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30" ~300yd Slinging (Read 1909 times)
Archaic Arms
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30" ~300yd Slinging
Jul 28th, 2021 at 1:26am
 
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« Last Edit: Jul 28th, 2021 at 12:03pm by Archaic Arms »  

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AncientCraftwork
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Re: 30" ~300y Slinging
Reply #1 - Jul 28th, 2021 at 4:21am
 
You're definitely better than me. Well done sir
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Re: 30" ~300yd Slinging
Reply #2 - Jul 28th, 2021 at 3:03pm
 
Ok, so my method of estimating velocity must be incorrect of looking at the motion of the sling. Can anyone point out where I'm going wrong with it?  I calculate about 50 m/s release speed.

I was looking at the last 2 frames before you release, the sling travels about 1/4 turn.. if it is 30" and your hand moves about a foot, that is over 1m in radius.
2*pi*(1m) = 6.724m
divide by 4 to get distance traveled in a single frame,

(6.724m / 4)*(1/30 s) = 50.42 m/s.

I thought just looking at the video you could get a decent estimate of release velocity, but it seems that is not correct, because 50.4 m/s only goes 258.7m MAX (without any drag).

Maybe adding in the distance traveled by the hand is wrong?
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Re: 30" ~300yd Slinging
Reply #3 - Jul 28th, 2021 at 3:22pm
 
Just check distance against time in the air for average speed.

Very nice slinging Thumbs Up

Now go make a 34 inch sling and see how much further you can get Smiley

So were they just rocks you found ?

Also some interesting noises whistle
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Re: 30" ~300yd Slinging
Reply #4 - Jul 28th, 2021 at 3:24pm
 
IronGoober wrote on Jul 28th, 2021 at 3:03pm:
Ok, so my method of estimating velocity must be incorrect of looking at the motion of the sling. Can anyone point out where I'm going wrong with it?  I calculate about 50 m/s release speed.

I was looking at the last 2 frames before you release, the sling travels about 1/4 turn.. if it is 30" and your hand moves about a foot, that is over 1m in radius.
2*pi*(1m) = 6.724m
divide by 4 to get distance traveled in a single frame,

(6.724m / 4)*(1/30 s) = 50.42 m/s.

I thought just looking at the video you could get a decent estimate of release velocity, but it seems that is not correct, because 50.4 m/s only goes 258.7m MAX (without any drag).

Maybe adding in the distance traveled by the hand is wrong?

What about the movement of the body? I think that can greatly affect that.
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Re: 30" ~300yd Slinging
Reply #5 - Jul 28th, 2021 at 3:43pm
 
IronGoober wrote on Jul 28th, 2021 at 3:03pm:
Ok, so my method of estimating velocity must be incorrect of looking at the motion of the sling. Can anyone point out where I'm going wrong with it?  I calculate about 50 m/s release speed.

I was looking at the last 2 frames before you release, the sling travels about 1/4 turn.. if it is 30" and your hand moves about a foot, that is over 1m in radius.
2*pi*(1m) = 6.724m
divide by 4 to get distance traveled in a single frame,

(6.724m / 4)*(1/30 s) = 50.42 m/s.

I thought just looking at the video you could get a decent estimate of release velocity, but it seems that is not correct, because 50.4 m/s only goes 258.7m MAX (without any drag).

Maybe adding in the distance traveled by the hand is wrong?


I would guess that the projectile continues to accelerate a lot towards the point of the release. So the average speed of the last 1/4 turn might be significantly slower than the actual speed at point of release (think how much you would spoil the power of a shot by releasing a 1/4 turn early).

I think the way you did the calculation more or less holds up in a rough sense, though it's true the reality is much more complex, you don't just have a straight rotor from the shoulder out to the projectile, it's more of a rotor around the hand which experiences a ton of angular acceleration due to the force from the hand. So it doesn't quite act the same way you would expect a big rotor to.
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Re: 30" ~300yd Slinging
Reply #6 - Jul 28th, 2021 at 4:27pm
 
JudoP wrote on Jul 28th, 2021 at 3:43pm:
I would guess that the projectile continues to accelerate a lot towards the point of the release. So the average speed of the last 1/4 turn might be significantly slower than the actual speed at point of release (think how much you would spoil the power of a shot by releasing a 1/4 turn early).

I think the way you did the calculation more or less holds up in a rough sense, though it's true the reality is much more complex, you don't just have a straight rotor from the shoulder out to the projectile, it's more of a rotor around the hand which experiences a ton of angular acceleration due to the force from the hand. So it doesn't quite act the same way you would expect a big rotor to.


The thing that surprises me, is that the actual release speed is minimum 52 m/s (no drag), but is more likely 60 - 70 m/s.

Though, from my own experimentation, acceleration does happen until release, so you are right on that point, averaging over that interval is not the same as the instantaneous velocity at release. The amount of increase in that last 1/4 turn is what is surprising to me. An extra 15-35% in velocity ?  I mean...wow. I'll have to go back and analyze my tennis ball throw and see what the difference is between the release and average velocities...
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Re: 30" ~300yd Slinging
Reply #7 - Jul 28th, 2021 at 4:38pm
 
@JudoP You are right.  The acceration in the last 1/4 turn is significant. From my overhead video,  I was getting an average velocity of 37m/s over the 1/4 turn, and actual release velocity was 47 m/s.  So, a 30% increase.

If the same acceleration profile holds true for Albion's throw, then release velocity is ~65 m/s. That seems about right with an estimated error of +- 3 m/s or so. SMOKING FAST!

That also puts the no drag distance at 437 m. 

