the auto spud cannon

Post questions and info about combustion (flammable vapor) powered launchers here. This includes discussion about fuels, ratios, ignition systems and anything else relevant to launchers powered by igniting things like hairspray or propane.

Postby killjoy_xt » Sun Jan 28, 2007 2:54 am

k here i will just post the plans on the foum

First off let me introduce the main piece in this arsenal, the spud bullet is designed just like the real thing, the chamber is preloaded with gas, and a small barrel is mounted at the front (just big enough to house the potato in it). Then you have 2 screws that are drilled in side my side (I think that they might cause the spark to jump too high up in this configuration so I sagest you drill them in a V formation). Then you take bicycle chain and you glue it to the bottom of the bullet. As you add more bullets, you simply keep the chain growing and glue more bullets onto the same chain.
<a href="http://photobucket.com/" target="_blank"><img src="http://i85.photobucket.com/albums/k76/killjoy_extreme/spudbullet.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>
<a href="http://photobucket.com/" target="_blank"><img src="http://i85.photobucket.com/albums/k76/killjoy_extreme/spudbullets.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>
Now this is how every thing works. You have a wooden bench as a platform. The bench is solid wood on all sides and doesn’t have 4 legs just woods plates on the sides to hold it up (there is a reason for this construction). Now here is the rear view
<a href="http://photobucket.com/" target="_blank"><img src="http://i85.photobucket.com/albums/k76/killjoy_extreme/rear.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>
Ok so what you just saw is the rearview of the chain gun. The black circles represent the bullets linked by the black lines which are the bicycle chains. We also see a gray circle with black pegs in it. This gray circle is a bicycle gear which is used to carry along the bullets as they line up to get shot out. This is how everything works. As you turn the bullets get pulled into place by the chain and gear. From the side view you see the slits that are made in the wood for the screws to pass through
<a href="http://photobucket.com/" target="_blank"><img src="http://i85.photobucket.com/albums/k76/killjoy_extreme/sidechain.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>
If you haven’t already noticed there is a barrel extension which is mounted at the front of the gun. This is the barrel in which the bullets will line up with. It is mounted in a flat board that is connected with the bench. Now to continue with how this thing works we shift over to the under view of the bench. This is where all the magic happens. As the bullet lines up with the slits in the bench it gets pilled across a rail like system. Eventually when they line up with the barrel they will also be meeting face to face with the ignition system. The ignition system is basically a battery (seen in blue) that is strategically placed so that it only makes contact with the screws when the time is right. To ensure that it only goes off when you want it to, there is a small metal obstruction, like a round edge at the end of the wire so that its briefly interrupted from its straight path and has time to go off without missing the barrel, but not in the way enough to completely stop it form moving forward. Now comes the reason why you use flat boards as legs instead of 4 pegs. In order to get the wire on the opposite side of the bench with out obstructing the bullets path, it skirts around the leg of the bench so that it passes under the side slits and re appears on the other side. Also, in order to keep the bullets feeding straight I threw in another bike gear so that there is 2 points of force on the chain so it travels straight. These are joined by the gray axle that should be able to safely pas over the screws so that it doesn’t obstruct its path.
<a href="http://photobucket.com/" target="_blank"><img src="http://i85.photobucket.com/albums/k76/killjoy_extreme/under.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>
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Postby killjoy_xt » Sun Jan 28, 2007 2:56 am

