEx center with armfuls of glands.  “Could you throw in a few more styrofoam peanuts and tape me shut please?”  I can just imagine the custom's sticker:

Items: Polish Slinger, glands, slings
Approx value: How did Dave convince me to do this?  Help me…

I doubt he'd ever make it to SC; Probably be locked up in Guantanamo Bay.  At least it’s warm in Cuba; Poland must be pretty cold right now.   

Chris
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Yurek
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Re: cute dimples
Reply #10 - Dec 12th, 2003 at 8:41pm
 
Guys Shocked  ???

I see the better solution. Simply I will sling some deep dimpled (they should come flying) glandes from Poland to the prearranged place in SC. At agreed time David will be waiting with the radar gun and with the tin hat on his head.

Jurek
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In the shape, structure and position of each stone, there is recorded a small piece of history. So, slinging them, we add a bit of our history to them.
 
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JeffH
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Re: cute dimples
Reply #11 - Dec 12th, 2003 at 10:29pm
 
Yurek, this won't work.  The heat from re-entry will melt the glandes before they get close enough to clock with the radar gun.

Maybe if you put a tungsten shell on the glandes they could take the heat, or at least keep the molten lead inside where its mass could maintain the velocity.

jeff <><
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So David triumphed over the Philistine with a sling and a stone. (1 Samuel 17:50)
 
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Yurek
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Re: cute dimples
Reply #12 - Dec 13th, 2003 at 7:04am
 
Jeff, it works. I forgot to mention before, that all glandes hit the aim after a big lag. So they must surround the earth (maybe several times). I know it seems to be incredible, but it is quite simple, just the inward (spiritual) forces keep the proper trajectories and shape of molten glandes. Low temperatures in Poland help too, very cold air inside the deep dimples makes the pretty protective layer. So a tungsten is not necessary.

Jurek 8)
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In the shape, structure and position of each stone, there is recorded a small piece of history. So, slinging them, we add a bit of our history to them.
 
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Chris
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Re: cute dimples
Reply #13 - Dec 13th, 2003 at 6:48pm
 
I thought I saw a gland whiz by my car on my way to work.  It must have been traveling about mach 7 or 8 from my calculations.  Nice work on the ceramic heat shield and the liquid nitrogen cooled dimples.  I think our next project will be to make a super-sized gland with human sized dimples. Forget airplanes; slings are the future of transportation!
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Yurek
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Re: cute dimples
Reply #14 - Dec 13th, 2003 at 9:29pm
 
I agree, a sling will become the most important source of mechanical power in the not far future. It will terminate all present energetistic problems on the earth. Alredy it is used even for acceleration space ships in the outer space, the well-known fact. I suppose that air crafts will be similar to dirigible, but wil be made of lead and dimpled. Sure, sling is the key to find the perpetum mobile.

So, slingers will very desirable in future.

PS. Chris, sorry for the whiz. I will try to sling higher.
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In the shape, structure and position of each stone, there is recorded a small piece of history. So, slinging them, we add a bit of our history to them.
 
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