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Accuracy Comparison & Competition? (Read 12507 times)
Dan_Bollinger
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Re: Accuracy Comparison & Competition?
Reply #30 - Feb 25th, 2004 at 3:28pm
 
DynaBee makes yoyos, a descendant of the sling.  That DynaBee ammo looks supiciously like my grooved glandes design of 3 years ago. However, I use the groove to accept a sling cord (no pouch needed). DynaBee says to us a normal sling.  There is a mention of an ancient grooved glandes design.

...

I'll send Chris that Larry Forsyth article to post. Dan
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Re: Accuracy Comparison & Competition?
Reply #31 - Feb 25th, 2004 at 4:03pm
 
No need to be suspicious.  If it's one thing I learned in product development, it's that in working in an area of high specificity, such as slinging, one will invariably find mirroring research.  Nice work BTW!  You may find it more advantageous to use a clip/cradle anchored to 2 sling cords whereby releasing one cord will dump the ammo from it's clip/cradle in such a way as to obtain the most efficient and clean release.  This may be aided by a lightweight flechette built into the clip/cradle assembly for complete flight stability during the duration of the sling event.  I have many other designs which, I am sure, must be being duplicated by someone somewhere at this moment!   (Well probably not some of it....some of it is quite strange!)

Good luck and keep em whizzing!

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« Last Edit: Feb 25th, 2004 at 7:00pm by Yahweh Bless you in Yeshua »  

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Re: Accuracy Comparison & Competition?
Reply #32 - Feb 25th, 2004 at 4:12pm
 
I thought I should add this suffixial bit of info....my choice in calling my ammo 'dynabee' was as a monicker in reference to the amazing 'Dynabee' gyroscopic wrist exerciser and was unaware of the 'dynabee' you are speaking of........suppose someone in a parallel dimension is slinging antimatter propelled buzzbombs at a wormhole in our neighborhood? 

(insert Rod Serling theme here)
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Re: Accuracy Comparison & Competition?
Reply #33 - Feb 25th, 2004 at 4:14pm
 
Larry
I have to disagree with you on this one. There are so many sources of information from the ancient writers spanning hundreds of years that testify of the accuracy of the ancient slingers. Alot of these slingers were shepherds, and they had sun up till sun down to practice. The Bible mentions in the book of Judges that the Benjaminites could sling at a hairs breadth, and not miss. Anyway, just my thoughts!!
Johnny
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Re: Accuracy Comparison & Competition?
Reply #34 - Feb 25th, 2004 at 5:08pm
 
Johnny,

I'm regretting my previous post because I do not want to foster contention among us friends, but your post makes my point for me. 

Assuming a hair is 1/100 of an inch in diameter, are you saying you believe they were accurate within 1/100 of an inch with never a miss?  At what distance do you suppose? 

As soon as it is recognized that these accounts cannot be taken literally, we have to interject common sense and experience to try to arrive at what is reasonable.

I'm certain they were very, very good.
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Re: Accuracy Comparison & Competition?
Reply #35 - Feb 25th, 2004 at 5:18pm
 
Larry
It doesn't say how many times they hurled(1 or 100times), or the distance. The Bible is silent on that part.  I agree with you that they were really good. I think there is nothing in the verse that goes beyond common sense. Being human, they are prone not to hit every time.
Johnny
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Hondero
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Re: Accuracy Comparison & Competition?
Reply #36 - Feb 25th, 2004 at 5:20pm
 
Quote:
There is a mention of an ancient grooved glandes design.

[


Interesting, can you recover it?
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Re: Accuracy Comparison & Competition?
Reply #37 - Feb 25th, 2004 at 5:24pm
 
Quote:
Yurek, just a guess: if the Larry distance record is about 430 meters with a 2 oz stone, wich will be the record with 1 oz lead glans and the same launching speed? (The weight of an arrow maybe about 1 oz or less)....



I'm trying to guess. The record will be bigger if slinger's skill is similar to Larry's one.


Quote:
Second guess: what can we do to throw this 1 oz glans with the same speed that the 2 oz projectile.


I think, that nothing special, it require a smaller effort.

Quote:
Third and last: how can we increase the launching speed of a light proyectil.


We should put a more energy into the throw, useing the proper way and proper a lenght of the reduced sling.

Quote:
[quote]Who knows the answers will be the next world record winner  Grin Grin


Am I right? But now I'm afraid that I'm not only one who knows that secret Wink

It reminds the anecdote about Japaneses, who have invented something so small, that nobody can see it and nobody knows what it is.

By then I imagine the team of slingers who are brandishing with  invisible slings and are sending invisible projectiles. Finding them will be a big problem Cheesy

But seriously, I think you are right, it is good to use as light projectiles projectiles as is possible for given slinger and sling. I think it is a very individual thing.

Jurek
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In the shape, structure and position of each stone, there is recorded a small piece of history. So, slinging them, we add a bit of our history to them.
 
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Re: Accuracy Comparison & Competition?
Reply #38 - Feb 25th, 2004 at 6:36pm
 
Quote:
... upon observing brook trout remain nearly motionless against a fast moving stream, went on to produce many strange devices that appeared to exhibit negative drag or at the very least, vastly reduced drag!....

Here is a pic of the DynaBee Ammo .... accurate and fasssssst flight! [IMG]



Hi TechStuf, do you means that DunaBee Ammo has a vastly reduced drag? I“d like to know how is that. Can you explain it? Though trouts are not grooved  Grin it“s certain that they remain still in the streams, I don“t “know how they do.

Welcome you and your ingenious devices.

