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combustion shell theory

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combustion shell theory

Unread postAuthor: dilweed » Fri Feb 29, 2008 5:27 pm

Hello im a noob t this havent built a combustion (yet) but i have had quite a lot of experience at airguns. My main idea is that the firing system works like a real gun, eg: a firing pin. Basicaly im not looking for power but effectivly coolness and if it will work. I know you need a spark or falme to ignite the propellent so heres my idea. also can some one please tell how to post a picture i drew in photoshop.

1.) the is a shell, spherical in shape and pointed near the projectile. I can be any size but preferably 2-5 inches long.

2.) you can precharge the shell by unscrewing the end and spraying hairspray or what ever. in the end of the shell and the unscrewable cap is a small cap gun gunpowder cap. when its struck by the firing pin it creates a small explosion, hopefully exploding the main propellant and gass and explosive force is funelled into the back of the hollowd out bullet, shoves the projectile out the barrel at hopefully acceptable speeds.

to charge and build the shell you need, pzc or metal tube with a thred and cap at one end. drill a hole throught the end of the cap and glue and place the cap gunn cap. whack the other non threaded end into a cylindrecal shap wihich is pointed.

1st open up the threaded cap and sray a burst of your chosen propellant. since the chamber is smaller i think you should spray a second or 2 but always experiment for best results. quickly screw cap back on.

2nd ram the projectile halfway into the cartridge creating an airtight seal and also to create a little back pressure.

insert cartride or shell into clip, breech what ever you want and......hopefuly fire out the end of the barrel. Based on my theory which i thought of my self ages ago and wich im pretty sure no one else did this enables, breech loading, bolt action, semi auto and yes Automatic!!!! please post your ideas.

remember what i said, i do have diagrams, just tell me how to post them. you'll understand it better.

peace-dilweed :)
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Unread postAuthor: pizlo » Fri Feb 29, 2008 5:35 pm

Sounds feasible, but I doubt you will get anything out of 1-2 cubic inches of combustion chamber.
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Unread postAuthor: pat123 » Fri Feb 29, 2008 5:46 pm

to add a picture look at the bottom of the page that you type your message on and it says filename hit the browse button near that and find the file you want. then hit add attachment.

It is a good idea but think about how big a normal combustin chamber is and compare that to the tiny shell you are talking about. I doubt that would be enough to even move the projectile out of the barrel. I would like to see the design to make sure I have it right. there is only one way to find out if it will really work though, try it :P
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Unread postAuthor: STHORNE » Fri Feb 29, 2008 5:54 pm

though the plan sounds pointless, im drawing up a sketch of what i think the projectile should look like.

EDIT: i just realized, with a small hole for the ignition, that isn't going to propel the bullet nearly as fast as it needs to go if it uses that same hole for the expanding gas to escape (propelling the bullet). It will probably just blow itself up if anything.
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Unread postAuthor: jackssmirkingrevenge » Sat Mar 01, 2008 1:16 am

combustion cartridge prototypes

[youtube]http://youtube.com/watch?v=V4q8QJr412Y[/youtube]
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Unread postAuthor: Eddbot » Sat Mar 01, 2008 3:23 am

good luck, i hope you're successful...
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Unread postAuthor: Jared Haehnel » Sat Mar 01, 2008 9:39 am

I think your best bet is to scale up the size a bit. Gun powder won't go off the same way a primer in a shell goes off. The primer is very pressure sensitive and the impact energy actually causes an explosive reaction. Gun powder require considerable more force and or a spark or flame. Believe it or not is a much more stable element then the primers...

