BigRed76
06-13-2009, 06:11 AM
I was having an "interesting" discussion with Lurker27 on PBN, and decided to share the discussion here. There is intense math-talk and big words, so sway clear if you are of feeble mind or resolve. This is your only warning.
Given we know the velocity (275fps, 280fps, 285fps), we can calculate the force in in-lbs required to propel it at that velocity. Since I'm a lazy SOB, I'll steal Lurker27's math for the velocity of 285fps with the math, and then the other two force requirements for the other two velocities. Lurker27 is the maker of the Eigen line of products, including the Eigenram. Part I changed is in bold lettering.
68in^3*4500lb/in^2 = 306 000 lb-in energy in the tank
3.2g paintball [average and rounded, suck it up decimal pinchers]
285 feet per second = 86.86800
KE=1/2*mass*velocity^2
.5*.0032*86.86800^2
12.0736791 Joules to fire a paintball 285fps
8.90508871 foot-pounds
106.861065 lb-in to fire a paintball.
99.49360404 in-lbs @ 275fps
103.14444372 in-lbs @ 280fps
Now, given those in-lbs force requirements, you can figure out with absolutely no loss and absolutely nothing else (like ram movement or solenoids) what amount a standard 68/45 can fire. Again, math is stolen from Lurker27 since he already wrote it out for me. No sense retyping something.
68*4500
306 000 lb-in/tank /106.861065 lb-in/shot
2863.53126 shots theoretical maximum.
3075.574585447 shots @ 275fps
2966.713367815 shots @ 280fps
Now comes the fun part. How much force (in in-lbs) does the ram assembly need, or whatever else cycles the marker? I based my math around the NecroPB NecroRam in a Gen3 Intimidator, which I find gets me around 2,200-2,300 shots per cold filled 68/45. I first looked at the throw of the ram. This is important, as it'll tell you the length for the cylindrical volume equation. Then you have to find the cylindrical volume and multiply it by the pressure being given to it by the LPR (in my case, 55psi). To find the volume of the cylinder, you need to know the equation, which is: 3.14*r^2 * length (the throw of the ram, in this case).
I am missing my notes at the moment that I did the math on, so I can only give you the results:
16.534 in-lbs required for the stroke forward to open the valve (rounded).
5.396875 in-lbs on the return stroke to put the marker's assembly into the "rest position."
21.924804687 in-lbs total to cycle the ram. This is with 2" of throw, a simple nice number since pulling out my marker from the gearbag clutter was not enticing at the moment.
Add the cyclic in-lbs required to the chosen firing in-lbs required, then divide the tank's in-lbs (68*4500 for a 68/45, which is 306000 in-lbs) and you have a top line for the efficiency of a Gen3 Timmy utilizing a NecroRam.
Given we know the velocity (275fps, 280fps, 285fps), we can calculate the force in in-lbs required to propel it at that velocity. Since I'm a lazy SOB, I'll steal Lurker27's math for the velocity of 285fps with the math, and then the other two force requirements for the other two velocities. Lurker27 is the maker of the Eigen line of products, including the Eigenram. Part I changed is in bold lettering.
68in^3*4500lb/in^2 = 306 000 lb-in energy in the tank
3.2g paintball [average and rounded, suck it up decimal pinchers]
285 feet per second = 86.86800
KE=1/2*mass*velocity^2
.5*.0032*86.86800^2
12.0736791 Joules to fire a paintball 285fps
8.90508871 foot-pounds
106.861065 lb-in to fire a paintball.
99.49360404 in-lbs @ 275fps
103.14444372 in-lbs @ 280fps
Now, given those in-lbs force requirements, you can figure out with absolutely no loss and absolutely nothing else (like ram movement or solenoids) what amount a standard 68/45 can fire. Again, math is stolen from Lurker27 since he already wrote it out for me. No sense retyping something.
68*4500
306 000 lb-in/tank /106.861065 lb-in/shot
2863.53126 shots theoretical maximum.
3075.574585447 shots @ 275fps
2966.713367815 shots @ 280fps
Now comes the fun part. How much force (in in-lbs) does the ram assembly need, or whatever else cycles the marker? I based my math around the NecroPB NecroRam in a Gen3 Intimidator, which I find gets me around 2,200-2,300 shots per cold filled 68/45. I first looked at the throw of the ram. This is important, as it'll tell you the length for the cylindrical volume equation. Then you have to find the cylindrical volume and multiply it by the pressure being given to it by the LPR (in my case, 55psi). To find the volume of the cylinder, you need to know the equation, which is: 3.14*r^2 * length (the throw of the ram, in this case).
I am missing my notes at the moment that I did the math on, so I can only give you the results:
16.534 in-lbs required for the stroke forward to open the valve (rounded).
5.396875 in-lbs on the return stroke to put the marker's assembly into the "rest position."
21.924804687 in-lbs total to cycle the ram. This is with 2" of throw, a simple nice number since pulling out my marker from the gearbag clutter was not enticing at the moment.
Add the cyclic in-lbs required to the chosen firing in-lbs required, then divide the tank's in-lbs (68*4500 for a 68/45, which is 306000 in-lbs) and you have a top line for the efficiency of a Gen3 Timmy utilizing a NecroRam.