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Compound sling vid (Read 1591 times)
Sarosh
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Re: Compound sling vid
Reply #15 - Apr 12th, 2019 at 1:50am
 
here are some pics i think these are what you want
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Sarosh
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Re: Compound sling vid
Reply #16 - Apr 22nd, 2019 at 3:49pm
 
anyone trying to figure out a better trigger/ or a mod that could release exactly when the main cord straightens out? Undecided
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joe_meadmaker
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Re: Compound sling vid
Reply #17 - May 25th, 2019 at 12:15am
 
I have made an attempt at a compound sling.† Forewarning and spoiler alert, this attempt was pretty much a failure.† But I am going to make some adjustments and try it again.

First things first.† Here's a picture of the sling:

...

I'll try to explain the setup without being too confusing.† There is a main retention cord permanently attached to a weight.† In this case the weight is a red plastic ball filled with silicon.† This is not ideal, but it's what I had available when building this prototype.† Another permanent attachment on the weight is a secondary retention cord that connects to one side of the pouch.

The other side of the pouch is attached to primary and secondary release cords.† The secondary release cord has a loop which is wrapped around a post on the weight.† The primary release cord is made of two pieces of cord.† The reason is so that it can come down on both sides of the secondary retention cord, and help to hold the projectile in place while the sling is rotating.

The basic idea is that when you let go of the primary release cord, the pouch is allowed to swing free on the secondary release cord.† As the pouch extends out, the loop of the secondary release cord will slip off the post on the weight, releasing the projectile.

There are a couple adjustments I tried to apply that differ from the design by Sarosh.† One is that I wanted to make the sling one handed, so a windup could be used without rotating your entire body.† Second, I wanted the projectile to be in a rotating motion during the windup along with the weight.† The hope is that less energy from the throw is needed to get the projectile moving when the sling is released.

Here is a video of this sling being used: https://youtu.be/5oPGFPuNbwY.† Sorry about the distance.† I was trying to stay far away from my phone during the recording because I had no idea where the projectile was going to go.

There are a few problems with this sling and the attempt.† One is that the weight and the projectile I'm using weigh the same.† They are the exact same red plastic balls.† Again, this was not ideal, but what I had available at the time of this test.† Second, the cords on the sling came out shorter than I wanted.† The sling needs to be spun around too quickly and it's difficult to see what's happening during the release.† And related to that, because the sling is spinning so quickly, it makes it much more difficult to time the release.† My first throw almost hit my phone (which I was using to record).† You'll see that in the video.

I'm not sure when but I'm planning to remake this sling with longer cords.† I also want to test with a projectile that is smaller and lighter than the weighted ball.† But for the moment, this is my attempt.† At this point I think the design by Sarosh is much more effective, but I'll report back after the next trial with my design.

Feel free to throw out any thoughts or ideas.† This is by no means a completed design† Smiley
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Sarosh
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Re: Compound sling vid
Reply #18 - May 25th, 2019 at 2:34am
 
Thanks for experimenting it's nice to see other people trying it too. Cheesy

some thoughts and ideas:
joe_meadmaker wrote on May 25th, 2019 at 12:15am:
I wanted the projectile to be in a rotating motion during the windup along with the weight.† The hope is that less energy from the throw is needed to get the projectile moving when the sling is released.


if the projectile mass is rotating then it means you put energy into it,
if the mass is low, the energy you put is negligible, the speed is also low so no reason to do that.This way you shorten the cord between booster and projectile which limits the arc of accelerating the projectile (bad).

if the projectile mass is high then the best place to put it  in order to put max energy to it is at the biggest radius, where the booster mass is, that would mean you got a simple sling but also a booster mass that steals you energy.

i would say you shouldn't care if the projectile mass has initial speed or not since the ratio should be: projectile mass<<< booster mass .energy should transfer from body to booster to projectile like a whip.

On the release mechanism:
I can't say i have completely understood how the secondary release cord releases from the pin on the red ball. how easily would it misfire?
i don't like non sliding booster mass because when you release the primary release cord the secondary cords will relax at first and then be pulled by the booster mass. And the booster mass retains a lot of it's speed which means low efficiency.

you should try it with a much lighter projectile mass, 5-10 times lighter than booster and see how it behaves.
you can lengthen the secondary cords and remove the primary release so that you pinch and release the projectile pouch, leading to longer arc of acceleration.



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joe_meadmaker
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Re: Compound sling vid
Reply #19 - May 25th, 2019 at 10:26am
 
Sarosh wrote on May 25th, 2019 at 2:34am:
if the projectile mass is rotating then it means you put energy into it,
if the mass is low, the energy you put is negligible, the speed is also low so no reason to do that.This way you shorten the cord between booster and projectile which limits the arc of accelerating the projectile (bad).

I agree with you on these points.† But there is another point that I forgot to mention.† Having the projectile in motion was also intended to help keep it in the pouch until the secondary release cord is free.† But you could be right.† This may be completely unnecessary.


Sarosh wrote on May 25th, 2019 at 2:34am:
On the release mechanism:
I can't say i have completely understood how the secondary release cord releases from the pin on the red ball. how easily would it misfire?

The pin in the weighted ball is just a small nail.† Which is also something I want to change, because it makes me nervous.† The secondary release cord basically has a finger loop tied at the end which is slipped over this nail.† During a throw, when the pouch is released, it will extend to the full length of the sling and the secondary release cord will just fall off the pin.† I'm not a big fan of this method.† But it's the only thing I can think of for an automatic secondary release.

