rof and accuracy

[Minimag4me]

i am doing a project for school and i need resorces for this question but there are none, if there are any reputitable people in paintball(like tom or someone who owns a field or store) that i can quote and use their reply for a rescorce

im putting this in deep blue because i need reputible people(like people that deep blue was origionally ment for)

the question is "does rate of fire affect accuracy?"

for example a benchmounted mag using varios different speed bursts(like 5 shotburst at 2 bps to 5 shot burst at 10 bps) will the different rof affect accuracy

[headcase]

You would be right, but he is talking about a stationary, mounted marker, so your not making adjustments when firing.

To answer the original question, it can...it all depends on what consistency can be acheived within the firing system. If all your paint is fresh and round with good bore fit, and your marker isn't moving, and assuming that the weather is favorable to this type of test, the only other factor is the velocity, and how constant it is. If you are firing +/- 1 over the chrono, it will be much more accurate than firing +/- 10, with everything else constant. So if there are restrictions in your air system, you starve the valve under rapid fire, which causes loss of velocity, which will cause shootdown and loss of accuracy.


Later
SSDD

[Minimag4me]

foo- the same # of paintballs are coming out of the gun from each burst, im talking about grouping accuracy not volume because the volume would be the same

headcase or anyone- do you know if more paint going through the barrel quicker(not like velocity wise but rof wise) will affect the shot to shot acuracy(maybe air from the previous shot hasnt all escaped and will affect accuracy at high rof's?)

anyone have any input im missing or can add anything?

[headcase]

Sorry can't help you here, I wouldn't think that in would make a huge change, from shot to shot as the ball has to displace air no matter if it is a single shot, or part of a string. But really I don't know.

GoodLuck
Later
SSDD

[AGD]

This is a poorly understood area in paintball and I can not give you an answer with any authority. Having said that, tests over the years give a hint that faster firing rates produce smaller groups. It could be each ball is moving through the turbulence of the one before it and that helps some how or the guns are more consistent at higher speeds.

It needs more research.

AGD

[Minimag4me]

very interesting thank you tom

[kilaueakid]

They call it drafting in NASCAR :cool:

[constantairhead]

ROF on the playing field does effect your chance of getting a hit. but to my mind it has more to do with tactics than physics. Its the difference between using a rifle and a machine gun. A rifle is designed to put 1 shot exactly where you want it (depending upon your ability). Where as a machinegun is designed to put a lot of rounds in a designated area. Different situations require different solutions to achieve accuracy. If your opponent is unaware that your are targeting him then taking 1 shot just right is more accurate than ripping a dozen rounds in his general direction. On the other hand if you are sweetspotting a player running to a new bunker you want to put as many rounds in the air as possible. This is because the chance of a hit is quite low so you are increasing your chance of a hit thru volume. In reality you actually want your gun to be slightly less accurate with a higher rate of fire. If your first shot doesn't hit him, having a dozen rounds hit within a inch of the first probably isn't going to help the situation much either. Sort of an interesting anecdote I have heard but don't know the validity of is that in the early 70's the barrels on the 50 caliber machine guns used by the Canadian army were to accurate. they were actually reworked to provide less accuracy and more spread on the rounds to increase the amount of damage they can do.

[clockworkmiller]

From what I understand about physics, accuracy can be severaly effected by many things. A small gust of wind can throw bullets off mark by a few feet, simply because the mass of the object is so small that it is easily effected by outside forces. For a paintball, this includedes a small vaccum created by the paintball in front of it.

A paintball, when flying out of a marker, leaves a wake, as does any other object moving through the air. As the paintball moves forward, it creats a short vacuum behind it that is quickly filled with more air. If the paintball is flying perfectly round, then the air would apply equal pressure on all sides, and therefor not have any affect on something traveling within that wake, but would make it more difficult for something to leave. Therefore, we can assume that the closer one paintball is to another in flight, the harder it is to be affected by outside forces, and will remain relatively consistant with the other paintballs.

A way of thinking about this is a line of jetskis. As the first on moves in a set direction, each jetski follows at an interval later. The second jetski finda that it is much easier to travel directly behind the jetski in front of him, and any attempt to cross the wake is met with resistance. Assuming the jetskis could not power themselves on their own, they would find it difficult, if not impossible, to leave the wake of the jetski in front of them. The closer he gets to the jetski in front of him, the tighter the wake is, and the less mobility he has. However, if he is far anough behind, the wake dissapears and the jetski is free to move on its own.

Thats the best way to explain it to you. Tom is right, from a theorietical standpoint, a faster firing rate should produce more consistant results.

