# "The YY" - new compound slingshot desing



## JoergS (Dec 17, 2009)

Hello,

the compound slingshot concept for flat bands was a very good and popular idea. I got many positive comments about it.

So I decided to work some more on the concept. I wanted to get rid of the guide rod that is necessary so the bands won't slip of the rollers, and also I wanted a design that has no forward extended rods for the bands so the hand is not in the way.

The solution: Wider pulleys and a more straight band attachment method. The slingshot that came out is a bit bulky, but very beautiful (I think). The ball bearings in the wide stainless steel pulleys make the action super smooth.

It is shot with the bands set up like in the first picture, the second picture is just to show the attachment method.

This is a very fast shooting slingshot! Let me know what you think.

Jörg


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## mr.joel (Dec 21, 2009)

Another masterpiece from zie miester! Is it just as powerful as the the compound W? Are you coming out with a compound gloveshot as well?


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## NightKnight (Dec 16, 2009)

Looks very nice!!

Question. Are the bands attached differently between the two pictures? It looks like the first picture has the bands attached after looping under the mounts, and the second one has them mounted directly.


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## MSG Hall (Jan 14, 2010)

very impressive! I have watched all you vids... you do have some talent! Excellent!



as a matter of fact it was your youtube vids that made me start to really think about the non-braced ones... now I'm really excited about getting back into this sport... well, new sport really, I have never once shot a non braced slingshot... I can't wait for my dankung to get here!


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## JoergS (Dec 17, 2009)

AaronC said:


> Question. Are the bands attached differently between the two pictures? It looks like the first picture has the bands attached after looping under the mounts, and the second one has them mounted directly.


No, the second picture simply shows the other side! The first pic shows it ready for the action. This is the way how it is shot.


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## NightKnight (Dec 16, 2009)

JoergS said:


> Question. Are the bands attached differently between the two pictures? It looks like the first picture has the bands attached after looping under the mounts, and the second one has them mounted directly.


No, the second picture simply shows the other side! The first pic shows it ready for the action. This is the way how it is shot.
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Hmmm. My eyes are certainly deceiving me then.... becasue I still think the bands at the bottom in the first pic look wider than the second.


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## Pavel8303 (Jan 13, 2010)

Nice one


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## pelleteer (Dec 19, 2009)

In other words, both pics are of the front of the slingshot (the side that faces away from the shooter). The first pic shows the bands in position for use, while the second pic shows them looped over the rollers backwards to show how they are attached.


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## NightKnight (Dec 16, 2009)

pelleteer said:


> In other words, both pics are of the front of the slingshot (the side that faces away from the shooter). The first pic shows the bands in position for use, while the second pic shows them looped over the rollers backwards to show how they are attached.


Oh, I see! Duh!


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## pelleteer (Dec 19, 2009)

AaronC said:


> Oh, I see! Duh!


Don't worry, it took me a couple minutes of looking at the pics to figure it out too.


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## Flatband (Dec 18, 2009)

Really Nice Joerg! Excellent idea with the rollers in a "V" shape. On other pulley-roller designs drag was always an issue. This negates it. I think you can even take the design further (and I know you thought of it too). Extend the attachment prongs downward another 6-7 inches from the bottom of the handle add a Palm strap for more strength,this will increase the drawlength even further and give more stability and more importantly- MORE POWER!!!!!!!! Great work Bud!







Flatband


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## JoergS (Dec 17, 2009)

Flatband said:


> Extend the attachment prongs downward another 6-7 inches from the bottom of the handle add a Palm strap for more strength,this will increase the drawlength even further and give more stability and more importantly- MORE POWER!!!!!!!!


Flatband, indeed I though about this. But if I use more extension, then I won't be able to use my full draw length, I am already pulling this band set to my half butterfly stance.

One thing I found out about extended forks is that you neet to use thinner bands. If you stay with the same band width, then the longer bands will result in more rubber molecules to be stretched. This brings you to the limit of your personal strength very soon. So you won't be able to stretch the rubber in full.

The advantage of the extended fork slingshots is simply the longer acceleration phase. There is less dead play in the setup. But there comes a point where this does not work anymore. If you have eliminated all the dead play and further you found your maximum band width/length, then you hit the end of the road.

Jörg


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## King Cat (Dec 19, 2009)

Excellent innovation. This design will add power and speed without increasing pull force. I can’t wait for the test results.


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## christopher (Jan 8, 2010)

Is it really a compound slingshot that has similarities to that of a compound bow has to a recurve bow?


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## mr.joel (Dec 21, 2009)

I wonder which is the more efficient design in terms of performance: the compound W seems like the bands have less interferance from the rollers due to less angulation from their attachment points. YY(or more accurately, the VY) is of course more compact, but I wonder if there is a loss there?

