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KE vs distance (Read 415 times)
J
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KE vs distance
Jul 26th, 2021 at 4:23pm
 
Does max KE equal max distance considering the launch angle is optimal?
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IronGoober
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Re: KE vs distance
Reply #1 - Jul 26th, 2021 at 4:24pm
 
Only if aerodynamics are not in play. They make a huge difference.
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John R.
 
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J
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Re: KE vs distance
Reply #2 - Jul 26th, 2021 at 4:26pm
 
wow that was quick.
I feel like I achieve very high KE (+150) with 200-300 gram stones but the distance is not more than 100 meters (with an arms length sling.)
Lighter stones fly further but I don't think their KE is higher. So an explanation they  fly furhter (for example 150 meters)
is because they sail the winds more?
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JudoP
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Re: KE vs distance
Reply #3 - Jul 26th, 2021 at 4:56pm
 
[[[Assuming no air resistance]]] the maximum range of a projectile is determined by the velocity of launch, not the KE.

The maximum range is in fact proportional to velocity^2. This means that you double the speed and you get 4x the range- tripe the speed and you get 3^2 = 9x the distance etc. But basically speaking; if you increase KE then you increase range in every case and vice versa. That is- until you change other variables like ammo weight.

So instead of trying to maximise KE, you should try to maximise launch velocity- you can do this by throwing harder, or using lighter ammo. In fact your maximised range without air resistance would be the lightest ammo you could find.

Of course, if you've tried slinging very small stones you will realise that minimising the projectile size does not produce maximised range. This is because of air resistance, which disproportionately slows smaller (lighter) projectiles more than heavier ones.

In practice the max range you produce is some balance between lighter projectiles (which allow higher launch speed given the same throwing action), and heavier projectiles which hold their speed much longer.

Add to above the complication of human throwing biomechanics- which means in practice people using different techniques with different ammo weights will produce different energies... and you've well and truly got a complicated relationship.
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Re: KE vs distance
Reply #4 - Jul 26th, 2021 at 5:05pm
 
Flight archers shoot super skinny pasta noodle arrows. Same concept.
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Re: KE vs distance
Reply #5 - Jul 26th, 2021 at 6:43pm
 
In my experience ammo (air resistance) makes the biggest difference in distance.
Launch velocity is a huge factor, but you could throw 5 different projectiles and get dramatically different results depending on how different the projectiles are..

In my experience density is probably the first thing to get “free” distance. Projectiles roughly the same weight but different sizes the smaller denser object usually wins. Not always perfectly true but close.

Next would be shape, a more aerodynamic shape usually outperforms a non aerodynamic shape.

Now there are some cheats when spin is in play with light projectiles, you can get some added lift and that might extend your distance a bit but likely a denser smaller object would travel further, depending on total ammo weight.

I also think there’s a benifit to a heavier projectile but this comes down to a combination of size/density and speed.

Golf balls are great at showing the possibility of lift, but it can be hard to get that perfect spin. But something like lead or tungsten just cut through the air. Horrible stuff for ammo recovery but , will bury into almost anything
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Albion Slinger
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Re: KE vs distance
Reply #6 - Jul 26th, 2021 at 10:20pm
 
From my findings, heavier stones generate more KE, and they don't fly as far. Today I managed to smash my own distance record with a 30" paracord sling, getting a verified 280m+ with ~50g stones (video proof coming soon). I think 100g stones go about as far, but I wasn't able to find many great ones of that weight. Heavy stones which no doubt generate more KE, no longer compete for max distance.
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280m_slinging_.png (1445 KB | 8 )
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Re: KE vs distance
Reply #7 - Jul 27th, 2021 at 12:04am
 
!!!! Dang!  !!! Nice work!

I think you are hitting 60m/s, minimum. I would love to somehow get a speed gun on you for your distance shots. If I get a chance, I will do this in September and try to get some verified distances along with velocities.  My folks place has a bunch of sandy area nearby that is very easy to spot the "splash".  I was throwing 100g stones, but was only getting to ~190m in June.
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Re: KE vs distance
Reply #8 - Jul 27th, 2021 at 4:34am
 
that's awesome.

I think we could get a 200+g stone to ~200 meters but it would require an ''artillery sling''.
https://youtu.be/agdbbSlT8Mo
https://youtu.be/WPw4WoVN3-g
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J
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Re: KE vs distance
Reply #9 - Jul 27th, 2021 at 5:40am
 
I think this fits the description of an artillery sling
Palestinians seem to be fond of them. ALthough they've probably killed/injured more of their own then their opponents with it.
It's probably the only way to get those +200 g rocks to decent distances,
probably 150 meters even with bad pouch orientation, probably higher if you get the angle right.
I'd personally use some variant of pirouette to use this long sling. I'll test out a 1.5 m sling with 200g+ rocks soon.
Of course you could just spin it and launc hit helicopter style but as a result I think can forget about controlling the spin angle , unless one really has trained to properly launch rocks with such a sling point forward.  which I think would require some sort of pirouette like Jlasud uses.
But I just made a 1.5 m sling and loaded a 200g rock, first impressions are; extremely dangerous to bystanders.
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Re: KE vs distance
Reply #10 - Jul 27th, 2021 at 8:01am
 
I have used 170cm sling alot and it is fun with stones 300g+ but needs to get used to. If they don't train with it enough I think I get it why they injure or kill more of their own. When I gave it to my friend to try it I ran away intto a safe distance Cheesy

Never tried it with pirouette, but I plan to do so in my next slinging session. I have more long slings to test, just got my hands on some 1mm dyneema cord so I made few slings.
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Re: KE vs distance
Reply #11 - Jul 27th, 2021 at 9:53am
 
https://youtu.be/Pnr56fAos4Y one of my first throws, don't have much stones to test with. I got lucky with the pouch angle on this one, the other 3 tries didn't release as cleanly
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Re: KE vs distance
Reply #12 - Jul 27th, 2021 at 11:13am
 
J wrote on Jul 27th, 2021 at 4:34am:
I think we could get a 200+g stone to ~200 meters but it would require an ''artillery sling''.

Definitely possible, and I don't think you need an "artillery sling" to do it either.  I recon I could probably get a 150g stone to go 200m with a 30" sling and stronger man could easily add 50g to that. I'll give it a try and video it.
I find when a sling gets too long, you lose the torque of your body and thus a lot of potential power.
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Lewis.
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Re: KE vs distance
Reply #13 - Jul 27th, 2021 at 11:41am
 
Those are impressive numbers. I just did a quick calculation (that is probably not quite the correct way to convert) of what my max velocity with a 24" sling and a 120g ball was (98 mph 43.8 m/s), converted it to a rotational velocity, then multiplied it by the longer pathlength of a 30" sling, and I'd still top out at 55 m/s release velocity.
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Re: KE vs distance
Reply #14 - Jul 27th, 2021 at 11:45am
 
JudoP wrote on Jul 26th, 2021 at 4:56pm:
Of course, if you've tried slinging very small stones you will realise that minimising the projectile size does not produce maximised range. This is because of air resistance, which disproportionately slows smaller (lighter) projectiles more than heavier ones.

I think because there is sort of a velocity 'cap' for a given length sling (say you sling a 30g 70m/s, but a 50g goes the same speed even though it's heavier) perhaps if you want to get maximum distance, you need to find the heaviest projectile that still allows you to sling at approximately maximum velocity. 
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