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General >> Project Goliath - The History of The Sling >> Air Drag On Sling Cords & Pocket https://slinging.org/forum/YaBB.pl?num=1146905055 Message started by mgreenfield on Dec 28th, 2003 at 4:52pm |
Title: Air Drag On Sling Cords & Pocket Post by mgreenfield on Dec 28th, 2003 at 4:52pm
Fellow slingsters, has anybody done research on this? Leather bootlaces are about 1/8"square. Two of these 32" long will present about 8 square inches of flat frontal area to the airstream generated on sling spin-up. Add frontal area of the pocket and projectile to this, and we may be looking at a huge impediment to launch speed of the projectile when "fat" cords and a large sling pocket is used.
Roman glandes were football shaped, which meant smaller pockets were needed per ounce of projectile weight. I'll bet if we could find a well preserved Roman army sling, we'd be surprised by the tiny pocket, plus very long and very skinny cords used. Modern "fat-corded" slings may be crude rock-lobbers by comparison. Any ideas?? mgreenfield |
Title: Re: Air Drag On Sling Cords & Pocket Post by JeffH on Dec 28th, 2003 at 9:54pm
I have been thinking about this some myself, of late.
Obviously, this smaller the cord and pouch, the faster we can sling. What is the limit, though? Is the size of pouch limited in smallness by the type of projectile? Can we get by with a small pouch for general slinging where we can't know the size of stone until we pick it up? Can we get a very thin cord to NOT tangle up after the throw or when being carried? Who knows? jeff <>< who is curious |
Title: Re: Air Drag On Sling Cords & Pocket Post by mgreenfield on Dec 29th, 2003 at 3:05pm
I went from 1/8"square leather bootlace cords to braided dacron fishline about 1/32"round. The thin bare fishline was hard on the fingers, so I put a 4.5" bootlace "handpiece" on the end of each cord. Length from center of pocket to toggle was 38" on both versions. Pocket size is 6" x 1.5", but with small slits in the leather to let it hold the ammo well in spite of being pretty narrow.
Standard golfball ammo was used with the bootlace version AND the fishline version. Results were these: 1/ Swinging a golfball (which is pretty light ammo at just 1.5oz) had a lot better feel in the fishline version. It didnt feel like I had to drag the sling around to make it spin, ....which was the feel I had swinging a golfball in the bootlace version. 2/ The fishline version is absolutely silent. NO cord whistle. 3/ Just "letting fly", I'd say the fishline version had maybe 1/4 to 1/3 again more range. 4/ String tangling was not a particular problem in use. However, I definitely will wind the sling on a spool for storage. FYI, the dacron is pretty slippery, so I painted all knots with clear fingernail polish to keep them from slipping. Any other experiences/experiments to report on??? mgreenfield |
Title: Re: Air Drag On Sling Cords & Pocket Post by Whipartist on Dec 29th, 2003 at 7:04pm
HEEEE HAAAAAAAA! I've been hoping someone would try this sort of thing out. My idea was using very thin steel cable with a larger section of larger material at the end for comfort on the fingers. The smallest pouch would probably be split. With these sort of sling upgrades, someone on here, probably Jurek, could beat the world record on distance. I believe it. 1/4 to 1/3 extension in range is a big extension! Whipmaking has taught me how important air friction is. A lead gland in a sling like that, will go forever!
Ben |
Title: Re: Air Drag On Sling Cords & Pocket Post by JeffH on Dec 29th, 2003 at 8:03pm
Ben,
How about plating 3 or 4 strands of spider wire, the kevlar fishing line, into the cords? It would still be very small in diameter, but rather strong. Attach these to a small pouch and viola, maybe this is it. What do you think? jeff <>< |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Dec 29th, 2003 at 11:42pm
The mgreenfield's tests absolutely prove Ben's idea about the considerable effect of reduce a sling drag. For my first tests with the glandes I have made (just inspired by Ben's and Hondero's posts) the more slender sling. It is rather the temporary design described here:
http://www.slinging.org/forum2/yabb/YaBB.cgi?board=1;action=display;num=1060740218;start=30#30 Durring the first throw of the glande I had a false feeling that this sling didn't give a pretty enough power, it was too quiet. No snap and only the gentle swish of the cords. I also tried this sling wih stones and I found they go markedly further than ones throwed by my previous slings designed for various stones. The 3.5 mm diameter of the used cords seems to be similar to mgreenfield's bootlaces. I wonder what a distance improvment I will get if I maximally reduce my sling. The 1/4 or 1/3 improvment would be fantastic! I have fired about 4 kg of lead until now. All these shots was observed by hidden persons, and now I'm sure that I can exceed 500m distance constantly. I know such numbers could cause scepticism or even distrust of some people, although I have decided to publish them here because just you guys caused the rebirth of my slingin passion and gave me a lot useful information. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by JeffH on Dec 30th, 2003 at 9:35am
Jurek,
It is not the distance you are slinging that makes us suspicious. We americans just have a natural dislike of "hidden persons". Make him come out where we can see what he is doing and we will be more comfortable. As for people doing big things... Well, americans are used to stories of big things. Our history is full of them. We might make you an honorary citizen if you pull off the record. And if we can't make you an american citizen, I sure Texas will take you regardless. Texans just love bigger than life stuff like slinging 1,600 ft. jeff <>< who hopes you make it |
Title: Re: Air Drag On Sling Cords & Pocket Post by mgreenfield on Dec 30th, 2003 at 10:39am
Cord material I used is a single strand of 40lb test braided dacron icefishing line. It's very limp & flexible. The earlier-used leather bootlaces were also pretty flexible. How does a sling perform when you use stiffer materials for cords? Seems like it could be a problem.
