Hi All,
I haven't talked about any of this since Deep blue was the fight club,we discussed reynolds factors and turbulence even back then.
I think there is a big part of the equation that is being missed. You have analysed until you are deep blue in the face what happens durring 99.5% of the paintball flight. That once you have a sphere traveling at 280fps, with the current wt of a paintball, you are going to have a certain level of randomness imparted by the turbulence behind the ball. I for one stand up and say bravo. You have explicitly defined something that we cannot change unless we play in a vaccum (deadly), or fundimentally change the paintball (not likely).
You have also effectively eliminated the need for people to worry about spin/rifleing unless the paintball gets heavier, changes shape, or we shoot it a lot faster.
I think Glenn's problem with all of this (not speaking for him of course), and mine, is that we are in an amazing way ignoring that first 12 inches of the balls travel. At this time we are not looking at the simple fluid dynamics of a ball. I am talking about what happens in the marker and in the barrel before it exits and the effect this has on the tragectory of the ball within the barrel and upon its immeadiate exit from the barrel.
This leads us away from much of Tom's data as he used the same gun and barrel for every shot and it was locked in a vise. This means he removed all of the parameters that we can effect and change to improve accuracy. All that was left was the randomness of air currents (Sorry Tom, not meaning to burst this scientific bubble, but I am the Slayer of scared cows, even yours).
So what matters the first 12 inches? Look at what we have.
1. We have a wall of force (air) accelerating the ball into the atmospheric air(no trailing currents there folks) and in some way disipating. Ok, that is why Tom created the Crown point barrel (he must have thought it mattered) and others created the ported barrel. If the barrel is ported and long enough the issues of the initial push may be eliminated (maybe longer barrels are more accurate).
2. We have the barrel. The ball is traveling through the barrel with forces places upon it. One is the force excellerating it, another is the force of the barrel pushing on a larger ball, or the force of the air passing the ball for a smaller ball.
3. We have a moving marker. I know you may think that doesn't matter but we know that a ball can ricochet around in the barrel from Tom's barrel tips and the talc test. The barel might not be perfectly straight or aligned or you may be moving it.
And doing the math:
The diameter of the paintball is 0.68 approx I am not sure of the bore of a 2 step
barrel but let us assume 0.7. If the ball is going down the exact center (which I highly doubt considering manufacturing tolerences) that leaves 0.01 inch that the barrel would have to move. The ball is only in the barrel for about 0.006 seconds.
Thats 0.01 inch divided by 0.006 seconds = 1.66 inches per second. All it takes is moving your barrel 0.01 inches at a rate faster than 1.6in/sec. That is while shooting 6 bps of perfect balls out of a perfect barrel to have a hit. I think maybe it hits more than you think.
Extrapolated From:
https://www.automags.org/ubb/Forum4/HTML/000019.html
So what who cares?.... Well you do. These are all elements you can change. They effect what direction the paintball is heading then it leaves the barrel.
So lets say our shot vector is one degree off straight when it leaves the barrel. At 5 feet it is 1 inch off mark, at 50 feet it is 10 inches off mark. Let us say our shot vector is at an angle of 0.5 degrees off center when it exits the barrel. That's 0.5 inch at 5 ft, and 5 inches at 50 ft, and 10 inches off mark at 100ft.
Maybe I am full of it maybe all paintballs leave all barrels and all guns at exactly the same angle. And maybe we always shoot with our gun in exactly the same position, and maybe we never move even 0.01 inch at a rate of 1.6in/sec while taking a shot.
I enjoyed the read on this post it was incredible. Keep up the good work. Now lets look at the other 0.5% of the game and maybe that will make all the difference.
Respectfully,
Your Friend
Hitmanng