Is lower FPS really helping?

[Burphel]

Ok, after my local field being closed most of the winter, some friends and I finally broke down and drove to the next biggest town to play some indoor. Now oddly enough, I came away from playing those 250fps fields with more, bigger welts and bruises than most days of playing speedball at a 300fps field.

It could be the closer proximity shooting, but I can't imagine that shots lose that much velocity over the 100ft or so on a speedball field that they'll do less soft tissue damage than 250fps at 10 ft.

My hypothesis here is that the higher velocity carries enough energy to break it's own shell against a softer surfuce (say skin and subcutaneous fat), whereas the slower velocity allows the ball to remain intact until it hits something of higher resistance to break it like muscle tissue or bone. This extends the familiar concept that bouncers tend to hurt more and cause more impressive bruises to hits that eventually *do* break, but 'penetrate' (for lack of a better word) farther before doing so.

I'd like to see this checked out in a scientific way rather than just guessing because pretty much every indoor field I've been to uses 250fps. The 300fps muzzle velocity was established to prevent bone/muscle injury as I understand it, and our goggles are all rated to handle multiple hits in excess of that. Fields commonly lower their velocities for 'comfort.' My point here is that if I'm right, these field may actually be doing their players a disservice. It may also provide interesting information for the insurance companies that cover indoor fields, as they'll want to reduce soft tissue inuries just as much as bone/muscle injuries.

[Slimm Jimm]

i'd also like to see some research on this, but i wonder if it could have something to do with the type of paint being used, since the only welts i recieved last time i played at an indoor was from a winter type formula.

[Burphel]

In this instance, it was mostly Worrpaint with some RP and Diablo thrown in (they let you pay a little extra to BYOP). Nothing that's ever been a problem in the past.

I dunno, maybe I was just having a heavy bruising/welt day. It's happened before.

[sieggy]

With paintballs ten feet in comparison to 100 feet makes a huge difference. It is because of the close play that it hurts more, and leaves bigger welts.

[TheTramp]

Yup, if you were shooting 300fps at that indoor place you'd have even bigger welts and bruises than the ones you got from 250.

You're just used to normally being shot from considerably further away.

[lamby]

I have been shot close range (less than 5 feet away) by both 260 and 300fps. I will tell you 300 leaves a nicer welt, but 260 will still draw blood on exposed skin.

Dont get bunkered, and it will all be better. :)

[Wes Janson]

Paintball speed drops off rapidly as distance increases. At 100+ feet your shots are far, far more likely to bounce instead of break, because of the velocity drop. I've stood out in the open and danced around shots at longer ranges, and I've heard of people catching paintballs in their hands at longer range. 300, 250 fps only applies to the first few feet of flight, after which speed drops considerably.

[Enemy]

ive also see another variable to throw into the mix..rarely ever is there a day with no wind factor and that will also slow paint down unless you are shooting with the wind..any how ive played both and the only noticable distance is range..but here is a tosser...why is it that shots coming from angels and other low pressure guns seem to hurt less than shots from spyders and tippmans.. it sounds bogus but i had a bunker from an angel hurt less than when i was hit from 20 ft with the other guns...also the field im at generally runs the lower guns at 280 while they just check the higher end guns to make sure they are under the 300 cap this guy was at 295??? just a thought

[bjjb99]

Unless you're at a field-paint-only field, the low pressure guns are probably using more brittle paint. When a paintball shell breaks quickly, the paint spreads out sooner and delivers the impact energy over a larger area. When the shell is less brittle, it takes more impact deformation of the paintball to cause it to shatter, thus delivering more of the impact energy to a small area on your body.

Higher energy "density" at impact == more "ouch".

Of course, one extreme of this is a paintball that bounces. Those generally hurt the most because _all_ the impact energy is delivered to a small area. I suppose the other end of the spectrum would be a paintball that broke on something right before it hit you... then all you're getting hit with is a blob of liquid that spreads out quickly and doesn't hurt at all.

BJJB

[frontrunner]

a few things, first byop night suck cause half the players use is cheap, chaep paint will either break in your barrel or not at all and if someones getting it down field to you think about it, next not all spots on your body welt the same and your bodys will differ from night to night depending on blood flow which is impacted by how hard you're playing, how long you've been playing and any food or drugs you have consumed in the last few hours. just my view

[sniper1rfa]

its entirely possible - when the paintball hits, the faster it breaks, the less it hurts. If its travelling at 300 fps, it may break fast enough to counteract the extra energy it has. *shrug*

i dont like people playing with low guns any more than high ones - more than once i've asked somebody to chrono and seen 240, 250 fps...

