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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.
whitt
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Fri Jun 05, 2020 9:59 pm

I am very new to this all and I was hoping someone could explain some stuff to me. Just what seems to be basic stuff, like what is the purpose of a fan in the combustion chamber, what is hgdt I have seen it quite a lot in older stuff from like 2010 and when I google it doesn't show up, also what is some advice for a beginner like my self I have built one combustion cannon so far and it runs off map-pro gas and has a 14-inch long combustion chamber at 3-inch diameter and 24-inch long barrel at 1-inch diameter and just a simple button press piezoelectric igniter in the back drilled into a screw-on cap and epoxyed on you have to unscrew the cap and spray the map in for like 5 ish seconds and that seems to go pretty good but I would love help to build one that could do better and lastly I would really love some help with some ammunition like APFSDS or similar or just some round that could do some damage, just for fun. Thank you so much!
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jackssmirkingrevenge
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Tue Jun 09, 2020 6:41 am

Welcome to spudfiles!
whitt wrote:
Fri Jun 05, 2020 9:59 pm
what is the purpose of a fan in the combustion chamber
When the fuel and air are properly mixed, this will boost performance and consistency. That being said, adding a fan is not going to double your power.
what is hgdt I have seen it quite a lot in older stuff from like 2010 and when I google it doesn't show up
HGDT is short for Hall's Gas gun Design Tool.

It is a program that allows you to virtually model the parameters of your launcher.

You can download it here.

Worth learning to use, you can answer questions like "how much more power will I get if I make the barrel 6 inches longer" without having to actually build it.
also what is some advice for a beginner like my self I have built one combustion cannon so far and it runs off map-pro gas and has a 14-inch long combustion chamber at 3-inch diameter and 24-inch long barrel at 1-inch diameter and just a simple button press piezoelectric igniter in the back drilled into a screw-on cap and epoxyed on you have to unscrew the cap and spray the map in for like 5 ish seconds and that seems to go pretty good but I would love help to build one that could do better.
One of the best things you can do is eliminate the "5 ish second" guesswork and accurately meter your fuel.

Have a look at syringe metering:


lastly I would really love some help with some ammunition like APFSDS or similar or just some round that could do some damage, just for fun.
Custom ammunition is a little harder to get into if you do not have more sophisticated tools.

I would look at ways to increase your cannon performance first, that means even a potato will do a lot of damage.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Moonbogg
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Tue Jun 09, 2020 2:30 pm

Can't believe I missed this post. JSR (guy above) covered it all. Welcome to the forums and keep us posted.
whitt
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Tue Jun 09, 2020 8:27 pm

thank you for this all! very helpful

I clicked on the link to download the program, but the domain expired is there any other way to get it?
Last edited by jrrdw on Fri Jun 12, 2020 4:42 am, edited 1 time in total.
Reason: Double post.
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jackssmirkingrevenge
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Fri Jun 12, 2020 5:48 am

hectmarr wrote:You have to make many weapons, because this field is long and short life
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