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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: Recruit » Fri Jan 12, 2007 2:26 am

Just shut up both of you.
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Unread postAuthor: SpudBlaster15 » Fri Jan 12, 2007 2:53 am

I will shut up if Crowley starts making posts that utilize more than 3 neurons.
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Unread postAuthor: MrCrowley » Fri Jan 12, 2007 2:55 am

How would you know im a slow learner? You werent here when I started out so you have no idea what I have and havnt learnt and obviously more then you.

Ok now re-do it but using the valve under generic instead of barrel sealer, this is what GGDT gave me:
ok it wont upload...bloody photobucket...anyway it gave me 627fps instead of 670fps under barrel sealer. And the .2" mod is just taking the nozzle of the blow gun everyone does it and they calculated that into the generic option wiht the opening time and what not.


Did you do the weight/inertia test yet? Have you finaly realised weight doesnt mean distance?
And incase you didnt read Joanna's responce:

"Posted - Jan 09 2007 : 07:12:48
--------------------------------------------------------------------------------

PotatoNick's claim is right, but the science is flawed. To straighten it out:

Assuming the 1.5" and 2" spud slugs are the same length, their weight is proportional to their cross sectional area (as their length is fixed), as is the drag force.

Under F=ma, . If the mass doubles, and the force doubles, then the end acceleration is the same. So, the deceleration from drag at the same flight speed is equal for both bores.

As the 1.5" slug weighs less and thus goes faster in the first place (lower bore, so longer barrel to accelerate along for the same chamber size), then that means that range will increase by a certain degree.
When it has slowed down to the same speed as the 2" slug would have, then it'll will have already gone some distance, and have more altitude - from that point it follows the same ballistic arc as the 2" slug would have done from the muzzle, ignoring tumbling and variations of wind with altitude.

I was messing with my range calculator to add an optimum projectile weight estimator. So far the findings are that light projectiles (for a given bore) slow down too fast to get enough range, unless they are carefully ballistically streamlined.

Heavy projectiles simply don't have the speed and hangtime to achieve the longest ranges.

In any case, a compromise needs to be found between the two to achieve the best possible range."


Oh and recruit not until either one or both of us have been proven wrong by some one who doesnt side with the other :P
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Unread postAuthor: SpudBlaster15 » Fri Jan 12, 2007 10:21 am

MrCrowley wrote:Ok now re-do it but using the valve under generic instead of barrel sealer, this is what GGDT gave me:
ok it wont upload...bloody photobucket...anyway it gave me 627fps instead of 670fps under barrel sealer. And the .2" mod is just taking the nozzle of the blow gun everyone does it and they calculated that into the generic option wiht the opening time and what not.


Ive said it before and I will say it again, stop posting when you have absolutely no idea what you are talking about! God, you are so (unjustly) arrogant. You claim to "know more than me" then follow with another series of incorrect statements! How can you expect anyone to take you seriously when you make posts like the one above?

Modding a blowgun consists of removing the nozzle to increase flow, increasing the thickness of the lever where it contacts the piston, drilling out the piston tube inlet hole to a larger size as to allow for more flow, and grinding the piston down to allow for maximum airflow around it. This increases the vent diameter to .2" as opposed to the .1" found with a blowgun that has only the nozzle removed. This makes a huge difference in the blowgun's ability to pilot the valve. Your latest readings using the generic option are even farther off, and you are making even more of a stab in the dark as far as opening and dwell times go.

Perhaps in time you will learn to accept that you are not always right.
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Unread postAuthor: MrCrowley » Fri Jan 12, 2007 3:28 pm

Ok first of all stop insulting me when we are trying to prove a point,not to see how many times you call me stupid and everyone thinks your a f*ck-wit.

The flow under barrel sealer is different to the generic option, If you chrony your gun you'll find it will shoot around the 630fps mark GGDT said, not the 670fps mark. The reason there is such a big difference is becasue a piston barrel sealer requires alot more flow then that of a blow gun, .1" difference wouldnt be sufficent, But a solenoid valve only needs a normal blow gun to pilot, increasing the flow to .2" wont make much difference.

Also you said~
"Increasing the volume by a factor of 4 makes a large difference, I will post the GGDT file in a bit."

By Increasing the flow from .1"-2" you get a 80ish fps increase,increase it to .3" and you get 2fps increase, Today im picking up my new paintball gun(FE's got welded)and Ill do some damage shots at some GIB board. With the normal blow gun piloting ti'll find out how many layers of the GIB the gun can shoot a paintball through, I'll mod the blow gun to your specifications and then do another test and see if it improves the fps,I guess with a normal blow gun it will shoot through 2 layers, with a modded blow gun it should shoot through both layers and a layer of cardboard. If there are any directions on modding the blow gun send me the link.

Stop on the insults, I dont care what you think of me and neither does anyone else, they are irrelevent to this discussion.
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Unread postAuthor: joannaardway » Fri Jan 12, 2007 4:38 pm

Whoa guys...

The way to win arguments is not to call the other person stupid and to have every 2nd word be offensive.

The way to win is to prove your own point right and their point wrong. Mixing that into a post that calls them an idiot will just annoy them so they can't be bothered to read what you said that is worth reading!

D_Hall has provided these figures himself for a sprinkler valve - it's on his own website.

Sprinkler Valve

Please note that it is a chamber sealer. (Noted two paragraphs above the data table)

You are both arguing incorrect points in your petty squabbling.

MrCrowley, the Generic Option on GGDT is there for a quick calculation, or ball valves. Most people model sprinkler valves with "generic" because they can't be arsed to remember all the numbers they need to know to do it as a chamber sealer.

