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a little help for the new guy

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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a little help for the new guy

Unread postAuthor: Mr.michael.2468 » Sat Jan 08, 2011 11:56 am

hello i'm kinda new to this website but i've built quite a few cannons, i have 3 cannons a combustion one, a sniper cannon and my huge spud gun, i just put a 1in modified sprinkler valve on my sniper cannon it seems to be a lot more powerful then my old 3/4in ball valve that i had on it but from animations and research it seems like the gap that allows the air through a diaphragm valve would be rather small compared to my 2in ball valve on my giant spud gun which i'm considering replacing with another sprinkler valve. if anyone could explain to me why the sprinkler valve would be so much more powerful? also i wanted to add the dual chambers with dual valves to my largest gun i've seen pictures but no ones really posted anything about it. at the moment my giant spud gun is as basic as it can get yet i can launch a 2in spud about 400 yards at 60 psi with it. id like to boost that even higher with some good sprinkler valves to replace my little 2 in ball valve. i can post pics of what iv got at the moment. finals are going on rite now so the sniper cannon is sitting around in pieces but i should have it done with some performance results posted soon. id like to use the GGDT thing but i cant get it to work :/ any help on that would be great too.
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Unread postAuthor: saefroch » Sat Jan 08, 2011 12:22 pm

A sprinkler valve provides much better performance than a ball valve because of the faster opening time. This thread on the opening time of a ball valve may be of interest to you. GGDT can model the opening time of a sprinkler valve, once you get it working.

Dual chambers with dual valves may give you a performance boost, but it will likely be minor. How do you plan to do this?

Are you running Vista or using a Mac?
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Unread postAuthor: SpudFarm » Sat Jan 08, 2011 12:34 pm

but it will likely be minor


If he is using valves that choke flow, using sevral valves will significantly boost performance.
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Unread postAuthor: Mr.michael.2468 » Sat Jan 08, 2011 12:37 pm

well i'm on my mac at the moment but i tried using it on my parents new pc with vista on it, i got it downloaded but its like i need a different driver or something to run it. it just shows up with a bunch of files and double clicking on any of them just wants me to try and find a driver for it. but that was my hunch on the sprinkler valve because it opens so incredibly fast. also i found for my sniper cannon its much more accurate because when you open a ball valve the guns jumps around and its impossible to shoot accurately. i just made a video of the sniper in action the shells i've made for it are actually very powerful and seem to have a very straight flight path, i made a video of it that i'm going to make and post pretty quick so u can see what i'm talking about a little more i know its hard to help with a visual. the dual valve system that i asked about i've only seen it before its like they rig both of the valves with a high pressure hose between the outlets were the blow gun would normally go and attach it to one blow gun so they open at the exact same time. seemed like this would really up the power because i've seen how much more powerful a little bit larger diameter valve is. so two super fast valves would seem to act like a multiplier to some extent of your chambers ability to vent quicker. i know this is getting a little long winded sorry for that...
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Unread postAuthor: Mr.michael.2468 » Sat Jan 08, 2011 1:12 pm

heres the video i hope its uploaded through youtube i didn't know how else to do it.[youtube] http://www.youtube.com/user/MrMichael2468?feature=mhum [/youtube]
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Last edited by Mr.michael.2468 on Sat Jan 08, 2011 3:57 pm, edited 1 time in total.
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Unread postAuthor: Technician1002 » Sat Jan 08, 2011 2:23 pm

I have found that a single large valve will outperform many small valves in parallel. If the valve is a flow restriction, a larger valve works best.

A quick note on opening sprinkler valves in parallel, with the pilots tied together and the outlets joined, when one cracks open it is the rise in pressure on the second valve to open will cause it to trip.

When the two valves are tied together by only the pilot, when one pops open, there is a momentary rise in pilot pressure as the diaphragm moves into the pilot air space. This would normally delay the opening of the second valve, such as a dual barrel arrangement. The drop in inlet pressure if the two valves share a chamber will also delay the opening of the second valve to open. The key is to have both valve outlets coupled together into a T to ensure they both trip.
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Unread postAuthor: Mr.michael.2468 » Sat Jan 08, 2011 5:22 pm

ya 1002, that makes sense, im not looking to invest a lot into these guns i dont really even have a job so im kind of limited by that... so im probably going to leave my larger spud gun alone for awhile but since im in the process of building my sniper any help on that would be great, i bought a little emergency air compressor that can do up too 300 psi it can fill that air tank thats like twice the size that it needs to be to 100psi in like a minute so im gona use that to compress it to like 200 for a normal shot is what im expecting to use as my normal shooting pressure im using a 1" rain bird valve can it handle that :?: and after watching that video the ammo i'm using are little electrical caps that are filed down a little bit to fit the sch80 pipe with the 3/8in steel ball bearings that i got as slingshot ammo, does anybody have any idea how these might fly for accuracy? i'm hoping for something like 50-100yrds pretty accurately? there based off of sabot styled ammo with the weight concentrated towards the front to increase accuracy.
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Unread postAuthor: Technician1002 » Sat Jan 08, 2011 5:34 pm

at the moment my giant spud gun is as basic as it can get yet i can launch a 2in spud about 400 yards at 60 psi with it.


400 yards with only 60 PSI is actually quite good. I don't think you can get much improvement by changing the valve. How did you measure the 400 yards?
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Unread postAuthor: Mr.michael.2468 » Sat Jan 08, 2011 5:42 pm

actually i used a range finder i have for hunting thats very approximated though could +/- 50 yds cuz u just kinda see a poof of in the distance and its hard to get a reading that far plus there was a wind and was a little down hill so i had some pretty good circumstances but i did that for like idk 30$? less than that actually the gun has a 180 degree bend in it and i've read that bends in the chamber disrupt the airflow causing you to lose a surprising amount of power, and thats with a like 1/.8 c/b ratio something like that it was just a rough estimate i did all i kno is u want like 2/1-4/1 ratio for optimum performance, though its nice and quite as it is :lol: plus its nice for when i dont have a gigantic air compressor to run it which sucks cuz i really should have one.
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Unread postAuthor: Mr.michael.2468 » Sun Jan 09, 2011 2:16 pm

i got GGDT working its pretty cool had to use my old dinosaur to run it for some reason lol
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