lozz08 wrote:I guess the drag on a bb of that size has a pretty set value for a certain speed, but a speed vs. Time graph wouldn't be too easy because of the fact that air resistance decreases as speed decreases, so we'd have a few too variables for my skills.
It's actually easier (and in this case, more useful) to calculate it as velocity vs. distance, because that follows a simple logarithmic relationship. In other words, you lose x% of velocity for every metre travelled, in a similar way to compound interest.
So, if you start at 100m/s and have got a velocity retention of 90% per metre, then you'll have a velocity of 90 m/s after one metre, and 81 m/s after the next... and so on and so forth.
Calculating the velocity retention is a bit harder to do from scratch, but there is actually an equation for the job: 1/e<sup>Cd*D^2/(2078*m)</sup>
Where D is the diameter in millimetres, and m the mass in grams.
Anyway, that gives your velocity coefficient, and for 0.2g BB, it's approximately 0.962. So, to work out the velocity at any given distance, you raise that coefficient to the power of the number of metres, then multiply by the muzzle velocity.
So, for 10 metres, a 100 m/s muzzle velocity 0.2g BB would be defined by:
100 m/s * 0.962<sup>10 metres</sup> = ~ 68 m/s
You can get time to a given distance by integrating appropriately.
Maybe you are looking at an old version?
Absolute latest, version 2.1.2 - downloaded it off the guy's site today. It's scarcely more than a week old (if that).
Whatever is happening at your end, if I put in 1 metre drop, and 100 m/s muzzle velocity, it's giving me a ~10.2m range - a two metre drop gives a ~20.4 m range...