04-15-2009, 04:34 PM
Salve David!
No, we won't be doing any penetration tests. This is primarily because I would like to use a target with well defined and repeatable characteristics and shields can vary in composition. Ballistic putty is expensive stuff so I'll have to leave that one for a while.
The main function of the tests will be to record and calibrate a set if ballistic tables for this particular machine. That involves measuring velocities, pull back force, firing angle and ballistic trajectories for each projectile fired. The main problem I see us having is in achieving a constant firing velocity when calibrating the ballistic table as the 'bow' string and springs will change subtlety over the duration of the test.
In an effort to come up with a compensating metric we will attach a strain gauge onto the foreside of each of the outer arms. This will allow us to know the pullback force for each shot. This can then be compared to the resultant firing velocity hopefully resulting in a calibration graph of strain versus velocity. We can then use the strain gauges to pull back the arms to a position where the resultant firing velocity is known and can be kept constant.
At the end of all this we should have a number of useful statistics. First we can measure the maximums such as pull back force, discharge velocity, distance etc. Secondly we will have a set of ballistic tables including projectile trajectories i.e. a series of tables relating pull back force versus firing angle. This will be done for 3 pull back settings and firing angles from 0 to 60 degrees elevation in steps of 5 degrees.
No, we won't be doing any penetration tests. This is primarily because I would like to use a target with well defined and repeatable characteristics and shields can vary in composition. Ballistic putty is expensive stuff so I'll have to leave that one for a while.
The main function of the tests will be to record and calibrate a set if ballistic tables for this particular machine. That involves measuring velocities, pull back force, firing angle and ballistic trajectories for each projectile fired. The main problem I see us having is in achieving a constant firing velocity when calibrating the ballistic table as the 'bow' string and springs will change subtlety over the duration of the test.
In an effort to come up with a compensating metric we will attach a strain gauge onto the foreside of each of the outer arms. This will allow us to know the pullback force for each shot. This can then be compared to the resultant firing velocity hopefully resulting in a calibration graph of strain versus velocity. We can then use the strain gauges to pull back the arms to a position where the resultant firing velocity is known and can be kept constant.
At the end of all this we should have a number of useful statistics. First we can measure the maximums such as pull back force, discharge velocity, distance etc. Secondly we will have a set of ballistic tables including projectile trajectories i.e. a series of tables relating pull back force versus firing angle. This will be done for 3 pull back settings and firing angles from 0 to 60 degrees elevation in steps of 5 degrees.
MARCVS VLPIVS NERVA (aka Martin McAree)
www.romanarmy.ie
Legion Ireland - Roman Military Society of Ireland
Legionis XX Valeria Victrix Cohors VIII
[email protected]
[email protected]
www.romanarmy.ie
Legion Ireland - Roman Military Society of Ireland
Legionis XX Valeria Victrix Cohors VIII
[email protected]
[email protected]
