Re: Ballistics and zero from sub-sonic to supersonic
To keep it simple, that drop you are looking for would be the maximum ordinate of the round along the trajectory curve (it's highest position along the curve).
Same information, different way of saying it. If it goes that high for POI/POA, then it goes to say that it drops that far when fired horizontally.
Also, your drop can be determined by figuring out how long it takes your round to go from point a to point b, then figure in the drop it takes over time, that drop will occur the same as it always does on Earth: 9.8m/s^2.
This will work okay to do it this way for shorter distances and where not much velocity is lost. The more velocity lost, the more difficult to impossible it becomes to get a valid answer without resorting to differential equations and a bunch of calculus. Though it could put you in the ballpark, and a few rounds afterwards tweaks the findings.
There is more to the math, but I'm not getting into it. If you don't know it, I can't teach you on here, and if you do then I have nothing to add. Just know that even those of us that do know the math seldom use it. For instance, I recently zeroed a .300BLK using a Leupold M/RT. I basically just zeroed it at 100m and at 200m using the supersonic loads, then I fired subs without making any changes. Measurements were taken between groups. The following shots were done with the adjustments dialed into the scope.
Is this what you are trying to get at? As far as a program goes, I don't use any, but when I do I generally just use an old multivariable physics application from .edu.