Basic design for launcher

[niglch]

I was bored over the last couple days so I decided to model a quick plan for my second cannon. I thought it was a little interesting because of the trigger and handle placement. I'm going for a 1.2:1 C:B ratio with the monster 72" barrel. Any comments are appreciated (like if it's going to blow up, please tell me).

Edit: Blender was used to create the models.

[spud yeti]

That looks pretty good. What program do you use?

[iPaintball]

Your rendering looks great! What program did you use?

Anyway, this looks good, but a few things I suggest that should be incorporated in your design are:

1. Add a chamber an to allow more cosistent fueling and firing
2. Wire multiple spark gaps in your chamber
3. If you can, build a propane metering system.

Propane burns much cleaner the aerosol sprays, and you will get mor power and more efficient coumbustion if you do build a meter.

Overall, I really like your design. I hope to see it when it is constructed.

[psycix]

Your rendering looks great! What program did you use?

Anyway, this looks good, but a few things I suggest that should be incorporated in your design are:

1. Add a chamber an to allow more cosistent fueling and firing
2. Wire multiple spark gaps in your chamber
3. If you can, build a propane metering system.

Propane burns much cleaner the aerosol sprays, and you will get mor power and more efficient coumbustion if you do build a meter.

Overall, I really like your design. I hope to see it when it is constructed.

then it wont be a basic design anymore, but an advanced one!

[SpudBlaster15]

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[niglch]

With the setup you describe, your ratio will be closer to 0.9:1. It amazes me how so many people cannot even do basic cylindrical volume calculations.

If you want to maintain the same (roughly) chamber volume and increase performance, use a 4" x 10" chamber instead. This will drastically decrease combustion time, and performance will skyrocket.

If you want a 1.2:1 ratio, go with a 4" x 14" chamber.

I was taking into account the pipe connecting the chamber to the barrel as part of the chamber volume (although I did not list it). I was only being approximate and subtracted some length from the chamber to compensate.
I will take into account what you have said about using a 4" diameter chamber, but I was planning on using dual ignition which may make a 3" chamber perform similar to a 4" chamber. The only other thing I'm wondering about is what I'm going to use for a sight or scope. I know potato guns aren't that accurate, but what the heck, everyone loves scopes.

EDIT: Oops, I happened to be looking at the "smart guess" thing on RatCalc which is where I made my error in chamber volume calculation (I guess the cut piece of chamber pipe will be about 18"). I guess I should have been less lazy and used good old pi*r^2*h.

[jimmy101]

Nice design.

You'll probably want more bracing between the barrel and the chamber, there'll be a heck of a lot of force on the U-bend from chamber to barrel.

[niglch]

I was thinking for a bit on this gun and I'm wondering what I would do if a spud was accidentally loaded down the barrel too far and got stuck halfway down the connector. This would probably cause the potato to jam and make the gun unsafe to fire (I'm guessing the chamber would burst if no gas was allowed out). There are plenty of over-under designs like mine though, so how do you prevent this kind of problem?

Thanks

[pyrogeek]

I use a ramrod long enough to push my spuds or golfballs down to where I want, and that's where they end up. That's good enough for me. Screwing a screw into the end of the barrel through the fitting would act as a stop though, if you want something more definitive.

[SpudBlaster15]

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[jimmy101]

I was thinking for a bit on this gun and I'm wondering what I would do if a spud was accidentally loaded down the barrel too far and got stuck halfway down the connector. This would probably cause the potato to jam and make the gun unsafe to fire (I'm guessing the chamber would burst if no gas was allowed out). There are plenty of over-under designs like mine though, so how do you prevent this kind of problem?

Thanks

I don't hink it is possible to jam a spud tightly enough to cause a problem. The spud will start to move, perhaps by fragmenting, when the pressure gets high enough. So I wouldn't worry about it too much.

[sandman]

as long as you use pressure rated parts i dont see this being a problem, the fittings should be able to take the pressrue

[niglch]

Agh, ok I was just thinking for a while about how I should go about that whole crazy BBQ trigger system I came up with. As already stated, the chamber will need to be sufficiently braced to the barrel with the design I have. Admittedly, I'm still quite a n00b and I'm not sure what to use to secure the trigger part between the barrel and chamber and have it play the double role of serving as a good bracing, too.

Sorry I'm asking so many questions but I've searched the forums a lot and haven't found much. At least I'm trying to keep my noobiness confined to this one topic

note: i'm now planning on using a shorter 4" chamber instead of a long 3" one.

Thanks again!

[Modderxtrordanare]

Agh, ok I was just thinking for a while about how I should go about that whole crazy BBQ trigger system I came up with. As already stated, the chamber will need to be sufficiently braced to the barrel with the design I have. Admittedly, I'm still quite a n00b and I'm not sure what to use to secure the trigger part between the barrel and chamber and have it play the double role of serving as a good bracing, too.

Sorry I'm asking so many questions but I've searched the forums a lot and haven't found much. At least I'm trying to keep my noobiness confined to this one topic

note: i'm now planning on using a shorter 4" chamber instead of a long 3" one.

Thanks again!

Take two pipe saddles (or tees you saw in half) and connect them (you'll need reducing bushings in them, since the barrel and chamber are different sizes) and use hose clamps to hold them to the barrel and chamber. That will be a sufficient brace to support the barrel and chamber. You could then attach your bbq ignitor to that and have one of your handles done.

[Redcoat]

thats a good clean design and would would work.

Post it when your done.If you are building it at all.

Happy Spuddin'