Technology?

[RePete]

So have we come to any conclusions after this scholarly debate?

Would everyone agree that once a ball leaves the barrel of a gun, the only things acting upon it are the forces of nature and that no after market, nickel plated, LCD enabled, computer controlled whosi-whatsit will have any impact on the accuracy of your paint?

The most important things affecting the trajectory of a paintball once it leaves the barrel are:

Mass (Fairly constant)
Surface area (Fairly constant)
Wind (Irrelevant as changes in wind can not be measured. Call it a controlled experiment ignoring wind factors)
The shape of the ball as it travels
The spin on the ball

So which of these factors can we control?

The shape the ball as it travels? Is it not part of the theory behind the accuracy of closed bolt guns. Before they are slammed with high pressure air, the action of the bolt going forward gives the ball a more gentle acceleration, reducing the amount of distortion to the ball?

The spin of the ball? The Flatline barrel and the Galactic Z-Body for the Mag are examples of this. Particularly if you like watching your paint bounce off your opponents at long range. What effect does the ball detent have on the spin.

Oh goodness this is going longer than I meant...

Bolts - *Groan* Venturi vs. open face relative to high/low pressure?

I think I'll stop there.

 

[Robbo]

Re: Re: Re: It's worse than that, it's physics Jim...

Originally posted by Flash-Bugout
Wow, an intelligent converstaion I can take part in

What choo talkin bout Flash ?

Any coversation I am involved in, is, by definition, intelligent !!!
Robbo

 

[Hotpoint]

Originally posted by Robbo
Hey Cube, I think you have just made the point, in a roundabout way that I was originally suggesting....it just remains for Hotpoint to rebut or to enlighten.
I await Hotpoint's reply with baited breath
Robbo

Now this is exactly the reason why I originally (and since then repeatedly) said I was talking about how mass effects the trajectory of two objects... of equal size!

Methinks I have been misjudged

It is a good disscussion though (Most thread hijackings don't tend to go this way)

 

[Robbo]

Originally posted by Hotpoint
Now this is exactly the reason why I originally (and since then repeatedly) said I was talking about how mass effects the trajectory of two objects... of equal size!
Methinks I have been misjudged
It is a good disscussion though (Most thread hijackings don't tend to go this way)

Oh come, come, now Hotpoint, you know I haven't misjudged you at all, in fact it is quite obvious to me, you know what you are talking about but maybe sometimes the Socratic method of exploration (or as some may call it, Devil's advocacy) can enlighten many others to what is going on when science is used to try and understand certain aspects of paintball.
As you know, there is sooo much bull**** talked about range, accuracy, trajectories and so on that it is sometimes good to have an extended dialogue covering some of these areas.
I'm just gald to see you were up to the job
Robbo

 

[manike]

At a risk of adding too much information...

The velocity limits we have are actually set not because of velocity but because of projectile energy. Now the powers be have deamed that 12ft/lbs is the maximum 'non lethal' energy. This energy is a factor of mass and velocity squared. That is why lighter projectiles can fly at higher velocities used to be allowed as they still have the same energy.

Ok so far?

Now how much energy a projectile has determins how quickly it is slowed by external factors.

The energy is actually related to mass and the velocity squared.

The resistance forces to pojectile motion are related to the frontal area of a projectile and increase by velocity squared.

Objects with a higher mass have a greater momentum/inertia and are less subject to being overcome by resistance forces. It works out with a sphere that a larger diameter and the resulting weight increase actually gives it more energy than the increase in size creates drag.

This means that with the same material a spherical object will conserve more energy in relation to wind resistance the larger it is. A smaller object at the same velocity will have less energy and so be more quickly overcome by resistances to motion (drag) and be more likely to be blown off target by wind and air currents.

Thus the more energy it conserves against resisitive forces the further it will fly. The larger and heavier you make your projectile the further it will fly given that it started with the same velocity as a smaller sphere.

This is partly due to air resistance increasing at the square of velocity and energy also increasing at the square of velocity times the mass. The first one working more against small projectiles flying quickly and the second factor working for heavier objects flying at the same speed or slower.

The best paintballs for energy and thus range and (thus breaking at distance) are the largest, heaviest paintballs you can find. If you could make a smaller heavier paintball then this would be better, but in general terms since the material is the same density, making it larger will give more benefit from the energy due to extra mass than it will forfeit from the increased wind resistance.

Heavier fills are good but also have a few negative points...

Heavier balls will fly farther. They have more energy at 300fps. In fact if you make them too heavy they go outside of what is legal in terms of the projectile energy limit.

Heavier balls will have more energy in them when they reach your target, especially at longer ranges, this means they are more likely to break and mark rather than bounce...