Remember, dont confuse consistancy with accuracy.

[Minimag4me]

i really like that jetski thing, thank you everyone for the replys

[Minimag4me]

headcase and clockwork miller if you are on can you guys please pm or post your first and last name so i can use your posts as research, thanks

[LaW]

Interesting post here: I didn't really read the replies but will later but was thinking that with rof on a stationary marker I'd think accuracy would be affect by the consistency of your tank and at what fps each paintball is coming out at like a +3/-3 difference in fps each shot...

[clockworkmiller]

Lloyd Miller

thanks, anything else you need?

[splat11756]

If its stionary i think it affects it. It makes it better. The ball infront of it the others breaks the winf. it also allows you to shoot farther. an example of this is a pack off geese the one flying in the front uses more energy to fly than the ones towards the back.

[Smoken]

That brings about an interesting point. If a paintball can "draft" (conserve energy by eliminating some wind resistance) would that mean that the second, third, etc. balls could travel farther than the first if they are fired in rapid enough succession?

[clockworkmiller]

smoken.

thats exactly what it means. In rapid fire, you'll have a tighter grouping at a greater distance

[Vegeta]

Air resistance is less behind a moving object. In racing, a driver stays behind the car in front of him up to about 4 feet behind his bumper until swinging out to pass. The wind resistance is less, giving the car more speed while in this draft.If you watch racign closely, you can see a car pull up behind the lead car easily, but when hte car swings out to pass, it hits a wall or air and slows down a bit. That is why most passing in racing doesn not matter on speed, but more on overbraking/underbraking your opponent.

Same thing applies in paintball. What is not good, is if while you are firing a string, say 10 balls, and are runnign or moving your gun. If this happens, each ball is lsightly behind the ohter, but also off set from each, so say each ball is 10 inches behind hte ball before it, but also 10 inches to the right, so the balls hit in a row (> > > > > > > >) Accuracy can be greatly affected if hte balls are too lcose, and the tail wind off the 1st ball hits the second ball, and 2nd hits 3rd and so on. Yes, the balls will group tighter is they are inline, but if they are offset like this, the corner of the draft produced could possibly throw off the ball next to it.

[AGD]

Vegeta,

Think about it, at 300 ft per second a ball will travel 30 ft in 1/10th of a second right? That means firing at 10 bps puts the balls 30 ft. apart.

AGD

[clockworkmiller]

The bad part about that Tom, is that most snap shooting contests take place much closer than 30ft. For front players, its an advantage to turn your velocity down, in order to reproduce the affect above. On the other hand, this whole concept of wakes, and tighter shooting patterns is just a theory. And we all know that theories are just their to be tested. So in two weeks, when no body cares about this discussion, and has in all proabability moved on to bigger and better things, I'll be takeing my truck, a vice, a chronograph, and my marker out into the desert to test this wonderful theory of ours.

[Vegeta]

ok that was enlightening, never saw it that way. What we really need to know, and I know AGD has this info vecuase I have heard you all talk abotu the expensive cameras u bought to photograph the PB leavign the barrel.. what need to knwo if how fast the air behind the paintball returns to normal wake. I would say, based on what Tom just stated, pretty fast. I know you all have see "The Matrix". What I am talking about are those little ripples behind the bullets. Notice my attached pic. It would be good if we knew how far that "tail" went.... until it disipated. If the balls really are 30 feet apart, I doubt those trails would be 30 feet.

[PBpunk]

its called bernuolie's principal (bad spelling?) moving air produces less pressure the stationary air. the faster its moving the less pressure it makes. its how airplanes fly but thats a different story. anyway here is my theory. and this would only work with a gun in a vise and a good paint/barrel match. it has been said before but i just wanted to say the concept has been researched in area's other then paintball (like flight or racing). as the ball travels through the air it leaves a "tail" like in the diagram except the tail is more turbulent so the moving air behind it leaves a low pressure "tunnel" for the next ball to go thru like in the jet ski illustration and if it starts to move out of the tunnel it hits the high pressure still air and moves back into the tunnel. of course this depends on how long the "tail" is and the wind and 100's of other factors so i would say its possible but it doesnt happen often if ever but if you could take advantage of it it might be an improvement

[Vegeta]

Yes, but as Tom said, the balls are 30 feet apart at 10bps. not always do u fire that quickly. HTe tails are definately not that long.

[PBpunk]

maybe they are 30ft apart but think about the tails as not something that is following he ball but more like the wake of the ball (the jet ski illustration). then think of how long it would take for the wake to close up. the balls are only a tenth of a second behind the next one. would the air stop moving in a tenth of a second? i dont know. just a thought.

