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me and my dad made one and it had a shoulder stock cuz it had recoil. had trigger and all. attatched a nail to the arrow (homemade too) and it got stuck on a wooden fence. BTW the crossbow is made out of WOOD and nails. and uses string. you wont belive it but it shoots pretty far
 

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Resident Nutcase
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thought I'd give copying and pasting a try. This is my torsion design less the rail. It first functioned as a torsion slingshot over 12 years ago, 65lbs pull,used duel tubes tied to a shared pouch shooting up to 1.25 diameter steel ball bearings which easily destroys cement and brick targets. Needing powerbands more powerful than the spring was a prob, so I switched out the powerbands for nylon rope and added a rail for a crossbow design after I tried shooting an arrow from it.

If the pic takes, it is sitting beside a reg. pistol crossbow fully cocked. Uncocked, the strings line up side by side but cocked as you can see I have about 400 to 500% more draw. In the pic it is cocked at just 21 inches of draw which is not bad for a pistol crossbow. By changing strings I can adjust both the power and draw, add a pouch for a catapult or rubberless slingshot.

The design springs from my original torsion assist levered slingshot which is held and shot exactly like a bow.

Sorry - copy and paste pic did not work. Will have to learn to post pics properly. If I still have Aaron email, I'll send it to him to post. I will first try and attaching file to post but am not real computer literate.

update: hmmmm. attachment did not take sorry.

W.
 

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Tints and shades Metal Monochrome photography Monochrome Bicycle part
[quote name='Warhammer1' date='20 October 2010 - 05:26 PM' timestamp='1287591993' post='31705']
thought I'd give copying and pasting a try. This is my torsion design less the rail. It first functioned as a torsion slingshot over 12 years ago, 65lbs pull,used duel tubes tied to a shared pouch shooting up to 1.25 diameter steel ball bearings which easily destroys cement and brick targets. Needing powerbands more powerful than the spring was a prob, so I switched out the powerbands for nylon rope and added a rail for a crossbow design after I tried shooting an arrow from it.

If the pic takes, it is sitting beside a reg. pistol crossbow fully cocked. Uncocked, the strings line up side by side but cocked as you can see I have about 400 to 500% more draw. In the pic it is cocked at just 21 inches of draw which is not bad for a pistol crossbow. By changing strings I can adjust both the power and draw, add a pouch for a catapult or rubberless slingshot.

The design springs from my original torsion assist levered slingshot which is held and shot exactly like a bow.

Sorry - copy and paste pic did not work. Will have to learn to post pics properly. If I still have Aaron email, I'll send it to him to post. I will first try and attaching file to post but am not real computer literate.

Update: think I was successful after a few tries. Before anyone asks yes this is an inswinger model where the arms swing inwardly instead of the reg. way. It is more mechanically effecient by a factor of 48 percent as recently proven by australian math proffeseur VG Hart in his paper "the hatra ballista - secret weapon of the past?"

I have since developed a new modification resulting in up 22% increase over current levels. Still having fun and enjoy reading new members posts.
 

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Resident Nutcase
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Well, I finally posted a picture of one my wild designs. Please forgive the uglyness of the brute, as I have not the skills of Joerg.
Its kind of a work platform more resembles a seige-engine which I later learned actually may have existed. The machine is powered by a washing machine spring which was pretty stiff and made for some fun times down in the basement. I have a complete sports line of slingshot bow crossbow UAV launcher, etc. The slingshot model is tamed down version but will still rock your world.

I would love to build a MUCH larger one to hook to a small car or go kart, but I dont think I would be able to find someone crazy enough to pilot it. Anyone want to get accelerated to 300 - 400fps in a fraction of a second? LOL.

Have fun and keep up the awesome work here. Aaron has turned this into a premier site!
 

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Resident Nutcase
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Heres a pic of my other project where I am helping a friend with his ballista. Scroll down to "the little experiment". I am trying to get Nick up to speed on developments, but it takes time to make changes on it. This is an "Orsova ballista" based on an archeological dig in Orsova Romania. http://wattsunique.com/blog/?paged=2

Too big for me and my efforts, I can only help with the engineering and design. The next build is expected to top 400fps with a 7500 grain "arrow". I will stick to my smaller machines as they are easy to build and have fun with. We hope to get a small spot on History Channel this coming spring or summer. The coming build will give the world a much different looking and performing ancient design seige-engine, which should rival todays fastest crossbow at 425fps.

Wish us luck.

Well, I finally posted a picture of one my wild designs. Please forgive the uglyness of the brute, as I have not the skills of Joerg.
Its kind of a work platform more resembles a seige-engine which I later learned actually may have existed. The machine is powered by a washing machine spring which was pretty stiff and made for some fun times down in the basement. I have a complete sports line of slingshot bow crossbow UAV launcher, etc. The slingshot model is tamed down version but will still rock your world.

I would love to build a MUCH larger one to hook to a small car or go kart, but I dont think I would be able to find someone crazy enough to pilot it. Anyone want to get accelerated to 300 - 400fps in a fraction of a second? LOL.

Have fun and keep up the awesome work here. Aaron has turned this into a premier site!
 

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Tex-shooter
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I remember that design and I am surprised that someone has not started making that one commercially Hoe! It's a great design with after market sales ramifications. – Tex-Shooter
 

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Hoe, I have experimented with this concept too.

My main issues:

- The rubber had to be pretensed much in order to do the job. Hence, it tires out quickly. Even when you don't shoot.