Slinging for distance would probably put the slingster: 1/ On the edge of a raised platform.... 2/ Spinning a very long sling, .....each cord 6-7ft or more. 3/ Each cord of fine stainless wire maybe. Here's where the concern with cord stiffness comes in. 4/ Loaded with a football shaped lead glande, experimentally weighted to maximize the interaction between weight, sling and slingster.... 5/ In a smooth pocket just barely large enough to control the glande. Anybody going to give it a try??? mgreenfield |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Dec 30th, 2003 at 8:03pm
Jeff,
When I was writing "hidden persons" I meant the observers who was hidden behind the shelter close the expected landing zone of the glandes. I mentined in my previous posts that observers was my son or my wife. If you want I will send to you our family photo :) Consider that I'm not anonymous here. I corespond with guy from my country, who has found me just through this forum. Probably my poor English is guilty of your incomprehension. But I hope this forum is open for slinging fans from all world and everyone who want to share own experiences is welcomed. I like this place because it is the best forum about the slinging which I know. I'm slinger like you and the others here and I tried to bring in some share. The slinging passion is the only reason of my stay here, believe me. For me nationality of the others here is not so very important as it what they say and think. Quote:
Jeff, it would be very nice, so I have the additional motivation now :) mgreenfield, Quote:
The thin stainless wire is the best due to an air drag but for me it has a big fault. It is dangerous for the slinger. In the summer I remember when I was slinging with the long-leather-cords sling the release cord whipped my left naked forearm, so it was a bit sore and red. I imagine how the long, sharp, heavy and quick cord could sting. I don't know sure but I suppose that too stiff and heavy release cord could impede opening the pouch. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Whipartist on Dec 30th, 2003 at 11:02pm
Jurek,
Wow, I've been reading your posts about your range achievements! I knew you could do it!! AWESOME!! I'm so excited. Don't worry about what Jeff said, it was just American humor. I think you are the next world record holder with the sling! We're all excited and displaying our pleasure. Heeeeeee Haaaaaaa! Man, you're making 500! You'll beat it easy when you fine tune things. As for making a highly aerodynamic sling. I was thinking about it today. I've never heard of spider wire, but the very thin, maybe 1/32"- about 1,5mm steel cable, is very strong and flexible. Infact if it was too flexible the cords would tangle. Which is what I fear could happen with fishing line. I haven't experimented, but I think a well made sling with the steel cable wouldn't be dangerous and would work really well. I've been reading about other topics too, but I'll reply here. I don't think that slight dimples on the surface of the glandes will affect the distance that much, but when every inch counts, I'd make those things as smooth as possible. Watch out for lead poisoning though. That stuff isn't good for you. Consider, just consider, that the last world record was made with a 2.5oz "dart." Does that mean that the guy put fins on it and a point? To me that seems like it would be a bad idea, but if anyone wants to give it a try, it's an idea. I believe just plain roundish glands will be best, but I don't want to discount anything. Jurek, I'm interested in what your new sling for glands looks like. If you have time, take some pictures and post them. And the glands too! So when you sling for distance, you always use a 47" sling? I don't want you to just beat the world record. Wouldn't it be awesome to demolish it?! The pouch or cradle aerodynamics is another big factor. It is traveling the fastest of any part of the sling and thus is very important. Any excess little area of leather or whatever, that isn't necessary, should be removed. I'm sure there are lots of ways to fine tune it, but if we really want to get radical, we could maybe drop it altogether. In otherwords, make it out of two pieces of steel cable that overlap. (in appearance like the Balearic slings but much smaller) But how would this grip the glandes? Cut grooves into the glandes at two places, like the stripes on a football. The cable could catch on the two grooves. Now that's getting efficient! Obviously such glandes would be a little more time consuming to manufacture, but only a few would have to be made and it would be pretty simple to get a small round file and carve the grooves into such soft metal as lead. This isn't regular slinging, this is the world record, and anything helps. Can you imagine what you could do with such a sling! That's prime efficiency! Space age slinging! Ben |
Title: Re: Air Drag On Sling Cords & Pocket Post by JeffH on Dec 31st, 2003 at 12:10am
Jurek,
Sorry that my humor was so obscure. I fully understood your english, and who your observers are. I was just pulling your leg a little, as we say. I am feverishly nationalistic and rabidly American, but not the least bit concerned about the nationalities of my friends here at Slinging.org. You are all great guys!!!!!!!!!!! Ben, Check out your local Wal-Mart or fishing store for spider wire. It is very thin, plaited kevlar (I think) fishing line. 50 lb test line is the same diameter as 12 lb monofilament, I believe. As for thin lines. I believe we may have also overlooked something here that is very important. Stretch in the cords. This is probably as important as the size reduction below 1/8". All my platited cords have some stretch and this is just an energy waster. I believe the spider wire would be worth a try due to its low stretch. Less stretch is probably due some of the credit for mgreenfield's better slinging. Jurek is also using some low stretch cordage, I think. On the subject of a record. I believe that there should be some reasonable limits set for the attempt. 1) Sling of max length equal to say 48". This should be a sling that could reasonably be expected to be used for hunting, warfare, etc. I don't think it would be good to allow a sling specially made for the record attempt. This precident is found in other sports, I think. 2) The attempt should be made on level ground from the ground, not a platform. This extends the throw if only a little, but again makes for a condition prepared especially for the attempt. 3) Limiting the projectile should be done carefully. I don't like the "dart" concept as this is an unnatural "stone" shape or object. The bi-conical glande, or any round object (rock, ceramic, golf ball) would be o.k. For that matter, an apple or canteloupe would be o.k. I will throw most anything I can get to stay in the pouch, but a "dart" just does not seem right. jeff <>< who thinks Jurek o.k. |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Dec 31st, 2003 at 2:43pm
Ben,
Great thanks! I like your post. I haven't time to write too much in this year. So I put quickly only a few pictures. There are my new sling (which is far to the optimal one) and the patterns for last my mold. I have the CIS scaner which is not good for 3-D stuff, so the pictures of the patterns are poor quality and a bit deformed. In the last tests I set up the sling at 50". See you guys in the New Year. Happy New Year! Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Whipartist on Jan 1st, 2004 at 3:44am
Jurek,
Very nice design. I thought it might look something like that. I like the way you doubled the leather on the ends of the pouch. That design looks efficient and very nice. I made an ugly looking, 45" sling with 1/32" steel cable today, after work. Didn't take long. In the picture you can see the grooves I carved into the gland. The cable fits in the grooves. This thing is so fast! It's too fast for my arm. I can't move my arm fast enough to keep up with it. I can't experiment with range because I don't have the place, but I can experiment with power. And it is powerful!! The cable tends to kink just a little bit if you don't treat it nice, but what I like about it, is it's stiff enough to not tangle. And it's tuff enough to not wear out or break. I bet there is higher quality cable that would do better. The filaments would have to be more fine than these. The drag on the sling is so small, it feels weird to use. I wish I had a place to experiment with range! It's incredibly powerful. Speaking of elasticity, it has none. I propose this type of sling to you as an idea for you to try out if you're interested. I think it will improve your range further with lead glandes than a more traditional design. It's ugly, but it's as aerodynamic and efficient as can be. Happy New Year. Ben |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Jan 1st, 2004 at 9:03pm
Great idea, I'm interested in, of course! Only still cables, no pouch. It seems there is impossible to find out somethig much more aerodynamic regarding to a sling. I imagine how it will be whisking! I must give it a try. The grooves are no problem because of they could be made on the patterns (models for molds).
Ben, it would be good to use stainless steel wire 7x19. This kind of it is pretty and flexible. The smallest diameter which I know is 2 mm, maybe it is possible to find a thiner one, but 2 mm still seems ok. In your newest sling the endings are very nice, I think it is your plaiting. On "dart", from the last record attempt, here is the quote from Lloyd's website (http://www.staff.ncl.ac.uk/nikolas.lloyd/weapons/sling2.html): "Recently, another sling enthusiast on the net quoted the following: "World record 2.25oz lead weight 477 meters!! (US), 8oz stone, 375 yards (British)". This is more like the ranges quoted for ancient warriors. The American record for the lead bullet used a bullet of typical ancient weight, but the British stone record used a remarkably heavy stone which surprises me. I do not know any of the details regarding these records." I suppose he speak about the same record which Ben mentioned, the distance is compatible but the weight is a bit different. If Lloyd had a reliable information, it looks like the lead glandes were used then. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Whipartist on Jan 2nd, 2004 at 4:53am
Jurek,
Hmmm. Lots of thinking huh. I got the distance record out of a Guiness book I found at our local California University. I've seen the other record in an older Guiness book I used to own. I'm not sure if I still have it. If you want me to look, I'll look tomorrow. My memory is a 7oz stone and around 375 yards. 372 comes to mind, but I could be just pulling rabbits out of hat. I think Lloyd's records are the same ones we are talking about. I don't know much about cable or wire, or spider wire, or any of it. If anyone has any ideas, try them. It works good, I can tell you that. I had a bit of difficulty getting used to positioning the wires in the grooves, it would have been helpful if they were deeper. But otherwise it worked great. Very powerful! Infact, this sling is 45" but if you want me to send it to you Jurek, or make you a 50" sling, I will. I'll send it to you for free, just give me your address. I don't need it, I'm just experimenting because I'm excited about your record attempt! Or you can make one yourself. I'm happy to be a part of this in any way. I remember my awe when I first read the world record years ago. I was especially in disbelief about the older record though. 7 or 8oz is a very large stone?!! Why would he not use a smaller one? It didn't seem right to me but it's recorded. Maybe he was a very big man, and the bigger stone helped his sling to overcome the air friction? Anyway, I ought to look into seeing if there is a higher quality steel cable and, attachments then the ones I'm using. Or some other material like the stainless steel wire, or the spiderwire, you guys are talking about. I'm pretty busy with other things right now, but I'll help in any way I can. If anyone can think of another good material, speak up. Lawn edger cord comes to mind. But it may be too coiled and not straighten out. It might also be too stiff and thick. Ben |
Title: Re: Air Drag On Sling Cords & Pocket Post by Whipartist on Jan 2nd, 2004 at 5:06am
http://www.mcmastercarr.com
Type in aircraft cable in the search field. Man they sell this stuff in so many varieties! Even teflon coating. Talk about aerodynamic huh? It looks like we have options if we want to go this route. |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Jan 2nd, 2004 at 5:41pm
Ben,
I appreciate your taking interests very much. You have a great part in my thinking about the attempt alredy. It would be nicely to have the sling made by you, but I don't want to cause your expenses. Thanks for the nice offering. Of course, your and others' hints are welcomed always. Another potential pretenders could use it too. I looked at this link, the excellent choice. I like 7x19 - 0.40" stainless steel wire with teflon coat. I suppose the thiner one make no sense. I just found in my country 7x19 - 1mm (~0.040") bare stainless wire, It costs 0.54 Euro (0.68$) per metre, it is much cheaper than previous one (1.50 per ft) and the delivery is more easy. I think that one is ok too. It will be like a scythe :) Jeff and mgreenfield mentioned about fishing matherials. I'm afraid too, they will too elastic, thin, and flexble, so will tend to making thenars. Maybe I'm wrong, have no experience with such stuff. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Whipartist on Jan 2nd, 2004 at 10:25pm
Jurek,
The stainless wire seems good if it's 7x19. The one I have for the sling I made doesn't have that many strands. The more strands the better, I think. I think it makes it more flexable and crimp less. Don't forget to buy the little sleeves that you use to put it together. I used a vice to crimp them, but I think there is a tool. If you have any trouble just ask me and I'll make you one myself. I'm glad to help, I like having a hand in all of this. Ben |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Jan 4th, 2004 at 8:57pm
7x19 is able to work on pulleys. For example, it is used as halliards on sailing boats. There is interesting way of conection the steel wire with rope. It is the special braiding. It would be fine to link the stainless wires with the rope endings of the sling. Maybe I will try to do it, if I get that one. But I'm afraid that it may be very difficult with such thin wire.
Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Whipartist on Jan 4th, 2004 at 9:49pm
Jurek,
Hey that's a beautiful connection. I know a few but was too lazy to try them. That one looks better than the ones I was thinking of. I hope it really works well for you. I'm excited to see how much range it adds to your throw. Ben |
Title: Re: Air Drag On Sling Cords & Pocket Post by mgreenfield on Jan 4th, 2004 at 10:52pm
For research, and for record attempts, how about we work in two areas like this:
1/ "Standard" Design Class slings. Units measuring not more than 1.25meters from center of pocket (or equivalent), to center of release cord knot. 2/ "Unlimited" Design Class slings. Whatever length someone manages to swing. All slinging distances measured on level ground. No platforms. No specs on ammo size, material, shape. All postings to mention center-of-pocket-to-knot distance on the sling being discussed. mgreenfield |
Title: Re: Air Drag On Sling Cords & Pocket Post by Chris on Jan 6th, 2004 at 5:32pm
Wow, this is pretty exciting. I've always wanted to make one of these super-light slings. Ben and Jurek, those are hansom looking slings. I really like that wire lovelock pouch! Steel cabling is heavier then spider wire of just plain fishing line. If you really want to maximize the force getting put into the sling, I'd just the latter two. Maybe a bradded or thicker version if it isn't strong enough. If Jurek can get near to 500m with the sling he posted a picture of, I think he can exceed 600m with one of these light-slings.
Can anyone follow up on what exactly the world record is and if there are any projectile weight classes? Exciting! Go Jurek! Chris P.S. Don't forget about us when you hold the record. ;D |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Jan 7th, 2004 at 7:14pm
I'm very curious how such sling is efficient too. I can't get the suitable stainless wire in the local hardware stores and I'm too impatient to buy that one via internet, so I decided to use just the fishing-line. I have got some just today. It is very thin, soft and slippery but strong thread. I'm thinking over a way of making the sling of it. Knots which I know are sliping out. So I think braiding will be necessary. Maybe it would be good to use the balearic way of braiding (dividual tress) :-/ I have no experience with braiding and I'm somewhat afraid it will be very toiful for me. Does anybody know a better way for the lazy man?
Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Whipartist on Jan 8th, 2004 at 1:36am
Jurek,
My only thoughts about fishing line are that I'm afraid the sling may twist when it's used? But it's worth a try. Here's how I'd do it. Braiding will take too long. Twisting is better. Take 4 strands of 10' each. Start by making the split cradle. To do this, divide them into two groups of 2 strands. Go to the center (cradle) section of each group and twist the two strands together loosely for 3" (You can twist strands together by taking each strand in either hand, and twisting them in the opposite direction as you intend their composite twist to be. Just like rope. You know.) Take the two groups of strands and put them side by side after you've twisted each section of the cradle. (So we are taking 4 strands and making them into 2 sections in the middle and then 1 on either side of the cradle.) Make a regular overhand knot on both sides of the cradle. The knot is done by taking the 4 strands, making a loop with them, and putting the end of the strands through the loop and pulling tight. Do that on both sides of your cradle. Then take each set of 4 strands and divide them into 2 groups of 2. Twist them together for 4' out and tie a knot. Do this on both sides. Then attach your rope ends for the loop and release cord. I hope that was clear? It works in my mind but it's hard to write out. Ben |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Jan 8th, 2004 at 9:34pm
Ben,
Your post has rescused me from deadly entanglin myself :)Thanks! It was clear for me. Here is the result: It rather does't look militantly. Actually I have no lead glandes, and the stones are hidden under snow. So I sended only a few patatos into the dark wood this evening. They flied prety long. You was right, this sling tends to twisting oscilations due to the supple stings. Tangling doesn't seem a great problem. It is quite silent and slinging is strange, require some habituation. It's difficult to believe, how something like that could send projectiles so far! I hope I will get time for making the new mold and projectiles soon. If so, I will let you all know more about its efficiency. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Whipartist on Jan 9th, 2004 at 2:02am
Jurek,
Awesome! I'm glad it worked for you. If it doesn't tangle, it looks like it will be very efficient! Let us know if it's any better than a regular sling, once you make the glandes! I'm excited to find out. I know what you mean about it being strange to use. The pull from the back is hard to do because it's sooo fast already. It changes slinging around some, so I don't know if it will be better or worse for distance! Maybe a slower windup will help? Ben |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Jan 9th, 2004 at 3:29pm
The short story of the short life of my newest super sling. hehe
Just today, eager of next tests of the "fishing sling" I took some potatos, a few beautiful shaped, smooth stones (from my small "emerency reserve" for "secial occasions"), and went to the secluded spot. I wanted to see how it would be work used with a full power. First, for warming-up I started throwing the potatos (it was specific way of winter additional animals feeding;). And what appears, this sling worked like a slicer. The potatos flied out as three pieces, often before the release. The first stone finished my play and the short life of my newest sling, it tore off the release twine just behind the split cradle and kidnaped that somewhere. Well, me thinks the next "supersonic" sling must be more solid and stiff. Too slender cords don't enable a control of the pouch angle which is especially important for elongated glandes. The soft stainless steel wire or something like that seems the best, however. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Whipartist on Jan 9th, 2004 at 6:43pm
Jurek,
I'm sorry to hear it broke :-/ I hope you're able to get the stuff you need for the sling in good time. I think that 7x19 stuff should be good. In the meantime, don't pull a muscle out there in that freezing weather! Potato slicing huh! LOL Ben |
Title: Re: Air Drag On Sling Cords & Pocket Post by Chris on Jan 11th, 2004 at 1:13am
When I made my 9 foot sling, the drag on the cords and pouch was very noticeable. I think a 9 foot sling using this type of design and materials would generate enormous power (and range). I was about to throw bricks about 200 feet (and I don't have range like Yurek even with regular stones), so smaller lead projectiles would just fly.
