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Slings (Read 3618 times)
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Slings
Aug 4th, 2003 at 1:47am
 
Hello everyone!

A question - are slings the same things that are used on catapults??  Do they work the same way?

Thanks!
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thrower1970
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Re: Slings
Reply #1 - Aug 4th, 2003 at 6:54am
 
To my understanding, a catapult uses a ridged arm and some type of spring or bow to provide the kinetic energy.  The one using a crossbow style set of arms is called a ballista.  Both of them are based more on an arm style of throwing (using force and a short travel to propell the projectile) and do not leverage (pardon the pun) the circular force and accuracy generation that a sling does.

If you are refering to a trebuchet (that is the one with a long arm, weighted on one end and designed to throw object very high and for great distances, not expressly for speed or great force) then that does use some of the motions and advantages of a sling.  This is limited in the advantage because it can only travel about 1/4 to 1/2 of a spin before launching the projectile.  To make up for it, the projectile is usually attached via a long rope (about half the length of the arm) to give is a better distance with the limits of the arm's reach and the radius of its swing.  If I have you totally confused, please see the following website for a better explaination and a couple of pictures.

http://www.howstuffworks.com/question127.htm

Thanks,

thrower1970
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Chris
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Re: Slings
Reply #2 - Aug 4th, 2003 at 12:48pm
 
You are refering to a trebuchet. 

Just as with a human arm, the trebuchet arm greatly benefits from the addition of a sling; it provides mechanical advantage.   As thrower1970 explains, the sling does increase the range. 

The sling does about a 1/2 to 3/4ths rotation before the release cord slips off the nail at the top of the arm.  A 45 degree release (above the horizon) is considered optimal. 

Here's a picture of my trebuchet in action:

...
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Stephen
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Re: Slings
Reply #3 - Aug 5th, 2003 at 11:59am
 
A sling staff is a good way to see the 1/3 arc in action. I've made 2 so far and they are a lot of fun to use.

perfect to hand to inexperenced people

Stephen
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BillB
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Re: Slings
Reply #4 - Aug 5th, 2003 at 3:55pm
 
Stephen,

Think you could post some instructions on making the staff sling?

In all my years of slinging, I've often thought that it would be nice to combine a hiking stick with a sling. However, I've never really been comfortable with the result, nor have I really researched it any. An old list I used to be on briefly discussed staff slings, after someone mentioned wanting to make a hoopak for their husband. I've since lost the instructions that got posted after the discussion moved to staff slings in general. I know I'd appreciate some instructions and general description of usage.

Bill B.
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Bill B.
 
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Stephen
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Re: Slings
Reply #5 - Aug 5th, 2003 at 6:01pm
 
one source is http://www.meridies.org/as/dmir/Arms&Armor/02/0217.html
Thats a start. I found another site before showing some good pics.
I found a bunch of sites on staff slings because they are used in SCA combat.(sometimes)

Stephen
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Chris
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Re: Slings
Reply #6 - Aug 5th, 2003 at 6:14pm
 
When you say 1/3 of an arc, is that relative to the end of the stick?  Because (and as you can see from my trebuchet picture) it's more like 3/4 rotation from the origional angle with respect to the ground.
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Stephen
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Re: Slings
Reply #7 - Aug 6th, 2003 at 2:14pm
 
Sorry, I was refering to a sling staff having about a 1/3ed arc. A trub has much more arc.

In my sling staff, I use it much like the movie posted elsewhere  on this site.

again, sorry for the confusion.

Stephen
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Chris
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Re: Slings
Reply #8 - Aug 6th, 2003 at 2:25pm
 
Acutally, I think I'm the one confusing people.  I was refering to the arc in regard to the sling's rotation. 

Chris
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Ripcord
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Re: Slings
Reply #9 - Aug 8th, 2003 at 4:11pm
 
Slings are found on Trebuchets and Onagers. (Onagers are also known as Mangonels, but they are the same thing mechanically.)

The do indeed work the same way as a staff or hand sling.  The only difference lies in the speeds, materials used, payload being hurled (cast), method of release, etc.

Hand slings don't have a "starting point" per se, although hanging straight down could be considered the start.  Some folk hold the pouch during the start though, so that leaves the question open a bit.

Onagers normally start with the sling hanging staight down.  In some cases this presents a problem since the sling is often longer than there is room to hang freely in.  This requires either digging a hole or setting the machine up a bit higher in the air.

Trebuchets start with the sling laying in a trough, horizontally.  As the throwing arm rotates, the sling is dragged along the trough until it picks up enough speed to lift the pouch upward. (Which usually happens very quickly.)  After that, the sling continues to rotate around the end of the throwing arm until it reaches the release point.

The release point is determined by a couple of variables, which I'll discuss if needed, but siffice for now to say that it should be at a point where the sling releases at about 45 degrees.  (Chris, the optimum release point is not 45 degrees, but close enough for this discussion.)

So, for an Onager the sling rotation angle is about 135 degrees. For a Trebuchet it is about 225 degrees.

For those interested in Trebuchets, visit my web site for a lot of information.

http://www.ripcord.ws
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Chris
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Re: Slings
Reply #10 - Aug 9th, 2003 at 5:35pm
 
"(Chris, the optimum release point is not 45 degrees, but close enough for this discussion.)"

Yea, I know.  I was simplifying as well.  Due to air resistance, it better to release it at a lower angle, around 40-42 degrees above the horizon. 

Chris
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Texassoroban
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Re: Slings
Reply #11 - Aug 29th, 2004 at 1:13am
 
after someone mentioned wanting to make a hoopak for their husband.


Sounds like somebody has been reading Dragon Lance....uh...I guess that would mean me also.   Grin
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