[brycelarson]

Terms

• Ball Stack - the balls "stacked" above the breech waiting to be fed.
  
• Barrel Break - when the ball breaks in the barrel - there will be fill and or shell in the barrel - the breech will be clean
  
• "True" or "Pure" Barrel Break - when a ball is loaded w/o damage then breaks in the barrel (this may not exist)
  
• Blow Back Marker - A paintball marker where a fraction of the gas that is released from its main valve system during the firing phase is used to re-cock the marker.
  
• Blow Back in a Marker - Blow Back is the term given to any gas that is released from in or around the breech-loading/bolt mechanism of the marker during the firing phase. In most current designs this gas is normally expelled through the feed tube of the marker and can cause any waiting paintballs located in the feed tube to be displaced away from the breech area. This, in it's most sever form can cause the balls in the ball stack to "jump" back up the feedneck.
  
• Blow Forward Marker: A paintball marker that uses the same gases that are stored in its primary firing chamber to propel the bolt mechanism forward during the chambering phase of the firing sequence.
  
• blowtest - using 5-10 paintballs from a case and testing each on until you find a barrel that the paintball stick gently in the barrel and only require a slight puff of your lungs to push them out.
  
• Bolt Clip - when the bolt interacts with the second ball in the ball stack
  
• Bolt Nick - when the bolt interacts with and damages the second ball in the ball stack - this can have varying levels from slight crack to fully removing the bottom of the second ball
  
• Bolt Strike - The act by which a paintball at rest in the breech is struck by the face of the bolt as it drives forward to chamber the paintball into the barrel prior to firing. The act of the bolt striking the stationary paintball may cause a fracture in the paintball, which may lead to total failure during firing.
  
• Breech - The area inside a marker where a paintball comes to rest after the loading operation, prior to being introduced to the barrel.
  
• Chop - when the ball breaks in the breech of the gun - there will be fill and or shell in the breech, feed neck and barrel
  
• Dump Chamber (or Firing Chamber) - The internal volume of a paintball marker that is used to store the volume of gas used to fire the next paintball. The Dump Chamber can be configured to either be open to the gas supply, or isolated from the gas supply during any or all parts of the firing cycle. A fixed volume dump chamber controls the volume of air released during the cycling process - while a non-sealing dumb chamber must control the volume of gas released by controlling the time that the valve mechanism is open.
  
• Loading Fracture - when the loading system of hopper, bolt etc. causes damage to the ball while it's being moved into firing position. This damage may or may not cause failure of the ball before it leaves the barrel. This may include, but is not limited to, factors such as Bolt Clip, Bolt nick etc
  
• matched paint to barrel - paint chosen using the blowtest - this is often considered to be using the paint that is the same diameter as the inner diameter of the barrel.
  
• overboring - using a barrel that has a larger inner diameter then the paintball being fired from it
  
• underboring - using a barrel that has a smaller inner diameter then the paintball being fired though it
  
• Spin - types: Top Spin, Back Spin, Side Spin (Left), Side Spin (Right), Twist (Clockwise), Twist (Counter-clockwise)
  
• SD or Standard Deviation - is a measure of the variability or dispersion of a population of a data set. In PunkWorks this is normally applied to velocity or accuracy. Lower numbers mean more consistent or accurate.
  
• Vector - the hypotenuse of the Standard Deviations of the x and y axis on an accuracy test. This can be thought of as a radius of a circle - the area of which is one Standard Deviation. A simple tool to compare overall accuracy during testing.

Terms in need of definition

• Slip Stream
  
• Confidence interval
  
• .

Please post up with more term suggestions - we'll move them to this first post once we agree on the meaning.

This post has been edited by brycelarson: 08 March 2010 - 09:37 AM

[brycelarson]

just to keep this really clean I'm going to kill the posts in which we discuss definitions. That should keep this to just the first post and the current in-debate terms. That cool with people? It'll make it easier to use this as a reference.

[betasniper]

Can you use the word slipstream in a sentence? This may help some of use to figure out it's definition.

[CovertRussian]

Might want to add Confidence Intervals to the definitions .

