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Back-spin (Read 2758 times)
Hondero
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Back-spin
Sep 16th, 2004 at 5:16pm
 
A good golf player can project the ball to 224 Km/h (140 mph) and get a range about 240 meters, due to the Magnus effect obtained with a good back-spin. The ascending Magnus force produced is about  half of the gravity, which means a greater elevation of the trajectory and a greater range. We know that with the slig can be obtained greater throwing speeds, around 400 Km/h. I think the spin that takes the ball sent with sling can be similar to the one of golf, and as the Magnus force is proportional to the product of the speed and spin, the value of that ascending force would approach enough the one of the gravity, getting in theory spectacular ranges.

Nevertheless we know that when throwing golf balls with a sling usually the reaches are not so spectacular, and that is due to the lack of back-spin in the launching, or even most frequent is that we give to the ball a top-spin, diminishing the normal range.

So, the secret to get good ranges with golf balls would be to find a good throwing style with back-spin. Maybe someone of you (Mgreenfield, Tech, etc) have some ideas on the matter. A grip with separation between the cords (necessary whenever we want to give some type of controlled spin to the projectile) and the reversal of the usual positions of retention and release seems to be important, that is to say, the retention in the forefinger and the release between the thumb and the middle finger for example, or holding the release end with all the hand but coming into below it.

Well , I´ve never tried it yet, but it would be funny getting similar ranges with golf balls than with glandes  8).
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Matthias
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Re: Back-spin
Reply #1 - Sep 16th, 2004 at 6:02pm
 
You mean we're not supposed to throw them so that they veer off strongly to the right before rolling and diving straight into the mud? I must be doing something wrong Grin... It would seem that most of the overhanders should have an advantage here.

Starts to flirt with controversy as to what defines a "sling projectile" again though! When you start to play with lift producing techniques and appendages it won't be too long before the "rules" guys crack down! And with good reason I suppose... The records for "hand-thrown" objects (disks etc) always seem a little dubious to me. I've verifiably thrown things more than a kilometer... all it takes is one thermal and you aren't getting that glider back.

Techstuf has mentioned these guys at least twice in the past little while:

http://www.x-zylo.com/

If you can throw one 200m unassisted, what are the possibilities with a little more sling assisted oomph? (oh and btw I take strong exception to the "invented by" part... these guys have been around for ages) Make sure to watch the video.

If you want to play, take a sheet of paper and fold the long edge up in about 1" folds until the width is reduced to ~3 inches. Roll the strip into a ring and tuck the folded parts together to hold it in shape. Now go terrorise the local kids/cats etc. I always found that a rugby style underhand throw was easiest (particularly indoors).

I can imagine that some little spun metal tube-wing glandes you could do some pretty serious damage. Another project... Come on Tech, we know you have the skills to put these together, we're all waiting for the prototype!

Matthias

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David_T
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Re: Back-spin
Reply #2 - Sep 16th, 2004 at 7:00pm
 
Pretty neat flying UFO!

Hondero,

I think I have back spin on golf balls by simply throwing overhand and straight over my head. If I do go off to the side, the ball slices to the right---but straight over the top it goes very straight and rises some as it flies.
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Gun
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Re: Back-spin
Reply #3 - Sep 16th, 2004 at 9:30pm
 
Would it be possable to get the golf ball to spin more if you had one end weight from on the inside? I am just thinking that if the golf ball was weight on one end it would have to spin a certin direction because of gravity. I don't know and i haven't tried yet either. Maybe this weekend. Another thought might be to check out some illegal golf ball. There are some golf balls that are illegal on the big golfing tours. It might be because the ball cause to much lift.
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Tint
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Re: Back-spin
Reply #4 - Sep 16th, 2004 at 10:20pm
 
Hondero,

I am a competitive tennis player.  When I sling, I sometimes use a similar motion to my serve:  The release is just like an overhand throw but at the wind up I let the rock drop behind my back for one extra loop before I let it fly.  I can get a lot of back spin on the rock using this method and the power is pretty good too!

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Hondero
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Re: Back-spin
Reply #5 - Sep 17th, 2004 at 2:14am
 
Matthias, my friend, you seem really very ironical and skeptic about dimpled sling projectiles  Grin Grin... I also like the sling as a primitive weapon but... are we going to prohibit dimples also in golf because of its artifitiality and to impose the smooth balls, that are more genuine?... or to suppress the weights and counterbalances, pulleys and triggers in modern archery and go back to primitive bow? I think that if some day the sling gets to become a modern sport, even olimpic, it will have to get a considerable modernization in its design, materials and projectiles, although for many of us that  means to lose most of its attractiveness and its character of weapon. Often the incorporation of a weapon to the sport demands to exchange that character of weapon by a greater reach and spectacularity.
Any way, the fact is that the Magnus force affect clearly the spherical clay projectiles (and even on a lesser extent those of stone), with increases of range of 20 % or more according to my calculations. If further we mold the projectiles with a dimpled surface the range would be greater.
In any case I agree with you that the use of golf balls as sling projectiles is really more an entertainment than a proper sling  shooting as we practice at present, with all its primitive flavor.

