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The "black death" pnuematic paintball gun

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Unread postAuthor: MrCrowley » Thu Jan 11, 2007 2:34 am

SpudBlaster15 wrote:
MrCrowley wrote:I would estimate 350-450fps,
If you dont want to sleeve it just put a piece of long circular wood under the barrel and tape it to it,leave it over night and it straightens it out,I leave mine on 24/7 though, it makes aiming easier.

Edit:Woah I just realised he using 1.5" as the chamber dia....ill re-estimate my ggdt guess


Why did you drop your estimate by 150fps when you realized I was using a 1.5" chamber? With that chamber size, I have already hit the point of diminishing returns. If I were using 2" pipe instead, the muzzle velocity would only increase by ~40fps. A massive, oversized chamber does nothing but decrease efficiency.


Because I know my paintball rifle at 120PSI with 2 FE's(9cm I.D, 30cm long each) only shoots 650fps with a 1.6m long barrel, I estimated with your gun at 100psi with your barrel and small chamber, When I only had 1 fire extinguisher as the chamber GGDT said 550FPS.One FE as more volume then your chamber then I scaled down the pressure 115-100psi and the shorter barrel and took 150fps of my orginial estimate. Its an estimate calm down.
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Unread postAuthor: SpudBlaster15 » Thu Jan 11, 2007 2:38 am

Here is the GGDT reading for this gun.

Image

I actually think the chamber may be slightly larger than 25 cubic inches, I havent done a fluid volume measurment on it, my calculations are based soley on pir^2h and are quite conservative.

See my point about diminishing returns? You have more than twice the chamber volume as I do, you are using a higher pressure, and your barrel is longer, yet your gun only shoots ~55fps faster. I much prefer a lower ratio as opposed to a hugely exagerated one.
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Unread postAuthor: MrCrowley » Thu Jan 11, 2007 3:35 am

Ok 2 problems there

1:You said the valve was a barrel sealer...wrong,you need to put it under generic
2.You put the barrel bore as .68" when its not, its slightly larger so there is some blow by but very little probably 2-3fps worth...no biggy :P

I just run it and got 550fps something I forgot...My original estimate wasnt too bad :P and my second was 100fps off :(
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Unread postAuthor: SpudBlaster15 » Thu Jan 11, 2007 10:48 am

No, diaphram valves ARE barrel sealers, and I am using data compiled by people (who actually know what they are talking about) from Spudtech.

Measured with a digital caliper, the paintballs are 17.27mm, and the barrel ID is 17.32mm. The difference is hardly worth mentioning.
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Unread postAuthor: joannaardway » Thu Jan 11, 2007 10:53 am

Hmm, I've seen muzzle velocities of 890 fps with paintballs - enough to put very serious dents in 1mm steel plate.

NoName wrote:Plus, the barrel of any pneumatic gun is at a pressure of 15 psi or less when firing.


I have to disagree with that. Simple calculations can disprove that in an instant - or even a glance at GGDT's "barrel pressure" graphs.

EDIT: I believe that actually, a sprinkler valve is a chamber sealer...
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Unread postAuthor: MrCrowley » Thu Jan 11, 2007 4:15 pm

SpudBlaster15 wrote:No, diaphram valves ARE barrel sealers, and I am using data compiled by people (who actually know what they are talking about) from Spudtech.

Measured with a digital caliper, the paintballs are 17.27mm, and the barrel ID is 17.32mm. The difference is hardly worth mentioning.


When I put your figures you supplied under barrel sealer there was an increase of 25fps then when I put the sprinkler valves REAL figures in under generic (which were gathered by people who know what theyre talking about from spudtech). hmmm funny that, I also believe D_Hall suplied them....and who is he again? Oh yeah he made GGDT :roll:

Why would D_Hall make a generic option when people would put it under a barrel sealer? The generic option is more acurate and the better way to do it.

And I was joking about that barrel I.D if you didnt read.
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Unread postAuthor: SpudBlaster15 » Thu Jan 11, 2007 6:44 pm

The "generic" option was created to allow users to estimate performance of a valve which does not fit into the other categories, ie. ball valves and butterfly valves. You can estimate the performance of a sprinkler valve using the generic option, but your figures are obviously quite off. Using inputs that you can measure with a ruler and a scale, GGDT calculates the numbers you have to guess when using generic. Here are the true figures.