Ok the semi automatic version works with more or less the same bullets of the chain gun, I actually hope to one day make it so that the ammo could be interchangeable (lol 700mm NATO rounds). Anyways it is mag fed and works on gravity to process the rounds. The mag as shown houses the bullets and keeps the screws in place by keeping them aligned on a track. This is what the mag looks like
<a href="http://photobucket.com/" target="_blank"><img src="http://i85.photobucket.com/albums/k76/killjoy_extreme/mag.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>
Now for the inside. The shell of the potato rifle could be made of wood. Inside it is a fairly simple construction. At the very bottom of the shell we see 2 gray lines with a circle, this is actually a metal strip spring system, but I will explain that later. When it fires the recoil generated will push the bullet back to the rear of the shell. Directly behind the shell is a wood plate with a square whole in it. behind the plate are 2 more springs that push forward (in order not to mix these up with the metal strip spring we will call it the metal strip) and a wooden peg. This hole in the plate is shown in baby blue. As the recoil propels it backwards the wooden peg passes through the whole and strikes the bottom left of the bullet. This causes it to tilt to the right, and shift directions from flying backwards to flying sideways leading to ejection. As for ejection on the right side there is a wooden flap that once it hits the wall (flap) it opens up and gets ejected out of the shell. Now this is where the gray strip comes in. to give the new bullets a chance to load properly. The metal strip springs up and catches the wooden plate as it attempts to spring back into place. The only way this lock can be removed is when the new round successfully falls to the very bottom and depresses the metal strip so that the end of the strip releases its hold on the wooden plate so that it can spring forward and push the new bullet into the firing position. Also I like to include another wooden plate that is located at the barrel. All it is is a plate with another barrel sized whole in it so that the tip of the bullet falls inside and prevents sifting from left or right and ensures a tight fit. This wooden plate is shown in pink. Oh ya I forgot to elaborate on the metal brace for the screws. Well in order to get a spark, the infighter is connected to 2 strips of metal that are suspended from the brace. Once is enters the shell the bullet falls out of the mag brace and lands on those 2 metal strips. All that is left to do is fire and BOOM!
<a href="http://photobucket.com/" target="_blank"><img src="http://i85.photobucket.com/albums/k76/killjoy_extreme/rifle.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>
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Postby Ric » Mon Jan 29, 2007 9:47 am

This is a pretty cool getup. May I suggest something in the way of a revolver-type mechanism, where you have your linked ammo picked up by the revolving "cylinder"... actually more like a gear designed to "mesh" with the linked ammo. The bullets will have to be within close tolerances to fire effectively, and you'll need some way to seal the bullet to the barrel. Operation would be simple... turn the crank(or hook up to an electric motor), and taters go flying.

Not that I'm the resident expert on tater guns(probably more like the black sheep), but I think you're onto something pretty awesome. Refine it, and post a video when you get it working!
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Postby Numbuh 16 » Mon Jan 29, 2007 12:56 pm

Also, you may want to try sheets of PVC instead of wood. Both lighter and easyer to work with.

Also less splinters. XD
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Postby sgort87 » Mon Jan 29, 2007 2:03 pm

You guys are making this a lot harder than it needs to be.

You need 3 things for a combustion: Fuel, oxygen, and a spark. That's it.

Just get all three of those things in that same chamber repeatedly and you're in business.
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Postby fullmetaljacket » Mon Jan 29, 2007 11:18 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">You guys are making this a lot harder than it needs to be.

You need 3 things for a combustion: Fuel, oxygen, and a spark. That's it.

Just get all three of those things in that same chamber repeatedly and you're in business.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Ah but sgort, you can't deny that <a href="http://media.putfile.com/carttest2">ejecting spent cartridges is cool</a> :D
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Postby sgort87 » Mon Jan 29, 2007 11:28 pm

Yes, indeed it is quite cool. :D That is if you can get it to work, and quickly. :p

You are definitely on the right track there. That thing is totally sweet. The launcher very functions well. Now how fast is its rate of fire?

The cost of producing a bunch of chambers is much higher than the cost of producing a chamber that can be quickly fueled over and over. Not to mention, it will take up a lot more space.
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Postby fullmetaljacket » Mon Jan 29, 2007 11:50 pm

sadly that <a href="http://localhost/forums/viewtopic.php?t=12997&SearchTerms=cartridge">project</a> was abandoned a while ago, although with all this talk of semi-auto combustions, I might just be tempted to re-visit it...