David, when I throw overhand or somewhat inclined, the projectile takes top-spin or spin to the left. I imagine that all depends on the position of the hand when releasing and of how you hold the sling. How is the position of your hand?

Gun, maybe to weight asimetrically the projectile is going to make a non straight flight, with oscillations besides a grater spin. It will be interesting to try.

Tint, it looks that  your tennis serve style helps with spin, but I´m curious about  the position of your hand when releasing, as I said David. Also the way that the pouche evolve along the snap must influence in addition, but in any case the important thing is to get a style that provides consistency in the spin.
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« Last Edit: Sep 17th, 2004 at 10:52am by Hondero »  

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Tint
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Re: Back-spin
Reply #6 - Sep 17th, 2004 at 6:08am
 
Hondero,

My hand would be fully extended above and slightly in front of my shouder with the palm facing the target.  The spin is very consistent. I also thnik that shorter sling would generate more spin. My favourite sling is a nylon braided open pouche with a finger loop, 30 inches long. It's quick and easy to handle.

I am not sure if weighting the golf ball asimetrically would create more spin.  My guess is that the heavier end would tend to stay in front once the ball is in flight, like a badminton bird.  If I am correct, then the only spin possible on the ball would be at right angle to the flight, like a bullet.  I wonder how that would effect the throw.
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Re: Back-spin
Reply #7 - Sep 17th, 2004 at 9:06am
 
Here are what the golfing pros said on varies websites

Quote:
"The challenge in golf ball design has always been to get a driver spin rate that's really low," says Dean Snell, director of research and development at Taylor Made's golf ball division. "That's really how you maximize your distance. Then you want a very high spin rate when you use your 8-iron or pitching wedge. That's where you want to maximize your control."
www.shark.com/sharkwatch/instruction/tip12.php

Spin comes from as I said.. compression and angle. If there is no friction on the clubface from compression then there will be no spin. It primarily depends on the lie. Think of it this way..

A table with dishes can have the table cloth pulled out from under it. Much as the clubface can slide under the ball. The dishes are affected very little by this maneuver. The ball can be deflected upward, but without friction there is no spin.

Get more backspin by making the ball spin faster by:
- Cleaning the clubface. No dirt,
- Cleaning the groves
- Clean powerful sweetspot hit - compressing the ball. (Hard for beginners)
- Good lie. No grass between ball and club
- Soft shell on ball to get good friction and compression
- Hit against the wind. Downwind is harder.
www.freegolfinfo.com/forums/m_833098/printable.htm


I don't know if any of this will help but here it is any ways.
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Hondero
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Re: Back-spin
Reply #8 - Sep 17th, 2004 at 11:24am
 
Tint, your style is very interesting and here in the forum there are some people that use it, like Newmanitou, the last Guiness record holder, and others. I think it´s very good to get range since the snap you can perform is very wide.
But usually, in the position you release, the spin you can get is just the rifle spin, that would project a glans point-first, wich is yet more interesting. Looking at the Yurek´s graph in the thread "the physics of the sling" you can see that in this position the sling is vertical upwards and the projectil would release point-first if the palm is pointing to the target. But maybe you perform the style in a way that the pouche move from backwards in a position suitable for back-spin and when the palm is pointing to the target at the release the pouche has not changed yet completely to the new position  Roll Eyes.  
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Yahweh Bless you in Yeshua
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Re: Back-spin
Reply #9 - Sep 17th, 2004 at 11:32am
 
Matthias.....sorry took awhile to find your post.  Regarding 'ring shaped' ammo.........already been doing it for awhile now.  A new company has been formed around several amazing technological advancements.....it is called 'Arcuate Innovations LLC." We have been gearing up for launch of a new website showcasing various technological innovations......and the latest iteration of VEGA ammo (Vortex Enhanced Gyroscopic Assist) will be among them.  

With this ammo and it's specialized sling adaptation, amost everyone here in this forum could eclipse (and for some of you.....I'm talking in 'full Solar fashion'!) the current slinging distance record.  It has the added benefit of accomodating virtually any sling style while maintaining consistent performance.

And that ain't the half of it...... 8)




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Douglas
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Re: Back-spin
Reply #10 - Sep 17th, 2004 at 11:42am
 
Maybe the dimpling on a glande might consist of words like "take that!" I wonder if it needs to be as regular as "XOXOXOXOX"?
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Hondero
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Re: Back-spin
Reply #11 - Sep 17th, 2004 at 12:05pm
 
Yes, sure these type of funny expressions (there are lots of them as to write a wide article, someones very sarcastic ) help to fly the glandes, though the lead ones are so little and heavy that the effect will not be very important, I think.
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solobo
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Re: Back-spin
Reply #12 - Sep 17th, 2004 at 4:24pm
 
Techstuff:
tell us more about this ammo!  It sounds very interesting.

Also, I always through using the overhand release, which I learned from nwmanitou's video.  Although the rock go so fast that I have a hard time telling, I believe that they have a lot of backspin on them.  When I throw glandes I have to use the side arm method, otherwise they fly much like a football (american) would if you held one point in each hand and kicked it.  I've never gotten the glandes to work with the overhand method.
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