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Video - Ancient Sling Bullets in Antikythera (Read 16754 times)
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Re: Video - Ancient Sling Bullets in Antikythera
Reply #15 - Mar 5th, 2011 at 4:52pm
 
Just a couple more things to really nail it.

Not only does lead have a low melting point, it has a low specific heat of 0.13 kJ/kg.degree. All this means is that it heats up quickly. However the only energy available to do this heating is the kinetic energy imparted during the throw so any energy converted to heat means speed loss and consequent loss of carry distance. But even so if all the kinetic energy in a gland thrown at 50 m/s were somehow to be converted to heat it would raise its temperature less than 10 degrees.

Also this supposition totally ignores the fact that at slinging type speeds the passing air would be a cooling factor not a heating one. Any thrown hot missile is going to arrive at the target colder than it started, not hotter. Sure meteorites burn up in the atmosphere but their speeds are thousands of times faster than those of sling bullets; the analogy doesn't hold.

The only time where heating sling ammunition may be of some effect is when hot stones were thrown onto thatched rooves with the aim of igniting them. I admit I've never done any experimentation with this but even this sounds pretty farfetched. I just can't see a stone being heated hot enough to ignite straw after having flown through cooling air for 100m or so. It might work with a large iron missile which can be heated far hotter than lead.

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Re: Video - Ancient Sling Bullets in Antikythera
Reply #16 - Mar 7th, 2011 at 2:21am
 
Aussie,I haven't done any experiments either with heated shot but I imagine that stones can be heated to 800 degrees C,if so it will be probably still really hot when it embeds itself in a 20" layer of thatching.The more dense and bigger mass the stone the better it holds the heat.The air would cool it's surface during it's 5-8 sec of flight but if embeds itself in a thatched roof it quickly gets really hot inside out.I think it's possible.And lead surely doesn't heat up during flight,only gets warm by impact(experienced it).Oh and an idea just came to test the heated shot:heat a dense sling stone,take it out from the fire,blow it with a powerful fan for 8 sec than drop it on a segment of thatching in a way like it would penetrated it,and see if it ignites it.This takes out the need for a fireproof sling and a thatched house to ignite and the accuracy to hit it from hundreds of meters.I don't how did they resolve the problem of a sling capable of holding heated shot...
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Re: Video - Ancient Sling Bullets in Antikythera
Reply #17 - Mar 7th, 2011 at 3:06am
 
The heated stone thing was done for a TV program about conquistadors. A folded bit of cotton protected the sling pouch and was replaced for each shot.
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Re: Video - Ancient Sling Bullets in Antikythera
Reply #18 - Mar 7th, 2011 at 10:51pm
 
Yes it COULD work but still very iffy. It would be far easier to merely sling small jars of already ignited flammable substance ala Molotov cocktails. The chances of a suitably heated stone, etc. landing in just the right place to transfer its heat and start a fire are definitely low.

I also agree that leaden projectiles do heat up from the deformation due to impact - slightly, but nowhere near enough to melt. It's a physical impossibilty.

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Re: Video - Ancient Sling Bullets in Antikythera
Reply #19 - Mar 9th, 2011 at 2:31am
 
David Morningstar wrote on Mar 7th, 2011 at 3:06am:
The heated stone thing was done for a TV program about conquistadors. A folded bit of cotton protected the sling pouch and was replaced for each shot.
Yes indeed I read it somewhere on the forum that cotton soaked in pitch? was wrapped around the heated shot and when slung it would burst into flames.It sound good and realistic,the hard part would be that somehow the cotton must be tied to the stone really good,and the hot stone would probably make the pitch smoke and ignite quickly I think.I know that you wrote about another version when you place a piece of cotton on the pouch as a "sabot" so the hot stone doesn't ignite the pouch.If you know a link about that TV show,could you post it ?I've looked after it but found other shows.If you can't find the link ,the name of the show would help too.
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Re: Video - Ancient Sling Bullets in Antikythera
Reply #20 - Jun 30th, 2011 at 10:30pm
 
C.A.
I entirely agree with you...  The idea of a lead glande heating up in flight is completely absurd!!!  I do wonder though...  Who came up with this idea, and how did it become so pervasive???

Science is wonderful, but scientists do not have all the answers, they only make educated guesses, and education may be flawed...
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Re: Video - Ancient Sling Bullets in Antikythera
Reply #21 - Jun 30th, 2011 at 11:56pm
 
There were probably two reasons that ancient peoples though sling bullets melted in flight. One, lead deforms a lot when it hits something and looks like a motion capture image of a splash of liquid. Two, the lead does heat up a little during flight from friction and on impact from adiabatic heating. Together they make it seem like the lead heated and melted in flight, but cooled off after hitting the target.
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Pikåru wrote on Nov 19th, 2013 at 6:59pm:
Massi - WTF? It's called a sling. You use it to throw rocks farther and faster than you could otherwise. That's all. 
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Re: Video - Ancient Sling Bullets in Antikythera
Reply #22 - Jul 1st, 2011 at 12:36am
 
Masiakasaurus wrote on Jun 30th, 2011 at 11:56pm:
There were probably two reasons that ancient peoples though sling bullets melted in flight. One, lead deforms a lot when it hits something and looks like a motion capture image of a splash of liquid. Two, the lead does heat up a little during flight from friction and on impact from adiabatic heating. Together they make it seem like the lead heated and melted in flight, but cooled off after hitting the target.


