can someone explain to me what "freeflow" is.

[FeelTheRT]

Freeflows are very much hyped up because there are many Cockers out there that preform very similar such as the Works, and the Rudy Custom Autocockers. I think the real reason why many Freeflow owners are loyal to ProPB and the Freeflow brand is because ProPB offers lifetime warentee on any Freeflow marker out there no matter who the owner is. So really what's it to you if someone else has lifetime warentee on their marker? hyped up.

[Conqueror]

Steveg: Hmm... that's interesting. While the fact that he's from MIT is indeed persuasive, I wonder if maybe that number at the bottom of his page is a theoretical energy extraction when the tank is used in conjunction with his "microturbine" or whatever it was. Also, the two numbers you cite (114000 and 202500 psi/in^3) are mystifying... psi/in^3 reduces to pounds per inch^5, and I have no idea what kind of unit that is. I think you were referring to in-lbs, or inches x pounds, which is an unconventional way of measuring the energy in the tank. A 45/45 tank does indeed have 202,500 in-lbs of "energy" inside; however, a 68/3000 has 204,000 in-lbs - a 68/3000 actually has a tiny bit more stored energy than a 45/45.

CQ

[steveg]

Ooops hee hee:o
that would be my bad math 68 X 3000=204000 45 X 4500 =202500

big hurry to leave this morning:o
yes psi x in3 does derive to lb-in
thats what you get for paying way to little to what
you are typing.

none the less the authors calculations would imply about
twice the energy storage than simple lb-in's to J conversion.

[manike]

not sure about the page you linked too...

but for me

68 X 3000 = 204000 inch pounds = 17000 foot pounds = 23000 J

45 X 4500 = 202500 inch pounds = 16875 foot pounds = 22900 J

an average paintball at 300fps has 10.4 foot pounds = 14.1 J

an average paintball at 290fps has 9.7 foot pounds = 13.2 J

an average paintball at 280fps has 9.4 foot pounda = 12.7 J

So for the 45 X 4500 tank for me you get

at 300fps 1624 shots at 100% efficiency.

at 290fps 1735 shots at 100% efficiency.

at 280fps 1803 shots at 100% efficiency.

Now the best proven test (decent test conditions) with any gun that I have heard of (it was an Excalibur I believe) gave the efficiency at 70-80% (can't remember the exact figure) but that's very efficient in my opinion (as compared to other energy transfer systems).

But if we use the 80% efficiency case then with the 45/4500 tanks

at 300fps we get 1300 shots

at 290fps we get 1388 shots

and at 280fps we get 1442 shotss.

And those numbers are much more like what we hear about happening in the 'real world' with very efficiently tuned and set up guns.

If you turn that into numbers we understand and given that some pods 'only' hold 140 paintballs and a hopper (Rev 180).

At 300fps you can shoot a hopper and 8 pods.

At 290fps you can shoot a hopper and 8.6 pods.

at 280fps you can shoot a hopper and 9 pods...

Now if some one was on the field just shooting at 280fps and shot 9 pods and then mistakenly thought their hopper held 200 balls and each pod was 150 balls you would get an incorrect total of 1550 shots instead of 1442. Which may account for some of the innaccuracy but not all of it...

Hey if we weigh the back block and bolt and cocking rod of a cocker as well as the hammer and cocking rod etc. we should be able to work out how much energy is used to cock the gun and close the bolt given a specific cocking pressure, and we can also use those figures to help get a more acurate set of values...

Opinions? Discussion points?

manike

p.s. Steveg try calculating the energy of the tanks yourself, I couldn't get any different result and I checked it a few times?... Can't see where I screwed up if I have.

[fearc7]

How effecient is the average automag? They seem pretty ineffecient but I don't really know what I'm talking about. How many shots do you get on a 45/45 with an automag?

[i-luv-my-rt]

WOW all this math is crazy. I'm pretty good in math and dont totally understand. I guess you cant argue with the exact math but it seems like you guys are having troubles to get the exact figures. Ethan is a very cool guy and very smart, I'll stand behind the stuff he says just because he is a good guy(and i'm to lazy to do the math). I did here the story about chicago and I know at world cup i think somebody shot like 1900 off a 68, i think thats what it was. I really dont see the need to argue about this, it's kind of like the BPS arguements. Everybody makes false accusations, i've learned to deal with it. You guys do sound very right though.

[steveg]

p.s. Steveg try calculating the energy of the tanks yourself, I couldn't get any different result and I checked it a few times?... Can't see where I screwed up if I have.

