# Barrel Efficiency, Tech Tip #1

Show 40 post(s) from this thread on one page
Page 1 of 2 12 Last
• 06-18-2001, 12:59 AM
AGD
Barrel Efficiency, Tech Tip #1

Guys,

I have decided to do a tech tips series of posts so you will understand certain technical processes that go on in the paintball gun. We have tested everything I will talk about and any speculations will be pointed out.

In the tech forum there is a long post on what is the most efficient barrel so here are the facts.

Barrel Efficiency, Tech Tip #1

Barrels are only there to accelerate the ball from a standstill to 300 fps. In theory they also help with accuracy but that's another post. The ball goes through incredible acceleration on its way down the barrel. The balls acceleration rate is approx. 50,000 feet per second to get to 300 feet per second in 10 inches. The entire barrel travel time is about 6 thousandths of a second and this means the ball is seeing about 1500 G's when its getting pushed out the gun. Although this may sound incredible if someone out there would like to do the math you will see that I'm close.

Air pressure behind the ball is what causes this acceleration to happen. This pressure varies between the different guns but is generally between 50 to 125 pounds per square inch at its peak. The air pressure peaks right when the ball starts moving down the barrel, after that, the ball moving down the barrel creates a bigger chamber so the pressure drops. This is why low pressure guns are a myth, in reality all guns shoot at considerably lower pressure than 200 psi.

Peak pressures above 150 psi tends to break balls down the barrel due to really high acceleration and G forces. If you don't have any way to control the peak pressure behind the ball, the only way you can change it is to go with lower pressure in the air chamber, hence low pressure guns. AGD uses the precise contour of the power tube tip to release air in a controlled manner behind the ball to limit peak pressures to around 60-80 psi..

It is simple to understand that the harder you push something the faster it will accelerate and get up to speed in a shorter distance. So what distance do we have to get the ball up to speed? The effective length of the barrel is from the balls position before it's fired, to the place in the barrel where the pressure gets released, This is usually at the first porting holes or the step in the barrel. Porting is there to release gas pressure!! You are effectively stopping the acceleration at the ports so your 14" barrel that is half full of holes only has an effective length of 7".

Now we understand that we need to limit the peak pressure behind the ball to keep it from blowing up, and that the pressure drops as the ball moves down the barrel. The next question we need to ask is, how far down the barrel does the ball have to go before the pressure gets to low to do anything useful? That answer is 8-10 inches. We know this from looking at the graphs that our gun dyno puts out. If your peak pressure is higher, say over 100 psi you can get away with a shorter barrel, if it's lower then you need a longer barrel. Since AGD is the only gun manufacturer to actually test their pressures behind the ball you might have a hard time getting this info for other guns.

So as far as our guns are concerned, the best efficiency would be had with an 8-10" effective length barrel. Since two piece ported barrels with an effective length of about 5-6" are the rage right now you hear a lot of complaints about gas efficiency. Under some circumstances there is a good reason to use a short effective length barrel. Short barrels cut off the acceleration abruptly by venting and this has the effect of tightening up the shot to shot velocity variation. If you need this at the expense of efficiency then go ahead. Tighter velocity control usually translates into some improvement in accuracy due to better consistency.

So if you want the best of all worlds, limit your peak pressure, let your ball accelerate all it wants, don't follow the crowd and keep asking questions.

AGD
• 06-18-2001, 01:06 AM
Miscue
Hey now! This is a great idea... hope you have a permanent place to put this so we can all go "See, I told ya so, says right here." http://www.automags.org/ubb/smile.gif

------------------
'Sacrifice the Body'
68 PF - HyperFrame - 68 Flatline - SS BigShot

Miscue's Profile
• 06-18-2001, 01:18 AM
Allen
Gee, I've been telling people that before... Not with the exact numbers, though. Plus I am no rocket scientist. 12in Lapco Bigshot-"effective" length of around 10 inches. I don't have mine here to measure, but the only porting on the thing is in a band right before the muzzle break.

------------------
"Don't spend so much on parts that you can't afford to play."
• 06-18-2001, 02:18 AM
X-Plosive
For those of you who don't understand a Barrel that has more effective barrel length is more gas effecient. Effective barrel length is the portion of the barrel that is unported. However barrels with less effective barrel length and more porting give you tighter shot grouping(more accuaracy). I know Tom explained it well but I didn't understand at first I thought I might as well simplify it further.