Maybe you could whip up a conventional 9 foot sling and see how you get on with it Yurek? Chris |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Jan 11th, 2004 at 8:18pm
Chris,
Once upon a time I tried to sling with my prolongated conventional sling. I simply pieced some rope on to each cord. I don't remember exactly how long this sling was, maybe something about my height. You are right, that one gave adventage for heavy stones (the main acceleration is durring twisting, not durring the whip) which I couldn't whip well with the normal-lenght sling. However, when used the optimal weight stones I wasn't able to whip dinamically. The sling seemed as if it didn't keep up, was too lazy, I hadn't a good "connection" with the stone. Probably there was three reasons together: 1. too stretchy cords 2. too big air drag 3. too big ratio of the sling to my arm lenght. The factors 1 and 2 should be minimalized, we know. But finding the best lenght of a sling is more difficult. I suppose there is the optimal lengh for a specified slinging way, body construction and projectile mass, due to the projecile speed, of course. If even factors 1 and 2 would be null and a mass of the sling would be null, then we couldn't prolong the cords overmuch, if we would like to get the dynamic whip. Finding an optimal projectile mass and sling lenght is an interesting question for physicists and biophysicist. Maybe some day they will expolore a sling, but nowadays we only may experiment alone and axchange experiences. Durring my last tests with glandes I used 50" sling. I feel that it is close to the optimal lenght, maybe not exacty, for such sling design and mass of used projectiles. When I make the new good aerodynamic sling and the new lead projectiles, I will try to lenghten the sling, as you Chris mentioned, but 9 feet seems to be too long for me. Jurek. |
Title: Re: Air Drag On Sling Cords & Pocket Post by Matolay on Jan 12th, 2004 at 6:28pm
Made a lil' research inspired by the bottomline quote and found this at some Hebrew site about ancient royal curtains :)
'Although the Bible does not specify HOW the KELIOTH were made we known that KELA means a SLINGSHOT and we know that slingshots were made of NET-LIKE MATERIAL (the holes prevented drag from the air and allowed the slingshot throwers to gain more momentum). It is thus suggested that the COURTYARD curtains were made in NET-LIKE form (With many holes).' hope its useful. |
Title: Re: Air Drag On Sling Cords & Pocket Post by Whipartist on Jan 12th, 2004 at 8:04pm
Matolay,
Yes that is helpful! Thanks. I've seen some Peruvian slings made with a cradle with a net center. Very intriguing. Ben |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Jan 12th, 2004 at 9:37pm
The net is great idea. It would premit to resign the grooves on the projectiles and additionally these could roll (swim) inside the cradle safely durring the sling rotations (I separate the cords by the fingers thus they don't go out from a one point). Maybe the small fishing net would be good?
Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by JeffH on Jan 14th, 2004 at 12:48am
Jurek,
Great looking sling up there my friend. Keep up the good work. jeff <>< |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Jan 14th, 2004 at 6:32pm
I'm going to try the "dyneema" 1.1 mm cord. It is multiple stronger than the stainless steel wire. You can read about its poperties for example here (bottom of the page):
http://www.gnmchandlery.com.au/rope.htm I have just booked some in the sailing shop via internet. Seems it would be that one we need. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 3rd, 2004 at 5:45pm
More one week ago I tested the lead projectiles. Some was ball-shaped and some prolongated. The weight of the balls was almost 120 g (4.2 oz). Although I intended to get 100 g but I didn't measured off volume of the modelling paste too precisely. Elongated ones was 100 g (3.5 oz), exactly as I wanted. I used the last ones in the previous test too.
The sling is made of the 1,1 mm (0.043") "Dyneema" thin line, according to the Ben's idea. That line is able to raise 90 kg! The projectiles had no grooves for keeping in the cradle, so I used the short and narrow sleeve made of chamois-leather. You can see that in the left-bottom corner of the picture. I throwed the glandes on the frozen and snow-covered lake. Alas, I wasn't able to find any of them due to the traces on the snow and coming dusk. So I have no conclusion what the shape and aerodynamic sling do for a range. I have written about it in some post before, but here are the pictures. My wife had painted the projectiles with the nail enamel :) I see that finding (marking) the fall-points is the big problem. I'm thinking about it. Maybe you guys... and girls :) have a good ideas? Here are the pictures: Greetings, Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by mgreenfield on Feb 3rd, 2004 at 6:52pm
.....I'd love to have a bag full of those 100gm lead glandes! Wow! Almost too pretty to toss.
For measuring distance to point of impact, how about throwing them onto a quiet open lake, with 2 observers stationed (say) 100m away from you, one on each side. Each observer to be equiped with a sailor's angle-finding device called a 'Pelorus' mounted on a solid camera tripod. Lay out the distances on the shore, measure the angles to the splashdowns, then calculate the distances. Lots of setup and work, but might be the only way given the small glande size and Jurek's strong arm. mgreenfield |
Title: Re: Air Drag On Sling Cords & Pocket Post by Dan_Bollinger on Feb 3rd, 2004 at 7:15pm
Very interesting discussion and one I'd thought about before. But then, what slinger hasn't thought about setting the world's distance record!?
This conjurs up all sorts of old memories. Hondero reminded me offline that I once had offerred to host an International Slinging Competition including distance. I have a piece of property long and skinny. I think it is almost 500 yards long, maybe not long enough! Some idle thoughts to keep the gears working: If you are going to place a world's record, it would be wise to observe the Guiness' methodology, even if you weren't going to send it to them. They've worked out the kinks a long time ago. Stretch in skinny cords is disconcerting (I know) and I'm sure it steal velocity, but it may increase spin. During the release, the cord shortens, pulling the pocket with it, spinning the glandes. As velocity doubles, drag quadruples. So, at some point, the drag on a long sling will actually REDUCE velocity! Consider using low drag cords. Not only reducing width like you have all talked about, but making the shape aerodynamic, or adding longitudinal grooves on the surface of the cord. Also, consider using aerodynamic glandes having a cross-section like a airfoil (plane strut). Somewhere I have a NACA foil shape CAD file that you can resize to any width and length if anyone cares for it. Finally, use something heavier than lead like depleted uranium to cast your glandes. ::) Ain't this fun! |
Title: Re: Air Drag On Sling Cords & Pocket Post by JeffH on Feb 3rd, 2004 at 8:30pm
For those not interested in making their own molds, commercial molds are available in the two shapes Jurek made.
Called cannon ball sinkers and egg sinkers, they are common shapes for fishing and are available in a variety of sizes including 2, 3, 4 and 5 ounce. They can be made without holes. Serch the web for the molds, many places have them. You can also buy the sinkers ready made. They cost around $0.60 or a little more in the 3 and 4 ounce sizes. Add shipping to this also. jeff <>< |
Title: Re: Air Drag On Sling Cords & Pocket Post by Dan_Bollinger on Feb 3rd, 2004 at 8:43pm
If anyone cares for the math (it is way beyond me) here is the formula for calculating the drag and power needed to rotate a pair of wires in a circle. How perfect is that!
http://www.mh-aerotools.de/airfoils/control_line_aero_3.htm What it boils down to is: Halve the cord diameter, halve the drag and power required. Doubling the velocity increases drag 4 times (like I mentioned earlier). Here is what surprised me. Doubling the velocity increases the power required to obtain that speed by 8 times! We've all experienced this trying to 'helicopter whirl' a sling faster and faster, but hit an upper limit. With a little more math one should be able to figure out what the ideal cord length would be for the fastest release velocity given the power available in the human arm. |
Title: Re: Air Drag On Sling Cords & Pocket Post by magnumslinger on Feb 4th, 2004 at 12:09am
Dear Dan,
How about a depleted uranium dart (like the one used for the guinness world record, which I'm still trying to find the picture of with no luck, so far!) or very elongated glande? I just posted a rough description of one of my distance sling designs for one of my ultra-light "magnum" slings under the "single or multiple projectiles" discussion category this morning usning my real name, as a guest, being too lazy, I suppose, to log in until properly, later. Actually, I was just excited about the slinging slogan discussion, and in a hurry to post, then one thing lead to another, and I also read something that reminded me to post this description for Yurek. Then, I cam ehere, and saw that this discussion was already going on here, so I then took time to log in. Anyway, if anyone here is interested, I've posted my own solution to the air drag question, and will hopefully soon have some pictures to post! Keep slingin', Jean B., alias, "magnumslinger"! |
Title: Re: Air Drag On Sling Cords & Pocket Post by Chris on Feb 4th, 2004 at 1:16am
Yurek! Those look amazing! I'll add them to the gallery at some point. What is the approximate cost of each one?
