# Long term project: Carriage Mounted Slingshot Cannon



## JoergS (Dec 17, 2009)

OK, I need a project that should be completed on my birthday (April 7th). I want to publish the steps in the making on youtube, like a mini series.

The goal: a slingshot cannon that fires steel Petanque balls (Boccia, Boule) weighing 725 gramms (1,65 lbs), size (diameter) 7,5 cm (three inches) at 70 m/s, 1,773 Joules.

That is a mighty goal.

Here is my thinking.

A cannon that is mounted on a carriage, with a double windlass. It works much like my latest project, just everything is a lot bigger.

I can shoot a 2,2 gramm 8mm steel ball at 70 m/s with a band that is 2cm x 1cm x 20cm. That is 30 square cm.

The Petanque ball is 330 times heavier, so it will need 9900 square cm of rubber to be propelled to 70 m/s.

So if I use 14 Thera Gold bands per side, 14 cm x 7 cm x 20 cm, that should do the job. We are talking maybe 500 kg draw.

The shooter would stand behind a shield (bulletproof glass), to be fully protected. The trigger would be pulled via string and pulley. Mythbusters style.

The windlass is behind the shield, too.

What do you think?


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## ZDP-189 (Mar 14, 2010)

Would a mortar arrangement and remote release work, or does it have to have an RPG form factor?


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## Hrawk (Oct 25, 2010)

I think you're crazy!

But your my kind of crazy!

I just cant wait to see the first instalment!

Just be sure to call Guiness, I'm sure there is a record or two there for the breaking!


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## PandaMan (Oct 14, 2010)

I think you could make it work.
Where would you test it though? Do you have at least a few acres for you garden? You'd need a ridiculous backstop to stop a ball that weight going at 70m/s.


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## ZDP-189 (Mar 14, 2010)

I've just plugged it into an on-line calculator (link) and the maximum range is about 500m (1/2km). Whatever/whomever it hits in that distance is going to be rather surprised and possibly unhappy.


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## bleachbone (Nov 15, 2010)

i would love to see a monster like that, it amazes me how youy even come up with these awsome ideas


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## JoergS (Dec 17, 2009)

PandaMan said:


> I think you could make it work.
> Where would you test it though? Do you have at least a few acres for you garden? You'd need a ridiculous backstop to stop a ball that weight going at 70m/s.


Well, a part of my garden is steeply uphill. My idea is to use several plywood boards and see through how many it crashes. Should it go through all of them, the ball would entrench itself into the lawn.


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## Ace (Oct 24, 2010)

Sounds like an awesome project to work on, be sure to include some destruction!

-Ace-


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## bikermikearchery (Sep 30, 2010)

I will be folling this with great interest. thanks for sharing.
Mike
BMA


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## PandaMan (Oct 14, 2010)

Ok, Jörg. I don't mean to be patronising, but be careful. You could get into trouble if something goes wrong...


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## dim1254 (Dec 19, 2010)

ok...i think this would be amazingly strong.....but how can u use it?


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## bunnymansp (Oct 25, 2010)

if this works it would awesome to make one


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## JoergS (Dec 17, 2009)

dim1254 said:


> how can u use it?


Crank crank crank....

"Fire in the hole!"

Poooooow!!!!

Oh my.... Look at the damage...


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## PandaMan (Oct 14, 2010)

JoergS said:


> how can u use it?


Crank crank crank....

"Fire in the hole!"

Poooooow!!!!

Oh my.... Look at the damage...
[/quote]

Indeed. In the destruction video, please could you test it on various fruit as well? Watermelons are relatively similar to a human head, I've heard!


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## huey224 (Apr 12, 2010)

or could you use a big frame like structure, and have bungiee cord for bands?


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## ZDP-189 (Mar 14, 2010)

Jörg, all these comments are for you only and I disclaim liability.

I suggest using welded angle bracket or bolted aluminum instead of timber, so we can be sure of the materials' integrity.

I recommend a longer draw; it would allow for a lighter peak force.

The width you describe is roughly 4 strands of full width TBG tapered 50%. I suggest 4 sides rather than 2 to reduce the chance of a RTS. 
Put on a block to limit elevation. Then you won't accidentally take out a kindergarten half a click away, or discover whether a canon ball has a lethal terminal velocity.

Consider Linatex. You're shooting massive projectiles and the advantages of thin bands is diminished.

You might use your invention of an elastic restraining band to reduce band entanglements.

I strongly suggest you situate the release mechanism so that you're not standing in line with the direction of firing (whether fore or aft).

The same goes for the winch. I think an electric winch would be much safer.

If you make it with 4 bands and 4 sides, the frame can be a box section. You can then add spacer blocks on the front to increase the draw length if necessary.

I think you should consider again the cord method of releasing the pouch.

Your corporation should obtain keyman insurance that covers acts of folly.


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## JoergS (Dec 17, 2009)

Dan, I also thought about increasing the draw length. 2 meters length should not be too much for a piece of artillery.

In terms of the material, I plan to use really thick timber beams as "rail barrel" parts. 15 cm x 15 cm probably. Two of them should be OK for the purpose.

I still like the mechanical winch as it has the medieval approach, but the first tests will be made with an offroad type electric winch, used to haul out stuck jeeps. And of course the trigger will be remote controlled. But those are easy conversions.