[lashcoin]

CovertRussian, on 07 March 2010 - 11:58 PM, said:

Might want to add Confidence Intervals to the definitions .

I'm an archaeologist!

May want to add bleed? Sorry if that's really noobish.

[brycelarson]

lashcoin, on 27 September 2010 - 09:34 PM, said:

CovertRussian, on 07 March 2010 - 11:58 PM, said:

Might want to add Confidence Intervals to the definitions .

I'm an archaeologist!

May want to add bleed? Sorry if that's really noobish.

as in to bleed air?

[betasniper]

Blow out: when an o-ring in a marker becomes dislodged from it's groove and interferes with the normal functioning of the marker.

[brycelarson]

betasniper, on 11 October 2010 - 02:57 PM, said:

Blow out: when an o-ring in a marker becomes dislodged from it's groove and interferes with the normal functioning of the marker.

I've never heard that used that way - but makes sense. Anyone else have input on that term?

[UV Halo]

brycelarson, on 13 October 2010 - 01:12 PM, said:

betasniper, on 11 October 2010 - 02:57 PM, said:

Blow out: when an o-ring in a marker becomes dislodged from it's groove and interferes with the normal functioning of the marker.

I've never heard that used that way - but makes sense. Anyone else have input on that term?

I've usually heard "o-ring blowout" as in the o-ring has become at least partially unseated (and usually stretched or broken). As far as interferring with the 'normal function' of the marker- well it's usually a given so, no further specifics are necessary.

Consider two examples- Ion breach area.

SFT o-ring blowout resulting in the o-ring being shot out of the barrel. Bolt scrapes against breech, consistency goes to crap, and gun is noisier (from metal on metal)

Bolt Sail o-ring blowout resulting in a jam of the bolt inside the rear of the breech assembly.

[betasniper]

Well, The marker won't be functioning normally if it is inconsistent but feel free to alter the definition. I also thought if someone has never heard this term before that they may not know that a dislodged o-ring will alter the functioning of the marker. Now I know most people will deduce this but its for people who don't always know what the effects are without experiencing them first hand.

[MrEeske]

I really like what y'all having going on here. One of the things I'm most disappointed about in the paintball community is the lack of science behind it. Now I don't mean that marker manufacturers don't do a quality job on design, but that the mechanism and science behind a marker's operation is generally unknown within the community of users.

Anyways, enough of my rant.

Slipstream: If we look at what others have to say about slipstreams, it's basically the "drafting" effect that car racers exploit when they ride up close to the bumper of another car. To paraphrase the first sentence from here, a slipstream is the area behind a paintball in which the air is moving at a similar velocity to the paintball.

They go on to note that there is a difference in slipstream characteristics between turbulent flow and laminar flow.

For those that don't understand the difference between these two types of flow, turbulent flow is like smoke that rises from a burning fire- the smoke doesn't go in a perfectly vertical line up, but instead it will swirl around, make mushroom clouds, and generally be chaotic in the direction that it flows.

Laminar flow gets its name from laminate, which is basically sandwiching two or more layers of material together. If you've ever had a cheap I.D. card (e.g., library card) where it has a thick, clear edge to it, that's a laminated object: plastic, paper, and plastic sandwiched together. So, back to air. Air can behave like this too, however this situation is more of a theoretical ideal for air that makes approximate calculations a little easier: ultimately air is turbulent, but calculating turbulent flows is a b**** to do, even in computer simulations. Imagine a cold knife cutting butter: the way that the butter moves out of the way of the knife is the same way laminate air behaves; if I were to say hot knife, the butter would also be melting, and that makes for a bad analogy.

Now, while the paintball is in the barrel, the air charge behind it is most definitely in a state of high turbulence. However, while the paintball is in flight (or more technically, in a state of free fall) the behavior of the air around the ball is more laminate. Again, laminate air is more of a theoretical ideal that helps with flow calculations; there is a lot going on with respect to air dynamics around that free falling paintball.