Once the snow clears, will you head out to some field for an official range test? Chris |
Title: Re: Air Drag On Sling Cords & Pocket Post by Ulrica on Feb 4th, 2004 at 4:33am
@ Jurek,
I can only agree with the others, they look really very nice! I have a metall-detector, maybe I should come and search them for you.. ;) Ulrica |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 4th, 2004 at 6:14pm
mgreenfield,
Thanks for an idea of measurment. It is very inventive and would be a good way but I'm afraid that GWR require that the projectiles should be marked and recovered. All must be probably documented pretty exactly, filmed and photographed. Lately I thougt about the local sport airdrome, the problem would be in good marking the points of impact on the concrete slab. The projectiles probaly will bowl far from the impact points , maybe not (?) Quote:
Me too, maybe the (mentioned by Jeff) snikers molds are the good way for it? Each time I casted limited number of the glandes in the plaster mold and they was finishing off too quickly :( Dan, Thank you for the quidelines. Each of them is worth consideration. I like that site about a lines drag. The formulas give some image of numerical influence of different factors, interesting. Jean, I have read your posts with care. They are interesting and substancial. I like idea of the net pouch and way of fixing it. It is pretty simple to do and really seems working well. I'm under the impression of your privity about different uses and techniques related with a sling. I'm sure I couldn't describe my slinging ways as well as you in my native language :) I never thoguh seriously about a sling as a defensive tool, because I'm not sure what my accuracy would be in the critical situation. Hope I never will be in that situation in the future. However it happened once when I was yang man. Then I really used the sling for the self-defence. But that story seems to be out-topic. Chris, They don't cost much money, bacause I have bought some lead cheaply on the scrap yard. The plaster (of paris?) and the modeling paste are pretty cheap too. But making the good mold required a trial-method. Casting and removal of some surpluses eat up a bit time too. Before I thought to do it at the ice-plate in the winter, but now I see that it require special weather conditions. It is almost impossible for me to hit them with all organisational job . Thus I hope it will happen in the early spring, probably at the airdrome-plate, when we won't be dependent on the weather so much. I would like to do it as quickly as possible. Ulrica, Thanks, the metal-dedector is great idea! I have no experience with it and I'm curious how sensitive that device is. I would be honoured seeing you as the second :) Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Whipartist on Feb 4th, 2004 at 6:59pm
Jurek,
Those glandes are simply beautiful. I was very impressed. They are just perfect! |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 4th, 2004 at 7:18pm
Thanks Ben,
I'm glad you like them :) It's really pity to toss them ;) Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 7th, 2004 at 6:55pm
Yesterday finally I had got the replay from GWR. I'm a bit confused. I'm wonder what kind of projectiles are hidden behind the word "a stone" in the rules. Whether "a stone" means exactly "a stone"? In the short description of the previous atempt they use the word "dart". Nikolas Lloyd has written on his website that there was used the lead glandes. Guys, read please and judge. I'm curious of your opinions.
"Rules 1. This record involves throwing a stone weighing at least 56 g 2 oz as far as possible, using a traditional sling, with a maximum length of 130 cm 51 in. The sling is to be made entirely of leather. 2. The throw is to be made on level ground, or slightly up a hill, but not down hill. 3. It is best if the stones to be thrown are painted a bright colour to make them more visible. 4. It is also suggested that an arc be drawn showing the position of the current record. 5. One official person must verify the point from which the throw was made. The thrower can use a run-up and should throw from a line such as one would have for javelin throwing. Crossing the line would invalidate the throw. Two officials should verify the location of the catch - they will have to follow the flight of the stone as it starts to come down. It would be the first point of impact with the ground that should be recorded. The distance should then be checked with a steel measure." "The current record is: The greatest distance achieved in hurling an object from a sling is 477.10m <I>1565ft 4in</I>, using a 127cm <I>50in</I> long sling and a 62g <I>21/4oz</I> dart, achieved by David Engvall at Baldwin Lake, California, USA on 13 Sep 1992." This description is similar or the same like Ben posted before. I hoped to get a little more exact informations. I probably must ask them for additional ones. It looks like our disusion about a sling tunning went in a bit different drection. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Chris on Feb 7th, 2004 at 7:20pm
The record says dart, so I don't think you have to worry about the stone ambiguity. You can't craft a dart out of stone, so it must have been made of some other material, so I think your lead glandes would be applicable.
Can you beat the 422m? Chris |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 7th, 2004 at 7:30pm
Chris,
I hope you are right abot the projetiles. When the lead ones are allowed I will overlap that distance probably. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Hondero on Feb 7th, 2004 at 7:42pm Yurek, this old message will interest you. It´s from the record holder of 1980: >Subject: Re: sling record keeping >Date: Sun, 22 Sep 2002 00:34:15 EDT > >Hi Ed, > >I'm glad you persevered and found me. I still love the slingshots and the >act of throwing but seldom do it anymore. > >I was 20 years old in August of 1981 when I broke Melvin Gaylors record. I >had been throwing since I was about 11 years old. As I got older and >stronger I realized the record was within my abilities and went ahead and >made the attempt. My sling pouch was made of elk hide leather and the >strings were of braided dacron thread. I had a leather loop I would put my >middle finger through and just a knot on the end of the string to release >for >the throw. The stone was oblong and would spiral like an American football >or a bullet when thrown so it was much more aerodynamic than a round stone. >I am 5' 9" tall and weigh about 180 lbs. That is the same as I was when I >set the record. > >I have wondered about making another attempt at the record. I have made >some >much superior slings compared to what I used in 1981. Also some better >projectiles. I am confident I could surpass 500 yards. Maybe by several >hundred feet. I haven't done anything to begin preparing for an attempt >and >I don't even know what the current record is. I am happy to correspond with >you and other interested people. Feel free to share my e-mail, phone >number, >etc. with others. I am interested in looking through the info you have >collected. > >Larry Bray |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 7th, 2004 at 7:50pm
Hondero,
Wow! This is the treasure!!! Thanks a lot!!! Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Dan_Bollinger on Feb 7th, 2004 at 8:52pm wrote on Feb 4th, 2004 at 12:09am:
From the tiny (emphasis on tiny) bit of aerodynamics I know, the optimal aspect ratio for low drag is 1:8, or so I recall. Something like this NACA 0012 foil. |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 8th, 2004 at 8:14pm
Dan,
