Hall Consulting's
Gas Gun Design Tool


Ballistic Calculator

While I personally concern myself primarily with the gun, I realize that many people are also concerned with what happens when the projectile leaves the gun. At these people's request, I have included a very crude ballistic calculator to estimate downrange performance (ie, how far/high will it go?). This calculator takes the muzzle velocity and basic projectile characteristics from the main window, adds a couple more variables, and makes a rough guesstimate of the projectile's flight path.

As is a common theme in GGDT, the top half of the window is for user input while the bottom half is for output.

And if you hadn't found it yet, the ballistic calculator is found in the Tools pull-down menu.

Drag Coef (Cd)
The projectile's subsonic drag coeficient. Again, this trajectory calculator is crude. Cd is assumed to be constant. As such, results are going to be very touch and go for projectiles that are either unstable or transonic (or even faster).

Elevation
The elevation angle of the gun barrel at the time of launch. 0 degrees is horizontal. 90 degrees is vertical.

Max Range
If the Max Range checkbox is checked, the ballistic tool will ignore the elevation angle specified and instead find the elevation angle that corresponds to a maximum range shot. This is another feature of GGDT that can take a second or three due to it's computational requirements on the computer.

Calc Trajectory
The button that tells GGDT that you're done with input and want it to do it's thing.


Time to Apogee
The flight time ellapsed when the projectile attains it's maximum height.

Apogee
The maximum height attained by the projectile.

Time to Impact
The flight time ellapsed when the projectile returns to Earth.

Range
The distance traveled when the projectile returns to Earth.

Print/Done Buttons
For crying out loud, if you can't figure these two out on your own....


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