@ Masiaka: Would you do us a favor and measure the weight of 2m of steel wire you have and specify the diam. of it?
My 110cm sling weights 17-20grams by feel. Soon i'll weight it.

As far as I know, for something to brake the sound barrier, needs some Kinetic energy to do it. And that comes from the slinger. Goes into the sling and not into the projectile.

When an average slinger can throw ~40-50m with hand,with a powerful throw,and 200m with the same stone,using a sling and less energy than with throwing by hand
There's got to be some efficiency involved,along with leverage.
I'm not an engineer,just a stupid slinger, and to me better efficiency means getting more result from the same or less energy put into your system.
If it's a stove,it heats more,with less wood,if it's a car, goes faster,uses less fuel,if it's a sling, it slings faster, farther,with less power put in the throw.

Accuracy is totally up to the slinger. As far as the sling not poorly constructed,having a huge knot at the base of the release cord that deflects shot in a not consistent way.

Yes, a sling is an extension of your arm. A lever,which can hold and release ammo by holding the knot and letting go of the knot.

You can't break the sound barrier by flinging a thread around. It doesn't have enough mass to "store" enough energy,and speed to combat air drag,and accelerate to supersonic speeds.
When a slingstone is released from the sling,and starts to roll off the pouch, rolls on to the release cord,while it's pushing it,it transfers KE to the cord itself.
If the release cord weights 1.5oz (heavy balearic sling for ex.)
it's going to take more KE from the slingstone to push it out of the way,than if it would weight 0.5oz.


So what's an efficient lever?
My answer would be: that does the leverage,with the least amount of energy spent in/ the lever itself,due to air drag, friction, bending,stretching etc.

That,to my understanding would be something like a spider wire sling.
Thin, light,fast to move,and retains as little KE as possible.

Masi: how You define a efficient sling?

How you define an economical sling?

Ok,i pretty much agree.
By "stored" energy ,i meant KE.
Momentum in fact. Yes, my physics notions are all over the place.
You're right about the release cord having inertia,and that alone is enough to open the sling upon release.
Hence a sling without being loaded still pops open when slung and released.
And thicker,heavier slings having more momentum,crack louder especially when loaded.
So maybe it takes away some energy from the stone to do that

To my understanding,heavier slings have more momentum because they will """store/have""" more of the KE you put into the system (sling+AMMO).
The point of slinging is to accelerate the ammo to speeds much higher than by throwing by hand.
The weight of the sling(lever) also needs to be accelerated.
And the ammo does push the release cord,and produces friction also by doing it. Does costs efficiency IMO.

jlasud wrote on Dec 14^th, 2013 at 5:03am:


Think of the sling like an electrical wire. The force you apply at one end travels instantly to the projectile like electricity is instantly flowing through an appliance when you flip a switch. To store energy/momentum means that the force doesn't immediately go into the projectile when the sling is taut. Something else would have to happen for the force to act on the projectile. Slingshots store energy because pulling back makes a force act on the rubber bands and when you let go the rubber bands then exert their own force on the projectile. The sling has KE and momentum as it's being swung, but it is not stored.

jlasud wrote on Dec 14^th, 2013 at 5:03am:


It's true that heavier slings will have more momentum at the same velocity and it's true that larger slings that can crack will crack louder. But cracking more loudly does not do anything to the projectile nor take anything away. It happens because heavier slings are less affected by drag (especially with a dense weight on the end) and can be swung faster. This gives more KE and momentum to the projectile during the throw rather than taking any away during the crack. And the stone will not be in contact with the sling at the moment that the crack happens.

jlasud wrote on Dec 14^th, 2013 at 5:03am:

Unless the sling is very heavy and has a lot of inertia, the release cord will not take energy or momentum away for the projectile. If it does, you will notice this as the sling fouling your shots and an inability to achieve a clean release.

Friction is not produced. Friction produces heat at the expense of other forms of kinetic energy. Negligible heat is produced from slinging, but it does not have a negligible effect. Friction between the pouch and the projectile induces the projectile to spin, which aids effectiveness while reducing efficiency. This friction is due  to contact with the pouch, not the release cord.

Bill Skinner wrote on Dec 14^th, 2013 at 7:48am:


The most effective length will vary from person to person. It's just the longest length that feels good with your favorite throwing style. Material doesn't matter as long as it's not stretchy, but I'd say paracord or something that diameter is a good starting point. Again, it will vary. Pouch material or style is least important because as far as physics is concerned the projectile and the pouch are one big mass gradient. The release cord needs something easy to grip, but I don't think it's mass would help the pouch much when opening.

Now that you know that when more long and thick less efficient is the sling... but that have no sense throw twenty kg at one meter, you need search the equilibrium, you sacrifice one little power and efficience in the change of the weight by the speed.

what is the equilibrium? it is a personal answer i think.

But you can start with the less thick and less weight thread possible and with the most density projectile and aerodynamic possible.

lakeslinger wrote on Dec 18^th, 2013 at 5:23am:


I don't have experience with paracord slings. I made my son a small one with paracord and a leather pouch and it tangled very easily.

Is this a problem inherent of paracord, or thin slings?

i find that a cradle sling can throw further, throw faster, and throw heavier ammo, and be more stable...
Paracord and leather. it really helps air resistance.