There is another thing that comes in to play.† With a primary and secondary release cord, there is a lot of cordage that could potentially be in the way of the projectile when it is released.† When I remake this sling to lengthen the cords, I think the retention cords will be left as paracord.† †But the release cords will be replaced with something thinner and lighter.† Probably hemp or flax because I have a lot of that.


Sarosh wrote on May 25th, 2019 at 2:34am:
you should try it with a much lighter projectile mass, 5-10 times lighter than booster and see how it behaves.
you can lengthen the secondary cords and remove the primary release so that you pinch and release the projectile pouch, leading to longer arc of acceleration.

Definitely agree with the lighter projectile.† Especially being that one of the original intentions of the compound sling was to throw small light projectiles.

I like the idea of having just one release cord, but because my design doesn't have a moving booster weight, I'm concerned that the pouch won't get momentum quickly enough to hold the projectile.† I will think on that though.

Thanks for the input.† †Hopefully I'll have some new results soon.† Smiley
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Re: Compound sling vid
Reply #20 - May 26th, 2019 at 11:11am
 
Definitely give you credit for not giving up after five tries. Nice job putting the work into this.
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joe_meadmaker
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Re: Compound sling vid
Reply #21 - Jun 13th, 2019 at 8:44pm
 
It took me a while to get around to it, but I finished the second revision of my compound sling.† Here is a new image.

...

The basic functionality is still exactly the same as in my previous description.† There are two changes with this revision.† The release cords have been replaced with thin braids of linen.† It's lighter and not as stiff as paracord so I hope it allows the sling to open more easily.

The second thing is I extended the length.† I don't think I ever took a measurement of the original.† The current sling has a length of 42 inches (107 cm) from the finger loop to the center of the counter-weight.† Once the sling is released, center pouch will extend to 58.5 inches (149 cm) from the finger loop.

The original was so short that it didn't allow any time to see the release of the throw develop.† I don't know if this one will either, but I have higher hopes than before.† One last change I'll be making is to switch the projectiles to golf balls.† The last time the projectile was exactly the same as the counter-weight and that was definitely causing problems.

I haven't had time to give this sling a try yet and I don't know if I'll have a chance this weekend.† But I'll get to it as soon as I can.† There will be video and I'll post a link once it's up.
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joe_meadmaker
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Re: Compound sling vid
Reply #22 - Jun 23rd, 2019 at 1:07am
 
I had a chance to try my revised version of the compound sling.† It's still not working very well, but it was an improvement on the first attempt.

The changes (which are detailed in my previous post) did make the sling a little more consistent.† Other than a couple misfires, one of which is the first throw in the video, I was able to pretty much throw forward.† But I think the projectile is being release earlier than intended.† I will give this version a few more sessions and then hit the drawing board to determine what my next adjustments will be.

This video also shows the setup of the sling better than the first one did.

https://youtu.be/J9cSaFlyr3M
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NooneOfConsequence
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Re: Compound sling vid
Reply #23 - Jun 23rd, 2019 at 4:06pm
 
That looks like good progress!  FYI, Iím working on a pouch design specifically to solve the retention and release problems with a compound... I hope to have something to show in the next week or so.
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joe_meadmaker
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Re: Compound sling vid
Reply #24 - Jun 23rd, 2019 at 4:12pm
 
@
NooneOfConsequence

Thanks!

Looking forward to seeing that pouch.† That is one of the larger concerns at the moment.† And not just releasing at the proper time, but also holding the projectile until the time of release.
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NooneOfConsequence
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Re: Compound sling vid
Reply #25 - Jun 23rd, 2019 at 11:50pm
 
Yup... hopefully Iíll have a good solution to that. It still needs a little more tweaking and testing to be sure it works though.
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Re: Compound sling vid
Reply #26 - Jun 24th, 2019 at 5:50pm
 
Could one simply scale down the sling considerably to make a more user-friendly design? Obviously this doesnt fix the release issue but just a question I had watching Sarosh using it.  If you guys could get this thing working to the point it could be aimed that would really be something else...

One thing I try to work on with my own slinging throw that has added a great deal of control, is to focus on slowing arm movement down as much as possible while increasing sling lag to the optimum point. Creating essentially what feels like a very efficient high gear ratio between arm and sling.

But this design takes that concept to a whole new level. I would think if the bugs could get worked out you could have very low arm movement (giving extreme control) while maintaining high velocity. Anyways just a thought.

Nice job Sarosh!  Smiley
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NooneOfConsequence
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Re: Compound sling vid
Reply #27 - Jun 24th, 2019 at 11:34pm
 
Ok. Here it is! Ring Sling 2.0:
I had some time this evening to build a rough prototype non-compound sling to show the mechanism for a compound sling... itís functionality is similar to my original ring sling, but construction is simpler and you donít need a big heavy metal ring.  This version ejects the tennis ball reliably and holds it securely until the release. Iíll try to get better photos and a video, but I ran out of time and daylight tonight.
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NooneOfConsequence
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Re: Compound sling vid
Reply #28 - Jun 25th, 2019 at 1:44am
 
For reference, hereís the first version from back in December:
http://slinging.org/forum/YaBB.pl?num=1545314198
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Sarosh
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Re: Compound sling vid
Reply #29 - Jun 25th, 2019 at 2:49am
 
thanks morphy

I tried recently to scale it up to a 5m main cord using the same trigger style. The thing became too tangly and unreliable on the release timing.
A new trigger release design is the main problem to be solved, then scaling up or down will be easy.

P.S.: that means, on my end this project is stalled.
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