[cockerpunk]

video - http://www.youtube.c...h?v=TJWiJvmcAvk

data - http://spreadsheets.google.com/pub?key=pym...HdSU6mMTaMXfLLA

discuss!

[Snipez4664]

Is there a way to compare this data with the paintball trajectory calculator predictions?

[Leftystrikesback]

Quote

Is there a way to compare this data with the paintball trajectory calculator predictions?

The averages line up pretty well but there's no way to put 50 ft into the calculator and see what the speed is there, so it seems like you have to just stop the calculator at a distance close to what you want.

I wrote my own code that uses the same equations but outputs velocities in a vector. I can use that to compare velocities at certain distances. Are you just wondering how much the theory lines up with the tests? It's going to depend pretty heavily on how accurately your drag coefficient is defined. He uses Cd = 0.5 and so did I in my code (IIRC, I'm not at home to look at it) but it actually can vary with velocity which makes things much more complex. But defining it that way would make the results more accurate.

I guess it would be nice to see whether Cd = 0.5 is an underestimate or an overestimate, is that what you were thinking?

This post has been edited by Leftystrikesback: 30 March 2009 - 04:08 PM

[Leafy]

do we know the minimum velocity at which a paintball will break? might be nice to add to the extrapolated data. and maybe add a bit of the extrapolated data to that graph so that it really shows the exponential decay of the velocity.

*edit how many times did you hit your 50' and 100' chronos before you got the paint to go through it? I only ask cause I notice that the paint "hits the ground" at 40 feet.

This post has been edited by Leafy: 30 March 2009 - 04:16 PM

[U83R 1337]

It would depend on the type of paint, temperature, how old the paint is, and what it hits

[cockerpunk]

Leafy, on Mar 30 2009, 05:13 PM, said:

do we know the minimum velocity at which a paintball will break? might be nice to add to the extrapolated data. and maybe add a bit of the extrapolated data to that graph so that it really shows the exponential decay of the velocity.

*edit how many times did you hit your 50' and 100' chronos before you got the paint to go through it? I only ask cause I notice that the paint "hits the ground" at 40 feet.

note under the assumptions it is listed as zero barrel angle.

obviously we had to elevate the gun to get it to hit the chrono at range. but remember, we are dealing with ranges and assumptions about the ranges of values. the extrapolated data is part of an ongoing project i have with viper the scenario producer.

[Leftystrikesback]

Leafy, on Mar 30 2009, 02:13 PM, said:

do we know the minimum velocity at which a paintball will break?

It definitely depends on the paint, but you can calculate a good estimate:
Every ball doesn't break after being dropped from 8 feet, so maybe after 10 feet would be like 90% breakage for an average paintball. How fast is a paintball going when it hits the ground after being dropped from 10 feet? I'm sure you can solve that for your self.

[Leafy]

Leftystrikesback, on Mar 30 2009, 05:56 PM, said:

Leafy, on Mar 30 2009, 02:13 PM, said:

do we know the minimum velocity at which a paintball will break?

It definitely depends on the paint, but you can calculate a good estimate:
Every ball doesn't break after being dropped from 8 feet, so maybe after 10 feet would be like 90% breakage for an average paintball. How fast is a paintball going when it hits the ground after being dropped from 10 feet? I'm sure you can solve that for your self.

ok its about 25 feet/sec thats what I got without factoring in drag and using 3 meters as the drop height and 9.8 m/s^2 for the acceleration due to gravity.

[weeebeep]

would you be so kind as to try the same test featuring the tiberius first strike round? I would really like to see how fs holds up against traditional paint.

[brycelarson]

weeebeep, on Mar 30 2009, 08:52 PM, said:

would you be so kind as to try the same test featuring the tiberius first strike round? I would really like to see how fs holds up against traditional paint.

that's on the list of tests for this summer.

[Snipez4664]

Leafy, on Mar 30 2009, 06:39 PM, said:

Leftystrikesback, on Mar 30 2009, 05:56 PM, said:

Leafy, on Mar 30 2009, 02:13 PM, said:

do we know the minimum velocity at which a paintball will break?

It definitely depends on the paint, but you can calculate a good estimate:
Every ball doesn't break after being dropped from 8 feet, so maybe after 10 feet would be like 90% breakage for an average paintball. How fast is a paintball going when it hits the ground after being dropped from 10 feet? I'm sure you can solve that for your self.

ok its about 25 feet/sec thats what I got without factoring in drag and using 3 meters as the drop height and 9.8 m/s^2 for the acceleration due to gravity.