[MrEeske]

I think that the word "operating pressure" that is often flung at paintball markers as a whole is terribly misleading, and I completely agree with brycelarson had to say:

brycelarson, on 06 November 2010 - 09:27 AM, said:

The idea behind using a single term for the general operation of the gun was to simplify the conversations. It's true that there are guns that are unregulated, some are single regulated, some are double or more. In the cases of those regulated guns it might be more accurate to have a split pressure - as in 750/180/40/65 (tank reg/HPR/LPR/breech) but that gets complicated, messy and we don't necessarily know what all of those pressures are.

With industrial products, such as anything available from Grainger's online catalog (I <3 Grainger ), there will always be a minimum and maximum operating pressure listed for products that deal with pressure in some fashion. Here, the term operating pressure refers to the range of pressures the product may operate at without failure; yes, a low pressure can cause failure too, it just won't activate instead of violently exploding.

While I think that all markers should be stamped with a minimum and maximum operating pressure (the range of pressures the gun will properly function in), saying that a marker as a whole has a particular operating pressure is silly. However, if you're marker was just a simple tube put over an air nozzle, then yes, that marker would have a single operating pressure: whatever the pressure the air is coming out of the nozzle.

But byrcelarson is right; our markers are complex machines that simultaneously use different pressures at different locations ("as in 750/180/40/65 [psi] (tank reg/HPR/LPR/breech)"). Each individual component has its own minimum and maximum operating pressure, and often times these components are linked in series so that the output pressure of one component become the input pressure of the next (e.g., like an electrical series circuit, or a string of really cheap Christmas lights).

There are a couple of terms I'd like to define. I'm not putting these here in a final "take it or leave it" state, but these are terms that I personally use on a regular basis.

• Inlet Pressure: The pressure delivered to a component. In the context of an entire paintball gun, this is typically the pressure that arrives from the vessel, and is usually around 800 psi.
  
• Outlet Pressure: The pressure produced by a component. In the context of an air pressure regulator, this is the output regulated pressure.
  
• Operating Pressure: The instantaneous pressure at a particular location. A paintball marker will generally have many operating pressures within it, due to the various air channels, orifices, and pressure regulators. If the paintball marker has an adjustable pressure regulator, then the operating pressure of components may change when the pressure regulator is adjusted. This is not a statistic like minimum and maximum operating pressures are, but is rather a measurement of what the air pressure at a particular location is for a particular point in time.
  
• Operating Pressure, Minimum: The minimum required pressure for a component to properly activate. A pressure less than this will typically not result in catastrophic failure.
  
• Operating Pressure, Maximum: The maximum pressure a component can withstand before failure. A pressure higher than this will typically result in catastrophic failure, such as a violent explosion.
  
• Vessel Pressure: The pressure inside of a compressed air tank. Typical pressures inside of a fully charged air tank may be 3,000 psi or higher. (This is not the vessel's maximum operating pressure, but rather the pressure that you actually fill it to. [e.g., for safety's sake, you don't fill a 4,500 psi tank to 4,500 psi])

This post has been edited by MrEeske: 06 November 2010 - 04:04 PM

[MrEeske]

Oh, another very important safety term that is frequently, and purposefully ignored:

Hydrostatic Test ("Hydrotest"): When a vessel is filled with pressurized water to test its integrity. Pressurized water is used instead of air for safety in case of a catastrophic failure of the vessel: if the vessel ruptures under pressure, water will not send fragments flying at high velocity.

Imagine two balloons: one filled with water and the other filled will air. Now, pop each balloon with a needle. What happens? The balloon with air makes a loud noise and will possible send bits of its rubbery self at your face due to the explosive decompression of the air; the balloon with water won't send bits of itself at you because water does not undergo explosive decompression. Check out these cool photos of a popped water balloon.

Different countries may have different laws requiring hydrostatic testing of pressurized air vessels (e.g., air tanks). This site gives a good quick-and-dirty of when to test your air tank in the U.S.A.

[brycelarson]

MrEeske, on 06 November 2010 - 03:58 PM, said:

• Inlet Pressure: The pressure delivered to a component. In the context of an entire paintball gun, this is typically the pressure that arrives from the vessel, and is usually around 800 psi.
  
