KalNet Message Board

Event Name: Relentless!
Location: KalNet Tactical Paintball Proving Grounds

Date & Time: Sunday July 10th, 2011 11:00am

Description: Join us for a day of non-stop tactical paintball action, as we continue our relentless persuit to change the face of paintball forever. All your favorite modes will be featured with all the thrills and kills you've come to expect from KTPPG.

Tell your friends!

Before we start this time we get to find out if someones gun is running hot or if I'm just a delicate flower that bruises easily because goddamn just look at this hit from last week:

I'll be there.

Granted I Don't have a gun or any other equipment, but I can do one of the two following things
A) beat someone up and take their stuff from them...
Or
B) borrow someone else's equipment.

I prefer option A though. Think of me as an environmental hazard to the field

I should be able to play at this one also I think my dad will be showing up for a bit as well. and for the time he is not there I can lend paul my dads stuff if need be

I have an extra Gun Paul can use as well. The only think I don't have is an extra mask.

eight_ender wrote:Before we start this time we get to find out if someones gun is running hot or if I'm just a delicate flower that bruises easily because goddamn just look at this hit from last week:

photo.jpg

We always chrono before every day starts, but someone could be changing it after. I doubt this, but rest assured that if I am there, everyone will be chronoed. Jon should have it now though since I have been missing games as of late.

[PX]IronFist wrote:I have an extra Gun Paul can use as well. The only think I don't have is an extra mask.

I left an extra mask at Homey B's as somebody sold me one

It's a really old, sh!tastic one so you may need RainX, dish soap, or spit to see outta the dern thing.

[PX] Nebuchadnezzar wrote:
We always chrono before every day starts, but someone could be changing it after. I doubt this, but rest assured that if I am there, everyone will be chronoed. Jon should have it now though since I have been missing games as of late.

No don't get me wrong, I'm not accusing anyone of foul play. For all I know I might have taken that one at close range and didn't notice, although I don't think we managed to chrono all the guns last week. Either way I really just wanted to show off my badass bruise.

I did have the chrono out and we did chrono pretty much everyone. Although I'm not sure if we did Bram's gun. And Quango's was pretty close to the line.

Ya I have 1 pretty good hit too

Approximate weight of a paintball = 3.2g

We chrono at 280fps or 85.344mps

For the maximum kinetic energy of the ball (assuming all energy is transferred 100%) :

KE = (1/2) x (mass) x (velocity ^ 2)
= 0.5 x 0.0032kg x (85.344m/s)^2
= 11.654 Joules

Take the cross section of a .68 for area of impact (ie. energy density):

Caliber (differences in caliber calcs)
0.68in x 2.54 = 1.7272cm

Diameter to Radius
0.017272m / 2 = 0.008636 radius

Cross-Section of Paintball
area enclosed by a circle = pi x r^2
= 3.14 x (0.008636)^2
=0.00023418275744 m^2

so 11.654 J / 0.0002 m^2


11.654 J to ftlbs = 8.595663077150023ftlbs as per Conversion (I don't have a textbook handily unpacked so I'll run with it)
0.0002m^2 to in^2 = 0.31000062 in^2

so 8.595663077150023ftlbs/0.31000062in^2

= 27.727psi

Side note:

Firearms comparison

.22 long rifle = 131 ft-lbs
7.62 nato = 2690 ft-lbs
.50 bmg = 12575 ft-lbs


PSI needed to bruise the body?

20

(Please feel free to dispute that as it's all I could come up with).



Homey J and B can check my calcs. Heck, get B Senior to check 'em

Conclusion:

With the evidence I have on hand, assuming maximum energy transfer, chrono'd guns will still bruise. I believe the impact cross-section not being uniform would only increase impact force; however, a lack of 100% energy transfer should negate that so I just did a quick and dirty calc.

Heat............kitchen...........yada yada

hahaha see thats why we have engineers in the world lol

So crazy math scenario I don't want to bother figuring it out so I just believe him.

These calculations make sense, but due to wind resistance and drag for the paintball to sill be travelling at 280fps you would have to be shot at point blank range. At 100ft a paintball has already lost half of it's velocity. At about 50ft the velocity of the paintball will be around 200fps (http://home.comcast.net/~dyrgcmn/pball/pballResults.html).

So if we put that data into the equations:

KE = (1/2) x (mass) x (velocity ^ 2)
= 0.5 x 0.0032kg x (60.96m/s)^2
= 5.95 Joules

5.95 J = 4.388552883906181 ftlbs

so 4.388552883906181 ftlbs/0.31000062in^2

= 14.157psi

Also, if the shot was through a jacket (which I'm pretty sure it was) then it would absorb some of the energy on impact. So unless Tyler was shot at point blank range on bare skin then that gun was probably shooting hot.

Although I do think that the biggest error in our calculations is the assumption that it only takes 20psi to bruise. I imagine this value is actually different for eveyone, and depends on where you get shot. Maybe Tyler just bruises easily

Yeah, my calcs were for the worst case scenario as per my stated assumption.

And what with Homey B playing, being shot at point-blank is always a possibility

Also getting hit twice in the same spot (at least for me) makes a nice angry bruise.