What? after my demonstration of my inability to do the simplest of arithmetic, with a calculator even

actually the 68/3000 45/4500 thing originaly was to show
that they had the same/similar energy capacity. (did a great job didn't I:o )

I have spent some time trying to find the calculations
for compressed gas energy storage (clearly for some-one else
to use ) to little or no success, as of yet.

The premise that I a working on at the moment is that
pressure X volume is not the correct way, Thus the link that
I posted.

Also I suspect that energy transfer from the expanding air
to the paintball is quite dismal even with the most efficient
of pb guns, leaving untapped potential
Of course I could also be wrong.

[wes]

Originally posted by Daroach
This is a 2k2 Lockout Edition Boxxer Freeflow



Hope you enjoy the pic

too bad it ALWAYS breaks.... I think I'm going to tanks on saturday (next weekend) you better have it back by then!

[Daroach]

ALWAYS?! ... i just got the gun, and i ain't goin to tanks next weekend, i am goin out to Conroe

[Conqueror]

Very nice Simon. We'd need a lot of measurements to accurately find the energy needed to cock the gun! (Both coefficients of the ram's internal friction, mainspring constant, weights/inertias of all the parts, LPR pressure, ram piston area, etc.) Too much work!

Your math and mine are in agreement however; our shot counts are within like 10 or 15 of each other.

OOH! I have the answer! Ethan must have taped 6 handwarmers to the tank as he was shooting. :)

CQ

[steveg]

Back again

after plugging 45ci 4500psi and 68F into this neat and handy calculator

http://www.hull.ac.uk/php/chsajb/general/ideal_gas.html

we find that there are 9.386 moles of gas

there are 8.3145 J per degree K per mole

68F = 293K

8.3145 x 293K x 9.386m = 22866J say ! where did I see that number before :o

At least I proved it to myself.(Damn MIT guy's!) Can I go back to my nap know?

[manike]

Nice one Steve :) So I guess we are pretty much in agreement now then.

I've also been searching through trying to work out where the discrepency was.

Certainly when checking the SI units everything seemed to work out for the simpler method of calculations...

With the MIT calculations when calculating the work done, I don't think he is taking into account the lose of energy used by the gas to expand (this is why things around the expanding gas go cold). I think it's a significant amount of energy is required to be lost this way (certainly we put a lot of energy into the tank filling them which is why they get so hot).

He even admits to taking the expansion as being adiabatic, which is far from the truth! It's not a reversible thermodynamic process that occurs without gain or loss of heat and without a change in entropy...

If he doesn't take this into account (which he isn't because for him the gas temp stays constant) then he is getting a lot more energy in the work done than he actually could in real life...

manike

I think we took this thread off topic kinda... but it's good stuff. Might even be worth cutting out this discussion and putting it into deep blue... or maybe it's a valid thread for Round Table! That'd be a first But I do think we just proved certain things about a manufacturer's claims?...

[Conqueror]

Thermodynamics were brought up the last time we did this type of discussion at PBC, but I think they're not applicable to this particular application anyway.

A certain amount of work had to be done in order to "cram" the gas into the tank. Getting cold means it's ABSORBING energy. Thus, even more energy has gone into the gas. Using U = Q+W, we can get the total resultant energy of the gas, but that work component (W) remains the same, and thus the same amount of work can be converted into the kinetic energy of the paintball. The heat (Q) is extraneous to the situation unless Q is negative, which would only happen if the tank got HOTTER (extracting heat from the gas and putting it into the tank material). Does that make sense?

CQ

[manike]

Originally posted by Conqueror
Does that make sense?

Nope. Thermodynamcs are absolutely relevant to this use of gas.

The gas uses energy to expand that's why stuff gets cold. It's taking heat energy from the surroundings, but it will also be using energy in itself to expand.

Entropy is important whenever work is done on or by the gas. In compressing or expanding the gas.

Compressing gas into the tank makes it hot. Not cold.

Expanding gas out makes the tank cold.

More energy has gone into getting that amount of stored energy into the tank than is stored.

Less energy (work) will be gotten out of the tank than is stored in it.

The temperature is vital in these energy transfers. That's why a flash filled tank is hot and reads higher pressure (and thus energy) than when it has cooled down.

manike

[manike]

Originally posted by Conqueror
Getting cold means it's ABSORBING energy. Thus, even more energy has gone into the gas

Nope...

The gas requires energy to expand. It takes that energy from it's surroundings. That's why it's surroundings get cold.