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The Slingshot Channel Thread

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Unread postAuthor: McCoytheGreater » Fri Dec 25, 2009 12:20 pm

That seems like it works nicely. Is the pouch pinching the vanes of the arrow? and if so, how does this affect the accuracy of the slingshot?
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Unread postAuthor: JoergS » Fri Dec 25, 2009 12:25 pm

The pouch does not pinch the forked plastic part at the end of the arrow, if that is what you mean. The rubber loops that I attached to the ends of the pouch will pinch around the arrow shaft, just before the thicker plastic part begins. This way the arrow is held very firmly in place and no accuracy loss occurs.

Wait for the video, things will become more obvious.
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Unread postAuthor: McCoytheGreater » Fri Dec 25, 2009 12:28 pm

I think I got it. I took a second look at the pic.
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Unread postAuthor: boyntonstu » Fri Dec 25, 2009 12:34 pm

Great design!

Have you considered carving a groove into the arrow near the nock into which a pouch ridge would fit?

It would hold the arrow in addition to squeeze friction.
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Unread postAuthor: JoergS » Fri Dec 25, 2009 12:38 pm

Another groove is really not needed. You know, the arrow does not need much force to be pulled back, it really is the grip on the pouch that needs to be strong. Now, you simply grip the rubber bunch like you would grip a steel ball through the pouch, and then you draw out. This works really well.

I think my new pouch design is the best part of my enhancements.
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Unread postAuthor: JoergS » Fri Dec 25, 2009 12:43 pm

Here is the video:

[youtube]http://www.youtube.com/watch?v=9cJ9JYcRlMk[/youtube]

Sorry for the grain, my camcorder doesn't like low light conditions.

Video embedded by jrrdw.
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Unread postAuthor: McCoytheGreater » Fri Dec 25, 2009 12:46 pm

I don't know how faithful you are to the leather pouch, but you could completely modify your slingshot to accommodate a bowstring instead of the leather pouch. Then you could pull it back with a release using one of these. Except make the bands super super hardcore. That would be neat.

EDIT Just watched the video. That thing looks so cool. almost like a very primitive crossbow.
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Unread postAuthor: JoergS » Fri Dec 25, 2009 12:53 pm

I tried the release/string method, it works. But the release is to cumbersome to operate. I just prefer the simple pouch method, I guess.
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Unread postAuthor: McCoytheGreater » Fri Dec 25, 2009 1:18 pm

I can deal with that. I'll be off forum for a while. Have a Merry christmas!
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Unread postAuthor: boyntonstu » Fri Dec 25, 2009 1:44 pm

I'd like to try your arrow in my Trom-Boyn and see how fast it goes.


Have you chronyed it?
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Unread postAuthor: JoergS » Sat Dec 26, 2009 12:44 pm

My chrony is damaged, left it in the rain for just one minute.

But I did a ballistic gelatin test, in comparison to slingshots and croosbows. Video will be up soon.
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Slingshots, slingbow, air rifle and crossbows vs. Gelatin!

Unread postAuthor: JoergS » Sat Dec 26, 2009 1:26 pm

Here:

[youtube]http://www.youtube.com/watch?v=gT7Yxgtzteo[/youtube]
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Unread postAuthor: jackssmirkingrevenge » Sat Dec 26, 2009 1:43 pm

Very interesting video as always :)

Since velocity is limited in slingshots, it makes sense to maximise the mass in order to get the best performance from the available parameters. It would be interesting to see how the different projectiles and launchers compare in other media, like say thin metal or plywood sheeting.
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Unread postAuthor: JoergS » Sat Dec 26, 2009 1:47 pm

Yes, the 19 mm lead ball delivers tremendous energy. It is too heavy for the commercial slingshots, though.

Thin metal can be perforated more easily with smaller steel balls. But the big balls cause a dent the size of an apple!
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"W" slingshot: Ball bearings added

Unread postAuthor: JoergS » Mon Dec 28, 2009 3:43 pm

Hello,

the "W" slingshot, my best concept so far, has taken the next step.

I noticed that the rotating grip did not self center when a very strong band set was fully drawn out.

The rotating mechanism was just a steel tube that rotated around a thinner steel tube, the thinner tube beeing welded to the frame. It obviously had too much friction to rotate when the system was set under full pressure.

So I ordered some parts and enhanced the setup.

I added two ball bearings, originally from a motorcycle engine. I pressed them on the 12 mm steel rod that was welded to the frame, then pressed everything into a fitting aluminium tube (the grip). I cooled and heated the parts for the pressing. They are totally firm and there is NO play.

It works very well Now the grip rotates smoothly, even when I draw out my toughest bands.

Regards


Jörg

Image

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