Heavier balls will hurt more (they have more energy) and will hurt even more if they bounce (greater change in momentum and no energy dissipated in the breaking of the ball... p.s. that why bouncers always hurt more )

Heavier balls at 300fps have taken more energy to get to that velocity, this means you will get less shots per tank fill as you are using more energy from your tank per shot.

I'm a back player. I like heavier paint (and boring the arse off of those of you that didn't want so much detail! sorry )

manike

 

[manike]

Re: It's worse than that, it's physics Jim...

Paintballs do NOT distort noticeably when fired from a marker. This has been proved by slow motion photography and clear barrels.

Almost all paintball guns, (including Angels, mags, cockers, Impulses etc.) fire with an actual pressure behind the ball of between 60 and 100psi. They all follow a very similar acceleration gradient and reach somewhere around 1500 g's! when fired from a 8-10" barrel and that relates to an acceleration of about 50,000 fps/s if you want to shoot at 300fps

Originally posted by Hotpoint
I've personally always theorised that low pressure/acceleration will lead to a more stable trajectory because of the effect of high gee force on the fill

Since there is actually very little difference in the pressure most guns fire at, and since the acceleration is very similar (effing huge!) I don't think your theory holds water sorry.

Also the acceleration of a paintball takes about 0.006 seconds... the fill of a paintball is such that it won't settle when sitting for months. And thus the heavier particles are extremely unlikely to move under a 6ms acceleration if they don't when sat under the force of gravity for a few days/months.

manike

 

[Robbo]

At a risk of adding too much information...

Originally posted by manike

Heavier fills are good but also have a few negative points...

Heavier balls will fly farther. They have more energy at 300fps. In fact if you make them too heavy they go outside of what is legal in terms of the projectile energy limit.

Heavier balls will have more energy in them when they reach your target, especially at longer ranges, this means they are more likely to break and mark rather than bounce...

Heavier balls will hurt more (they have more energy) and will hurt even more if they bounce (greater change in momentum and no energy dissipated in the breaking of the ball... p.s. that why bouncers always hurt more )

Heavier balls at 300fps have taken more energy to get to that velocity, this means you will get less shots per tank fill as you are using more energy from your tank per shot.

I'm a back player. I like heavier paint (and boring the arse off of those of you that didn't want so much detail! sorry )

manike

Agreed with all of that, unsurprising really considering science is alive and well and thriving on the pages of P8ntballer but one thing did confuse me......You did say,

' Heavier fills are good but also have a few negative points...'

Apart from the greater gas consumption (which is for the most part academic since available bottles have more than enough capacity at 4500 psi pressure), I am at a loss to identify any more
Robbo

 

[manike]

Pete,

The only serious negative ones in my opinion could be the impact energy into someone. With heavier balls expect more pain and more bruising. (Especially if they bounce!) and the legal issue...

I don't think they would need to get much heavier before markers start pushing the legal enery limit (since it's mass X velocity squared) a small mass increase would take it over the edge. And then if someone did get hurt and they checked the paint... if the energy was over 12ft/lbs... that person would have in theory been using a 'lethal weapon'.

I must admit I was stunned when a certain company started marketing small bore paint (although I now know the reasons why ) especially when others market big bore paint.

I say bring back forest Heavy

manike

 

[Robbo]

Originally posted by manike
Pete,
I don't think they would need to get much heavier before markers start pushing the legal enery limit (since it's mass X velocity squared) a small mass increase would take it over the edge. And then if someone did get hurt and they checked the paint... if the energy was over 12ft/lbs... that person would have in theory been using a 'lethal weapon'.
manike

Hey Si, is it that critical because isn't the energy given to us by the equation of 1/2M.V squared ?
In which case, the critical factor or rather most significant is the velocity, since it is this that is squared, then any small changes in velocity are more likely to tip it over than any small changes in mass.
Pete

 

[manike]

Absolutely right Pete, the velocity is the critical factor. At the moment we have a safety margin.

The equation (with all correction factors in it to make it easy) is Energy (ftlbs) = (speed(ft/sec) X speed(ft/sec) X weight(grains) )/450240

I couldn't think of a good way to post it to look right so I hope that makes sense.

The heaviest paintballs are (or at least were 4 years ago when I measured them ) currently about 54 g. And that gives us an energy of 10.8 ft lbs. We have a buffer of just over 16fps! with such paint before they would be at 12ftlb's energy.

In terms of hot guns then we all know 16fps is very possible!

If a paintball went up to 60g then at 300fps it would be right on the legal limit for energy. Any hot guns would be a 'lethal weapon'

So velocity is critical but we have to take it in context of the projectile mass also.

manike