Sling Torsion - Internal Ballistics of the Sling

[@IronGoober]

This was a very needed breakdown of sling physics. Excellent explanations and demonstrations.

[@crunchyman5330]

This is incredible, this guy is the hero we all need.

[@TW_SlingStone]

Absolutely loved the old training video style intro

[@SaveliyShabanov]

You are the best slinging content maker ! Thank you for you work, it’s inspires me a lot

[@Mr89Falcon]

I agree! And he can actually DEMONSTRATE good technique as well, which is unique amongst so many slinging "armchair quarterbacks" out there.

[@schlingellore258]

Please keep making content like this. These are physical insights that seem familiar to many active slingers, but if you get the physics explained well again you have a much better understanding of whats goning on. You should teach courses followed by a discussion

[@Mr89Falcon]

FANTASTIC analysis of the physics of the sling motion. The more I practice, the more I have noticed these effects, and your video is just what I needed to piece together the concept in an explainable and understandable manner. Thank you for this fantastic and entertaining deep dive in to sling physics!!

[@othelloperrello6604]

Amazing analysis. Gonna have to watch this a few more times to totally understand that last triad diagram. Thanks for your work

[@nathangrueber9834]

Thanks so much bro!! This is the video i was asking you to show again. Information helps you design a sling for you. Thanks again!!

[@nathangrueber9834]

This video is brilliant thanks so much for re making it. Its going to be my favorite video in my slinging collection. You are getting so much better every time i see you!! Your becoming more fluid and natural. Your timings way better. When you transferr your weight onto your left foot; see how it feels swinging through with your right foot and letting it swing you round naturally so its almost pointing at your target. I started doing this to stop my upper back twisting; as this is where i have disc ruptures. And i was really surprised when doing this that i didnt fall over. Id end up standing on one foot with the other in the air. And still even when swinging fast the energy transferr stayed the same. Its really weird?!

[@jonburgart8649]

what an incredibly valuable breakdown. this is the kind of thing people need to study and I will be returning to review as I continue to develop my sling building and usage skills.

[@Wolfstrapp]

Amazing how much work you put in this video, great work

[@oevr37]

Magnificent work!

[@Javier-ec2tc]

I can tell you invested a lot of time and effort in this video, chapo! Keep the good work going, always interesting to watch your videos!

[@slingshotwarrrior8105]

Awesome and informative video bro!

[@jaylerms]

Amazing! This is high level work that very few (if any) seem to be actively doing right now, especially on YT. Please keep it up, Acro!

[@joe_meadmaker]

Brilliant breakdown! 👍

[@bagyi6010]

Good Master 👍👍👍👍👍💯

[@williamholm2020]

Enjoying the videos you've been putting out😊

[@TdHf-g7o]

Εξαιρετικό!

[@marqis08]

Hi, great video, keep making content like this. I have been watching you since the pandemic started, and you are a refference in sling throwing. It would be cool if you could make a video showing execises to practise slinging. In 4 years i'm still struggling to get the rocks on point, and would love to achieve half the consistency ur shots have.

[@MitchMersa]

Dude this is awesome!! I hope you continue to do videos like this. Loved it

[@IndigoBees]

Great video, thank you! I have some data to add. I do figure-8 style, and like many figure-8 style slingers, I struggled with top-spin causing my projectiles to dive to the ground (and to the left) quicker than gravity would alone. Very pronounced arcs, even though I was throwing fast. I always used a wide grip, thinking to better control the angle of the pouch, and I would try to throw with the thumb-side of my hand leading, little finger following. This made a difference, but it felt awkward, was physically straining, and I had mixed success at best. But now I can pretty consistently throw with back spin resulting in a much straighter flight path (curves a bit to the right now), and without straining to turn my hand in awkward ways. To my surprise, the thing that solved it for me was using a more narrow grip. When I moved the loop from my ring finger to my middle finger, my top-spin problem improved. From there I experimented with sling lengths. I made many slings that were the same except for their length, and found that they each tended to spin the projectile differently. I settled on one that gave it the backspin I was looking for, and have been happy since (30 inches/ 76 cm when folded in half, though I'm sure the ideal number would be different for everyone). This of course feeds in to what you were saying about frequency and lengths. But it was interesting to me that I found success when I stopped fighting the physics, and instead just found a sling that puts itself in the right position for my technique. It has thin cords, and I'm definitely not always consistent. But it's so much better. You've got me curious how much more consistent I would be with thick cords. One aspect you didn't touch on: a wide grip causes the projectile to roll back and forth in the pouch more. Not because the pouch wraps around the projectile less, but rather because throughout the motion, the cords will be lengthening and shortening by the distance between your little finger and your thumb. While spinning, when the pouch passes the thumb-side of your hand, the release cord will effectively be longer, and when the pouch is passing the little finger side of your hand, the retention cord will be longer. If your grip is narrow, this effect disappears. I'm not sure how this might affect flight, but it is interesting to think about. Hope that made sense. Keep up the good work!

