Internal Balistics When fireing a 21 grain Kodiak pellet
Calculate the Mean Effective Barrel Pressure when firing a .22 cal 21grain pellet
From a 24 inch barrel, at 1000 Feet Per Second.
Pellet mass in kilograms: 21 gr = 0.001360777 kg
Average velocity of pellet (the pellet starts at zero velocity and ends at 1000 ft/sec as it travels down the barrel)= 1000 ft/sec divided by 2 = 500 ft/sec
Pellet transit time @ 500 ft/sec average velocity in a 24 inch barrel : 2ft barrel length divided by 500ft/sec = .004 seconds
The pellet transit time is the time it takes the pellet to go down the barrel.
Average pellet acceleration = 1000ft/sec divided by .004 seconds = 250000ft/sec squared
Convert above acceleration to metric: average acceleration = 76199.67 meters/sec squared
Newtons first law: Force = Mass times Acceleration F=MA
Average force on the pellet = pellet mass times average acceleration
F = 0.001360777 kg times 76199.67 meters/sec squared = 103 newtons force
Convert 103 Newtons force to pounds force = 23 pounds force
This means that the average force on the pellet, as it travels down the barrel is 23 pounds.
Now we calculate the Mean Effective Pressure to push this pellet:
Area of a .22 cal barrel : pie R squared
Area = .038 square inches
Pressure = force divided by area = 23 pounds divided by .038 inches squared = 605 PSI
All this math amounts to this:
In a 24 inch .22 cal barrel, fireing a 21 grain pellet at 1000 feet / second
1 The pellet transet time in the barrel is .004 seconds
2 The average force on the pellet, as it travels down the barrel is 23 pounds
3 The average pressure in the barrel is 605 PSI
IF ANYONE CARES!
I HAVE EXPLAINED ALL THIS TO MANY MANY SMALL ANAMALS, AND MOST OF THEM UNDERSTOOD PERFECTLY.
Mark
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I’d bet NASA has something that would work just fine… 😉