Hondero
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Re: Accuracy Comparison & Competition?
Reply #39 - Feb 25th, 2004 at 6:48pm
 
Sorry, Yurek, you have failed the three questions  Grin. It was a previous theoretical exam to go to the Guiness. I think you are not prepared yet ???
My PC is given me trouble now, I“m afraid I have to stop. Tomorrow I“ll give the right answers... well I“m not sure of them...I“m not prepared either  Grin
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Re: Accuracy Comparison & Competition?
Reply #40 - Feb 25th, 2004 at 7:08pm
 
It gets quite complicated, but essentially, yes.  Gyroscopic precession and complex aerodynamics are both brought into play to increase the efficiency by which this deceptively simple shape propagates itself through the air.  I have since improved upon the shown example markedly but cannot reveal such here in this forum at the present time.  Here is a link to some interesting research into Schauberger's discoveries:

http://www.frank.germano.com/airship.htm


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« Last Edit: Feb 25th, 2004 at 11:36pm by Yahweh Bless you in Yeshua »  

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Dan_Bollinger
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Re: Accuracy Comparison & Competition?
Reply #41 - Feb 25th, 2004 at 8:09pm
 
Hondero, It is in the Blackmore article. Depending on which way I hold my head it says different things. The photo above is my interpretation of what Blackmore was describing.

"An Egyptian sling of c. 800 B.C. in the Flinders Petrie Collection at University College, London, is made of woven and plaited strings with a diamond-shaped pouch in the middle. One end of the cord has a loop which fitted over a finger and was retained in the act of throwing. A modern reconstruction of this sling achieved ranges of from 50-100 yd.  The strip of material could be replaced by two cords holding the pouch, and the latter was sometimes dispensed with, the bullet being grooved to seat it in the cords."
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Re: Accuracy Comparison & Competition?
Reply #42 - Feb 26th, 2004 at 12:33pm
 
Yurek, these last days I have been thinking about the subject of the weight of the projectiles and these are my conclusions in relation to the three questions. I dont“t know if they are right:

1- The one oz. projectile will be more restraining by the air that the one of two oz. because in spite of its smaller frontal surface, it is decelerated more due to its smaller mass: F = m x a. The deceleration is finally inversely proportional to the radius (for a espherical projectile). Perhaps however, being the projectile of 1 oz made of lead, and of stone the one of two oz., the effects are compensated and the same range is obtained or even a little more range is reach with the one oz. projectile.

2- The effort to send the one oz. projectile would be something smaller, although for so small proyeciles its weight is almost despicable with respect to the weight of the arm, that it has also to move at the speed of launching, driven mainly by the muscles of the shoulder, that are in charge of the effort. Actually I think that the max. speed of launching of both projectiles would not be very different. But there is another effect to consider, and is the tension in the cords due to the centrifuge force of the projectile, that would be inferior for the small projectile, being left the cords most loose, providing a bad turn around and less strong clutch of the projectile in the pouch, which would be translated in loss of projectil release speed. If in addition we are using a long sling for greater range, the air drag on the cords would even relax them more. Therefore, it seems that the lightest projectile would have more disadvantages, and would be necessary to also resort to very light slings.


3-  Considering all this, the problem is to evaluate if the small increase in the speed of launching, due to the smaller weight, compensates the other two negative effects of the greater deceleration and the worse behavior of the sling. This is the tactically important point, to determine the "border" weight of the projectile for a determined sling, below which the range would be lesser than with one heavier. By intuition I place this " border weigh" in 30-40 grams for a very light modern sling. The more light and the less drag it has, the border weight would be also smaller.


I don“t know if your opinions are similar to mine and in any case it is necessary to experiment. The worse thing of all will be to find the very small glandes afther been shooted, ha ha. It will be necessary to engage some meticulous Japanese people you mention  Grin.
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Re: Accuracy Comparison & Competition?
Reply #43 - Feb 26th, 2004 at 5:05pm
 
Hondero,

Quote:
1- The one oz. projectile will be more restraining by the air that the one of two oz. because in spite of its smaller frontal surface, it is decelerated more due to its smaller mass: F = m x a. The deceleration is finally inversely proportional to the radius (for a espherical projectile). Perhaps however, being the projectile of 1 oz made of lead, and of stone the one of two oz., the effects are compensated and the same range is obtained or even a little more range is reach with the one oz. projectile.


I think the 1 oz lead projectile has a better ballistic coefficient yet. Consider that lead density is 11.3 but the stone one is about 2.8. An air drag is proportional to cross-section area. Wait moment...

I just have calculated, for that for ball shaped ones, the cross-section area of the lead projectile is about 4 times less than the second one (the 2oz stone). Then drag should be 4 times less for the 1oz lead projectile, if we assume that the air drag coefficient is the same for both projectiles. How is really, maybe 3, or 2 times. I don't know, but If even that is a bit more than 2x then is enough yet.

Quote:
2- The effort to send the one oz. projectile would be something smaller, although for so small proyeciles its weight is almost despicable with respect to the weight of the arm, that it has also to move at the speed of aunching...


I agree with that point and the next one too. Well... it looks like we should play with unhealthy lead, yet. Smiley I haven't a big experience with lead projectiles. I used the 100 g ones because I used heavier stones and more fat slings before. The winter doesn't be friendly for experiments. Anyway that all is very interesting end exciting. Thanks Hondero.

Jurek
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« Last Edit: Feb 27th, 2004 at 5:27pm by Yurek »  

In the shape, structure and position of each stone, there is recorded a small piece of history. So, slinging them, we add a bit of our history to them.
 
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Re: Accuracy Comparison & Competition?
Reply #44 - Feb 26th, 2004 at 7:05pm
 
Something has gone wrong in the fast calcules... My results are 4 times biger the drag force for the 2 oz projectil, and so the deceleration will be 2 times biger. But even that, is a great result  in favour of 1 oz lead glans.
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