[@IronGoober]

I'm glad I'm not the only one who noticed the marked difference in spin axis when you place the retention cord on different fingers. It definitely makes a difference.

[@Acroballistics]

I started with narrow grip, fig-8, karate chop giving some nice straight backspins with a cotton sling. When I learned to do spiral throws I fell in love. I didn't talk about pouch roll because I focused on torsion but I don't have a problem with pouch roll. I can see it become a problem if the wrist is stiff.

[@IndigoBees]

@@Acroballistics Cool I haven't heard anyone else talk about pouch roll, glad you've thought about it too. Spiral throws are interesting. I have questions which I truly don't know the answer to. Maybe you do. But in the case of a spherical projectile that flies far enough to have a noticeable arc, if it starts out with a perfect spiral spin (axis of rotation in line with the flight path), by the time it's done with its arc, the angle of the flight path will have changed, but the axis of rotation won't have. In the typical case, the axis of rotation will still be pointing slightly up toward the sky, while the ball is headed slightly down toward the ground. The axis of rotation won't reorient itself like an arrow, will it? I'd expect this to result in a projectile flying straight at first, but curving to the side more as it progresses through its arc. And I'm pretty sure I've seen this effect in my spiral throws. This would mean a perfect spiral is impossible to maintain across an arc, at least for a spherical projectile. I'm unsure how this would change for projectiles of different shapes. Does an elongated shape reorient itself like an arrow? How do the gyroscopic forces work against that?

[@Mr89Falcon]

Excellent observations and interesting mention of pouch roll. Makes perfect sense. Cool how you were very methodical and thoughtful about testing sling designs. You have inspired me to do the same! I am a figure 8 thrower and have noticed that I can put pretty consistent back spin on rocks, but objects such as tennis or golf balls often result in front spin. I just couldn't figure out why but I feel that this video, and subsequent discussions from smart guys like you will lead me closer to a solution. What a fun journey and, as I tell complimentary passers-by, "cheap entertainment!" 😁

[@EJMunoz-ec9gz]

Olé! 👏👏👏👏

[@jamesmcconaghie3679]

I'm just learning slinging. I've been slinging a dog toy that sometimes get returned.😊 Would a large tassel on the release line give the projectile a cleaner release from the air drag? A slow motion video would be very interesting.

[@ANTNDavid]

Bravo

[@johnjacomb2645]

I was lucky enough to be able to buy the linen Egyptian sling you were selling on your etsy store, not only is it my favourite sling by far but I'm also terrified if I lose it, I don't think you'll be making any more of them although I think it would be a great idea to (plus I can buy more)

[@Acroballistics]

Thanks for the support! soon there will be some more egyptian style slings

[@johnjacomb2645]

@@Acroballistics fantastic, means I can grab a few more of varying lengths if possible

[@jlasud]

One could make a sling with a brass knuckle tied to the retention cord, and make a wider grip ,than possible with bare hand. By adding a sidebar to the "brass knuckle" wihich should be light,maybe aluminium.Adding vanes to the pouch could help achieving more constant rifle spins. I had these ideas ,that I never tried..IF you're interested you might try it..

[@AwestrikeFearofGods]

I'd be curious to see what effect projectile density has on torsional frequency. For a simple pendulum, it has zero effect on the natural frequency, because gravitational force is directly proportional to mass. I suspect the same is true in torsion. String tension is directly proportional to projectile mass (ignoring sling mass), and tension has some kind of proportional relationship to torsional stiffness. Damping force and sling mass would be confounding variables.

[@tylerbrown9797]

Do you think you could rig a sling to throw a disc golf driver? I think this would be a really interesting project to try, I have disc golf drivers and some slings but the question I have for you is whether you think rotation around the length of the sling (and just the power of the throw in general) can be translated into a rotation parallel to the plane of throwing (i.e., the disc golf disc is released cleanly, spinning with no wobble). It seems like naturally a sling throw would attempt to force the disc golf disc to "tumble" end over end, not spin correctly like a frisbee but it still seems like with a bit of tweaking of throwing mechanics and a nice cradle mechanism that it could work. Obviously a forehand disc golf throw is the most intuitive to translate to a sling, but somewhat surprisingly it also seems entirely possible to do a more traditional frisbee backhand throw with a sling as well. I think this could be a really interesting development in throwing disc golf drivers, I mean on one hand disc golf drivers are specifically kept from becoming too sharp and thin so that they don't become too dangerous, and a sling is kind of a way to just get around that artificial limitation, but on the other hand if throwing disc golf drivers with slings is possible it would be fun as hell and totally safe so long as you didn't try to roll through a normal disc golf course built in public parks throwing wayyyy harder than the course was safely designed for. What I do know for sure is if someone can figure out how to throw a really beefy disc golf driver HARD with a sling, I think it would really turn a lot of peoples heads and catch their attention who have never even bothered to check out slinging. Also, I bet slingers would have a blast slamming disc golf drivers 500+ feet as it would open up a whole new world to explore with slinging discs. You would think someone would have tried throwing discs with slings at some point in history and if it worked it would have taken off, but before modern plastics and disc golf driver design the distance potential of a disc throw was never really a serious one, and any material that was light enough to make a throwing disc was probably far too brittle to withstand any kind of throwing impact... so maybe this is an entirely new discovery awaiting modern slinging that just wasn't possible before? It is an exciting idea, specifically because the point of a high speed distance driver is to store a ton of energy in the spin of the disc, and slings are incredible at producing spin.

