I wish it were that easy, but the Cd changes with velocity over a very wide range.... It may not be much of a problem if you stay below 900 fps at the muzzle, because by the time the pellet has travelled just a short distance, the velocity has declined to the point where the drag is tending to plateau, and a single value of BC can be made to work quite well.... However, if you push the velocity closer to the speed of sound, the drag goes up so quickly that the pellet slows down drastically within the first few yards.... What I hope to accomplish is a better understanding of how the drag changes over a wider range of velocity.... Then using any of the available methods, radar, two velocities, or two drop distances (along with the starting velocity) could be used with that improved drag model to predict pellet behaviour over a wider range of velocities, and hence over greater distances.... I agree with everything you say, that the BC can vary from gun to gun, and certainly with velocity.... I would like to improve the model, so that we can gain knowledge of, and make better use of, how the velocity decays over longer distances.... If I can accomplish increasing the accuracy of predictions to the point that it will duplicate a drop table over many distances from zero to 100+ yards, for various muzzle velocities, without having to shoot every combination.... I will feel that I have added to the body of knowledge.... You probably remember when it was common to use a constant Cd to calculate the BC of pellets.... That method is so glaringly wrong, when used to compare a velocity of 500 fps to one of 1000 fps, as to be a joke.... The G1 model is better, and the GA model slightly improved again (for pellets).... but from the measurements I have made, neither account for the huge increase in drag as a pellet crosses Mach 1.... Perhaps that doesn't interest anyone, but that doesn't mean we should settle for using a drag model that is in error.... when the technology now exists to measure and quantify drag in the transonic region.... If exploring that region does nothing more than discouraging the use of velocities over 1100 fps with pellets, by showing graphically how fast they decelerate.... it will focus people on doing what DOES work.... Ultimately, if this whole exercise turns out to be a monumental waste of time.... then at least it will be my time that is wasted doing it.... For me, the journey will be worth it.... Bob
As far as I can tell a gun firing an energy pulse , would not be considered a fire arm , there is the future , set your cell phone to stun ! LOL
Something for you to ponder and comment on.... I have a dream.... I would like to build up a database of Cd curves for every pellet and bullet we can test.... over the widest possible range of velocities.... I don't know how practical that will be, but I do know that even the attempt will give us huge amounts of knowledge about ballistics as it applies to airguns.... Imagine if it turned out to be feasible, and ended up being adopted by a program like ChairGun.... When you select the JSB King, it selects the appropriate drag profile, you put in your muzzle velocity, and it crunches all the numbers for you.... The result is a much more accurate representation of what to expect downrange.... IMO, it can and will be done eventually.... The only question, really, is now the time?....Bob
Patience is a virtue....Bob