• Outlet Pressure: The pressure produced by a component. In the context of an air pressure regulator, this is the output regulated pressure.
  
• Operating Pressure: The instantaneous pressure at a particular location. A paintball marker will generally have many operating pressures within it, due to the various air channels, orifices, and pressure regulators. If the paintball marker has an adjustable pressure regulator, then the operating pressure of components may change when the pressure regulator is adjusted. This is not a statistic like minimum and maximum operating pressures are, but is rather a measurement of what the air pressure at a particular location is for a particular point in time.
  
• Operating Pressure, Minimum: The minimum required pressure for a component to properly activate. A pressure less than this will typically not result in catastrophic failure.
  
• Operating Pressure, Maximum: The maximum pressure a component can withstand before failure. A pressure higher than this will typically result in catastrophic failure, such as a violent explosion.
  
• Vessel Pressure: The pressure inside of a compressed air tank. Typical pressures inside of a fully charged air tank may be 3,000 psi or higher. (This is not the vessel's maximum operating pressure, but rather the pressure that you actually fill it to. [e.g., for safety's sake, you don't fill a 4,500 psi tank to 4,500 psi])

these are all very reasonable terms. How would we use them? In the case of most guns these number aren't published nor are they even known in many cases. What's a term that we can use in day to day conversations for the pressure at which a paintball gun operates. This would normally be after the fist regulator past the tank reg - or in the case of unregulated guns - the tank output pressure.

For example - using your terms what would you lable the aprox 400 psi output pressure from the reg on a cocker?

[MrEeske]

brycelarson, on 06 November 2010 - 04:40 PM, said:

these are all very reasonable terms. How would we use them?

That's a fair enough question. The above terms I use are generalized, and apply to pressurized components in general. I do deal with pneumatics outside of paintball markers, so I need a generalized vocabulary for myself. If what you're asking is terms specific to the operation of paintball markers, lemme see what I can hammer out using what I've said above.

Mind you, another reason I am generalizing these terms is because my current paintball marker design will work in a very unconventional way. For example, "breech pressure" will not apply to it due to its nature, nor will some other terms that y'all have defined. Also, the Lund Variable Velocity Weapons System (a military-grade paintball marker) operates in a way that also can not use some of the narrowly defined terms that we, as a community, have used in the past.

But, back to the topic at hand- popular vocabulary for the common paintball marker.

brycelarson, on 06 November 2010 - 04:40 PM, said:

What's a term that we can use in day to day conversations for the pressure at which a paintball gun operates. This would normally be after the fist regulator past the tank reg - or in the case of unregulated guns - the tank output pressure.

Looking over at my other post where I asserted that the minimum theoretical pressure required to accelerate a paintball to 300 ft/s in 8 inches to be approximately 41 psi, what I would consider a paintball marker's operating pressure is the input pressure (e.g, the output pressure from the final primary air source regulator) that is required for the paintball to accelerate a paintball to 300 ft/s for a given barrel length.

First, I threw out a new term that I haven't yet defined: primary air source. This is the air that ultimately applies force to the surface of the ball; it may go through many channels and be conditioned many times (e.g., regulators), but it eventually finds itself pushing against the gelatin shell of the paintball. If there is a primary air source, is there a secondary air source? Yes, but I call it the utility air source. An example of this utility air is the air pressure needed to operated a Tippman A-5's Cyclone Feeder. This air has nothing to do with applying force to paintball, and is purely used in a utility fashion. And by "utility" I mean that it supports the operation of the marker, and is an integral component, but does not participate in direct application of force to the paintball.

Back to the definition of operating pressure when viewing a paintball marker as a whole. In this context I define operating pressure as the set of regulated input pressures required for the marker to accelerate a paintball to a target exit velocity for a given barrel; in most all cases you can replace "target exit velocity" with 300 ft/s. If you noticed, the length of the barrel is unknown in this definition, and that's because different operating pressures may be required to achieve an exit velocity of 300 ft/s for different barrel lengths and designs. Porting a barrel changes its acceleration characteristics, so a non-ported 8 inch barrel may required less operating pressure than a ported 8 inch barrel. A marker's operating pressure is highly dependent upon barrel length and design.