Ok, GGDT inputs for 1" and 3/4" Orbit Watermaster valves

Valve Type: Barrel Seal
Flow Coef: Still trying to work on figuring these out, for now I would go with current estimates... around 6 for 1"
Seat Diam: .95" in a 3/4"...1.1" in a 1" (diameter measured at where the seat actually seals if anyone is wondering where that came from)
Piston Diam: 1.8"
Piston Mass: .8 oz
Vent diam: .05" with solenoid, .1" to .2" depending on the blowgun. .2" usually requires modification on most blowguns.
Pilot volume: 1 in³
Dead vol: up to the end of the threads. 1.5 in³ in 3/4", 2.2 in³ in 1"


Read the "CV list for various valves" to further reduce your level of ignorance.

890fps is acheivable, but you would need, at the very least, an 11 foot barrel and a chamber to match to aheive such velocities at 100psi using a sprinkler valve. "Portability" came to mind while designing this gun.
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Unread postAuthor: Zorrowannabe9 » Thu Jan 11, 2007 10:38 pm

SpudBlaster15 wrote:Those speeds are not possible with my barrel size. I would need a 6 foot long barrel and a 300 cubic inch chamber.


your barrel is exactly the same length as mine (actually about 1" longer if its truely 4')
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Unread postAuthor: MrCrowley » Thu Jan 11, 2007 11:53 pm

SpudBlaster15 wrote:Read the "CV list for various valves" to further reduce your level of ignorance.


F*ck of man, are you stupid or what! Where the f*ck do you think I got those figures from D_Hall.... Erghh are you f*cking dumb!

That thread has all the CV's people have calculated where else would I get them? I got the other info from another thread that D_Hall posted some figures for a 1" sprinkler piloted by a blow gun, I think he knows what he is doing, Obviously you dont, So I think your the thick one here mate.

And why would reading that thread reduce my ignorance level? I read it when I first got my sprinkler valve awhile back,I know the figures off by heart now, but the people who posted in that thread know sh*t loads more then you buddy.

Why are you having a go at me? I took an estimate judging by the barrel length and chamber volume and valve used. Its an estimate not a statement. I didnt run one part of my estimate through GGDT, what did you expect? And for the barrel sealing part most people I knw put there sprinklers under Generic, Those people are also the smarter people and get better figures. Why would you put one thing under another when it has its own area to put it under? Like putting a Jack Russel in a Labrador kennel....they are both dogs but you just dont do it.
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Unread postAuthor: SpudBlaster15 » Fri Jan 12, 2007 1:27 am

Why am I having a go at you? Because you are ignorant and stupid and dont even realize it, and you are spewing it all over my thread!

Your last post proved nothing aside from that you can throw insults around without actually backing your information. "He said this in this thread" isnt gonna cut it.

Let me ask you, if you were to mod your blow gun as I just did, increasing your vent diameter from .1" to .2", how would you alter the numbers for a calculation using the generic setting? By using the more accurate barrel sealing option, I simply changed the parameter directly, and the estimated velocity increased by 85fps. Piston valves and diaphram valves are almost identical in their operating principle.
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Unread postAuthor: MrCrowley » Fri Jan 12, 2007 2:02 am

I just cant take anyone seriously who thought this:
Originally posted by SpudBlaster15
Originally posted by PotatoNick
a 1.5" barrel is going to get to you more range and velocity than a 2".


More velocity yes, but range, no. A larger (and thus heavier) projectile will have more inertia than a lighter projectile, resulting in a lesser drag effect, and thus, more range.


You must be stupid to think a heavier projectile or a bigger bore barrel automatically makes the projectile go further then a smaller bore.
It takes more force to push out the heavier projectile and it cant gain the same speeds as its heavier then the 1.5" projectile, Also theres more surface area meaning more drag and resistance. If you shot a 1.5" supah ball out of a 1.5" barrel it would go further then a 2" supah ball fired out of a 2" barrel(with the same volume chamber,and same valve)even if the 2" supah was say 15gm heavier

And I dont see how increasing the blow guns flow by .1" increases your velocity by 85fps. Unless your stupid and worded that bad.\

I still dont get what you have against the 'CV list for various valves' Thread on SGTC.