You right the suitable (for the projectile velocity) NACA shaped projectile would be the best if it would be throwed correctly. But what is a chanse to do it with the clasic sling. That projectile the most probably will catch the release cord and get the chaotic flight, even if the pouch position is proper. Does it is posible to throw correctly such elongated projectile constantly. There is a chanse reach it with projectiles which have a ratio 1:2 or maybe 1:3 but in this case useing the NACA shape seems doesn't give a significant profit, because the ratio isn't fited to the velocity of slinging. Just only my reflection, maybe I'm wrong. Hondero, Here's the interesting fragment from: http://www.concentric.net/~Ssbray/braygar.htm I posted that quote in October but I repeat it here again. " After Larry graduated from high school (in 1979), he married Mary Ellett from Loa, Wayne County, in 1980. They lived in Loa for a while, and in 1981 Larry made it into the Guinness Book of World Records for throwing a stone with a sling 1,434 ft. 2 inches, at Loa, Utah on Aug. 21, 1981. This type of sling is one of the most ancient weapons; it was used by shepherds for defense against wild animals and to help keep their sheep; it was also used for hunting and warfare, and of course is mentioned several times in the Bible such as when David killed Goliath. Garland had taught Larry to use a sling at a very young age, and he had become quite adept in both distance and accuracy, and knew that he could break the record. The old record was around 1000 feet, and it was set in 1970 in England. Larry broke the record in 1980 at the Wayne County fairgrounds in Loa, but the Guinness people wouldn't accept it that year because they said that he didn't have sufficient proof or documentation. So he broke the record again in 1981, and this time he had nearly all of the officials in the county there to watch and certify everything. They marked each stone just before it was thrown, and when the stone was picked up after it was thrown, they checked the mark to make sure it was the same stone, and then the surveyors measured the distance very accurately, and it all had to be photographed, certified, and notarized. It was quite a big event." I'm full of admiration for this man. I'm very interested on his next posts, if they exists, of course. Hondero, do you have maybe a contact with this man? Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by magnumslinger on Feb 9th, 2004 at 12:17am
Dear Yurek,
How about just moulding one of your optimumly-weighted glandes to best approximate the shape of the front section of that 8-to-1 ideal sectional foil design (which, if it had fins and an attaching hook uderneath its belly, would look interestingly like that picture of the World's Record 500+ meter "sling dart" I saw in the Guinness Book in that elusive book stall which I'm still trying to find. I'll bet that that was one of their secrets!), and THEN attaching a COLLAPSIBLE tailing section shaped exactly like that desigh with collapsible rubber fins to the BACK END of the glande, thereby achieving the proper shape in flight AFTER release, while maintaining a conventional GLANDE SHAPE in the pouch PRIOR TO release? Originally, I envisioned a sort of tiny hard, light plastic Easter egg-like shell container, made up of collapsilbe segments much like one of those collapsible camping cups, which would lengthen with the air resistance and "setback" inertia (like old Soviet-style Tank "setback-armed rounds designed top be fired from non-rifled barrels to achieve higher velocities and mass production simplicity, whereas ours were "spin armed, using centrifugal force to armt he rounds after they were a safe distance out of the barrels, etc.) to extend it once it cleared the pouch/socket. Otherwise, a small piece of celophane tape stuck to the tip of the tail on the end of an inch-or-so thread could be sewn, of tied to the center, or edge of the pouch, and taped to the tip of the tail to "open" it with negilgible resistance/energy loss as it tore free of the puny tape as lt left the sling socket. It would extend to something looking sort of like an insect larvae. But then, I though of using a properly-shaped rubber baloon-like tailing segment, which could also be folded/collapsed over the gland in the socket, and a small lead or copper BB paced inside its tail tip, or the thread-and-tape or similar method could be used to open it up to the 8-to-1 wing foil sectional "dart"shape without hurting the weight or launching characteristics of the glande. That way, you could throw the thing normally, and it would extend to the proper shape in flight, and hopefully would fly a lot farter from your conventional sling, while not deviating much in design or expense, from a conventional sling stone/glande! I hopoe you can make this "long-range" bullet work for you, as I know that you are a good practical mechanical engineer as is obvious from your pictures of your sling and glande experiments. Your friend always, Jean Bradberry |
Title: Re: Air Drag On Sling Cords & Pocket Post by magnumslinger on Feb 9th, 2004 at 12:29am
Oops, I forgot to mention that tiny fins couls also be moulded, glued, epoxy-ed (even made from some sort of epoxy, perhaps) or taped to the tail segment, which could be made of plastic, rubber, heavy paper, etc. A hole could be punched inot the center of a tiny square of duxct tape and tied to the thread, which in turn would be tied to the pouch, and the tape then tuchk to the rear of the tail segment, just enough to allow it to extend on release, and then the tail segment and glande to which it was firmly attached could easily pull free with minimal force expended to achieve the extension and separation.
Jean B. |
Title: Re: Air Drag On Sling Cords & Pocket Post by Chris on Feb 9th, 2004 at 12:44am
You could make the fins slightly twisted (like an arrow) so that it cork-screws through the air like a bullet. Straight ones are ok, but a slight spin on the projectile adds gyroscopic stability and helps diffuse air around the projectile, reducing drag.
Chris |
Title: Re: Air Drag On Sling Cords & Pocket Post by magnumslinger on Feb 9th, 2004 at 1:09am
Dear Chris,
Twisting the fins slightly like an arrow is a TOTALLY COOL IDEA!! 8) WOW! Perhaps that idea of painting half of a glande to see how fast and in which direction it tends to want to spin when Yurek throws it (that was mentioned the other day) could be used to determine at what angle they should ideally be curved? Or might just doing it similar to how they do it for an arrow also be a good place to start? |
Title: Re: Air Drag On Sling Cords & Pocket Post by Dan_Bollinger on Feb 9th, 2004 at 8:52am wrote on Feb 8th, 2004 at 8:14pm:
Jurek, An aerodynamicist could tell us the best aspect ratio, no need for us to guess. A slingstone leaves the pouch at 30m/s (67mph) in order to fly 145m (Richardson). To go ten times that distance the velocity is going to be faster. Such speeds will profit by a well-shaped stone. I think a special sling pocket would have to be made for this projectile. Pehaps lined with thin rubber to help spin the projectile? Quote:
Attaching hook? Now THAT's interesting. About three years ago I worked on this same problem of long distance throws. I came up with that NACA shape for the glandes, and I came up with a pocketless sling, too. The pocket is a huge velocity thief. Lots of air resistance at the high speed end of the sling. My design used an internal release mechanism, not external like the 'hook', but the idea was the same, eliminate the pocket which Jurek points out is going to be a problem with the glandes/bolt/dart, |
Title: Re: Air Drag On Sling Cords & Pocket Post by mgreenfield on Feb 9th, 2004 at 9:32am
FYI, at an aero museum near here there are models of the x2 bombs dropped on Japan to end the war. These bombs are VERY! short and fat, with fins on the rear end. They're much shorter/fatter than Jurek's cast lead glandes.
But are we sure fins are needed? I recall one of the record-setters saying his football shaped stone did fly with a spin that kept it point first. Also, it seems like a pocket maybe could be designed to fit a particular projectile, that would not add much drag on spinup. Jurek's wire sling used with slightly grooved glandes seemed promising. mgreenfield |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 9th, 2004 at 3:02pm wrote on Feb 9th, 2004 at 8:52am:
Dan, You have quoted my words in this way: Quote:
I believe you did it only due to compactness, but that quote gives a false view of my thinking and opinion about the profit of useing the shape which you showed. Your quote changes a sense of my post. I don't question that this shape (1:8 ratio) is the best for "sling velocities". I only fear that proper release of such elongated projectile must be a problem with a clasic sling which is required by GWR. I think the quote should be rather like following, and I hope that one is clear. Quote:
Excuse my finicality :) Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by SnapCut on Feb 9th, 2004 at 3:18pm wrote on Dec 28th, 2003 at 4:52pm:
The slings that I made were from leather boot laces with small leather pockets. When used they sounded like the crack of a whip or a 22 being fired. I guess that means some part of the sling is going faster then sound. |
Title: Re: Air Drag On Sling Cords & Pocket Post by Hondero on Feb 9th, 2004 at 5:12pm wrote on Feb 8th, 2004 at 8:14pm:
I´m writing a slinging friend from New Zealand that posted him and David P.Engevall, just wait if he answer me... two years without contact. |
Title: Re: Air Drag On Sling Cords & Pocket Post by Dan_Bollinger on Feb 9th, 2004 at 6:08pm
Jurek, Thanks for the clarification, I didn't understand your point. I think a pocket could be made for a long dart. Some of the point and most of the tail could extend past the pocket. After all, cestrosphendrons can be tossed with a sling and they have a 1:30 aspect ratio! Where is it said that GWR requires a classic sling? I've not read that.