[@Acroballistics]

I have made 2 videos related to disc style slinging. kzbin.info/www/bejne/m4XIgIZ3lriNi9U kzbin.info/www/bejne/eqGaloiCq8-SbbM I also tried the monocord sling with a fin to stabilize the pouch, it didn't seem to improve. at longer ranges it would curve a lot. Maybe a bigger sling works better with the discs you want. If you try it let me know

[@tylerbrown9797]

@@Acroballistics Oh wow, I didn't expect this good of a response. Your monocord disc sling is almost there, I don't know if that scales up to a full size disc golf driver, but it even looks like with some proper stabilization of torsion along the length of the string that it might even be possible with a traditional sling design based on your second video. Check out this montage of disc golf forehands, it is the same exact mechanics you are using to throw in both of those videos you just linked. You are basically doing a disc golf forehand and I bet if you were able to modify a sling and get a feel for it you could absolutely slam a disc golf forehand with a disc golf driver extremely far. kzbin.info/www/bejne/Z5fVlZSuiNqspsU I feel like there is actually a fairly good chance we live in a reality where a whole separate hobby spent decades refining throwing discs and accidentally made them perfect for using with slings it's just nobody has put two and two together yet....

[@tylerbrown9797]

I experimented with it a little bit, yeah with a normal sling and the disc in the sling (I tied a string from one of the sling sides to the other on either side of the pouch to cradle the disc) so that the disc (starts) parallel with the rotation plane of the sling rotation plane and is held in place from rolling out of the single point of contact with the sling pouch by the crossbar string arresting its rotation from the other side. Somewhat comically I have found the sling throw definitely gravitates towards releasing the disc golf disc end over end, but I have gotten a few releases where it didn't do that. I think introducing a counterclockwise twist in the sling (so looking down the length of the sling with something in the pouch as a right handed thrower, thread the release cord counterclockwise around the anchor cord so that there is a single twist in the sling) seemed to help somewhat. I also wonder if you could make a three point sling where the original two cords are held as anchors and a third string is tied to a crossbar cradle string that holds the disc from behind the normal sling pouch (the disc being held by the tension between the original pouch and the crossbar cradle). Perhaps the release flick that creates a rifle-style spin can be modified into a release flick that creates a disc style spin in this fashion, especially if the disc isn't spun in circles before being thrown like with a normal sling throw. I will keep experimenting!

[@LuciusQuinctiusCincinnatus111]

👍👍👍👍👍👍👍👍👍👍👍👍👍👍

[@JudoP_slinging]

Excellent video. I've done that very same test for testing torsion resistance by prerotating and seeing how it reacts. Have you experimented with round braids? I've found them to be by far the better performers at resisting torsion, although once a sling is thick enough (ala balearic) it does feel like overkill and I still personally prefer flat braids in most cases.

[@Acroballistics]

recently I made a 4 double strand round and a 12 strand herringbone(square braid) egyptian the 12 strand herringbone performs better in the test. Haven't used them yet though to get a feel of speed and interference.

[@secondreality1]

Extremely informative! I was wondering though; i pinch my static cord and release cord in the same fingers, making my grip width practically zero. This seems to completely eliminate projectile slip, but i see everyone slinging using two sets of fingers and so a wider grip. Am i missing out on greater sling feedback? I find it simply easier and more accurate, but maybe im just avoiding a steeper learning curve?

[@AwestrikeFearofGods]

A wider grip would increase torsional stiffness. As you noted, it would less securely hold a projectile due to a difference in what might be called "angle of envelopment". As an extreme example, a straightened sling with (both cord ends pulled as far as possible from each other) has high torsional stiffness, but does a terrible job of wrapping a projectile.

[@Acroballistics]

if you use light ammo and relatively thick cords or low velocities then you are compensating in those aspects. is it better or worse? I'd say if you can hit your target you don't need to change anything. I'd try a wider grip just out of curiosity

[@IndigoBees]

Definitely experiment and see what works for you, but I started wide and have gone more narrow. Can look at my other comment on this video for that story

[@CapraObscura]

I use a flat band Catapult to hunt small game and am learning how to sling bigger projectiles with a sling, can a sling take out big game?

[@Acroballistics]

I haven't hunted with a sling but it seems possible with the right ammo and a good shot

[@beepboop204]

🙃🙃🙃

[@GoodShepherdPicture]

🧐