Dan,  I should have double checked the weight earlier.  An electronic scale from the school's chemistry lab showed 1.836 oz. (52.04g) for the stone when I weighed it this morning.  At least the postal scale was accurate to the nearest ounce!  Close enough for government work, right?

Larry

Larry, That is typical for the USPS, they round up to the nearest ounce!  Thanks. I would have bet it was over 2 ounces, not under. 

And, it is interesting that David's 'stone' was not permitted to weigh less than 2 ounces and weighed in at 2.2 ounces.

What would you think is an optimal glandes weight for you?  Dan

Larry's disclosure, in my mind, makes the record he achieved even more amazing.  That is a very light projectile and being launched by a sling which was not aeorodynamically optomized to boot!  I found that anything less than 2.5 oz.  would put great stress on my launching arm.  Something must be said for the shape of the stone used in the record breaking attempt...assuming, as I must, that the stone spun rapidly about it's longitudinal axis,  It appears that an optimal composite dynamic was achieved.....(ie.  Larry knows his stones!)   I also found that enlongated stones with a ratio close to 1.7 to 1 favoring length with a shallow 'scallop' on one side would occasionally produce fantastic launch speeds.  This can be observed when launching stones by hand as well.....there is much more to be learned about the interrelation between gyroscopic motion and aerodynamics, to be sure.....

Back in the day when my ammo supply was a bucket of stones, it didn't make sense to get too technical about projectiles.  I knew that "ellipsoid" shaped stones flew better and would in fact spin on their long axis.  I felt like the record stone was about right and it turned out to be a little under two ounces.  It was a basalt type (tertiary lava) stone from a local gravel pit, probably rounded by water action over the millenia.  But remember, I just picked it up out of a bucket of other stones, gave it a fling, found where it landed and measured it off.  There were a few others I threw that day that we thought went further but we could not find.  I don't recall anything special about their weight or shape but they were similar I am sure.  

Now that I am casting lead projectiles, I need to put in a throwing session on my favorite bluff and try to hurl one to the far shore.  I suppose I should cast some 2 oz., 2.5 oz., and maybe 3 oz. pellets and observe which works best.  Again, the trade-off between release velocity (lower for heavier projectiles, higher for lighter) and ballistic coefficient (higher for heavier projectiles, lower for lighter) will dictate the optimum weight.  My guess is that for me it will be two ounces or just over.  There was just too much variability between stones for this kind of trial to make sense back in the old days.  

I've been catching up on some reading.  This thread is awesome!  I've wondered about those world records for years.  If only the old timer world record holders were with us now.  I gasp at the ranges that Yurek, Larry, and David achieve, but I could never even comprehend slinging 7 oz stones more than 80 yards, let alone over 300.  

I see this thread is 20 days old at the youngest, but I have some thoughts.  Aerodynamically, arrows are supposed to be very efficient, because of a lot of weight (extending backwards) concentrated behind a small point.  I can see the same is true for David's darts.

However, he's using a Cestro here, and I doubt the dart really does fly perfectly straight on release.  

In flight, from what I've seen in my own home hobby experiments with my catapults, and other "toys," even the slightest wobble produces quite a bit of drag on a dart, as the sides of the fins are exposed to the airflow.  The fins at the back are there to keep the dart straight, through the use of drag, but a little wobble can make the whole thing quite inefficient and rob a lot of initial velocity from the start.  On a steel dart, it may not be really noticable, but I believe it would have it's negative effect.  Even without wobble, fins are an enemy of aerodynamics.  A necessary evil, with arrows, bolts and darts, inorder to keep them on course, but when using a sling, there's no need that I see for them.  I think they may partially defeat their purpose.  That's up in the air some I guess, but....

Offhand, I'd predict significantly more range out of just plain lead glandes, then out of the cestro darts.  I've seen personally, how much more efficient lead is as a projectile, than steel.  That density makes those things go like rockets, and perhaps about 1/3 extra range can be gained with lead, over rocks.

Lead glandes are historically accurate projectiles, and Guiness, should have no reasonable trouble with accepting them in their records book either.  Between Larry and Yurek, and maybe if David joins us,..., I think we might have some real fun!!

My only other thought about the world record- that I've had for some time- is in using the absolutely most aerodynamic sling possible, made of a split cradle of 1/16" material joined together to form the cradle and the cords.  This is more aerodynamic than what David or Larry have used in the past.  Jurek, I see from the picture posted earlier, is waiting to experiment with one.  I can't wait to hear of the results!  I'm confident, that it will be the most efficient sling yet!    

                                        Ben  
 

Great idea about the get together Larry.  Maybe someday we'll set up our own competitions for accuracy, and range.  We might set new records all the time that way.  I really have hopes that with slinging.org, we may be able to get this sport back into the olympics.  By saying "back" I'm assuming it used to be there, back about 2000 or more years ago.  Maybe Hondero knows?  I've read references to even catapult shooting competitions being held back then. 

You're right too.  It wouldn't be a party without Hondero, Jurek, and Ulrica! 

I wish you all the best with your aging arm.  You might want to try some weight training here, especially on your shoulders.  It might really help your speed, and give you better joint stability for when you start tearing that sling through the air.  I know there are some on the forum who've hurt their arms slinging and that can really set you back. 

I don't doubt your guess about the range you could've achieved with better equipment.  I hope you get another chance at it.  I do wonder about David's experiments that led him to such "hi tech" equipment.  I really feel a lead gland is the ultimate, next to a silver one, or better yet, a depleted uranium one 

Thinking about weight training again....  I wonder if anyone knows anything about how fastball pitchers train for high velocity throws.  I suspect that due to the possibility of injury, they must avoid polymetrics.  But I wonder?  Pro Baseball, may be a good resource of study for us slingers.

                                     Ben

Hey Ulrica,

If we have a REALLYYYYY  BIG BOAT, then it might work.  If we have Jurek with us, it will have to be atleast 800 meters long I think. 



                                     8) Ben

Quote:


It would be great, it´s nice you´ve thought in us, there would be some  fanatic slingers encouraging you, though, as Ulrica say, family circunstances use to put difficulties in these plans... hummm. It´s a good idea to find one of these primitive weapons meeting, generally dedicated to the atlatl and bow, and thus the sling event would have a good repercussion too. I think the sling rarely joins in this meetings, and had to do it.

Ben,
I think that unfortunatelly the sling was not either in old Olympic games. At least this is my information, not very exhaustive of course. But never is too late for correcting the error, this would be our task   .. well, at least to start it organizing sling competitions and sling clubs in differents places around the world