True, having to make a lot of cartridges and refill them separatly is a pain in the behind, but the final effect is a lot more gratifying in my opinion.
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Postby killjoy_xt » Thu Feb 01, 2007 2:33 pm

hey guys

finally found a simple way to make the semi-auto version gun automatic. its pretty simple just remove the sparker and replace it with a battery, and in the place of the trigger make a split in the wire going to to the metal brace, so that when you squeeze the trigger the circuit is completed meaning that as soon as it makes contact with the brace the rounds will fire. but at the same time once you release it the gun stops firing cuz you just broke the circuit. although there are still minor modifications with the internals to be done, it is more ore less the same interior design. also i have been working on a Gatling gun version that self fuels, vents, and loads a projectile, so that you dont have to keep replacing spud bullet.
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Postby killjoy_xt » Thu Feb 01, 2007 5:31 pm

"Spud Gatling Gun" "feeding homeless people at 10 servings per second"

The spud Gatling gun is a very complicated piece of equipment, although if built you might get a rate of 5-10 or even more potatoes per second. This new weapon no longer relies on spud bullets but instead refuels and vents itself as it turns. First off let me show you how the loading works. Loading has been simplified. All it is is a piece of PVC pipe with a separator in the middle allowing an opening in it. Then as the barrel comes into position the bullet drops into the barrel lining up with the rest of the barrel. A bullet is simple; all it is is a small piece of PVC tubing with a potato in it. In the pic below the potato is brown, the barrel is green, the PVC bullet cartridge is blue, and the round holder is pink
<a href="http://photobucket.com/" target="_blank"><img src="http://i85.photobucket.com/albums/k76/killjoy_extreme/bullet.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>
Next comes the ignition system. Again it seems fairly simple, all it is is a regular chamber, except the wire for ignition(pink) passes inside the chamber and lies flat on the lip of the outside of the chamber. Another pointer that you guys might find odd is that non of the chambers have a breach,. They are completely opened in the back to allow for the other processes. The only thing that keeps the gasses in, is the fact that it presses firmly against the brown rear plate which will be explained later.
<a href="http://photobucket.com/" target="_blank"><img src="http://i85.photobucket.com/albums/k76/killjoy_extreme/chamber.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>
The system that keeps everything in place is basically a big shaft that runs the full length of the gun holding everything in place. It is described in this picture as being light brown(picture is of the inside of the gun). It is connected to the gray handle and rotates according to it. It on the other hand is separated from the dark brown rear plate which doesn’t move and is glued or nailed onto the base.
<a href="http://photobucket.com/" target="_blank"><img src="http://i85.photobucket.com/albums/k76/killjoy_extreme/insideg.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>
Ok so let me show you the controls. As you can see this is the rear of the gun. In gray you can see turning handle and in light brown you can see the main shaft. The guns refueling system works as follows. The dark brown circle is the stationary fuel system and the light brown is the main shaft which is connected to all the individual potato guns. As the shaft turns is puts the potato guns through a refueling phase comprising of 4 phases. 1: venting, venting is the longest process because it is the most important to rapid fire. All it is ia a metal mesh that enables the exposed rear to breath for a few seconds. You might want to add fans back there to speed it up for a more rapid rate of fire. Next is phase 2, the spud bullet is loaded into the barrel,. After comes phase 3 which is fueling. Fueling is basically a hole that is connected to a nozzle that is connected to a propane tank (yellow), which is left on during use. as the bullets pass through this phase, they get filled up rapidly by the high pressure propane that is being pumped in the back. Finally phase 4 where the chamber lines up and the circuit(green) is completed ultimately firing off the round (battery is cyan).
<a href="http://photobucket.com/" target="_blank"><img src="http://i85.photobucket.com/albums/k76/killjoy_extreme/controls.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>
The final product looks like this. Oh and by the way for those who love to see ejection shells, you will not be disappointed. Although they fly out at the bottom its still a nice scene to see a pile of shells on the floor
<a href="http://photobucket.com/" target="_blank"><img src="http://i85.photobucket.com/albums/k76/killjoy_extreme/done.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>
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