There is a historical note about grooved glandes being tossed by a simple loop of cord. I forget where. I machined one and it works. It looks like a yo-yo. Did you know that yo-yos are descendants of Phillipine hunting slings? www.claycritters.com/sling/groovedglandes.jpg |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 9th, 2004 at 7:38pm
magnumslinger,
Thank you for the interesting tips, as usual. They have given me the idea. If we wrap up (maybe two or 3 timesand maybe a bit slantwise) the projectile and folding fins tightly with the band (belt,tape ?) of a soft leather or something like that, and fix the free ending of the tape to the ending of the retention cord, than we will get the tight roll rested in the cradle. That roll should sit in the cradle pretty stably. Durring the release the dart will roll off and will get the good spin and the free fins will spread themself. I know that rolling off will take a part of energy but it will give the pretty good rtotation instead. Tan maybe the fins would't be unnecesary? Just idea. But I'm still not sure if such projectiles will admited by GWR, since they have said "a stone" in rules. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 9th, 2004 at 7:46pm
Dan,
Go to the site nr 5 of this thread. I have quoted the GWR rules and the information about the last record. I have got this information just from GWR. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 9th, 2004 at 7:54pm wrote on Feb 9th, 2004 at 5:12pm:
Hondero, Please, let me to know if you will get something new. I would be grateful. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by adair3 on Feb 10th, 2004 at 4:50pm
Wow,
This is a long thread. I will throw in my two cents. Most of my slings have used had oval or diamond shaped pockets. Generally these measure 6" x 3". The one I am currently using is more of an oval. I have tried various things for the cords. Round leather lace from Tandy leather (1/8") was susceptible to breakage. Mason layer's twine was fair but tended to twist and tangle. On my current sling I used 1/4" square cross section leather lace. Going from diamond to oval pouches has definitely increased the size of the rocks or dirt clods I throw. They are held more securely but with the combination of the increased pouch area and larger diameter cords wind resistance is increased, I think? To compensate for this missile size has increased. Scott Adair |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 10th, 2004 at 5:36pm Quote:
Dan I just have seen that picture, before it didn't download itself. This is interesting, I'm curious if that missile isn't rubing the cord. I understand that the groove must be deep due to stability but it seems to make the release more difficult. I'm also curious if the missile gets a strong rotation. If the thin split-cradle is used than two grooves on the projecile may be more pointless. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 10th, 2004 at 6:00pm
Welcome adair3
I see you use rather a big pouches, the same like me not long ago. My new stone slings have reduced pouches however. Now I see that smaller ones are more efficient due to smaller drag and an easier release. Often the full surface of a big pouch isn't holding up the stone. I think it is good to cut surpluses off a bit. Unless you throw very big rocks. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Dan_Bollinger on Feb 10th, 2004 at 6:24pm
Yurek, The cord in that picture is very thin, about 1.0mm, probably too thin for this glandes. And, I think the groove doesn't need to be that deep. However, the deeper it is the faster the rotation will be. Of course, brass is a poor material for a glandes, too slippery and too expensive. I just made this because it was easy to do on my lathe.
|
Title: Re: Air Drag On Sling Cords & Pocket Post by adair3 on Feb 11th, 2004 at 10:41am
Yurek,
I saw a post of yours with a picture of several sling pouches. What is the length and width of your pouch with the split running down the center? Scott Adair |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Feb 11th, 2004 at 3:04pm
Scott,
That pouch dimensions are 3 x 13 cm (1.2" x 5.1"). That one is a bit used and streched now. I have made that for lead glandes but I use that for stones too. If stones aren't too big or irregular, they sit in that pouch not so bad. This is mainly the "sport" sling for ranges. Normally I use a bit bigger pouches for stones. Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by mgreenfield on Apr 10th, 2004 at 4:54pm
What is there about the classic Roman lead glande shape???
I was out today picking up stones I'd pitched the last few days. I found one about 50% further out than the bunch on the ground at my usual range. It weighs 55grams and is an almost perfect copy of the Roman glande shape, ....just a little more blunt on the ends, and just a little more rounded on the edges. What IS there about that shape??? mgreenfield |
Title: Re: Air Drag On Sling Cords & Pocket Post by Sean on Apr 10th, 2004 at 6:14pm
Im not sure if anyone has sugusted this or not but if u were using something that hurt your fingers you could put a small piece of leather or something around your finger. Im not sure if it would mess up your performance but its worth a shot if your sling starts to hurt cuz you because it is so skiny. just a suggestion.
|
Title: Re: Air Drag On Sling Cords & Pocket Post by Chris on Apr 11th, 2004 at 11:38pm
Mike, I often wonder the same. I'm in contact with a physicist who does fluid dynamics. I'll keep everyone apprized of any developments.
For those that are wondering what that shape looks like: |
Title: Re: Air Drag On Sling Cords & Pocket Post by mgreenfield on Apr 12th, 2004 at 10:02am
Chris, .....the white glande in the inset pic looks just like the "magic" rock I pitched. About the same size & all. I pitched it again. Same result. Wouldn't we all really like to know why that shape is "magic"!! Makes "superslingsters" out of common guys. ;D mgreenfield
|
Title: Re: Air Drag On Sling Cords & Pocket Post by justin Ball on Apr 12th, 2004 at 11:56am
I'm really surprised at 3 things, folks
1- that this topic caused 8 pages of replies in just a day or so... 2- that this topic hasn't been beaten to death...I'd been slinging oh, maybe 20 minutes when I made a second sling using 0.75 to 1mm nylon line, as I'd worked out the surface area, just like Mr. Greenfield. Same goes for large hood ornaments- save 1% of your fuel a year by removing yours! A loose woven pouch would also help reduce surface area. 3- the tear drop shape can be found in many things that must move through fluids- sumarines of the 60's, airfoils, concept cars...I'm supposing that a tear drop shape would probably perform better than a symetrical football- though harder to make. Justin |
Title: Re: Air Drag On Sling Cords & Pocket Post by mgreenfield on Apr 12th, 2004 at 12:51pm
Justin, ....we think it's more than simple streamlining. There's something else going on. Perhaps an interaction between the pouch and "almond shaped" glande. Cross section of these glandes isn't circular like a torpedo, and round cross section glandes dont work nearly as well.
These glandes have cross sections flattened to maybe a 3:1 ratio oval, with surprisingly small-radius curves at the sharp edges. This is the "magic" shape that takes off like a rocket from a sling. mgreenfield |
Title: Re: Air Drag On Sling Cords & Pocket Post by WildAtHeart on Apr 12th, 2004 at 5:19pm
Perhaps the "airfoil" or almond shape of the rock gives it lift! That is, assuming it doesn't tumble through the air.