Come on now Masi, what difference does it it make if the slinger is a diabetic or not? Wink
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Re: Video - Ancient Sling Bullets in Antikythera
Reply #23 - Jul 1st, 2011 at 2:16pm
 
I had a batch of clay glandes in the kiln that I wanted to cool quickly, they were too hot to touch but not as hot as when I fired them, I dropped them in the dog water bucket.  They hissed as they hit the water and made some small bubbles but seemed to cool quickly.  I picked one out, it was wet but rapidly evaporated the water and pretty quickly got too hot to hold comfortably.  I think that if you heated it red hot and wrapped it in something to protect the sling, it would still be hot enough to start a fire when it got there.  Bill
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Re: Video - Ancient Sling Bullets in Antikythera
Reply #24 - Jul 1st, 2011 at 8:40pm
 
Bill Skinner wrote on Jul 1st, 2011 at 2:16pm:
I had a batch of clay glandes in the kiln that I wanted to cool quickly, they were too hot to touch but not as hot as when I fired them, I dropped them in the dog water bucket.  They hissed as they hit the water and made some small bubbles but seemed to cool quickly.  I picked one out, it was wet but rapidly evaporated the water and pretty quickly got too hot to hold comfortably.  I think that if you heated it red hot and wrapped it in something to protect the sling, it would still be hot enough to start a fire when it got there.  Bill


Try it and see. You don't have to actually sling it, merely lift it out of the fire wait 30 seconds or so and place it on a pile of dried grass or leaves. Let us know if it works - I'm just basing my supposition that it won't on how hard it can be to light a fire even with a full flame.
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Re: Video - Ancient Sling Bullets in Antikythera
Reply #25 - Jul 1st, 2011 at 8:48pm
 
I think clay would be much better for starting fires than lead because clay and ceramics hold heat for longer than metals can.
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Pikåru wrote on Nov 19th, 2013 at 6:59pm:
Massi - WTF? It's called a sling. You use it to throw rocks farther and faster than you could otherwise. That's all. 
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Re: Video - Ancient Sling Bullets in Antikythera
Reply #26 - Jul 1st, 2011 at 9:03pm
 
Masiakasaurus wrote on Jul 1st, 2011 at 8:48pm:
I think clay would be much better for starting fires than lead because clay and ceramics hold heat for longer than metals can.


Again, I invite you to do some experimenting; bound to be worth any amount of theorizing.
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Re: Video - Ancient Sling Bullets in Antikythera
Reply #27 - Jul 1st, 2011 at 9:19pm
 
I think I have a lead sinker or two that could be improvised fire starters. I just have to make sure I have enough to equal a glans. The 4th of July is coming up, and it is traditional to light fires (or fireworks)...
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Pikåru wrote on Nov 19th, 2013 at 6:59pm:
Massi - WTF? It's called a sling. You use it to throw rocks farther and faster than you could otherwise. That's all. 
~Engineers like to solve problems. If there are no problems handily avialable, they will create their own problems.~
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Re: Video - Ancient Sling Bullets in Antikythera
Reply #28 - Jul 2nd, 2011 at 4:38pm
 
I had actually never heard of shots heating up in the air, but the discussion is interesting...  Just one comment on that, if the below quote is true and the bullets supposedly only get as hot as a human heart (if I am reading that right), then It really wouldn't be that hot, they could conceivably get that hot on a hot day.  I've burnt myself on rocks that were left out under the sun.  Perhaps these tales stuck around not because the heat made a real difference in fighting, but because it was just really intimidating to pick up a shot that was just fired at you and find it to be hot...
AussieJohn wrote on Mar 4th, 2011 at 10:08am:
* One of the references in the interview was to Ovid, the Latin poet, saying in a poem that someone's heart was likened to the heat of a sling bullet thrown by a Balearic slinger.

One other thing, remember that not all metal of the time was created equal.  Slight differences in thickness and composition could make or break a breastplate (so to speak).  Also, the angle at which an 'almond' shaped bullet hits the metal could also factor in...
That's all, Eo out.
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Re: Video - Ancient Sling Bullets in Antikythera
Reply #29 - Jul 2nd, 2011 at 7:58pm
 
Also keep in mind that specific heat is measured in heat/mass, and lead is very dense, comparing heat/volume between lead and clay might be interesting, however, you could heat clay much hotter than lead due to its low melting point.
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