I once drew up a design for a cannon that was breech loading with cartages originally it was for paint balling basically a two inch section of pipe was the cartridge. Inside the cartridge it contained a fan and a spark gap space for a fuel air mixture then wadding and the piant balls. The rear of the cartilage was capped with four screws that served as contacts. The from of the cartridge was thread for a two inch thread and would screwed onto a thread couple. The cartridge was around 18 inches long and held
about fifty piantballs

The cannon had a three inch chamber and a two inch barrel. You screwed the cartridge into the rear of the barrel then screw the cap on the chamber the contacts on the rear of the cartridge would match up with on the contacts on the cannons. You flipped the switch for the fan aimed and pulled the trigger. The idea is you had several pre-charged cartridges and reload time would be quick giving a ideal shotgun or artillery for woods ball

My hope was the plastic wrap and paint balls would act as a burst disc making up for the lack of chamber volume however I never got around to building it and I can see some flaws that I would have to work out before it would work... not to mention I am not into paint balling the way I use to be.

Anyway it was going to be real expensive to build and with no real garentee it would work I stuck it away with many more of my projects that never were...

A word of caution we aren't really suppose to be talking about gun power or anything similar to that here on this forum. Gunpowder is dangerous and should not be fooled around with. It was created for a purpose and when used out side of that purpose it tends to wreck more havoc then good.
Take it from a guy who uses it to reload his own ammunition if its not weighed and measured correctly by some one who has a reference you risk blowing up your gun your self and people around you...
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Last edited by Jared Haehnel on Sat Mar 01, 2008 10:18 am, edited 1 time in total.
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Unread postAuthor: jackssmirkingrevenge » Sat Mar 01, 2008 10:12 am

If you're going to use a cap to fire the cartridge, why bother with a fuel-air mix? There are adapters you can buy that will allow you to shoot 0.22 pellets from your 0.223 rifle using just the primer and getting very decent velocities, adding propane to the mix would have little effect.
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Unread postAuthor: frogy » Sat Mar 01, 2008 10:42 am

Primers used to\still? contain Lead Azide\KClO4 with Copper\Zinc\Antimony for fuel

I think Lead Azide has been replaced with Lead styphnate and Tetrazine though...

Sorry, that's kind of random.
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Unread postAuthor: Jared Haehnel » Sat Mar 01, 2008 11:06 am

.... the reason being the KCI04 leaves salt in the barrel. Otherwise known as corrosive ammunition...commonly bought up as military surplus.

If I'm right and please correct me if I'm wrong (cause thats how I learn).... KC is potassium chloride and the only way to really get it out of the gun is to boil it out... or pour really hot water down the barrel to wash it out and give it a through cleaning and drying afterwards.

I had to do it after I put some military surplus .303 shells through my Lee Enfield
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Unread postAuthor: frogy » Sat Mar 01, 2008 12:06 pm

KCl is Potassium Chloride... You should be able to wash it out with a bore cleaner... Most people still use corrosive primers with muzzle loaders and shotguns I believe.
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Unread postAuthor: Jared Haehnel » Sat Mar 01, 2008 12:26 pm

I've been told that bore cleaner will and will not and honestly I love my rifles to much to risk it either way. Since my first encounter with corrosive ammo I won't use it again. Not in my WW2 relics any way.

I've seen a few bores that were pitted worse then the pit of a peach because the owner thought he had cleaned it well enough but hadn't...

As far as I now commercial cartridges do not use corrosive primers...but that doesn't go to say people don't make them. They are probably cheaper but I would rather spend a few extra buck and get the better ammunition then to take any risks.
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Unread postAuthor: dilweed » Sat Mar 01, 2008 5:15 pm

i think some of you are getting my idea wrong,the small cap has about 1 millimeter of gun powder in it, it's function is a percussion cap which is striked by a thin pin pushed by a spring.
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Unread postAuthor: Jared Haehnel » Mon Mar 03, 2008 7:15 am

You will not be able to set regular gun powder off with that kind of device.

A primer does not have gunpowder in it. Its a compound similar to nitroglycerin very sensitive to procession...
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Unread postAuthor: dilweed » Wed Mar 12, 2008 1:58 pm

yes but i have tested it with a quick jab of a nail, anyway i have lost intrest in this now and will build a coilgun
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