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June 15th, 2006, 01:13
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#31 |
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I think I might have something: A design that would weigh about 0.32 grams using the same material as 0.2gram BBs, with an estimated (calculated) ballistic coefficient of 0.148. Keeping speed to 410fps (125m/s) results in a muzzle energy level of 2.5 Joules. This ignores the possibility of minimum firing ranges, with higher energy levels (ie wherever pellet has only 2.5J).
Here's the ballistics I worked using the engine you showed (it has lower velocity limits, which is good). I set a zero at 50yards so one can aim COM and still hit only 6 inches high, to that point, for kicks.  And for comparison here's another calculator, but it has 500fps minimum: Ballistic Coefficient: 0.148 G1 Bullet Weight: 5.00 gr Diameter: 0.243 in Muzzle Velocity: 500.0 ft/s Chronograph Distance: 10.0 ft Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead (yds) (in) (moa) (in) (moa) (ft/s) (none) (ft•lbs) (s) (in) (moa) 0 0.0 *** 0.0 *** 501.5 0.449 2.8 0.000 0.0 *** 10 -0.6 -6.0 0.0 0.0 497.1 0.445 2.7 0.060 0.0 0.0 20 -2.7 -12.7 0.0 0.0 492.8 0.441 2.7 0.121 0.0 0.0 30 -6.1 -19.5 0.0 0.0 488.5 0.438 2.6 0.182 0.0 0.0 40 -11.0 -26.4 0.0 0.0 484.3 0.434 2.6 0.244 0.0 0.0 50 -17.4 -33.3 0.0 0.0 480.1 0.430 2.6 0.306 0.0 0.0 60 -25.4 -40.3 0.0 0.0 475.9 0.426 2.5 0.369 0.0 0.0 70 -34.8 -47.5 0.0 0.0 471.8 0.423 2.5 0.432 0.0 0.0 80 -45.8 -54.7 0.0 0.0 467.7 0.419 2.4 0.496 0.0 0.0 90 -58.4 -62.0 0.0 0.0 463.7 0.415 2.4 0.560 0.0 0.0 100 -72.6 -69.3 0.0 0.0 459.7 0.412 2.3 0.625 0.0 0.0 110 -88.5 -76.8 0.0 0.0 455.7 0.408 2.3 0.691 0.0 0.0 120 -106.0 -84.4 0.0 0.0 451.8 0.405 2.3 0.757 0.0 0.0 130 -125.3 -92.0 0.0 0.0 447.9 0.401 2.2 0.824 0.0 0.0 140 -146.3 -99.8 0.0 0.0 444.0 0.398 2.2 0.891 0.0 0.0 150 -169.0 -107.6 0.0 0.0 440.2 0.394 2.2 0.959 0.0 0.0 The bad news, moulds costs between $2000 and $8000, so I'm going to need to do a lot of my own experimenting and research before committing to have a mould made. Damn, at those prices the design would have to be perfected, for sure. |
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June 15th, 2006, 01:25
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#32 |
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Hmmm, I dont know. Even though it has a max rise of 6 inches out to 50 yards, it has a drop of 54 inches at 100 yards. Out of curiosity's sake, how did you come up with a coefficient of 0.148? That seems very, very high. A 30 grain boattail, which is a rather efficient design, has a similar coefficient. Just wondering how a 5 grain could compare with a 30 grain boattail.
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June 15th, 2006, 02:09
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#33 |
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A paintball carries some 3 joules at the muzzle, and retains alot of it until impact.
Alot of that energy is dispersed when the paintball breaks (inelastic collision). Paintballs still hurt quite a bit. Think about how much more they hurt when they bounce. A solid pellet carrying 2.5 joules that will collide elastically with a person is going to hurt like hell, plus at only 6mm diameter, there's a much smaller surface area, which means all that force isn't going to be distributed as much. So that one small area where it hits is going to be getting pounded. I don't think you can achieve "accuracy at long range with a standard trajectory", and "can still safely shoot each other with it". These two worlds seem unwilling to collide. |
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June 15th, 2006, 05:14
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#34 | |
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Quote:
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June 15th, 2006, 08:37
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#35 |
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cool. fun to think about anyways.
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June 15th, 2006, 13:57
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#36 |
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Calculated B/C by painstaking hand calculations of the volume of the designs, then assuming the same plastic used in 0.2g BBs, to arrive at a mass.
Then multiply the weight in grams by 1.422, divide that total by the square root of the diameter, and multiply by form factor. I used the worst form factor possible to be conservative, that of a plain jane wadcutter (flat-nose lead, ff 0.8). Lead doesn't refer to the density so much as the surface friction. |
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