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The whistling sling balls of the Burnswark battleground (Read 8149 times)
johan
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Re: The whistling sling balls of the Burnswark battleground
Reply #15 - Aug 17th, 2016 at 2:39pm
 
gravity is a conservative force

the amount of energy gravity takes out of the projectile when it goes up it will give it back when it goes down.
when the target is at the same height as the release point is then there is no loss of energy due to gravity.
the amount of energy lost if you aim something higher than you is

U=mass*g(9.81m/s^2)*height

and vice versa it is the amount of energy you get when aiming something lower than you.
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Curious Aardvark
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Re: The whistling sling balls of the Burnswark battleground
Reply #16 - Aug 17th, 2016 at 3:24pm
 
lmao - can we just say that lead bullets come down damn fast and hurt a lot.
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Bill Skinner
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Re: The whistling sling balls of the Burnswark battleground
Reply #17 - Aug 18th, 2016 at 8:30pm
 
Nope, gravity robs some of the acceleration as the projectile goes up, when it comes down gravity does not accelerate the projectile as fast as the initial velocity.  It does give some back just not as much as it took.
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Re: The whistling sling balls of the Burnswark battleground
Reply #18 - Aug 19th, 2016 at 3:44am
 
Bill Skinner wrote on Aug 18th, 2016 at 8:30pm:
Nope, gravity robs some of the acceleration as the projectile goes up, when it comes down gravity does not accelerate the projectile as fast as the initial velocity.  It does give some back just not as much as it took.


correction:
air resistance robs some of the kinetic energy as the projectile goes up(and then down), when it comes down gravity does not accelerate the projectile as fast as the initial velocity.  It does give back the amount that air resistance didn't took.

in vaccum where there is no air resistance it would come down in the same velocity
the real energy (or velocity)stealer is not gravity it is air resistance.

another explanation:
it's like going uphill then downhill , with no friction you will have the same velocities at the same heights, but when friction comes into play all changes that means energy leaks through friction not gravity
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Re: The whistling sling balls of the Burnswark battleground
Reply #19 - Aug 19th, 2016 at 6:56am
 
what no one has yet mentioned (if you're going to be pedantic - then do it right Smiley is the effect the gravity of the missile has on the earth.

As the earth's gravity pulls the missile down, the missiles gravity pulls the earth up !

Enough slingers, in the right place, with big lead missiles could alter the earths orbit and change the world's weather !

Oh yeah  dancing banana
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Re: The whistling sling balls of the Burnswark battleground
Reply #20 - Sep 11th, 2016 at 7:38am
 
The terminal velocity of a lead ball is greater than the speed at which it can be launched from a sling.


Whenever I have launched lead glandes on high arc distance shots, they almost seemed to accelerate on the way down.

If you can keep track of it that long.


Those balls are pretty small. The whistling grapeshot theory makes the most sense to me, if indeed they were used as projectiles...

Then, you'd think there would be a lot of them in one area.
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Re: The whistling sling balls of the Burnswark battleground
Reply #21 - Sep 11th, 2016 at 1:56pm
 
Sub cal training, maybe?  You have to launch something or all the force never leave the launcher, which results in some very violent recoil that can damage the launcher.

If you draw a bow to full draw and release the string without an arrow, the bow can and will literally explode from the recoil forces.  It can also do that with an arrow that is too light.

So maybe the projectiles are or were loaded in a cup or bag and only partially drawn.  After the shot, the crew retrieves the bag and shoots it again.  The scattered balls are from rips on the bag?

Try pouring a dipper of lead from about shoulder high into water and see what the results are.
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Re: The whistling sling balls of the Burnswark battleground
Reply #22 - Sep 15th, 2016 at 2:12pm
 
why have balls in a bag ?  (um, yeah lol)

Just have a ballista with a cup.
Or launch from a trebuchet.
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Re: The whistling sling balls of the Burnswark battleground
Reply #23 - Sep 22nd, 2016 at 11:57am
 
I slung some old lug nuts yesterday and they whistled pretty well.  Though only the ones without a hole going all the way through.  It is an interesting sound and en masse would be very disconcerting.
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Re: The whistling sling balls of the Burnswark battleground
Reply #24 - Oct 16th, 2016 at 3:28am
 
Guys, I did work some more on the issue. In fact two young physicists calculated the effect, but I was skeptical. So I put this to a test, by building a proper test device.