- At the end of the motion during the shot, you have to stop the swivel arms. The metal levers have a pretty high momentum if you use enough rubber to make it a powerful weapon. The stoppers (I used steel) and lever arms suffered much from these impacts, they warped and dented.

Finally I gave up on the concept, went back to a straight arrow shooter (harpoon like).

Jörg
 

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Hoe, I have experimented with this concept too.

My main issues:

- The rubber had to be pretensed much in order to do the job. Hence, it tires out quickly. Even when you don't shoot.

- At the end of the motion during the shot, you have to stop the swivel arms. The metal levers have a pretty high momentum if you use enough rubber to make it a powerful weapon. The stoppers (I used steel) and lever arms suffered much from these impacts, they warped and dented.

Finally I gave up on the concept, went back to a straight arrow shooter (harpoon like).

Jörg
Thanks for sharing the experience, so now I don't have to go through a proven, failure experiment.
 

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I wonder if it wouldn't work better as an in-swinger design, similar to a scorypd crossbow or a inswinger ballista.
I believe that you have something there.

An in swinger would add velocity at he end of the pouch travel.

I can see it with 2 sets of stretched rubber for the arms, whereas an out swinger needs only 1 rubber.

(A compression spring would also work.)

Can it be done with a single?

The elastic need not be pre-stressed.

I use a short stub of Green Theraband connected to Red.

The Green is not stretched until the Red imparts enough force.

 

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SSF Founder
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Hmm. Maybe you could use two sets. Maybe the one set would be really heavy and fast, like a Theraband Gold, and would drive the arm action. The other set could a ligher Theratube, like a red. That way you are getting the snap of the thin and fast tubing, but have the power of the heavy band + lever action of the arms. Ill bet that would give you maximum velocity with pretty heavy shot.
 

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Resident Nutcase
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I wonder if it wouldn't work better as an in-swinger design, similar to a scorypd crossbow or a inswinger ballista.
- YOu know it will. The slingshot in the vid I sent you was a torsion based inswinger.

So is the pic I posted on this thread, where it is in catapult mode.
Here it is in crossbow mode, 65 lbs pull,and up to 25 inches of powerstroke (inswinger of course). http://warhammer1.wordpress.com/mini-ballista-pistol-type/

Here is the scorpyd fully cocked with arms locked at 175 degrees of rotation, and the other at rest (not cocked). http://warhammer1.wordpress.com/scorpyd-ballista-completed/

Sure the design had challenges but none that I wasnt able to solve. The torsion inswinger slingshot is pretty wicked. Not only do you get to use the energy of the rubber band, but an additional and equal amount of energy stored in the metal spring. A thirty lb pull will load the machine with sixty lbs of energy. It doesnt matter what kind of powerband you put on it, it will always produce and release double the amount of energy your regular slingshots do - thus you get higher velocities.
 

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Resident Nutcase
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Yeah, the inswinging design works just fine. Powering it with latex bands has drawbacks in cold weather and subject to breakage. Falcon Archery wanted to manufacture my inwinger slingshots for bowfishing a few years back, and had ideas of using the latex powerbands instead of a spring - a marketing thing I guess. I dont know why I didnt take him up on it, but I think it was simply a trust thing. I used to be all worried about someone stealing my designs which I am not so concerned about these days anymore.

the main about the design is that it doubles the amount of stored energy from a single pull or draw, and is very effective in transferring that energy directly to the projectile. Using a powerband instead of a string steals away from the max potential energy, but the end result of higher velocities is all but unavoidable. The slingshot powerband energy is all lineor, and by utilizing the inswinging design, adds another component that causes acceleration in and of itself. The true beauty of using a powerband instead of a string or cable is that the powerbands allow a certain degree of centrifical force into the equation provided the bands are long enough.

As you can see my springslinger is very versatile.(pic at very bottom of page) Add a few pulleys, a string...crossbow, bow, slingshot. Who needs powerbands anyway. Properly built it will outpower anything else I have seen on this sight or youtube. I havent bothered to try heavy bands but one day will get around to using Trumark black bands but in all honesty, Im happy with the present power and speed unless I was to go hunting with it. I have bagged many concrete blocks and patio stones and also red clay bricks. Over ten years old now the axle casing are getting worn out, but she stills performs flawlessly.

A word of warning tho. Shooting one will ruin you for ordinary slingshots, but if you love archery without the expense this is a nice substitute. JoergS has a very nice shoot through slingbow design for arrows I really like. That design would certainly take care of the recoil this thing has.

As for slingshot crossbow fans - heres another one for ya! http://www.crossbownation.com/forum2/topic/11618-crossbow-with-bungy-cords-rather-than-limbs/page__st__20__gopid__119159

Unfortunately this is classified as a speargun and not legal to hunt with unless you are under water and your prey has fins and gills.

I wonder if it wouldn't work better as an in-swinger design, similar to a scorypd crossbow or a inswinger ballista.
I believe that you have something there.

An in swinger would add velocity at he end of the pouch travel.

I can see it with 2 sets of stretched rubber for the arms, whereas an out swinger needs only 1 rubber.

(A compression spring would also work.)

Can it be done with a single?

The elastic need not be pre-stressed.

I use a short stub of Green Theraband connected to Red.

The Green is not stretched until the Red imparts enough force.



[/quote]
 

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Resident Nutcase
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Hey Tex, pm me your email ad and I'll send you a vid of it. Aaron has seen it and also he suggested you might even be interested in giving it a try. Im also interested in seeing what it would do using them flatbands as they are reported to be faster.

I remember that design and I am surprised that someone has not started making that one commercially Hoe! It's a great design with after market sales ramifications. - Tex-Shooter
 
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