Which is more effective, the design of Yurek with two loops or the design of Hondero with a loop and a pouch?  ;D ;D...  Well, the design more simple and easy to use is based on the sliding knot sling I showed in the "inventors nook" thread and that I called lasso-sling. You just put the shaft end, after the fins, into the loop and clench it. The wood does not have to be polished there, so that the sliding knot hold it well. When throwed, the dart leaves straight and without any type of problems, although in my opinion the range is a little smaller than with the sling of pouch and loop. The dart here is about a replica made some years ago following Livy description, but its performance is inferior to modern cestro with which I experiment now and that you know. In spite of its simplicity and effectiveness, this lasso-cestro is not a historical cestro, and if Greeks didn´t use it would be because his design was better or more powerful  ::).

http://perso.wanadoo.es/hondero/Album/cestroclasico.jpg

How is it released?

Hondero,

I didn't test your previous design and even mine yet. I have just made the arrow of round pine stick with the 4 feathers of a raven. Added some weight as the head. I will give that a try, when the weather is better.

The "lasso sling" is a very good idea, especially for cestros, that one should keep an arrow be safer than a stone. IMO there is only one fault, that one doesn't keep the arrow tangently. It makes some wastage of energy, during the windups and before the arrow will get the stable fly.

I think that my sling design from the "Inventors nook" should work for arrows pretty well too, but the arrow must be well situated in the pouch or the tail loop should be added.

I have got an idea of the "lasso sling" variation, the clench loop situated in the centre of gravity of the arrow. Durring release the loop is quite open, so the arrow have no hitch and should start clean. If I have some time, I will make a sketch.

Jurek, who likes brainstormings :D

PS. I wonder why the fethers are almost in the middle of your arrow. That doesn't seem to be efficient.

Yurek,  


If all goes well,  I should have a batch of toys coming my way fairly soon.  These are release mechanisms of unique design which will enable one to sling darts of uniform diameter ranging from 1/4" to 1/2".  Judging by the prototype,  this device should provide the most efficient, clean release for a wide variety of darts.  Currently I am using the same arrow bolts I used in the CO2000 arrow gun.  They are six inch long Easton 2512 aluminum arrow shafts cut down from a single, full length shaft and filled with sand with conventional inserts and fletching.  I simply mark the balance point of each shaft, which rests in the release mechanism until the moment of release.  This device is the simplest design I could conceive of while giving a smooth, clean release.   I have another design which involves moving parts, the concept of which I gleaned from those women's cantilevered hair clips.  The design works well.  It uses centripetal force to hold the dart clamped between it's 'pincers' and provides a very clean release, however it is of more complex design and more expensive to produce.   I will most likely market these as a full sling system however for members here on the forum,  I will sell the release mechanism (which is easily reproduced) separately if requested and one could provide their own sling cords.  It, like most good designs, is quite simple and very effective and I am positive that it would prove quite amicable to a distance record attempt........stay tuned.....I don't want to oversell the concept but.....suffice it to say,  the video footage should prove somewhat hard to believe.  I've got other projects going so this is getting the 'hobby' treatment but progress is being made and I am doing it largely for the interest of my 'compadres' here in cybertown.  This is my impression of some of your faces when you see some of the penetration shots.....  :o ??? :-/ :o

Tech
I can't wait!!!!
Johnny

wrote on Jun 15^th, 2004 at 5:55pm:

IMO there is only one fault, that one doesn't keep the arrow tangently. It makes some wastage of energy, during the windups and before the arrow will get the stable fly. I have got an idea of the "lasso sling" variation, the clench loop situated in the centre of gravity of the arrow. Durring release the loop is quite open, so the arrow have no hitch and should start clean. If I have some time, I will make a sketch. Jurek, who likes brainstormings :D PS. I wonder why the fethers are almost in the middle of your arrow. That doesn't seem to be efficient.

Yes, the windup is less efficient due to the fins, but you can use small fins because the dart is placed in the right position at the end of the snap and leave the loop straight ahead and fly stable from the beginnig. The fins in this cestros are placed in the center of the shaft because it was the only cestros I keep by now and was a Livy replica, so it´s designed for a conventional cestros sling. But with the lasso sling the dart would be with the fins almost at the end.

About to place the dart in the pouch or loop by its gravity center I think it would be very difficult to keep it tangential in the windup. In theory it would be the best but in practice I think it is uncontrolled. I´ve to try too when have the time... Many thinks to experiment in this research team!  ;D ;D

I know this spound strange, but the more i look at the Cestrosphendon it makes me wonder. The sling propably evoled from a bolo or a rock with a string attanched to it. What if this happened with the Cestrosphendon also. A heavy dart with a string attached to it. What do you all think?

