The drawing defines the measurement used in the program for a tennis ball mortar - in this case one Dom built for me about four years ago. The interior ballistic program currently makes correct calculation when the chamber is filled with powder. I still have to introduce the effect of the second dimension caused by the changes in volume as the projectile travels through the barrel for correct calculation of muzzle velocities with load densities less than one.
I have written 3 programs - one that calculates the ballistic coefficient for the projectile, the second an external ballistic program that calculates the projectile path after it leaves the barrel, and an interior ballistic program that calculates the pressure and velosity of the projectile until it leaves the barrel.
DD requested I ballistic calculations for a Tennis Ball Mortar firing a Zinc Ball.
Mortar Dimensions:
Elevation: 45 degrees
Fuse use for ignition
Bore Length: 6.58 inches
Bore Dia: 2.68 inches
Chamber Height: 1.45 inches
Chamber Dia: 1 inch
Frustum Height: 0.56 inches
Zinc Ball:
Dimenter: 2.59 inches
Weight: 16,100 grains or 2.3 pounds
Powder Charge 250 grains fg:
Muzzle Velocity (Calculated): 242 feet per second (fps)
Calculated Ballistic Coefficient: 0.6502
Calculated Range: 1517 feet 505.7 yards
Powder Charge 250 grains ffg:
Muzzle Velocity (Calculated): 277 feet per second (fps)
Calculated Ballistic Coefficient: 0.6541
Calculated Range: 1910 feet 636.7 yards
I am currently trying to refine the data for ffg and fffg powder loads if you have velocity data and accurate load and projectile data I would appreciate you consider sharing the information.
Thank you