Now why did I defined operating pressure as a "set of ... pressures" instead of a single "specific pressure"? Well, as you mentioned before, there are "unregulated" markers, for example the ubiquitous Tippman 98 Custom and its many spin-offs. Technically, the input pressure into the marker is still regulated from the tank, usually around 800 psi; if it were truly unregulated, the marker would be receiving vessel pressure of 3,000 psi or higher. Anyways, in these markers, control of exit velocity is done through the compressive force of a spring; an input pressure of 800 psi can be used to reach speeds from 200 ft/s to 400 ft/s, just as an exaggerated example. In this case, the operating pressure will always be 800 psi (or whatever you choose, such as with a Low Pressure kit) for an entire range of velocities. The above definition of operating pressure still holds true, but it just looks a little weird when you compare a Tippmann 98 Custom (velocity controlled by spring compressive force) to an Automag (velocity controlled by adjusting air regulator).

Taking this idea of using a spring to control exit velocity one step further, a Tippmann 98 Custom can use a range of input pressures to achieve 300 ft/s. In order to do this, both the compression force of the spring and the output pressure from an adjustable air pressure regulator much be modified in unison.

To restate everything in fewer words, there is a many-to-many correlation between marker operating pressure and exit velocity.

brycelarson, on 06 November 2010 - 04:40 PM, said:

For example - using your terms what would you lable the aprox 400 psi output pressure from the reg on a cocker?

I think you already said it- "output pressure from the regulator." However, if this 400 psi coincidentally happens to be the required input pressure to the marker to achieve 300 ft/s, then it will also coincidentally be the marker's operating pressure.

[brycelarson]

MrEeske, on 06 November 2010 - 06:46 PM, said:

brycelarson, on 06 November 2010 - 04:40 PM, said:

For example - using your terms what would you lable the aprox 400 psi output pressure from the reg on a cocker?

I think you already said it- "output pressure from the regulator." However, if this 400 psi coincidentally happens to be the required input pressure to the marker to achieve 300 ft/s, then it will also coincidentally be the marker's operating pressure.

so in this situation operating pressure as a term will remain similar the way we're currently using it. It's the pressure entering the gun after the last in-line regulator before the gun's main valve system. Sound about right? In other words - 2k cocker = 400 psi, Ion = 180 psi, Tippy 98 = 800 psi etc.

The reason that I consider 98s etc unregulated guns is that there is no regulation in the design of the gun. yes, using HPA there is a regulator at the air source - but when using CO2 there is no regulation in the system. Single regulated guns would be those with one, in-line regulator after the air source but before the valve / operational system of the gun. Multiple regulator designs would be those with LPRs or other more exotic setups.

Now, I guess the real question is this; how many of these terms are needed to actually discuss the operation of a paintball gun? The reality is that the only one that REALLY matters is the pressure that's acting on the ball. That's my breech pressure. How the particular gun gets to that theoretical 41psi or the measured 60-110 psi is of little importance.

I would take a second look at your comment about "secondary air source". your example of a cyclone doesn't really jive. That's not a source, it's a system using air from the primary air source. A secondary source would have to be an input of pressure - not a system using pressure. make sense?

[MrEeske]

brycelarson, on 06 November 2010 - 07:10 PM, said:

so in this situation operating pressure as a term will remain similar the way we're currently using it. It's the pressure entering the gun after the last in-line regulator before the gun's main valve system. Sound about right? In other words - 2k cocker = 400 psi, Ion = 180 psi, Tippy 98 = 800 psi etc.

Yes, but I was intentionally forming the definition around that- that's what you were trying to get out of me. In the end, all I was doing was creating a formal, mathematical definition to a phrase that you already use. Who am I to start dictating how people should act and what they should say? I'm just flowing with the community.

brycelarson, on 06 November 2010 - 07:10 PM, said:

I would take a second look at your comment about "secondary air source". your example of a cyclone doesn't really jive. That's not a source, it's a system using air from the primary air source. A secondary source would have to be an input of pressure - not a system using pressure. make sense?