SpudBlaster15 wrote:Let me ask you, if you were to mod your blow gun as I just did, increasing your vent diameter from .1" to .2", how would you alter the numbers for a calculation using the generic setting?


Why would you even enter those numbers? The FPS increase wouldnt be noticable. You'd be better of increasing your barrel length by 10cm
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Unread postAuthor: SpudBlaster15 » Fri Jan 12, 2007 2:16 am

Wow, you are by far the stupidest person I have talked to on these forums.

You must be stupid to think a heavier projectile or a bigger bore barrel automatically makes the projectile go further then a smaller bore.
It takes more force to push out the heavier projectile and it cant gain the same speeds as its heavier then the 1.5" projectile, Also theres more surface area meaning more drag and resistance.


EDIT: I should have worded this differently. In some cases my post would be true - if the frontal surface area was the same. This comes into play when discussing projectiles of similar sizes, but differing densities. Also, a larger (heavier) projectile fired using the same amount of energy as a smaller projectile would go further, however, a 2" circle has twice the surface area of a 1.5" circle. With drag being proportional to surface area, there is a reduction in the effect of inertia. I suspect close to equivelant speeds in practice.

And I dont see how increasing the blow guns flow by .1" increases your velocity by 85fps. Unless your stupid and worded that bad.


Good job, you avoided the question as you cannot answer it, but you just made yourself look even stupider. Increasing the volume by a factor of 4 makes a large difference, I will post the GGDT file in a bit.

I still dont get what you have against the 'CV list for various valves' Thread on SGTC.


I have nothing against it, in fact, that is where I derived my numbers from. But I guess you are "just stupid and worded that wrong".

Why would you even enter those numbers? The FPS increase wouldnt be noticable. You'd be better of increasing your barrel length by 10cm


Do I have to use the 6 letter word that begins with an S again? I think I will use 'intellectually inadequate' this time.
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Last edited by SpudBlaster15 on Fri Jan 12, 2007 2:49 am, edited 2 times in total.
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Unread postAuthor: Recruit » Fri Jan 12, 2007 2:18 am

Ok the two of you cut it out
Spudblaster is it worth proving MrCrowley wrong?
You might be could be right or you could simply be trying disprove crowley so you will look good but if you are right just let him stay ignorant if he wants to be ignorant let him. I highly doubt Crowley would be wrong considering how many post he has made and how long he has been a member since June 24, 2006 and you have been here since October 19, 2006.

MrCrowley is it worth proving spudblaster wrong?
You might be right to probably are and same for you if you are right just let him stay ignorant if he wants to be ignorant let him.
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Unread postAuthor: MrCrowley » Fri Jan 12, 2007 2:22 am

SpudBlaster15 wrote:
I have nothing against it, in fact, that is where I derived my numbers from. But I guess you are "just stupid and worded that wrong".


Well since you wrote this......Read the "CV list for various valves" to further reduce your level of ignorance.

Ok see you did diss that thread.

And did you not even bother to read Joanna's responce on SGTC to the whole intertia thing? Run it through GGDT you'll find the 1.5 supah ball goes a whole 100' further.

"It is obvious you dont understand the concept of inertia. When you finish elementary school, come back and talk to me. Given the same muzzle energy, a heavier projectile will go farther due to inertia."

No it wont, not all the time. I dont even know wtf elementry school is....like Americans don't know who David Beckham is.....(News report on it I saw today :lol: )
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Last edited by MrCrowley on Fri Jan 12, 2007 2:29 am, edited 1 time in total.
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Unread postAuthor: SpudBlaster15 » Fri Jan 12, 2007 2:24 am

I hate it when people base one's knowledge on their post count and longevity on the forums. Crowley seems to be a slow learner and obviously hasnt picked up alot throughout his duration here.

Anyway, here are the new GGDT numbers... 670fps at 100psi.

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