Once again you really are on to the goods I think, Joerg. Don't stop now, keeep it coming. I get so excited when I see your devices pop up, and know I'm not alone.


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## pelleteer (Dec 19, 2009)

christopher said:


> Is it really a compound slingshot that has similarities to that of a compound bow has to a recurve bow?


I wouldn't say so. In fact, I haven't seen a slingshot yet that looks like it truly achieves the purpose of a compound bow, which is to allow a heavy draw but light hold (i.e. "letoff"). I believe the term has a differnet meaning when it comes to slingshot design. When referring to a slingshot as a "compound," I believe we are talking about a slingshot that somehow "compounds" the velocity of the projectile in some way, without necessarilly increasing the draw weight. Other's opinions may differ, of course.


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## JoergS (Dec 17, 2009)

Pelleteer, you are right, a compound bow uses excentrical cams and therefore reduces the strain in drawn out condition. That does not work with slingshots.

I couldn't really find a universal definition of the term "compound", but MY definition for slingshots is "a slingshot that features moving parts in order to enhance the performance".


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## smitty (Dec 17, 2009)

Why wouldn't it be possible to use excentric cams to use with a slingshot? I have often wondered about that. Seems very hard to experiment with at home with limited resources.


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## mr.joel (Dec 21, 2009)

smitty said:


> Why wouldn't it be possible to use excentric cams to use with a slingshot? I have often wondered about that. Seems very hard to experiment with at home with limited resources.


 What are those? I really like the cams on the Saunders models, It would be great if they could be machined from steel. is that what you are referring to?


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## smitty (Dec 17, 2009)

I'm just thinking about the type of cams they use on compound bows, that once the cams flip around on the draw, it eases up quite a bit on pull weight to enable shooter to hold at full draw with less strain.


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## JoergS (Dec 17, 2009)

Smitty, the problem is that a bow stores all the energy in the bow frame itself, the bow string does not stretch (ideally). Therefore, the CAMs can do their job. On a slingshot, the energy rests in the drawn out "string" (= the rubber) itself. So the CAMs could only store the little energy of the small rubber part between the cam and the fork. The longer part of the rubber (between CAM and pouch) is not affected.


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## smitty (Dec 17, 2009)

OK, I get it now. Between the pouch and fork would still be pulling all the rubber. Thanks Joerg.


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## christopher (Jan 8, 2010)

I see, it's not so much the pulling force (draw) is easier, as the force is non-linear on a single roller and thus harder. but the force required to hold the potential energy is less because the rollers aid in the holding force. Same concept of pulling up a bucket of water on a single pulley. The pulley doesn't compound the energy needed to pull the bucket up, but it does compound the needed force to hold the bucket in place on the draw.

So you could hold the draw of stronger bands more easily and lever against the rollers. I can see that fitting into a compound definition for a slingshot for some. But more appropriately it's a pulley slingshot or a folded starship slingshot.


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## smitty (Dec 17, 2009)

I guess we need some help to understand this type of slingshot, because I think the whole purpose of the rollers at the top of the forks is to remove the dead rubber from the draw length. If all the dead rubber is behind the rollers, away from the shooter, then the rubber is stretched all the way from fork to anchor point. So, you have a 29 inch draw length: with rollers the rubber will be stretched 29 inches.
Without dead rubber gone from draw means you lose the amount of stretched rubber equal to the length of your bands that hang from the forks. So with a 29 inch draw length and 7 inches of dead (unstretched) rubber, you only have an actual draw length of 22 inches.

Well it sounds pretty logical to me.


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## mr.joel (Dec 21, 2009)

Not really a pocket shooter, but not exactly pocket power either! It really would store nicely in a shoulder bag, a real advantage over the W with rollers. Is it as easy to shoot, or is it much different to use?


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## JoergS (Dec 17, 2009)

mr.joel said:


> Not really a pocket shooter, but not exactly pocket power either! It really would store nicely in a shoulder bag, a real advantage over the W with rollers. Is it as easy to shoot, or is it much different to use?


It is easy to shoot, will do a video this WE.

The term "folded starship" is very accurate. That is what the design really is! The fact that the draw length increase is not achieved by a forward, but a downward extension makes the slingshot shootable without wrist braces. Forward extended slingshots will "want" to turn around in your hand, towards the shooter, and only a wrist brace can avoid that. A downwards extended slingshot has no such tendency.

Extended slingshots are always more bulky that conventional ones. But the pulley based design is more compact than a starship.


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## ZDP-189 (Mar 14, 2010)

Does this result in any more wrist strain?


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## JoergS (Dec 17, 2009)

No, the wrist strain is the same as on a conventional slingshot.


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## ZDP-189 (Mar 14, 2010)

It looks pretty much optimal, then.


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