I will then test the penetration of the balls against bulletproof glass etc., and will make a safety shield that can withstand a full, direct hit. So a returning ball won't be an issue. Now that I live in the countryside, open space is not an issue, so I can shoot without dangers for others.

I am still thinking about the best material for the pouch. It has to hold 500 kg drawweights, after all. I am looking at cordura. Fortunately tests can be conducted with little risks, just a winch, rope and no projectile.

Jörg


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## Deimos (Dec 24, 2009)

Wrongpost :/


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## Deimos (Dec 24, 2009)

awesome.
Angle the shield forward, so it something comes at you, it recoils downward?
As used in backstops?

Any idea on accuracy?

April 8th we'll get a news message, Several petanque balls have been launced in to orbit by a unknown source, they are causing mass distruction to satelites left and right. GPS, GPRS and news satelites are failing, people start getting confused and start wandering around. Not long after, the first canibalism cases break out.
ZOMBIE APOCALYPSE!

This was your plan all along, wasn't it?


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## JoergS (Dec 17, 2009)

Deimos said:


> This was your plan all along, wasn't it?


aaaahhahahahaha!


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## ZDP-189 (Mar 14, 2010)

Somewhere in Jörg's former garden there is an old and scarred tree breathing a huge sigh of relief.

I bet Jörg's neighbours see this thread and serve him with an injunction before he can test it. Shortly thereafter, the German legislature will update the law to prosctibe not only wrist braces, but any slingshot mounted upon a vehicle.


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## zille (Oct 25, 2010)

if there's a petanque-ball-sized hole in your car-window...I will just refer to this thread by stating...I informed you thusly...


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## JoergS (Dec 17, 2009)

Well, don't laugh, I am contemplating to buy a junk car and use it as a target. Maybe even renting a car junkyard for a day. I guess people would find that interesting.

Jörg


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## Devoman (Oct 15, 2010)

Very interesting! Sounds like a lot of work, good luck. I don't think I would make one, but the destruction video in super slow motion...now that would be interesting!


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## JoergS (Dec 17, 2009)

I am thinking about making a pea shooting mini version of it, 1:10 (20cm draw length).


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## brockfnsamson (Aug 25, 2010)

JoergS said:


> This was your plan all along, wasn't it?


aaaahhahahahaha!

http://www.youtube.c...h?v=Zvvw3YKyKkc
[/quote]

Greatest band ever! The only concert I went to in the past 20 years.


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## Dan the Slingshot Man (Nov 21, 2010)

wow


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## zille (Oct 25, 2010)

JoergS said:


> Well, don't laugh, I am contemplating to buy a junk car and use it as a target. Maybe even renting a car junkyard for a day. I guess people would find that interesting.
> 
> Jörg


interesting? would be hilarious







and I'm talking tenacious d hilarious!


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## Dan the Slingshot Man (Nov 21, 2010)

awesome, just slow to load


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## Hrawk (Oct 25, 2010)

Here's a thought, why not start with a cheap or second hand boat trailer?

There is half the framework and wheels in place + it comes with a winch already. Plus you could add a jockey wheel and you have traverse as well control over elevation!

You could make the uprights/forks collapsible and be able to drive up the highway without anyone looking twice.

I have already chosen the backing music for the destruction video for you!

ACDC 'Big Balls' - Perfect!


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## JoergS (Dec 17, 2009)

I was thinking about a classical civil war type carriage. This thing would look like a wooden Gatling gun pretty much.

And AC/DC is a no-go, I can no longer use commercial music because I am a youtube partner. As such I have to make sure all of the intelectual content is mine.

Jörg


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## zille (Oct 25, 2010)

Maybe this is a little covert advertising, joerg. I do sell "gemafreie musik" our website is: www.addloops.com. If you're interested, contact me and we'll work something out.

Best regards zille


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## Tobse (Nov 4, 2010)

wow this is a great idea! I like strong Slingshots! I would like to see the destructive power of the cannon!!

i think this slinghot needs a litle bit of engineering calculation







wish you good luck!!!


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## ZDP-189 (Mar 14, 2010)

I've just seen the Canon splits wood like cardboard video, but Youtube is only semi functional and I can't post comments.

Well done. I think that would be able to shoot more massive projectiles without much loss in velocity. BTW, I think safety glasses are inadequate for this experiment.

BTW, how about this for a carriage?


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## MedMan (Nov 10, 2010)

JoergS said:


> Dan, I also thought about increasing the draw length. 2 meters length should not be too much for a piece of artillery.
> 
> In terms of the material, I plan to use really thick timber beams as "rail barrel" parts. 15 cm x 15 cm probably. Two of them should be OK for the purpose.
> 
> ...


If I may.. Great project.. Totaly dangerous but then lots of things are.

Have you considered using paracord? I reckomend WEAVING a pouch from 550 parachute chord..

One strand can hold 250 kilo. 4 strands holds a ton. 2 strands will hold 500 kilos. A woven pouch could in theory hold many tons..

I have just completed several Slings. I wove them from paracord type 3 and some from natural fibres using braids plats and weaves!

I found instructions on Slinging.org.... An excellent website for those interested in slings and David and Goliath!

Beware ..Weaving weapons is addictive!

Med-Man


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