I'm wondering if we can come up with approximate rules of thumb/equations for a certain distance (optimized) meaning a certain release velocity for an optimal throw (favorable projectile shape and orientation). This would be 65% of the theoretical distance. Some simple math would get you the release velocity of any throw if this ratio holds approximately true.

Edit: 8/13/2021 I went back and looked again at my overhead data (this time looked at the video and the xy plot rather than just the xy plot), the acceleration for the last 1/4 turn was a bit less than I said earlier, more like 20% extra (above the average) rather than 30%.
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« Last Edit: Aug 13th, 2021 at 6:06pm by IronGoober »  

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Re: 30" ~300yd Slinging
Reply #8 - Jul 28th, 2021 at 5:01pm
 
IronGoober wrote on Jul 28th, 2021 at 4:38pm:
@JudoP You are right.  The acceration in the last 1/4 turn is significant. From my overhead video,  I was getting an average velocity of 37m/s over the 1/4 turn, and actual release velocity was 47 m/s.  So, a 30% increase.

If the same acceleration profile holds true for Albion's throw, then release velocity is ~65 m/s. That seems about right with an estimated error of +- 3 m/s or so. SMOKING FAST!

Very interesting work! which throw/s did you analyze?
I felt at the time one of the best throws was this one: at 3:53. https://youtu.be/DZ4XJ5qnNbU?t=233
Don't know whether it was faster than any of the others, but it went really far with a low release angle. Could be down to the shape of the stone. Tongue
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Re: 30" ~300yd Slinging
Reply #9 - Jul 28th, 2021 at 10:08pm
 
Great stuff Albion!  Lot of power in that throw.  One thing I noticed when I did the distance slinging with big stones (which is the only time I've ever measure distance slinging) was how important the vertical release angle is.  A lot of my shorter throws weren't caused by less power in the throw.  It was because the release angle was too low.
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Re: 30" ~300yd Slinging
Reply #10 - Jul 28th, 2021 at 11:09pm
 
@Albion Three things about your throwing that you do really well.
1. Shoulder to hip separation, Your hips move to point toward the target first, and your shoulders lag behind. This really allows you to transfer power faster into the sling.
2. You get your arm up over your head and your hand motion makes a biiiig circle. That's something I have a really hard time doing.
3. You get a lot of external rotation with your shoulder (lie back) so that when your arm comes through, it whips forward. This is another thing that I just don't have good shoulder mobility (or mechanics) and my lay back is not great.

I actually really wish that you'd filmed yourself from a bit further away so we could see how you are using your hips/legs as this is how I think you get so much power from short slings (and apparently long slings too!).

Also, in regards to your other question, if you look @37s in your video, the two frames before and at release are almost exactly a 90° rotation of the sling from what I can tell.
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Re: 30" ~300yd Slinging
Reply #11 - Jul 29th, 2021 at 10:45am
 
Curious Aardvark wrote on Jul 28th, 2021 at 3:22pm:
Now go make a 34 inch sling and see how much further you can get

So were they just rocks you found ?

Also some interesting noises

Made a copy of the sling but 34" yesterday, and spent a few hours yesterday trying to get it to compete with 30", but alas I don't get the 'torque' with 34" like I do with 30", and so 30" still takes the cake. I can get 'torque' with a 28" facing the target, but not 30". To get 'torque' with the 30", my upper body has to face away from the target like in the video, to make the power-stroke sufficiently longer.
Yes the stones I used are just from the pebble beach at my feet. The consequence is that solid footing isn't possible...
And as the day went on, the slinging 'grunts' became more prolific. I suppose it's how the cavemen got more power out of their throws.  Wink
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Re: 30" ~300yd Slinging
Reply #12 - Jul 29th, 2021 at 10:57am
 
what's the design of the sling (pouch)
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Re: 30" ~300yd Slinging
Reply #13 - Jul 29th, 2021 at 10:59am
 
joe_meadmaker wrote on Jul 28th, 2021 at 10:08pm:
Great stuff Albion!  Lot of power in that throw.  One thing I noticed when I did the distance slinging with big stones (which is the only time I've ever measure distance slinging) was how important the vertical release angle is.  A lot of my shorter throws weren't caused by less power in the throw.  It was because the release angle was too low.

Thanks! Yes I found the same. The high angle release really allows you to 'pull' on the projectile, and also facilitates high angle releases too. I can certainly see that and overhand release would make it easier to get closer to that 45 degrees when hurling those small boulders.  Grin
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Re: 30" ~300yd Slinging
Reply #14 - Jul 29th, 2021 at 11:09am
 
IronGoober wrote on Jul 28th, 2021 at 11:09pm:
@Albion Three things about your throwing that you do really well.
1. Shoulder to hip separation, Your hips move to point toward the target first, and your shoulders lag behind. This really allows you to transfer power faster into the sling.
2. You get your arm up over your head and your hand motion makes a biiiig circle. That's something I have a really hard time doing.
3. You get a lot of external rotation with your shoulder (lie back) so that when your arm comes through, it whips forward. This is another thing that I just don't have good shoulder mobility (or mechanics) and my lay back is not great.

I actually really wish that you'd filmed yourself from a bit further away so we could see how you are using your hips/legs as this is how I think you get so much power from short slings (and apparently long slings too!).

Also, in regards to your other question, if you look @37s in your video, the two frames before and at release are almost exactly a 90° rotation of the sling from what I can tell.

Enlightening analysis! I personally don't really know the do's and don'ts, I just go with what feel's good. Grin
Regarding your question, when I get the 'high velocity' 30" made, I'm going to do close range velocity tests (where my whole motion should be in frame).
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