Also, I think we should try and find a textile engineer who could tell us what types of thin filaments don't tangle and twist. I'm sure there are some that are less likely to get tangled simply because of their molecular structure - I believe someone mentioned steel cable. That might be the best. |
Title: Re: Air Drag On Sling Cords & Pocket Post by slingmeister on Apr 12th, 2004 at 11:35pm
Hello All,
New here, nice forum, appreciate lack of profanity and lack of flames. Am experimenting with air resistance, anyone try making a pouch from net material such as fishing net? Thanks for any ideas (smile). Slingmeister ><> |
Title: Re: Air Drag On Sling Cords & Pocket Post by David_T on Apr 12th, 2004 at 11:46pm
Welcome Slingmeister,
We all try to run a clean ship ;D We love sling stories and info so keep on posting!! Check out the Gallery and videos |
Title: Re: Air Drag On Sling Cords & Pocket Post by Chris on Apr 12th, 2004 at 11:53pm
Welcome Slingmeister,
Matthias made a sling from netting. You should talk to him. Chris |
Title: Re: Air Drag On Sling Cords & Pocket Post by David_T on Apr 13th, 2004 at 12:01am
Chris,
Neat sling! Who is Matthias? Has he posted here before? The name does not sound familiar. |
Title: Who's Matthias? Post by Matthias on Apr 13th, 2004 at 1:14am
I am ;D (a he though - and just recently delurked) (chris - mistake corrected)
Thanks! The pocket is not made from netting (as in already made - hard to find suitable stuff and a pita to attach) but rather netted in place. The net pocket works pretty nicely for irregular ammo... I made it mostly as a challenge based on the materials at hand (It is made with a single 6ish foot length of trawl twine, unbroken (including the net). The netting cuts down on the "sail area" quite significantly. It will obviously have more drag than some of the spartan twin-aircraft cable designs shown in this thread. Matthias |
Title: Re: Air Drag On Sling Cords & Pocket Post by srgs9 on Apr 13th, 2004 at 9:26am
Matthias ,
I was going to ask how you did that. Half heartedly playing with some netting left over from my guillie suit just caused more head scratching. The "how-to" on that would make a great article IMHO... Somewhere in my piles of junk is a sack full of P-cord gut. Other than patching my jungle hammock,guillie suit and making some simple sling cordage that's all that's been done with it. It would seem to be perfect for split pouch and net pouch slings.(Yeah I know I'm a bit slow sometimes :-/. ) I'll try and get some pics posted this weekend of some of my sling stuff and prehaps some other sillyness that I call hobbies. |
Title: Re: Air Drag On Sling Cords & Pocket Post by slingmeister on Apr 13th, 2004 at 6:54pm
Mathias,
It looks like you made the net part yourself. If so, how did you do it? Making it myself would probably be better because I could make a pocket in it to hold the stone. slingmeister |
Title: Re: Air Drag On Sling Cords & Pocket Post by Matthias on Apr 13th, 2004 at 10:03pm
Ok, here goes... (knots are pretty hard to describe unless you are working with a common vocabulary... I'll try pics) I'm guessing at the embedded pic tags, If Chris changes them I'll edit the post - they won't show up at first.
The Sling: This was a first experiment. The twine used was 3.5mm polyethylene/polyester braid (8 strands of each) with a filament polyethylene core. We use a range of fibres in trawl nets, up to and including dyneema/kevlar. The modern PE twines match up pretty well with the super-high-tech stuff, at much lower cost. The challenge here was to make a sling with ONE piece of twine. The sling was eye-spliced in the middle for the retention loop and "sleeved" until the split. The core was withdrawn from 3/4 of the length and braided. The two halves (both sans core) then rejoin coax style again until the retention knot. In the photo below, end 2 is spliced for the loop, and drawn through the hollow core until the pouch split. End 1 (with core) is spliced into the hollow end 2. You can use "real" splicing tools, or you can tape a point onto the end that you are threading. Taping the end to a piece of wire or similar can make it easier too. The top image to the left shows the path that I netted the pouch with. A further refinement would be to carry the number of cords needed through the sling cords, or split a larger core into several. Even numbers are probably better - 6 seems to be about right. A planned refinement is to try another sling using a twelve strand round braid for the cords, split into 2 three strarnd braids for the pocket edges and 6 for the netting. All 12 strands rejoin in the release cord... The lower pic might help explain. I think this will be a pretty elegant braided sling - a little different. The Netting: And here is the crux... Netting is easy once you get the hang of it. Watch Greek fishermen mending their nets for a knot speed tying clinic. Traditional diamond mesh nets used to be made by hand using a netting needle to hold twine and a mesh stick to gauge the size of the meshes. The mesh in the sling is too tight for a needle, so I had to thread the knots by drawing the entire length through each mesh. The mesh stick assures consistency, but isn't neccesary - I used a pencil for some of the meshes and the corner of my pinky for others. The first row of meshes is cast on the sling cords using Clove Hitches. Lark's Heads could be used to, but 98% of fish nets use clove hitches - there must be a reason that I don't know; I'll ask my friendly neighbourhood Icelander next time I see him! The knots used to make the net are Sheet Bends. When tied in a net they are known by various names, including Netting Knot, Weaver's Knot, Mesh Knot... They can be tied a few different ways, depending mostly on what village or island you grew up on. The pics describe it better than I can. Using the technique shown is quite a lot faster and more accurate than methodically tying individual sheetbends the way most people are taught. The mesh stick (shown with the hanging meshes looped around) gives you nice even meshes. Care must be taken when drawing the knot tight to avoid "capsizing" the knot - at this scale it is a little bit easier to misform the knots. Try practicing with larger meshes and twine before tackling a sling pocket - it will go much smoother. The pouch on the green sling tapers at the ends in a mostly freeform way. I think the second design with all six strands carried through to the ends might be a little tidier. Hope that helps a bit! Questions welcome... Matthias |
Title: Re: Air Drag On Sling Cords & Pocket Post by Chris on Apr 14th, 2004 at 1:28am
Matthias,
Great description and images. You think you could write than up into a mini article and submit a copy to me for the articles section? Chris |
Title: Re: Air Drag On Sling Cords & Pocket Post by Yurek on Apr 14th, 2004 at 8:11am
Matthias,
Thanks for your effort! Really good work. Your drawings are excellent. Pity I haven't proper skills to do the same :( Veeerrrryyyy nice sling! Jurek |
Title: Re: Air Drag On Sling Cords & Pocket Post by Matthias on Apr 14th, 2004 at 11:56am
Thanks guys. Man it is tough trying to get concepts across in text - I'm quite proud of the knot tying sequence! we won't discuss the rest...) You can see why there aren't any 16 strand braiding articles yet :o... I'll wait to see if this generates any dialog that could be incorporated but I'd be happy to rework the info into a proper article.
Matthias |
Title: Re: Air Drag On Sling Cords & Pocket Post by slingmeister on Apr 14th, 2004 at 11:01pm
mathais,
Thanks for the info, I'm probably not good enough to make that complicated of a sling yet but I will probably try it at some later date. Thats cool how its made of only one piece of twine, nice work! slingmeister ><> |
Title: Re: Air Drag On Sling Cords & Pocket Post by goblin on Apr 23rd, 2004 at 4:10pm
although i havent posted in this topic till now, i like it alot, and i don't want to see it fall into oblivion.... lets keep this one alive. there is so much great stuff in this topic. any other ideas for this topic and different types of slings? i am currently going to be developing some ideas and i want this topic to stay on the general discussion forum 1st page.
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Title: Re: Air Drag On Sling Cords & Pocket Post by lobohunter on May 11th, 2006 at 1:34pm
I have made a lot of thin spider wire slings. One's with netting for a pouch. My first ultra light sling came straight out of cliff savages book. It was made of 100# monofiloment fishing line and hardware cloth as a pouch.
I have given up on theses ulta light slings. for two reasons. 1. I find they only increase my distance by a few feet I have tested them besides my other slings of the same length made 1/8 leather jump rope and leather pouch. 2. they usaly tangle so the power gained in short range is negated do to the fact the tangle limits the amount of shots there by limiting pleasure in target practice. or limiting effectiveness in hunting Granted if you were in a heated world record compitetion where a few feet would matter every thing. Then the ultra light sling would be the way to go For me the small gains of the ultra light sling. Are not worth the amount of pleasure that is lost from this great sport/ hobby of ours. |
Title: Re: Air Drag On Sling Cords & Pocket Post by TechStuf on Jun 17th, 2006 at 11:35pm Yes, it's true that such cordage can be difficult to work with.....yet it's also true that such difficulties can relatively easily be overcome. As mentioned before, the tangling issue is easily settled by proper employment of loops in the retention cord to arrest the release cord before such can occur. As for a nominal distance increase of only a few feet.....I offer the fact that I have experienced an appreciable increase, anywhere between 90 and 200ft.....the highest gains, of course, are realized during extreme distance efforts where the difference in drag quickly becomes more pronounced. LH is correct in that very thin, virtually zero stretch fibers offer little or no benefit for short to midrange accuracy exercise. However, I'm certain that they are of appreciable benefit to extreme distance attempts. TS |
Title: Re: Air Drag On Sling Cords & Pocket Post by jauke on Aug 7th, 2020 at 12:32pm
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