What is the VOLUME of air required to go 300 FPS?

[hitech]

Re: bingo

Originally posted by QUINCYMASSGUY
...by offering a screw-on front to the dump chamber for the purpose of being able to insert "de-spacers" for varying volumes...

BTW, the power tubes are screw on. They are loctited on. If you want to remove it, remove ALL soft parts and boil the front half of the valve. That should loosen the loctite enough to remove the power tube.

[QUINCYMASSGUY]

front?

The whole front of the power tube is? I haven't looked at one recently, too busy loving AKA products more, lol. Well that would definitely be cool to test this, it would basically involve the following parts:

1.) The valve with the front treating as hitech specified

2.) Cylinders milled to be a precision fit to the inside of the dump chamber, in intervals that would allow 10% decreases in volume to properly test the varying setups

3.) Springs identical to the AIR valve spring that when substituted in, would allow the higher pressures.

4.) A strap wrench and loctite to properly reinstall the power tube.

I think the only thing that I am a little nervous about is the risk of additional kick, but if it's minor then it's worth the added efficiency. And again, the option of non-permenant, low cost modification is a huge selling point of this.

"Devolumizers! Up your mag's efficiency by 20%!"

And wouldn't it also aid the recharge rate?

[Koosh]

I was under the impression that they welded the Power tubes now...

It made me feel special that my gun was "cool" enough that the powertube unscrewed

[pbjosh]

Hey Howdy!

I was wondering if you still wanted to jaw about air effeceintcy or not. I chunked up a good bit here on a couple of the first pressure/volume=energy threads, and most of it is still in the forebrain somewhere.

As for the mag and pressure changes, I believe it was Fox River Games who had a higher pressure mod for the Mag, and it competed with the SP 'Magic Box' way back when. People still bough more of the 'Magic Box' than the FRG version, but the smaller Dump Chamber did increase effeceintcy by about 20%, but you had to run the mag at 600psi IIRC. The SP 'MB' lost about the same percentage of shots, and the performence was not really changed between the two, though the FRG conversion recharged faster.

As for a chart, it would be Pressure x Volume = Energy.

Figure the pressure, figure the volume, multiply, you have the energy.

Figure the mag uses 230-250in*lbs per shot. That puts it about middle because most guns run between 150 (aka) and 365 (old shocker, badly tuned cockers) with the average being about 250.

A 100% effeceint gun would use 114in*lbs per.

114/250= 45.6%. Not too shabby (mag, most cockers)

114/150= 76%. Rather good (aka on a good day)

114/365= 31.2% Horrid (old shocker)

Josh

[the electrician]

when you say 600 psi, you mean 600 psi inside the dump chamber?

seems like there would be a way to make a mag design to shoot at lower pressures, without sacrificing efficiency.

why are AKA guns efficient?

I recently took my time and burned up some paint doing a fairly accurate count on shots per tank for my cocker. I got 1559 shots from a 68/4500 that I painstakingly got as close to 4500 psi as I could. the cocker runs on 200 psi.
I figured it out to be 187.5 in*lbs. per shot.



hitech- you sure those power tubes screw on? seems like they are pressed in.

[pbjosh]

~E~,

How is it going?

Yes, 600 psi in the dump chamber. Mind you, that was several years ago, I might be wrong. It might have been 550 psi.

AKA has a very short throw, about 1/16th of an inch. And the action of the air moving past the cup seal helps close the valve really fast.

For a well tuned cocker, that is about perfect. Which valve layout are you using? I was using nearly the stock setup, even stock springs, and getting nearly 155-160inch*lbs per at 285fps. The only change was my bolt, but the velocity wasn't much different from the stock bolt. That was a pure stock 2003 cocker with a Raceframe, and later with the Mutant/Deviant bolt.

Now, people making claims that their guns get 1800 shots from a 45/4500 are total bs because they claim to be using 111in*lbs per.

Uhm- 102.7% effecient? I don't think so.

But a 68/4500 is do-able at 170in*lbs.

Now, not ALL aka setup are getting that, but most can come close. And most can come close with stock valves and springs. But I have seen more badly tuned cockers in the 250-350in*lbs per shot in under 200per. Most straight from the factory. And evo, shocktech, Macdev, eclipse are all that way.

