Redkey
10-20-2002, 03:12 AM
I know this was kind-of talked about before... But, I wanted to revisit the issue.
A 0.68 diameter ball travelling 300 ft per second would block the beam of an optical gate for roughly 0.000189 seconds. If the output of the gate is used to trigger a 20 MHz timer it would collect something like 3778 samples, with each sample representing around 0.08 ft/sec.
What else needs to be considered? The width of the gate beam, the speed of the gate, is the beam blocked at max ball diameter, true diameter of the ball... I would guess that the ball diameter would be the biggest issue. If one ball is 0.005" inches larger than another the velocity calculation would be off by about 2 fps.
Does anyone know if the ball retains it's shape as it travels down the barrel? If the balls were to have different amounts of squish as they scooted down the barrel it would cause even more troubles with the calculations.
Anything else? I might start with two gates and see how the numbers compare... depends on the amount of free time I have.
Thanks for any suggestions.
A 0.68 diameter ball travelling 300 ft per second would block the beam of an optical gate for roughly 0.000189 seconds. If the output of the gate is used to trigger a 20 MHz timer it would collect something like 3778 samples, with each sample representing around 0.08 ft/sec.
What else needs to be considered? The width of the gate beam, the speed of the gate, is the beam blocked at max ball diameter, true diameter of the ball... I would guess that the ball diameter would be the biggest issue. If one ball is 0.005" inches larger than another the velocity calculation would be off by about 2 fps.
Does anyone know if the ball retains it's shape as it travels down the barrel? If the balls were to have different amounts of squish as they scooted down the barrel it would cause even more troubles with the calculations.
Anything else? I might start with two gates and see how the numbers compare... depends on the amount of free time I have.
Thanks for any suggestions.