Dyneema is very good modern material for slings

joe_meadmaker wrote on Jun 27^th, 2021 at 12:20pm:

How does that compare to this?  It should take 200 lb split between the two cords.
Aramid rope ARABRAID ø0,4mm 500m reel 6-strand braided by Kanirope® - high-quality product manufactured in Germany, braided of high-quality Twaron® yarns. Aramid rope is very tear- and heat-resistant, non-flammable and extremely low stretchable. Aramid ropes do not melt at high temperatures, but starts charring from 932° F (500°C).

Diameter: 0,4mm
Length: 500m
Construction: 6-strand braided
Breaking load: 45daN (kg)
Working stretch: <1,5%
Breaking stretch: 2-4%
Material: 100% Aramid
Colour: yellow

joe_meadmaker wrote on Jun 27^th, 2021 at 12:20pm:

spring means the energy is stored and returned to the bullet at release. This is good. Damping absorption of energy just wastes the energy by  heating the rope as it stretches.  this is very bad.

if you stop energy putting in hopefully that is the release point and the bullet will not stop.  I have used springy slings that do store potential energy.  I have also used golf clubs whose shafts bend and release that energy as well.

A lot of focus on reducing air resistance we place on making our cords aerodynamic while neglecting the pouch, yet the pouch is one of biggest drags

Especially pouches that are  quite a bit longer than the projectile when the stone is seated, and pouches that are thick.

You can get rid of the pouch attachment knots because these also provide drag and figured out various knotless attachments

I think a fine split pouch provides the least drag, but since that is unfit for very thin slings in my opinion, a knotless netted pouch or a small a small soft leather cradle that isn't any larger than it need be.

I don't think.  The stretch of the cord (and therefore the force it creates) are going to be inline with your hand and the pouch.  But the stones path when it is released will be at a 90° angle to this.  So the stretching of the cord is only really going to give you a larger radius of rotation, and an effectively longer sling.

This isn't an image of a sling but it will do.  The circle represents the sling's rotation.  The radius represents the sling and direction of any stretch that it has.  The tangent vector represents the direction the stone will fly when it's released.  Any stretch or spring of the sling will not aid this directly because it's not in the same direction.  If your sling had an elastic quality and you stopped your motion, the sling would ultimately be trying to pull the stone back toward your hand because the centrifugal force would no longer be pulling it away.

joe_meadmaker wrote on Jun 29^th, 2021 at 8:16pm:


You can only ever apply force nearly 90 degrees to the motion. acceleration  vector points to your hand always.
i taught hs physics, while i was in hs.