• 06-18-2001, 04:25 AM
manike
Quote:

<font face="Verdana, Helvetica, sans-serif" size="2">Originally posted by AGD:
Barrels are only there to accelerate the ball from a standstill to 300 fps. In theory they also help with accuracy but that's another post.</font>
I'd like to read that other post please when you get time http://www.automags.org/ubb/smile.gif

thanks

manike

• 06-18-2001, 06:18 AM
Dubstar112
Finally Im going to make use of my printer
• 06-18-2001, 06:28 AM
Dubstar112
oh yeah and that means the 98 only has like 4 inches of barrel.... damn
• 06-18-2001, 06:45 AM
luke
Cool, meat and potatoes, I like it!
• 06-18-2001, 06:59 AM
cphilip
Sorry to hear you are in "rain delay" but you loss is our gain. You got time on your hands huh? http://www.automags.org/ubb/wink.gif

Phil
• 06-18-2001, 07:09 AM
DarkRipper
Good information. Stuff I've known about (except for the AGD testing info) but still a good refresher.

http://www.automags.org/ubb/smile.gif
DR

------------------
Owned a PF mag in 96.
=)
• 06-18-2001, 07:31 AM
azzkikr
isn't it nice to know and talk to someone who knows what they are talking about. Later AZZKIKR
• 06-18-2001, 08:02 AM
Jeb_Hoge
What about bore sizing? Is it as substantial an issue as it's been made to be lately, or is it not so important (ref. the Palmer theory of the paintball distorting under the initial impact of the airburst so that all sides are in contact with the barrel breech when acceleration begins)?
• 06-18-2001, 08:13 AM
luke

Jeb_Hoge,

EXCELLENT question! AGD..............
• 06-18-2001, 08:31 AM
FeelTheRT
how does a stock Emag/RT barrel's efficancy compare to a 12" DYE one peice barrel..?
• 06-18-2001, 10:28 AM
LCDmag1
So the effective barrel lenth is before the porting starts on an unsteped barrel.
• 06-18-2001, 12:07 PM
Speed_Mag_22
whoa... i actually learned something... Gun Dyno's! http://www.automags.org/ubb/biggrin.gif
• 06-18-2001, 02:10 PM
chaoticorigin
The Dye 12" one piece has 7" of unported length. Shouldn't I measure the length from the beginning of the paintball? It would be less then. I was thinking of putting tape around the gun end of the porting covering about an inch so wouldn't that in effect make the barrel more efficient?

The 2 piece dynamics confuses me a little. As the paintball goes to the 2nd step. Doesn't the ball continue to accelerate until it hits the porting? I think the acceleration should still continue but at a lower acceleration because the bore is larger. I gotta try some experiments this weekend with a boomstick. I heard 8-12 was the ideal unported barrel length.

Why doesn't AGD make some good barrels as an optional buy? They seem the most serious about paintball dynamics. My stock barrel shoots decent but it doesn't have a mirror finish interior which gives less friction.
• 06-18-2001, 06:24 PM
kero
Excellent info. Now this is quality service to your customers http://www.automags.org/ubb/smile.gif

Keep it coming and many thanks. Maybe sometime you will address the biggest paintball myth... that closed bolt guns shoot farther than open bolt guns.

• 06-18-2001, 08:05 PM
JRSJKD
This is exactly why I've played with a mag for over ten years. AGD never talks any smack about other manufacturers but if you ask the right question they will give you the answer and back it up with real science and data. From there they let us make a decision based on fact not hype.

Tom, is www.paintballphysics.com ever going to become a reality or will the info just be put in the tech tips area?
• 06-18-2001, 08:13 PM
Allen
Speaking of closed bolt vs. open bolt-

http://www.warpig.com/paintball/tech...osedopen.shtml

Who other than WARPIG and AGD should we rely on to confuse us, stun us, educate us, and entertain us?

------------------
"Don't spend so much on parts that you can't afford to play."
• 06-18-2001, 08:27 PM
splatterp8nt
Thumbs up to AGD for their markers, their advice and the awesome customer servie they provide.
• 06-19-2001, 03:53 AM
manike
Now paintballphysics.com is definitely a site I would like to see.

Open up those archives and show the world some real data http://www.automags.org/ubb/smile.gif although the 2inch folder on mag bumpers could probably be left in the draw... http://www.automags.org/ubb/wink.gif

I would really like to have that film of the ball being shot through a glass barrel available for all. The close up of the ball in the breech and the ball exiting through the smoke trail (I know there's a bit on the RT video). As well as the ball in flight, that stuff is amazing to watch.

I also think some barrel testing with and without ports and some sort of trace element in the gas to actually see if it does exit the ports behind the ball as it goes past would be very interesting!

