Slinging.org Forum - Dimpled glans

jlasud

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Dimpled glans
Jan 2^nd, 2013 at 5:20pm

Soo,this has been somewhat discussed before,but,I found this bit of info.
It seems like it works for rifle bullets also,not just spheres.
Rifle bullets have a flat tail,so dimples help air rush in behind the bullet faster,and reduce drag if i get this correctly.
So I'm wondering if,bipointed glans wouldn't benefit at all by having dimples ,or would they?
I've made a few pieces of clay glans before with dimples,but it wasn't much of a research,so i can't tell.
Here's the link:http://www.longrangehunting.com/forums/f19/army-test-new-long-range-bullet-40899...

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Atlatlista Ex Member	Re: Dimpled glans Reply #1 - Jan 2^nd, 2013 at 5:36pm Cool beans! I'm going to start dimpling all my arrow shafts now
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scoteeball Senior Member Offline Slinging Rocks! Posts: 281 Gender:	Re: Dimpled glans Reply #2 - Jan 2^nd, 2013 at 7:10pm http://bulletin.accurateshooter.com/2009/04/us-army-team-tests-radical-new-dimpl... The article was posted on April 1. Some of the posts seem to suggest an April fools joke Dimples keep a golf ball in the air much longer than a smooth ball but it has back spin. I don't think the physics is the same for a rifle bullet.
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Bill Skinner past-moderator Offline Slinging Rocks! Posts: 3292	Re: Dimpled glans Reply #3 - Jan 2^nd, 2013 at 8:09pm It was a joke.
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jlasud

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Re: Dimpled glans
Reply #4 - Jan 3^rd, 2013 at 2:53am

I noted someones post,that it was an april fools joke. If so,i quite bit the hook Cheesy

As far as I knew,dimples raise the Magnus effect of spheres(golf balls) so with a backspin,they produce lift. And possibly help air to fill the void behind the flying ball faster.
So was it officially a joke?
Then i have to limit myself to dimpled clay balls Undecided

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Dan Interfector Viris Spurii SlingingGuide Moderator Offline Slinging Rocks! Posts: 3974 Gender:	Re: Dimpled glans Reply #5 - Jan 3^rd, 2013 at 10:30am I think you'd be better off just polishing and making sure your gland is perfectly symetrical and pointing the tips than trying to add dimples. I've never had problems with glands 'cutting' like golf balls do because glands are so dense and they orient very easily. FMJ glands. I really can't see anything else being any better.
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LightSlinger

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Re: Dimpled glans
Reply #6 - Jan 3^rd, 2013 at 12:03pm

The Magnus effect basically allows you to create a consistant curve in a golf ball. It does help a golf ball to fly farther but that's mostly because you can create a killer backspin, allowing the ball to achieve a higher altitude faster while the ball still has good momentum, thus carrying it further. Throw a golf ball with a Cobra's head pouch, releasing the trigger cord with your palm facing you and you'll see the reverse. A wicked top spin that will drop that ball much sooner than it normally would, and roll forever...

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Masiakasaurus past-moderator Offline mah-SEE-a-kah-SOR-us Posts: 6069 Alabama, USA Gender:	Re: Dimpled glans Reply #7 - Jan 3^rd, 2013 at 2:14pm Part of the effect is a change in the way air flows over a dimpled surface. Dimples create turbulence which is lower in pressure than smooth air. The low pressure, turbulent air makes the projectile more slippery. But glandes are too massive, too small, and too fast to benefit from dimpling.
Back to top	Pikåru wrote on Nov 19^th, 2013 at 6:59pm: Massi - WTF? It's called a sling. You use it to throw rocks farther and faster than you could otherwise. That's all. ~Engineers like to solve problems. If there are no problems handily avialable, they will create their own problems.~ IP Logged

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Re: Dimpled glans
Reply #8 - Jan 3^rd, 2013 at 2:34pm

Masiakasaurus wrote on Jan 3^rd, 2013 at 2:14pm:

Part of the effect is a change in the way air flows over a dimpled surface. Dimples create turbulence which is lower in pressure than smooth air. The low pressure, turbulent air makes the projectile more slippery. But glandes are too massive, too small, and too fast to benefit from dimpling.

