My buddy's crazy rubberband gun.

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WOW .. how lond did it take to set all the bands up ...?
 
ha ha thats great!!! and its so funny to hear someone mention a potato gun cuz 2 summers ago while camping we met these guys with a potato gun powered by a big propane tank somehow and man it shot them like 2 to 3 hundred yards i swear!!! i laughed my butt off
 
man, i love seein' people's inventions. also love seein' people make, craft & invent r/c stuff!
 
thats cool...potato guns...man we made them all the time as kids...except the propelnt was from a flame and hair spray...as we got older we made tennis ball launchers...
 
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I have also built several potato guns, but I always try to avoid doing anything half ***ed, and a traditional "Spray in the propellant, close the cap" system was too inaccurate for me. Hence the propane meter that injects a perfect 4.2% propane into the chamber, forming a stoichiometric mixture. The potatoes are cut and loaded through the cam lock fittings at the beginning of the barrel, and a ball valve is mounted to the end cap to enable faster venting of the combustion products than a standard screw cap. There is also a fan in the chamber to vent the chamber and mix the air and fuel more quickly than waiting an hour for entropy to do it... The ratio of chamber volume to barrel volume is nearly optimized to transfer as much energy as I can from the fuel to the barrel... As you can see I don't half *** stuff... however in the picture the meter is missing its pressure gauge. If anyone wants to know how the meter works just let me know...

IMG_1675.jpg


Here is a better picture of the same meter on the original chamber that I built back in 2006. The new chamber is significantly stronger and better designed.

Picture546.jpg


And before you all come yelling "OMG YOU'RE GOING TO BLOW YOURSELF UP", I have pressure tested all of these fittings to 5 times the maximum pressure they will see in use and they held up, so I know that they are perfectly safe.
 
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lol I built the same meter no gadge... got it off spud guns .com or something close to that. I used mapp too. thats too funny
 
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that thing is sweet man. i love home made guns. check out this potato cannon ascender made some of you know him
100_1056.jpg






 
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that rubber band gun took some serious engineering to come up with all the timeing and to get it to work...... nice work ... now find a bully and let him have it lol you know the bully you had in the back of the class zinging rubber bands at the other kids...uhhhhh wasnt me teach i swear lol......
 
NITROMITE said:
that thing is sweet man. i love home made guns. check out this potato cannon ascender made some of you know him
100_1056.jpg
Click to expand...

That looks like a commercial 2" diaphragm valve, those things are not cheap.

Pretty basic but nice pneumatic cannon.
 
inb4lock said:
That looks like a commercial 2" diaphragm valve, those things are not cheap.

Pretty basic but nice pneumatic cannon.
Click to expand...
i bealive so. you would have to talk to ascender to be shure. i love the sound that thing makes when fired "never heard anything like it"
 
It appears to have a decent sized pilot valve, so the main valve should actuate fast, and the report should sound like a pretty loud crack. I've built a few pneumatic cannons myself, but nothing of that size.
 
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