How about a new breed of two piece glass barrels lol... gotta keep up with fashion http://www.automags.org/ubb/smile.gif

manike
• 06-19-2001, 08:25 AM
FireWall
So whats the Dilly? Why do they put porting on barrels then??
• 06-19-2001, 08:45 AM
FlipFlops
manike, along with glass barrels we'd need colored N2 :-)
• 06-19-2001, 12:20 PM
-§on-
WoW, Tom To Much Spare Time... http://www.automags.org/ubb/biggrin.gif
• 06-19-2001, 12:21 PM
Webmaster
HEY MANIKE! Nice to see you on here, mate! Sure theres lots of stuff you can contribute!

take care!

------------------
Webmaster - AutoMags.Org
webmaster@automags.org
----------------------
"Good...bad...I'm the guy with the gun." - Ash, Army of Darkness
• 06-19-2001, 01:29 PM
Hoyahdestroyah
Great info!! That's why AGD makes the best guns in the business.
• 06-19-2001, 01:35 PM
PCI2000
Firewall,
Porting is there to release gas pressure and to quiet the sound. An unported barrel is very loud when you fire a paintball through it.
Unported = loud but more gas efficient
Ported = quieter but less gas efficient

Gotta find that happy medium ssomewhere...

------------------
Black Teflon ReTro Mag
Warped Sportz Drop Forward
68ci/4500psi Centerflag Hyperflow 420 tank
Benchmark 45 grip frame w/Dye sticky grips
KAPP foregrip extender w/Benchmark foregrip
• 06-19-2001, 04:18 PM
manike
Quote:

<font face="Verdana, Helvetica, sans-serif" size="2">Originally posted by Webmaster:
HEY MANIKE! Nice to see you on here, mate! Sure theres lots of stuff you can contribute!

take care!
</font>
OK I'm wondering who the webmaster is... My Yanky friend John? How's the theory of light speed travel going? And the Religious debating?

or another of the crew http://www.automags.org/ubb/smile.gif Eric?

It's not one of the brit John's is it? Hiding behind a Kansas City Origin, lol.

I have a suspicion it's Bonich, but the US origin bit is throwing me... If it is JonBon we need to talk some CAD/CAM stuff matey http://www.automags.org/ubb/smile.gif

Ahh just had a thought... it's not Mr44 is it?

Bill posts under something else so it aint him, Dawn? .... aarrrgghh too many possibilities http://www.automags.org/ubb/smile.gif

manike

[This message has been edited by manike (edited 06-19-2001).]
• 06-22-2001, 11:42 PM
M-a-s-sDriver
Man, I hate to do this: I believe you have the acceleration rates wrong. They are a bit overstated. The rate to push the ball is not 50,000 fps. That is about the escape velocity to achieve earth orbit. To hit that number in 10 inches would push the g-forces to over 22,000, enough to permanetly compress titanium. If you are talking about the initial acceleration from zero to any number, that is proportionally the highest attainable acceleration number on the curve, and mathmatically approaches infinity. Also, if you did go to 50,000 fps, you have to decelerate the ball down to the 300 fps mark and therefore put the paintball through double the stress. Am I off-base here, or did I miss something? Brent Jackson, Pink Fluffy Ballerinas.
• 06-23-2001, 01:08 AM
SniperWolf
glass barrels eh? take a look at the new pirhana barrel, clear. theyre made out of polycarbonates i believe, like bullet proof glass. now about this effective length, i understand that porting makes it less gas efficient, but does the porting really vent all the accelerating gas that early? wouldnt the severity of the porting also dictate effective length. like the 98 barrel, it has a ring of porting very early on, but is that venting area enough to blow off all that gas i dont think so. and the palmer theory, palmer is a very smart guy, but their is video where someone powdered the barrels and shot through it, and showed that a paintball rides on the 2 highest points, like rails. so palmers spoken like a man who doesnt makes different bore barrels. though he does have elliptical honing, which is a whole other barrel of monkeys http://www.automags.org/ubb/tongue.gif

------------------
Frag'd, toe tagg'd and body bag'd,
hell son, you mustve just been automag'd
• 06-23-2001, 04:08 AM
hitmanng
Jerk is a mechanical term for a specific aspect of motion: the rate of change of acceleration with time or in this case ft/sec/sec/sec. I do not believe that is what Tom is using.

Velocity is defined as the rate of change of position with time, and measured in paintball as feet per second.

Acceleration is the rate of change of velocity with time; acceleration is measured in paintball terms in feet per second per second.

Jerk describes the way acceleration itself changes; it is reckoned in the even more unwieldy units of in paintball terms feet per second per second per second.