SO sad, nice guns, bad tech.

But, I could wax away the keyboard talking about badly tuned cockers.

Shots per tank is a good measure of energy usage. A New shocker can barely get 1,100 out of a 68/4500- lets see:

278in*lbs per.

Not to bad- 41% effeceint- up from 31%

Josh

[hitech]

Originally posted by the electrician
hitech- you sure those power tubes screw on? seems like they are pressed in.

That is what Tom told me when I asked about making a smaller dump chamber. I might have mentioned (can't remember) that I was thinking of trying it on a classic valve. So it could be that only classic valves are that way. Tom could be wrong, even he can't remember everything!

[QUINCYMASSGUY]

worth

Might be worth bringing back the old days... this would be a cheap mod and if people wanted to leave it the normal way they're free to.

I love massive piles of useful data! Thanks pbjosh, and a huge welcome to the thread, please stick around for all the fun! Those are some very good points!

I'm playing around with an AKA Merlin as soon as Destructive Customs is finished with it, I can't wait to play around with springs/pressures/etc and see what I can find out.

[the electrician]

pbjosh-
this is what I see alot of in badly tuned cockers:
a dye or shocktech body, stupid weak valve spring, really weak hammer spring, but then the velocity adjuster is cranked in, in an attempt to get the gun to shoot at 150 psi, then they buy an after market valve, overpriced bolt, and an e-blade frame. so then to get it to shoot fast they cramk the cocking pressure up to 110 psi and rely on the eye so they don't chop paint. then everything rattles to death and the solenoid valve starts leaking.
yuk.

anyway, I'm using stock valve, stock hammer, slightly lighter than stock valve and hammer springs, but pretty well matched. I use a custom all delrin bolt w/no o-rings.
it's the best design I've used yet. delrin pull pin and back block, AL pump arm, ANS mini w/QEVs (of course) and the electro-grip is my old homemade one, direct solenoid actuated sear, MAC valve for recocking, morlock to control them. It'll get 15 bps with only 40 psi going to the ANS, and at the 200 psi input. not ,much extra kick with it.

the stock parts are pretty damn efficient if you use them right.


to change the subject just a bit, I wonder if anything could be done to the lvl 10 bolt to get better flow, or basically more efficiency. seems like it loses some.

I don't have one yet, but for those who do, does the trigger seem a bit lighter with the lvl 10 bolt?

[pbjosh]

I normally used the stock hammer spring from WGP or whichever medium spring I could find, then I would find a light spring for the hammer and turn the adjuster all the way back.

Stock hammer only.

Well, the Deviant bolt is what I ended up using so I could get a good seal.

I liked it if the hammer wouldn't open the valve at all when gun would sit without air in it. I would run the gun at about 200-300psi or so.

I have some stories about the light cocker setup, like the 'Pink' you get when you shoot the eclipse is because the hammer hits the valve nut. Ouch!

But I have to run. See you all on monday-

Josh

[SSMercury]

Originally posted by pbjosh
As for a chart, it would be Pressure x Volume = Energy.

A 100% effeceint gun would use 114in*lbs per.

114/250= 45.6%. Not too shabby (mag, most cockers)

114/150= 76%. Rather good (aka on a good day)

114/365= 31.2% Horrid (old shocker)

Josh

I'm just curious how you're determining needing 114 in-lb per shot.

[pbjosh]

We figured it out on the Tinker's Guild a while back-

I couldn't find it on a search, but the previous links posted in this thread bring us back to the energy per shot topics and it might be buried in there.

Josh

[nippinout]

pbjosh, I think you may have rounding errors.


A 3gram paintball going 300fps has 111.005 in-lb of energy.


Assume:
3gram paintball
300fps velocity

Units:
3gram = .003kg
300ft = 91.44m
1 joule = 8.8507457 inch pound

Paintball kinetic energy:
= .5 * (.003kg) * (91.44m/s)^2
= 12.542J
= 111.005in-lb

[pbjosh]

Nope- Memory errors!

Okay- 111in*lbs it is!

Josh

[SSMercury]

Ah, thank you. I shall now meditate on this.