Doubling the .1" of the vent port to .2" will increase the flow by a factor of 4 - because flow is proportional to area, not diameter - and area is proportional to diameter squared

You've posted fairly good evidence yourself - the doubling of diameter produces about 80 fps increase.

Spudblaster, range is a very funny thing. For the same muzzle velocity, a 1.5" and 2" round of the same length will go the same distance - neglecting tumbling of the round.

It's too long and winding to put in a short post, but it's easier to get a 1.5" to go faster for basic reasons - mostly to do with C:B ratios.

And to anyone who is interested: The 890 fps was from a piston valved pneumatic at 160 psi with a 150cm barrel (4' 11"-ish), with a small bit of wadding.
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Unread postAuthor: MrCrowley » Fri Jan 12, 2007 4:44 pm

Woah, 890fps with a 150cm barrel! What was the volume/dimensions of the chamber? Who made it and was it chronied(sp?) or done on GGDT? Any pictures?
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Unread postAuthor: joannaardway » Fri Jan 12, 2007 5:04 pm

890 was the average, with some spiking over 900 fps or more.

It was chronied by a homemade (but nonetheless accurate) chronograph, with similar results from a GGDT test.

The C:B ratio was about 1:1.
The builder was my brother ("Ragnarok" as he calls himself online), with one of his piston valves (piloted by another one) - He's got a hell of a lot of experience, so he's learnt some tricks to get the best opening times and flow out of his valves.

His next project will be capable of exceeding 1000 fps with a paintball if the GGDT data is correct.

I'll badger him to post the cannon here if you want - Normally he hides at UKSGC.
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Unread postAuthor: schmanman » Fri Jan 12, 2007 5:20 pm

Recruit wrote: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


post count has nothing to do with it. I have been a member since early march, 2006, a couple three months before him, and I have less posts than him. he just posts a lot.

no offense, crowley :D . not trying to get involved. pc guy has many less posts than either of us, and he most defiantly knows more.

just pointing out that post count has nothing to do with knowledge. :wink:

joannaardway, what is the porting on the piston valve?
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Unread postAuthor: joannaardway » Fri Jan 12, 2007 5:32 pm

20mm barrel, 26mm chamber, 13mm pilot, but specially arranged (or so I'm told).
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Unread postAuthor: MrCrowley » Fri Jan 12, 2007 5:51 pm

schmanman wrote:
Recruit wrote: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


post count has nothing to do with it. I have been a member since early march, 2006, a couple three months before him, and I have less posts than him. he just posts a lot.

no offense, crowley :D . not trying to get involved. pc guy has many less posts than either of us, and he most defiantly knows more.

just pointing out that post count has nothing to do with knowledge. :wink:

joannaardway, what is the porting on the piston valve?



No offence taken :P

Joanna get your brother to post on here more often :D I've been over to the UK site several time looking at all the copper guns :lol: but havnt seen his.

@Recruit - Post count has nothing to do with it, i have over 1000posts here but on spudtech i have 60 something, im still the same person.
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Unread postAuthor: schmanman » Fri Jan 12, 2007 6:07 pm

well, said, crowley, well said. I have 16 posts on spudtech, and on here I have 1042 posts.
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Unread postAuthor: SpudBlaster15 » Fri Jan 12, 2007 6:47 pm

Valve Type
Chamber Seal
# of Valves
1
Flow Coef
23%
Seat Diam
1.2 in
Dead Vol
3.1 in^3
Piston Diam
2.0 in
Piston Mass
22 gm
Vent Diam
.15 in (1)
Pilot Vol
1.1 in^3 (2)


Thank you joanna, for finally shuting him up with cold hard evidence that conctradicts the entire basis of his argument. Had I know such a page as this existed, this argument would not have extended past 2 - 3 posts.

I love how people automatically change the topic as soon as they are proved wrong.

Using the figures taken from Dave's site along with a vent diameter of .2", GGDT is now predicting a muzzle velocity of 723fps at 100psi. At 125psi (the sprinkler valve's rated limit), it reaches nearly 800fps.
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Unread postAuthor: MrCrowley » Fri Jan 12, 2007 9:06 pm

Why dont you just shut the f*ck up spudblaster, i was waiting for someone i trusted and new what theyre talking about to interfere(sp?) with this discussion before I would continue on, She said what she had to say its over, I was wrong you were wrong we were both right and wrong, so just drop it man,you are being a total cock right now and everyone knows it.


P.S I was wrong about the barrel sealer part in GGDT and my esitmate,
You were wrong about the range with the heavier projectile.You were also wrong about the barrel sealer as the valve is actually a chamber sealer.

Just leave it alone, I changed subject becasue it was over, we had discussed what needed to be said and we were both corrected in some ways, Why carry on, the only thing left was to change subject and get back on topic. Why arnt I allowed to change subject and ask Joanna about her brothers spudgun?

Edit: Ok so using the new figures and putting valve under chamber sealer my paintball rifle shoots at 838fps at 115psi :shock: It defiently doesnt look like that when I shoot it. :?
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Unread postAuthor: SpudBlaster15 » Fri Jan 12, 2007 10:15 pm

I am willing to drop the argument as it is pointless.

The numbers Dave supplies on his site look accurate, although I dont believe a standard blow gun has a vent diameter of .15", I think it is closer to .1". If you take one apart and look at it, the flow is constricted in almost every possible way. The inlet hole is half the diameter of what it could be, the piston shaft is twice as thick as it could be, and the piston only moves about 3/4 of the way down, uncovering a tiny, almost unoticable outlet for air to move around. With a standard blowgun, I would expect your launcher to chrono at about 750 - 800fps. With a modded blowgun, im sure you could reach 850fps.
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