Mind you, a "source" of air doesn't have to come from a new bottle. Here's a simple question: can the A-5 cyclone feeder properly operate at 800 psi? I don't mean that the primary air source is feed 800 psi, but what would happen if you shot 800 psi directly into that cheaply-made cylinder? Before I go deeper into explaining my thoughts on the A-5, let me pull up a more common example.

Would you consider the pressure created by the Low Pressure Regulator of an Autococker still the primary air source, or a new air source? It goes through a "proper" air regulator, right? Does this low pressure air (< 100 psi) directly interact with the surface of the paintball? No. The purpose of this new source of regulated air is to operate the firing control mechanisms (e.g., cock the gun). By my definition of a primary air source, that is, air that is used to directly transmit force to the paintball, this newly regulated air can not be primary, so it must be something else; that "something else" I call utility air source.

Now back to the A-5. While the air supplied to the cyclone feeder does not go through a "proper" air pressure regulator, it is regulated none the less. As we generally agree, the input pressure into the A-5 is 800 psi. Some of that air is diverted through a very small hole, into the banjo bolt, and then directly to the cyclone feeder's cylinder. This very small hole acts as the pressure regulator (Venturi effect). If the input pressure will always be the same (approximately 800 psi), and the size of the orifice will always be the same (very small), then the pressure drop that occurs inside of the banjo bolt will also always be the same. Therefore, the input pressure into the Cyclone Feeder cylinder will always be the same (plus or minus quality air control fluctuations). Just as the Autococker's Low Pressure Regulator uses the primary air source as its input pressure, so does the Cyclone Feeder. They are very similar in how they create the utility air source for the marker, they just regulate it using different techniques.

The terms primary air source and utility air source are not dependent upon where the air comes from, but rather where the air goes.

brycelarson, on 06 November 2010 - 07:10 PM, said:

The reality is that the only one that REALLY matters is the pressure that's acting on the ball. That's my breech pressure. How the particular gun gets to that theoretical 41psi or the measured 60-110 psi is of little importance.

I absolutely agree with you on that point- and that's also the point I was trying to make, through math, when I was trying to figure out the rate of a paintball's acceleration down an 8 inch barrel; the only thing that matters is the force applied directly to the surface of the paintball.

Don't worry, we see eye-to-eye on this topic. It's also the core value behind the design of my own marker- the only thing that matters is putting force to paintball. Too many markers take a long, silly, and complicated route on what should be a very simple machine when you reduce it to its most basic concepts.

brycelarson, on 06 November 2010 - 07:10 PM, said:

Now, I guess the real question is this; how many of these terms are needed to actually discuss the operation of a paintball gun?

It all depends on how thorough you want to get. I personally use them all, and then more, but that's because I'm worried about the dynamics of every microsecond of every millimeter of these machines. The terms I've thrown out are not terms that I created, oh no. They are general engineering and physics terms that are used in industrial design. I don't pretend to be doing something that hasn't already been done, I'm just trying to do it a little better. With the exception of how we're trying to put our collective thumbs on operating pressure, everything I've said can be found in an engineering hand book written 50 years ago. And yes, I do have access to said book at my university.

Lemme twist your question a little and throw it back at you, so I may better understand you: what's your concern with the operation of a marker? You seem to like preaching the gospel of breech pressure, which is great, but what are your goals concerning the understand of breech pressure?

[CovertRussian]

These formulas took some time to find for me, might be a good idea to add them to the top of the list to make it simpler for others

Vector: =sqrt(SDx^2+SDy^2)
Standard Deviation: =STDEV(A:B ) (A through B )

This post has been edited by CovertRussian: 25 December 2010 - 01:07 AM

[MLP]

Thanks man this is a great post

[PlasticPi]

For slipstream, I suggest something like this:

The air affected by an object's movement through it.

I think getting more complicated than that belongs more in the definitions for things like magnus effect, coanda effect, etc.