Lloyd. I put the information that you published about your rig into my modeler. I used some friction information that I had collected from trials that I had performed in the past. I have a break away friction of 7# as an average of all the .22cal barrels that I have measured with various pellets, so that is want I am using for breakaway friction. My returned predicted velocity is 1269.5fps. That looks fairly close to your graph. This was based on 1800 psi with 100% porting. I'm gonna input the other variations to see how close they are.
I need Tylenol aspirin , you guys do it to me everytime but yet I come back for more. David
I for one is that stupid guy which would raise my hand in class asking stupid questions. Also not knowing if this question pertains truly to this discussion. My question is there a pressure lost between the lands and grooves of the barrel? Could it be part of the equation also on different barrel lengths?
Bob, I'm thinking more to do with the air in the barrel in front of the projectile. I'm thinking the forces needed to move the air out of the way of the projectile increases (not linearly) as the projectile speeds up nearing the speed of sound through air. So the energy needed to move the air at say double the speed requires more than double the energy making a curve in force needed.