Maybe if you threw the Glande in a sideways orientation. Like instead of it looking like this from the back : O

If it was thrown looking like this: <O>

But, even this way I think that this orientation would cancel out the effects of dimpling anyway..

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squirrelslinger Interfector Viris Spurii Offline peace through superior firepower Posts: 2870 Ky, USA Gender:	Re: Dimpled glans Reply #9 - Jan 3^rd, 2013 at 3:05pm Masiakasaurus wrote on Jan 3^rd, 2013 at 2:14pm: But glandes are too massive, too small, and too fast to benefit from dimpling. Wait. Bullets are smaller than glands, weigh about half as much, and are faster. They benifit from dimpling. Let us try it, before saying it doesn't work.
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scoteeball Senior Member Offline Slinging Rocks! Posts: 281 Gender:	Re: Dimpled glans Reply #10 - Jan 3^rd, 2013 at 3:49pm Bullets spin on their long axis (rifling) where as golf balls when struck properly are spinning on an axis perpendicular to their direction.
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Dan

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Re: Dimpled glans
Reply #11 - Jan 3^rd, 2013 at 4:01pm

Bullets don't benefit from dimples, skim the thread above and you'll see it was an april fools joke.

I chuckle when I see the movie 'Sniper' and there is a scene where he is 'sharpening' his bullets with a file so they are 'more precise'. Obviously, thats not real at all.

The standard polished FMJ bullet is just about as precision made as can be.

As others said, dimples benifit back spin, not rifle spin like you get with a sling.

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I was pretty good at slinging like 10 years ago.

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Masiakasaurus

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Re: Dimpled glans
Reply #12 - Jan 3^rd, 2013 at 5:42pm

squirrelslinger wrote on Jan 3^rd, 2013 at 3:05pm:

Masiakasaurus wrote on Jan 3^rd, 2013 at 2:14pm:

But glandes are too massive, too small, and too fast to benefit from dimpling.

Wait. Bullets are smaller than glands, weigh about half as much, and are faster. They benifit from dimpling. Let us try it, before saying it doesn't work.

Bullets don't really benefit from dimpling. They're way too small the get enough dimples deep enough to alter their flight, so dense and massive that they fly very efficiently without dimples, and they're so fast that the bullet will almost always be in front of the layer of turbulence it's creating. The math's just not there from an aerodynamics perspective. This was definitely an April Fools prank. On something larger, less dense, and slower (like a car) dimples are pretty effective. Back spin is not necessary, just so long as the dimpled object isn't rolling forward and driving itself down the dimples will work.

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Pikåru wrote on Nov 19^th, 2013 at 6:59pm:

Massi - WTF? It's called a sling. You use it to throw rocks farther and faster than you could otherwise. That's all.
~Engineers like to solve problems. If there are no problems handily avialable, they will create their own problems.~

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jlasud

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Re: Dimpled glans
Reply #13 - Jan 13^th, 2013 at 1:04pm

Hmm...I made a few dimpled clay balls,and some without dimples...couldn't tell much difference,but then i realized,i can't give them a backspin.
One would have to sling it with your thumb facing the throwing direction,which is a very awkward potion for an arm during throwing.
The dimpled balls, also had a SHHHH noise to them,that's more drag. But they were travelling about as far as smooth ones so again,nothing groundbreaking in sling technology.

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Rat Man

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Re: Dimpled glans
Reply #14 - Jan 13^th, 2013 at 8:52pm

jlasud wrote on Jan 3^rd, 2013 at 2:53am:

I noted someones post,that it was an april fools joke. If so,i quite bit the hook Cheesy

As far as I knew,dimples raise the Magnus effect of spheres(golf balls) so with a backspin,they produce lift. And possibly help air to fill the void behind the flying ball faster.
So was it officially a joke?
Then i have to limit myself to dimpled clay balls Undecided

Don't feel bad, jlasud. It had me going for a minute also.

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