Turns out the boys had a big error in their calcs and in reality things are different. The air resistance on a 22mm lead ball weighing 60 grams is quite substantial. When shot at 45 m/s (ancient sources named this as the average speed of the slingers), then the ball will fly about 160 meters far. Its end speed will be around 36 m/s, so it has lost 20% of its initial speed.

The Burnswark scenario was such that the slingers had to hit a target 120 meters away, but 40 meters up. The only way they would have hit is to shoot at an angle of around 2 degrees.

The clever Romans set their launch position exactly far enough for their average slingers to hit the target. Even five more meters and the Caledonians on the hilltop would have been out of reach.

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Re: The whistling sling balls of the Burnswark battleground
Reply #25 - Oct 16th, 2016 at 5:01am
 
@JoergS
there are a lot of variables at the experiment.
the condition of the roman slingers, were they just soldiers or professional slingers?
what slings they used? (material bulky,heavy ,longish ?)
pros with good slings would reach 50-60m/s an average soldier levied just for the occasion would reach 45m/s


about aerodynamics : projectile shape plays a huge role, bbs have a lot of drag in comparison to oblong streamlined body.
as the guy mentioned in the video magnus effect also plays a huge role
slings can orient their spin and they produce a lot
whereas slingshots they produce a lot less spin but you cant predict the axis of rotation

,so we can take advantage of magnus effect when throwing a ball shaped projectile
and we can "rifle" spin an oblong shaped projectile (most of the time)


the funny thing with physics is that it cannot predict real world situations that easily so it ends up doing the explaining afterwards

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Re: The whistling sling balls of the Burnswark battleground
Reply #26 - Oct 17th, 2016 at 7:00am
 
actually the balls don't need to spin to whistle.
It's just fast air moving over the surface and going into the hole that produces the sound.
Like a set of panpipes.  That's one reason the size and depth of the holes is so consistent in the found ammunition.

Quote:
Even five more meters and the Caledonians on the hilltop would have been out of reach.

No they would not have been.  The slinger would just have slung harder.
Seriously, next time you;'re doing this let me know - you need a proper slinger up there.
That distance with a lead ball is pretty much point blank range for me. Even at that low a trajectory, it's not an issue.
I've slung those distances and angles with 60gram clayballs - all day long for two days. Lead goes further with less effort.
Credit your slingers with more ability.

What historians almost never seem to understand is that our ancestors were extremely competent with their everyday tools and weapons. Far more so that most people alive today.
A sling is a tool, even the roman soldiers would have used regularly them for hunting.
So even your bog standard sling conscripts would have been a lot better than most contemporary slingers. They would also have trained regularly to keep up a long bombardment. They also would have been usign slings from childhood.

A decent slinger with a lead bullet/glande could expect to exceed 250 metres fairly easily.
Initial sling engagement of the enemy, with lead bullets would most likely have been at the 300-350 metre range.

Even with spherical ammunition you are looking at an average of 200-250 metres range. 

The 120 metre mark is most likely to avoid the larger stones that the defenders would have been slinging back. Hillfort caches do show that the defenders favoured big rocks. 120metres would put the romans out of the range of the largest rocks and shields could have deflected most of the rest.

That's the most likely explanation of the range used - absolutely nothing to do with the sling range of the attackers using small dense missiles and everythign to do with the defenders using large not so dense missiles.
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Re: The whistling sling balls of the Burnswark battleground
Reply #27 - Sep 20th, 2022 at 4:43pm
 
I see this has been tried.. Im am also looking into what sounds i can make with a sling glandes.

All for the fun of 3d printing, Im not trying to recreate anything historic as im sure it was with just a hole drilled in.

Worth noting that solid 3d printed Glandes hold up well in most filaments. I throw them in a place where they often hit rocks too.

Some tests... more to come https://www.instagram.com/p/Cilok-Xpvwb/
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Re: The whistling sling balls of the Burnswark battleground
Reply #28 - Sep 26th, 2022 at 10:22am
 
What filaments are you making the solid glande from ?

Also to properly hear the sound you need to be at the impact end Smiley

I've had a lead glande slung directly at me, and just one glande sounds like a swarm of bees !
But makes no real noise at the slingers end
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