"although in my opinion the range is a little smaller." Hondero

I suspect the lack of range is because the release velocity is less and the reason release velocity is less is because this Cestros is being spun laterally (sideways) and not point first where air resistance is less. The lateral (sideways) area is about 10-20 times greater than the frontal area.

It is easy to assume that because centrifugal force acts on a spinning body that when released, it will fly directly away from it's parent body, in this case ones hand.  However, in reality, it will always move at a right angle to the force that keeps it in it's 'orbit'.   And for our purposes, that is the sling cord.  Such factual information infers, naturally, that the most efficient method involves the dart being released while pointed in the direction of travel at the exact moment of release.  I hope that makes sense, as this might seem somewhat 'counterintuitive' to some.  

Tech
Have you done alot of research on centrifugal force? I would like to read some good info on this. I read of a tragic story where a group of teens tied a long rope to the back of a truck and wrapped the other end to a playground merry-go-round. A teen held on, thinking the spin would be fun, but the centrifugal force was so strong it propelled her 30 yards in the air to smack onto the pavement, killing her.  Never underestimate the power of centrifuge!
Johnny

Been studying the dynamics of orbital mechanics since I was a kid.  My head's been spinning ever since!   If you are curious to know more....google Viktor Schauberger.   I am curious to know the reason behind the 'movement' to relegate centrifugal force to the realm of 'misleading fiction'....instead referring to centripetal force as real.  To me, 'centripetal force' is the 'fictional force' if either of them are.  For it is really explained by gravity in the case of celestial mechanics and the sling cord for our purposes.  Now,  I don't know about you, but where I come from.....a sling cord is not a 'force'.   While on the stump  I would like to quote a meaningful phrase.....most apprapo in the halls of 'higher learning' these days:  "Teach a man to think that he's thinking and he will love you!  Make him really think, and he may hate you!"  Johnny,  believe it or not, like it or not,  we are living in a 'technological dark age'......this of course sounds preposterous given the amazing advances all around us, however the real WOW factor science is situated behind a veil that is kept in place largely by carefully disseminated misdirective information.  Such social engineering efforts are directly responsible for our modern order, such as it is.

Gun,
A dart attached to a string is also a good way to throw it. I´ve made a lot of variants of this solutions, even sets of darts, like the bolas for hunting birds. Nevertheless, the air drag of the string decrease the range and is better to use a sling and that the dart flies alone.

...modern cosmological folks say no such thing as either centrifugal or centripetal forces.  Simply the inclination of bodies in motion to remain in motion, and to move in straight lines (relativistically speaking).   Spooky stuff for an old guy :D    mgreenfield

The centripetal force only keeps the missile on the circular orbit and doesn't accelerate the missile on its trajectory, because that force acts perpendicular to the trajectory. That job makes the tangential force, which is component of the pulling cords force. In other words, we must pull the cords for keeping the missile on the circular trajectory and for accelerate that. That's why our pulling palm must go around the centre of the missile trajectory. Durring release the free missile always goes away tangently to the trajectory in the release point. So it is the best when the arrow is oriented along the trajectory during windups, but not along the cords. I'm not in dubt about it.

Jurek

Quote:

...About to place the dart in the pouch or loop by its gravity center I think it would be very difficult to keep it tangential in the windup. In theory it would be the best but in practice I think it is uncontrolled....

I tested my dart, attached to the piece of cord in the centre of gravity and whirled that. I noticed no problem with the arrow orientation. That one pointed itself immediately and was staying in that position pretty stably, even during a slower windups.

Jurek

Thanks Hodero for post something back. Sometime I feel like I am not even here. First, how heavy was the bolt or arrow you used. Wouldn't a heaver one over come the drag. Would you even need fleching if the string was behind it? Would the string at as the flechings and make enough drag to keep the dart steady in flight?

wrote on Jun 16^th, 2004 at 2:40pm:

I tested my dart, attached to the piece of cord in the centre of gravity and whirled that. I noticed no problem with the arrow orientation. That one pointed itself immediately and was staying in that position pretty stably, even during a slower windups. Jurek

I had never tried it before, but you are right... it works!!
The drag on the fins orient it very well. The problem would be, maybe, not in the windup but in the snap. As we all know the windup is only usefull to tighten the cords, but the proper momentum comes from the snap. The snap modifies suddently the circular trajectory and the speed then is so high that the dart could not follow well oriented the movement of the hand. The difficulty is to see clearly what happens during the snap. But as David Engeval throw his dart this way, so it can work too.

wrote on Jun 16^th, 2004 at 3:29pm:

Thanks Hodero for post something back. . Wouldn't a heaver one over come the drag. Would you even need fleching if the string was behind it? Would the string at as the flechings and make enough drag to keep the dart steady in flight?

A heavier dart would overcome better the drag but the range would be shorter. All depend on your purposes. You can also remove the fins and the string will orient the dart, but it will oscillate at first and the drag will be more.