jackssmirkingrevenge wrote:Wow, I only had time for 1 test but this is remarkably accurate! Of course I need to do more to validate it as a scientific method compared to a commercial chrony, but it looks very promising.
I shot a shotgun sabot at a metal plate 4 metres away, the chrony reading was 299.1 feet per second. I got two distinct peaks on audacity that were 0.06966 seconds apart, going by ant's calculation this gives a velocity of 286.1 feet per second. The chrony was 1 metre away from the muzzle, all in all I'd say it was pretty much spot on.
I had to back down on the pressure for relatively low velocity in order to get two discernable peaks, so for high velocity projectiles you'll need a significant distance to the target in order to get usable results, a laptop would certainly help.
Nice job maan!! Awesome.
I did some calculations: If your chrono gives 91.6m/s at 1 meter from the muzzle then the muzzle velocity must be 95m/s (assuming that the projectile is a platic bb). I also calculated that the projectiles speed at 4 meters must be 82m/s. >>The average for the sound chrono thus gives: (95+82)/2=88.5 m/s , this is really close to ur result 87.203m/s(286.1 feet per second). So in other words, for next time put the chrono half way the distance of the mic chrono length. So if the mic chrono distance is 4m then the real chrono must be placed at 2m from the muzzle inorder to get real results.
The test u did shows that the speeds are really close, but they cant be compared as u were measuring different averages. The method above should do the job.
But yeah thank u really much for testing this out, it shows that anybody in this forum can do a reasonable speed measurement. I am eager to c what further test show, but yeah just c if you have time as you wont have any use to this data anyways as u have a real chrono already