Hello,
       I'm interested in finding out how to calculate the arc of the trajectory of sling ammunition so that a model of range could be applied to different topography in the interest of archaeology.  This interest stems from an iron age hillfort site in Wales, Great Britain where a hoard of sling-stones was found which must have been collected from the nearby coast due to rounded smooth shape.

Sling stones travel through the air approximate to a parabola but we were having difficulty deciding how to calculate the parabola as it is difficult to measure the height of a projectile traveling at high speeds.  We tried to film the arc of prjectiles on a beach but it was very difficult to see it.

Has anyone done anything like this before or does anyone have any suggestions?

Thanks
Sean

Neat idea.

You can find out the parabolic properties by knowing the other values.  In this case, you know range and time (in the air).  Those two values should let you solve for initial velocity.

Use the projectile motion equations:
http://www.usafa.af.mil/dfp/cockpit-phys/md2th2.htm

Here is a nifty java applet to visualize the motion:
http://www.phys.virginia.edu/classes/109N/more_stuff/Applets/ProjectileMotion/jarapplet.html

Your calculations should be good even with the uneven terrain.  Lets say your at 0 feet and you sling and at time=4 seconds, it lands on a hill 100 feet high, you can still plot the trajectory (Y=hieght, X=time).  You just have to account for the overshoot as if it continued like normal.

Hope that helped.   Let us know how your fare.  

Chris

P.S.  I'd love some pictures of the site and a copy of the paper.  

Thanks for the advice Chris, this is going to take some time because I've got some other projects going on at the moment but I'll let you know how we get on.  

You can read all about the site on the website www.castellhenllys.com/ and there should be some pictures there too.

We did most of our practice shooting on the beach where we believe these stones were likely collected in the Iron Age.

Thanks again

Sean

Looks like a great project!  Are you a student at The University of York?  What are you trying to determine?  Engagement distances?  Projectile flight time (why)?

Chris

Hello again,
       I am an undergraduate student at the university of york in archaeology.  The cheveaux-du-frise is a band of sharp standing stones on the defence rampart of the fort (you may have read about it on the web site).  We think this may have been constructed to slow down attacking advances to give slingers a more static target.  I'm not 100% sure why we need a parabola but the director of the site reckons it would be useful in determining the effectiveness of these weapons for hillfort defence.  At one point there was a palisade fence around the upper bank and we would be interested to see if this would affect the flight path of a sling fired from within the fort or from outside it.  It would also be interesting to see if the construction of the hillfort was modified with the introduction of a new weapon such as slings and if so how.

Speed of the projectile would be useful in determining at what range the weapon would be deadly or if it was more of a deterrant.  We have seen from our practice that most people can begin to get the hang of it in a day (at least some distance) and this tells us that men, women and children may have assisted in defence in the event of an attack.

This is the sort of thing we want to know more about anyway.  If we get a good model of the flight path, speed and range of the weapon it should be fairly easy to make it applicable to other sites around the country and the world.

I am also interested in trying different designs of sling and ammunition.  I've constructed a couple of different types of sling and can get some good distance out of them both.  We baked some clay ammo in the shape of a rugby ball aswell as some of these were found on a different archaeological site in England.

At the moment I am working on my dissertation which is also weapon related.  It is a forensic case concerning three mummies in the Valley of the Kings in Egypt.  We did some experimental damage to dead pig carcasses with different weapons.  It was on a show on the discovery channel in America but isn't being shown in england for another week.  The programme is called 'Nefertiti Returns' and I think you can get it on DVD or video in the US now.   I am wearing a lab coat and hacking the pigs.  One of them we vaccum dried to try to make the characteristics of the tissue similar to that of a dried out mummy.

Enjoy,

Bye for now,

Sean

Wow Sean!

I'm so jeleous.  I'm writing my senior thesis on Medieval Archaeology, but all of my work, without access to sites, remains quite theoretical.  Perhaps someday I'll actually get to travel to England and do a little bit of experimental archaeology myself.  

I'm also very much interested in matters pertaining to militerism, defense, and weapons use.  Please keep us updated on your research with the sling!!!

Cheers,

Leon

The parabola is important because thats how projectiles fly due to gravity.  They don't arc like a circle.  

Here is a site with some good formulas:
http://www.xs4all.nl/~mdgsoft/catapult/ballistics.html

You should be able to get a good estimation of your "muzzle" velocity based on your range.  

What you need in a physics student.  He could whip you up an accurate flight path in less than 10 minutes.  Im a bit rusty and it's hard to explain it by text.  

Chris

Hey Sean, who are you working with out there?  It sounds like a great project!

Rob

I Necro thee!

Sasquatchslinger wrote on Apr 11^th, 2013 at 9:28pm:

I Necro thee!

You know this is a 2003 thread, right?

Squirrel, that's the point of the Dak Arts of Necromancy, reviving the long dead...


But then, it only have a purpose if you can add some useful new information or other great thought on-topic.
As it was done, it kinda miss the mark and therefore is pretty useless.

Well, he seems to have revived what was one of the very first threads on the forum. Not entirely sure if there was a point to it, but it does remind one that the forum is ten years old this August.

If anyone wants to start celebrations, now is the time to start the organization.  ;)

Also that the people who were early members the forum were interested in hill forts (what did happen to that research?) just as now.

Squirrel, as you should already know, it is virtually impossible to revive such a thread without realizing it, provided one reads a little, that is. Given the content of his message, he obviously realized it.

I feel like if someone wanted to make a range this would help greatly.

Sasquatchslinger wrote on Apr 12^th, 2013 at 6:40am:

I feel like if someone wanted to make a range this would help greatly.

Any they can't find it the way you just did? :-?

Masiakasaurus wrote on Apr 12^th, 2013 at 7:06am:

Sasquatchslinger wrote on Apr 12th, 2013 at 6:40am: I feel like if someone wanted to make a range this would help greatly. Any they can't find it the way you just did? :-?

Stop trying to ruin my fun!

  It is a cool thread, well worth reading again and also worth more research.  I don't think anyone wants to ruin your fun but usually when one of us necros an old thread we have something to add to it.