Thanks for your comment, but I realize now the inaccuracy of the super domes is due to the pellet spiraling out of the barrel. My surge shoots jsbs at 920fps, a guy at the range was kind enough to let me shoot a few through a chrony.
To go transsonic, the pellet first has to go supersonic.
SummaryBullets fired from handguns follow general rules of physics and behave like gyroscopes. The angular motion of these bullets can be understood as a superposition of two oscillations, most easily be demonstrated by a two arms model (the animation above).Practically all handgun (short) bullets are statically stable, many pistol and revolver bullets (and pellets) even have excessive static stability. However, dynamic stability is not automatically guaranteed. Some bullets are dynamically unstable at the moment they leave the muzzle, others may loose dynamic stability during flight after being decelerated (eg. increased pellet spiraling with distance).At the moment no reliable method exists, except experimentation, to foresee dynamic bullet instability, especially at long ranges. Some highly sophisticated computerized procedures (numerical solutions to the Navier-Stokes equations) to attack these problems are just being developed by ballistic researchers.
Bob
Trying to model a non-linear function with a straight line, to me, doesn't make sense.... Sure, you can model a SECTION of the velocities that way.... but what do you do if the pellet starts out at 900 fps and slows to 600 over 100 yards (which is typical).... Which straight line do you use then?.... Have a look at the G7 Model, how would you model that as a single straight line?.... You can't....\
None of the existing "G" models are straight lines, for the simple reason there is a discontinuity in the drag in the transonic portion of flight.... Below Mach 0.8 the drag is relatively constant, above Mach 1.2 it is again relatively constant, but between the two the drag increases by a factor of 3 to 5.... Could we use three straight lines?.... sure.... but it wouldn't represent the change in drag as closely as an "S" shaped curve....
I do agree that since every pellet is different, we can't have one model that will work for everything.... However, the closer the model is to reality, the less the BC will change over the entire range of velocities when you use that model.... Right now, if you calculate the BC of pellets using the G1 (or GA) model you will get vastly different results subsonic and supersonic.... Using the old linear drag model (CD=0.20) the values were totally ridiculous.... The BC on a JSB Exact would start out at 0.04 and drop below 0.01 at supersonic speeds.... Therefore, you couldn't use one BC over the entire range and get anything that even remotely resembled how the velocity decayed with distance.... If we can come up with a model that is closer to reality, then using that model will more accurately predict that velocity decay.... That is my goal.... Bob