Multiple barrel cannon with reroutable chamber/ barrel paths

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
geniusbomberman
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Thu May 28, 2009 10:21 pm

I am trying to design a new spud gun, it will have three ignition chambers and three barrels. However, this is not three spud guns glued, taped, or welded together. look at the below design for the rough idea. Obviously, I have not included ignitors, exhaust valves, or the hatch that propellant is inserted through. Barrel II is 3 or 4 inch while the others are 1.5 or 2 inches. Chamber B is larger, and may possibly use a stronger fuel. Would standard ball valves work to seal off certain barrels from certain guns? This is designed so that there are multiple configurations, such as each of the chambers connected to the central cannon or each to the one in front of it. Would this work, and if so, what would be good fuels.


P.S. Steal my design without my permission or saying it is my design and you owe me a design, a gun, some spuds and a rifled barrel.
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this is the basic design
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Technician1002
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Fri May 29, 2009 12:18 am

geniusbomberman wrote:I am trying to design a new spud gun, it will have three ignition chambers and three barrels. However, this is not three spud guns glued, taped, or welded together. look at the below design for the rough idea. Obviously, I have not included ignitors, exhaust valves, or the hatch that propellant is inserted through. Barrel II is 3 or 4 inch while the others are 1.5 or 2 inches. Chamber B is larger, and may possibly use a stronger fuel. Would standard ball valves work to seal off certain barrels from certain guns? This is designed so that there are multiple configurations, such as each of the chambers connected to the central cannon or each to the one in front of it. Would this work, and if so, what would be good fuels.


P.S. Steal my design without my permission or saying it is my design and you owe me a design, a gun, some spuds and a rifled barrel.
The physical layout as shown would have structural issues with recoil and stressed joints leading to failure. The flow rate of smallish ball valves between the side chambers and the center barrel would be too restrictive to be useful. 3 Spud guns bonded together with close nipples joining the chambers for a common ignition would be fine. Short (close) nipples would reduce the torque stresses that the spacing the ball valves would have.

I don't think you have much worry about your design being stolen. Not too many people would be interested in building it.
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Moonbogg
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Fri May 29, 2009 12:37 am

What are you trying to achieve with this design? Answering that question would be a good starting point.
geniusbomberman
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Fri May 29, 2009 8:04 am

the idea was that the central barrel could be raid fired 2 or 3 times without taking time to allow the chamber just fired to cool down. If I removed the other guns from this design, could it be useful for that?
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inonickname
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Fri May 29, 2009 8:51 am

To answer your question, no.

You can have a nicer appearing cannon with much more performance still have a respectable ROF.

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I don't know why you could want a more rapid ROF for recreational use than that. Unless you want a paintball marker.

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Which would be that.
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geniusbomberman
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Fri May 29, 2009 9:23 am

what about 1 chamber with multiple barrels attached that Valves could switch between? Not removable barrels, but like I would be able to load 3 potatoes and fire them 1 (or 2, or 3) at a time, only pausing to reload the chamber with the aerosol, gas, or pressurized air.
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inonickname
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Fri May 29, 2009 9:40 am

A well designed gun would work better. Loading time with cam locks is insignificant and allows quicker venting anyway. Even less with a magazine. If you fire multiple barrels at the same time you get more recoil, much less power and then lose all gas as soon as one clears the end of the barrel.
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Ragnarok
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Fri May 29, 2009 12:34 pm

geniusbomberman wrote:P.S. Steal my design without my permission or saying it is my design and you owe me a design, a gun, some spuds and a rifled barrel.
Now, why is it always the newbies that barge in with an idea and threaten people with nastiness if it's "stolen"?
I can't think of many veterans doing it, but that's probably because the veterans keep back the ideas they don't want stolen (and don't need to ask for help on them).

Anyway, if that's your principle, I think you might be owing someone some stuff, because I'm fairly sure I've seen something similar in the past.
I can't remember immediately remember where, but it may come to me later.

~~~~~

Also, your design needs an extra ball valve between Chamber B and barrel 2 - else if you were firing off a side chamber, then it would either ignite chamber 2 (if it were fuelled) or the chamber would just be a vast dead space.
Does that thing kinda look like a big cat to you?
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Fri May 29, 2009 1:29 pm

geniusbomberman wrote:P.S. Steal my design without my permission or saying it is my design and you owe me a design, a gun, some spuds and a rifled barrel.
I wouldn't worry too much about someone stealing your design;
1. The design sucks.
2. The chances of a newbie thinking up something that is truely new is pretty much zero.

All that piping is going to make mixing a PITA.

All that piping significantly increases the surface area, which increases heat loss, which reduces performance.

There is really no need to let the gun cool down between shots. It doesn't get that hot and you can't load, fuel, mix, fire and vent all that fast.

Even having three chambers preloaded and then fired through the same barrel won't heat the barrel up that much.

The time it takes to get decent mixing is going to offset the ability to fire quickly.

Any design that treats the combustion gases as if they are just compressed air isn't going to work very well. The energy in the gases is due to their very high temperature. But gases have very low densities and low heat capacities. Add those three factors together and you get a system that looses energy very quickly. You can't just pipe the gases from one place to another. By the time the gases get there they will have cooled off and the pressure will be back near zero PSIG.
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