[Lohman446]

its entirely possible - when the paintball hits, the faster it breaks, the less it hurts. If its travelling at 300 fps, it may break fast enough to counteract the extra energy it has. *shrug*

i dont like people playing with low guns any more than high ones - more than once i've asked somebody to chrono and seen 240, 250 fps...

Agreed, I took two across field to the head the other day, now I will grant they snuck in above the mask, then when I ducked it hit the back of my head.. and I had to take a couple moments to gather myself to walk off - I asked the person to chrono because it is the only time that being hit has caused that much pain 240 I was like WTF?

[Trick]

Speedball tournies are 300, right?

They bunker the everloving snot out of eachother, but I have had worse welts from my 250 fps indoor.

You folks may be on to something...

[Burphel]

Trick - My point exactly. Most tourneys are 280/290 nowadays. The idea being to have an additional 'safety margin' below 300. Which already has a safety margin built into it.

If the trend, as it seems to be is to lower velocities 'for comfort/safety', is this goal really being accomplished? I think we can all agree that getting hit above 300 tends to hurt like a banshee, but what's the lower end at which you start doing more damage again? And don't you think insurance companies would be interested in this as well?

[Number13]

Consider the following:
F: Force
m: mass
a: constant acceleration
t: time
u: initial velocity (t = 0)
v: final velocity (t=t)
s: displacement during interval t

F = m * a

v^2 = u^2 + 2 * a * s

Assume identical paintballs (i.e. identical mass) travelling at different velocities.

If final velocity (v) is equal to zero, meaning the paintball has stopped moving from impact, then we arrive at:

0 = u^2 + 2as

From our formula for force, let's solve for variable a so that we may substitute the force into our velocity equation.

a = F / m

0 = u^2 + 2 * (F / m) * s

Since for our example the acceleration is a negative one, we may change the equation to:

0 = u^2 - 2 * (F / m) * s

The displacement of the two balls will be equal, since we will discard any prior motion and only deal with the moments before impact and their relatively constant velocity before impact. Whether we assume the displacement is .001 cm or 1 cm is irrelevent for this example, the displacement may be treated as a consant between the two different velocities. With this arrangment, our only remaining variables are: Force; initial velocity.

There will be two initial velocities and two resulting forces. We will use 250 feet per second (fps) as the first equation's initial velocity and 300 fps as the second equation's initial velocity.

u[1] = 250 fps
u[2] = 300 fps
F[1] = force of impact at u[1]
F[2] = force of impact at u[2]

0 = u[1]^2 - 2 * (F[1] / m) * s
-u[1]^2 = -2 * (F[1] / m) * s
u[1]^2 / (2 * s) = (F[1] / m)
(m * u[1]^2) / (2 * s) = F[1]

0 = u[2]^2 - 2 * (F[2] / m) * s
-u[2]^2 = -2 * (F[2] / m) * s
u[2]^2 / (2 * s) = (F[2] / m)
(m * u[2]^2) / (2 * s) = F[2]

Since everything in these two equations are constant except force and initial velocity, the equations show that a higher initial velocity (i.e. u[2]) will result in a higher force (i.e. F[2])

or
0 = 62500 fps^2 - 2 * (F[1] / m) * s
-62500 fps^2 = -2 * (F[1] / m) * s
31250 fps^2 / s = (F[1] / m)
31250 fps^2 * m / s = F[1]

0 = 90000 fps^2 - 2 * (F[2] / m) * s
-90000 fps^2 = -2 * (F[2] / m) * s
45000 fps^2 / s = (F[2] / m)
45000 fps^2 * m / s = F[2]

From these two equations you see that 45000 multiplied by the constant m / s is greater than 31250 multiplied by the constant m / s, which yields F[2] as the greater force.

So, getting hit at 300 fps appears it would hurt more than getting hit at 250 fps, all else equal.


[EDIT]
My hypothesis on bounces proved quite inaccurate. It clearly has to do with elastic versus inelastic collisions. Elastic collisions inflict higher net forces on each object. This means that a bounce that hurts more than a break has applied more force to the ball (as well as your skin) than the ball that did break on you; the shell simply did not break under the higher force. More pain results. A lower velocity impact that bounces hurts more than a ball that at the same velocity breaks. The question for the physicists/mathematicians becomes, "At what velocities does a ball that does not break generate equal pressure as a ball that, travelling at a higher velocity, does break?"
[/EDIT]

Thank you,
MC