Right.....Because when I play paintball, I do so wearing blocks of oak at right angles to those shooting me. It's much, MUCH easier to go the other way (hard to get breaks at 150 feet, therefore this velocity is about what it takes to break on a human).

[Leftystrikesback]

Snipez4664, on Mar 30 2009, 07:27 PM, said:

Right.....Because when I play paintball, I do so wearing blocks of oak at right angles to those shooting me. It's much, MUCH easier to go the other way (hard to get breaks at 150 feet, therefore this velocity is about what it takes to break on a human).

You and your "logic"

This post has been edited by Leftystrikesback: 30 March 2009 - 09:30 PM

[Leafy]

Snipez4664, on Mar 30 2009, 10:27 PM, said:

Leafy, on Mar 30 2009, 06:39 PM, said:

Leftystrikesback, on Mar 30 2009, 05:56 PM, said:

Leafy, on Mar 30 2009, 02:13 PM, said:

do we know the minimum velocity at which a paintball will break?

It definitely depends on the paint, but you can calculate a good estimate:
Every ball doesn't break after being dropped from 8 feet, so maybe after 10 feet would be like 90% breakage for an average paintball. How fast is a paintball going when it hits the ground after being dropped from 10 feet? I'm sure you can solve that for your self.

ok its about 25 feet/sec thats what I got without factoring in drag and using 3 meters as the drop height and 9.8 m/s^2 for the acceleration due to gravity.

Right.....Because when I play paintball, I do so wearing blocks of oak at right angles to those shooting me. It's much, MUCH easier to go the other way (hard to get breaks at 150 feet, therefore this velocity is about what it takes to break on a human).

you dont? it can be the eigencammo.

but you're correct, but now how do we test human bounce? have one of you friends lay down on the floor and drop it on his chest off your roof?

[Snipez4664]

Leafy, on Mar 30 2009, 10:31 PM, said:

but you're correct, but now how do we test human bounce? have one of you friends lay down on the floor and drop it on his chest off your roof?

You shoot them, over a chrono. I'm happy to volunteer you for this duty. Remember, bouncers hurt the most!

[Spitlebug]

Snipez4664, on Mar 30 2009, 07:47 PM, said:

Leafy, on Mar 30 2009, 10:31 PM, said:

but you're correct, but now how do we test human bounce? have one of you friends lay down on the floor and drop it on his chest off your roof?

You shoot them, over a chrono. I'm happy to volunteer you for this duty. Remember, bouncers hurt the most!

Bwhahahahahahahaha.

Seriously though, it would be interesting to get the final velocity at or around 150 feet (is that a standard field length?) so as to know the speed the ball is travelling and then get a rough idea of the centroid for accuracy at that range. This information may be pertinent to fixed and inflatible bunker design.

[AndreS]

awesome test!

This post has been edited by AndreS: 31 March 2009 - 02:45 AM

[brycelarson]

Leafy, on Mar 30 2009, 09:31 PM, said:

but you're correct, but now how do we test human bounce? have one of you friends lay down on the floor and drop it on his chest off your roof?

I don't think we can quantify bounces off a human target - there are too many variables. you've got joints, muscle and fat. I guarantee I'll get more bounces from my belly than from my elbows. We're looking at a massive density range depending on the location of the hit.

I would agree with the 25 fps number - for a mask, pod, gun or hopper hit - but obviously not for a chubby guy's belly.

[Lord Odin]

You could always make your own ballistics gel to simulate human flesh and bounce off of that. There are plenty of links on how to make it yourself. Just have to make sure you keep the formula the same for consistent viscosity for different batches. Wouldn't want one target to be softer/harder than another.

This looks like a good one.
http://www.firearmstactical.com/tacticalbr...r2/article1.htm

This post has been edited by Lord Odin: 31 March 2009 - 11:19 AM

[cockerpunk]

brycelarson, on Mar 31 2009, 10:41 AM, said:

Leafy, on Mar 30 2009, 09:31 PM, said:

but you're correct, but now how do we test human bounce? have one of you friends lay down on the floor and drop it on his chest off your roof?

I don't think we can quantify bounces off a human target - there are too many variables. you've got joints, muscle and fat. I guarantee I'll get more bounces from my belly than from my elbows. We're looking at a massive density range depending on the location of the hit.

I would agree with the 25 fps number - for a mask, pod, gun or hopper hit - but obviously not for a chubby guy's belly.

maybe your belly!

but mine is hard as oak and washboards!

[Spitlebug]

cockerpunk, on Mar 31 2009, 09:45 AM, said:

maybe your belly!

but mine is hard as oak and washboards!

Yes, I am definately as hard as wood as well.