A paintball accelerates from 0 ft/sec to 300 ft/sec over 0.83 ft if the rate of acceleration were 50,000 ft/sec/sec the time period would be 0.006 seconds
That's 300ft/sec / 50,000 ft/sec/sec = 0.006 sec
The acceleration of gravity is 32 ft/sec so That's 50,000 / 32 = 1562.5 G
I believe those are the numbers used by Tom above.
Tom is using acceleration here and simply forgot or figured most wouldn't understand or care about the units used. I know I didn't care as it was not needed to understand what he was trying to say.

Last week Phase chemistry, this week physics. Maybe next week we will look into molecular biology. Maybe Organic chemistry study up on your function groups.
Tom Kayes paleantologist, astronomer, enginer and physicist.
Now right now Army is going. Wow all that and he cannot even spell. LOL
Hitmanng

------------------
"I would rather hit once than miss 140 times."
• 06-23-2001, 05:37 AM
DarkPhoenix
Porting also helps the paintball in its movement through the barrel. The porting helps bleed off the air in front of the pball as it moves forward, because the paintball also has to deal with the pressure of the air in front of it, in an non-ported barrel, I believe the air in front gets a little compressed and the paintball must overcome this pressure, so porting and the barrel break help in this regard. I may be complete off base here, but I believe that these are other factors that come into play when considering barrels, as non-ported barrels are usually louder but more gas efficient, while ported barrels tend to be quieter, less gas efficient and, some say, more accurate. It is my personal belief that this accuracy is obtained by the effective venting of the pressure both in front and behind the ball. Though, I have been known to be wrong before....

------------------
RT Pro P/F
w/ AGD Flatline
• 06-23-2001, 01:42 PM
RobAGD
Actually Tom has high speed vidoe of that.

There is nothing being pushed out the end of the barrel by the ball. It was long held that the ball would be pushing a colum of air out BEFORE it exited the barrel.

Toms high speed video shows that the onlt thing exiting the barrel is the Ball then a gas plume. The Smoke was intact until the ball broke its plane.

-Robert
• 06-23-2001, 07:43 PM
MajorDamage
PORTING! Porting also helps with ACCURACY! Imagine shooting a bullet into the water, it just curves like crazy and stopps. Its thesame with paintballs pretty much. But the holes in the barrel slowly get the paintball used to the air, helping it to not just be suddenly introdued into the air. SO THATS WHY PORTING IS GOOOODA!

ENDO!

------------------
*************************
My Battle cry!
Spoon Spork Purple Monkey Dishwasher Hoo Ha!
• 06-23-2001, 08:27 PM
SHAG
Hi,

The fellow above does have a point and I would like Rob or Tom to elaborate this in more detail. I remember in the AGD video that Tom discussed the "new" Crown Point barrel. He was mentioned it ressembled the V ducts on Indy cars. Also it was to aid the ball with a smoother transition into the air. What happened with the CP barrel design? Other than that, Tom, Glenn, and Colin have alot of time in barrel design. I feel they are on track when it comes to the barrel. The best barrel design that does mix the effective barrel length and porting is the J&J Ceramic. It is the best of both worlds.

Later,
Alan

PS Nice to see on here Jeb

------------------
Paintball cannot be that big. No one has really been able to sponsor a stock car or a race yet. (local people do not count in this case :))
• 06-23-2001, 09:15 PM
klm5
Thanx for the info, I'll do some side-by-side comparison shooting with my AA & shorter, un-ported Armson.

------------------
• 06-23-2001, 09:20 PM
hitmanng
You have to remember the speed of travel, and excelleration here. The ball is moving faster than the air could "Move out of the way". Playing in a vaccum would be great but not an option. The Idea of the crown point was to create a gradual transition from the air in the barrel to the air outside the barrel. I think it never took off because with all of the forces on the ball the crown point was not he most important factor. Do you realize that we can hit a can with a gellatin paintball, filled with fluid, 50 ft away, being propelled by air. That is a remarkable feat. I think asking for much more is too much. The fact is you can do this with most barrels. No new designs can overcome all of the uncontrolable factors.
Hitmanng

------------------
"I would rather hit once than miss 140 times."
• 06-24-2001, 08:19 AM
Webmaster
Manike -

Yes - it is Mister.44

cheers!

------------------
Webmaster - AutoMags.Org
webmaster@automags.org
----------------------
"Good...bad...I'm the guy with the gun." - Ash, Army of Darkness
• 06-24-2001, 12:58 PM
The Taoist
Great post tom. Very helpfull information. webmaster (aka Mister.44), just wanted to let you know that i enjoy you reviews / articals in APG. Good work guys!!
Show 40 post(s) from this thread on one page
Page 1 of 2 12 Last