[ButtersAutoMag]

Well from my personal experience as a mag owner, and a person whos has shot a regular mag and one with a hyper frame, it does affect it. With the hyper frame i used i think 5 round burst and it shot fast, but it only like grouped the shots. I hit like a bunker but I hit it like 4 feet from the center, with my mag I got a double trigger benchmark and hit it an average bout 1 foot from the center.

[clockworkmiller]

Well, here's the trick.

It does work, but only if you are constantly shooting in the same direction. In other words, it would only work if the balls were intending on following the same path. And even if the first ball does swing wildely inaccurate, say on a dimple, then it still lowers turbulence directly in front of the barrel, which may give you an extra foot in range overall.

[CHK6]

Minimag4me,

I haven't read any of the reply posts, except the one with the picture. The picture is TOTALLY wrong and I say that with much conviction. Basic fluid mechanics easily shows that a sphere traveling through the air creates turbulent wakes in it's path and not smooth latent layers the picture shows. In fact it creates a mini swirl behind itself and pressure distortion around the ball occurs.

As for ROF and accurracy I haven't read any coralation between the two. However ROF might and can have an affect precision. Not to confuse precision and accuracy. If I was you I'd look up the differences between the two to fully understand what I'm saying.

In my theory {basically the mind's eye} rapid fire is like NASCAR drafting. The subsequent trailing balls meets less resistence to air than the leading ball. This is the basics behind drafting in NASCAR. And it has been shown in theory and in practice to be true.

By creating a path for subsequent balls to travel through the tightness of the pattern on impact will get smaller. This is called precision.

[Vegeta]

I stated that:


In racing, a driver stays behind the car in front of him up to about 4 feet behind his bumper until swinging out to pass. The wind resistance is less, giving the car more speed while in this draft.If you watch racign closely, you can see a car pull up behind the lead car easily, but when hte car swings out to pass, it hits a wall or air and slows down a bit. That is why most passing in racing doesn not matter on speed, but more on overbraking/underbraking your opponent.

I also tried to get he whole swile thing going, and brought up "The Matrix" and bullet time, how hte bullets make swiling bubbles in the air. I just couldn't find a way to show that in a pic.

[CHK6]

I posted first as not to be biased to what others have posted before me and then went through the posts afterwards. It's cool that I'm not way off base with others.

The length of the tail the ball creates I don't believe matters as much as the wake/air-path it leaves behind. I wonder how long that wake lasts? If it's 10 bps then in the path the balls take only 1/10 of a second passes before the next ball travels through the same point in space. Being that the space is fluiditic, there will be a time of distortion following the point in space.

Got math?

[athomas]

It is theoretical that in ideal conditions, turbulance can be present and last for a period long enough to disrupt a paintball following another paintball in flight. It follows the same concept of airplanes and turbulance. That is why planes are directed to stay certain time/distances away from other flight paths when attempting to take-off. If a plane takes off too soon following another, it could get caught in the low pressure turbulance left by the previous plane. It has cause planes to literally fall out of the sky during take-off due to the lack of required pressure for the engines and wings to push against to gain speed and lift. For a 2nd paintball to follow the same path as a previous paintball, it is theoretically possible that this lack of pressure could act like a tunnel and provide a path for the 2nd paintball too follow.

I don't know how you would test this. Maybe we could get someone to build a series of highspeed cameras and fire some shots past them under controlled conditions and possibly some smoke particles for viewing the turbulence and pressure void.

[PBpunk]

a good way to test it may be in a wind tunnel maybe you could put a ball in a wind tunnel then use those little smoke jet things that you see in car adds ands stuff. you may be able to tell what the trails look like and how long they last and stuff. i dont know who would have access to a wind tunnel. i bet AGD could. maybe talk to Boeing or NASA or Lockheed Martin or something. if nothing else it would be interesting.

[Minimag4me]

so probably the distancy and velocity is increased by this drafting but by how much? is it enough to be measureable?

[Vegeta]

AGD has already done some about this in testing. They supposedly used a Cinipex (?) camera, which runs at a high framerate, soemthing to the effect of 1200 frames/sec. to photograph a ball leavign hte barrel. They flowed grren smoke over the ball to study how it went around it. Spent big bucks. At least that is how I heard it. Tom, if you could confirm this and tell us more about your research, we'd love to know.

[Gup44]

Chk6... As far as how long the trails are I keep thinking about canoing. If you have ever paddled in a canoe, then you have watched the water swirl behind your paddle and continue to swirl for some time even after the paddle is out of the water. I would venture to say sometimes up to 15 or 20 seconds or possibly more.

I don't know the math and the differences between water and air, but I would guess that the "trails" behind a paintball could last some time... Definately long enough to effect a the next few paintballs in a sting at 10bps.

:confused: I don't know if this makes sense. But it was my own <i>mind's eye</i>.

-Gup44

[AGD]

Deep Blue is really coming along nicely here, I am enjoying the high level conversation.

The aviation term is "Wake Turbulence". It's generated by the wings in the form of vortexes on liftoff by large airplanes. The swirling air can persist for quite a while and can cause accidents.

We have not specifically studied the effect of turbulence and it's effect on the ball following but there are some tantilizing clues. There have been reports of bench mounted guns shooting tighter groups at higher speeds. There is no known explanation for this (or if it is in fact true). Paintballs positively generate wake turbulence because you can hear them buzz by you out in the field. This is an understudied area worthy of some effort.

Water is commonly used to study aerodynamic forces. It is not a direct one to one comparison because water has more mass and viscosity. In order to match flow effects between such diverse mediums as water and air you have to use some fancy mathematics. The math forumulas generate Reynolds Numbers which are used to match the different flow characteristics. In general if you have a sphere about 1 foot wide at 150 mph and want to test it in water you would use one about 1 inch wide with a water flow of a few miles per hour. This is a ballpark from work we did in the 80's on cooling drag in motorcycles and airplanes.

The airflow around a sphere is a classic study for first time aerodynamicists. It's is well understood (and it sucks). The notable points are the fact that laminar flow exists around the front of the ball and the laminar layer stays attached for some distance past the mid point. Just past the midpoint it detaches and becomes turbulent in unpredictable and random ways. A boundary layer exists near the surface where the air transistions from high speed to virtually not moving on the surface of the ball. The thickness of the boundary layer is one of the determining factors of how long the laminar flow stays attached. The longer it stays attached the more aero the body. Golf ball dimples try to influence the boundary layer.

There are several cool experiments you could do and be the first ones to reveal these secrets. Find a room you can fire paint in an created a cloud of smoke that hovers in mid air. Fire a paintball through it while video taping and you should be able to time how long the turbulence effect lasts. Make sure you fire from far enough away that the gun blast does not affect it.

Another thing you could do is get your fishing pole and glue a nylon ball to the fishing line and drag it through the water like a lure. The movement of the ball would demonstrate how the ball flies through the air. We know for a fact that paintballs "wobble" back and forth in flight and that this is the major contributor to accuracy reduction.

Keep up the good conversation guys this is really interesting.

AGD

[clockworkmiller]

Im am so doing that experiment with the smoke. Im no numbers wiz, but i'll get the data down and find a physics professor who would help with calculations. We have the basement in the frat house that is never used, and has very stagnant air, which would be perfect for this experiment.

Thank you tom very much for the information. If you have any other ideas on experiments, just post them, and Im sure I, or someone else would be more than willing to help out. See you in march.

[media]

Dimples. OMG, don't throw away that old dimpled paint! I wonder if anyone has tried to make a paintball with a surface simular to a golf ball. It'd probably shoot fine since proper paint to barrel match only requires the paintball to just skim the barrel. I'd assume it would be to expensive to manufacture though.

[Wat]

Gawd...fluids...i had a fluids lab at MIT where i had make a velocity flow meter out of a ping pong ball suspended on a string. Four weeks of collecting data, writing ugly equations and a Mountain Dew drip and i had a flow meter that was 5% accurate.

Anyways...the thing with fluids, is that the equations involved are whats called non-linear. Otherwise known as pains in the buttocks. These equations cannot be solved and the only way to find the answer is through actual experiments or massive computer number crunching.

In solids, the equations are mostly linear and we can do pencil, paper and brain analysis and come up with a reasonable answer without ever getting our hands dirty. But in fluids, we can't. We can't say with much certainty without running experiments, computer models or looking up numbers in those big books of data, which is really just someone else's experiments.

I applaud AGD for actually getting in the lab and running tests instead of just spewing marketing myths. If anyone can program, someone should write up one of those SETI like screen savers/distributed number crunching programs and we could use every pballers computer to model the flow around a paintball.

[Minimag4me]

i believe the golf ball dimple thing was tried but it didnt work or at least not well enough(little gain) to be manufactured.

I wish i had a place to do that smoke/room thing. That would be interesting.

[PBpunk]

my friend has a fog machine but i dont think my mom would like me shooting paint down the hallway:D