Because different users have different preferences and different projects have different requirements, HGDT allows the user to customize the unit system(s) used for simulation input/output as well as vary the amount of input required in the first place. The configuration screen is accessed through the File pulldown menu. A description of the effects of each option is found below.
Unit System -> Temperature
When selected (checked), HGDT uses Centigrade as the temperature scale for input and
output. When not selected, the Fahrenheit scale is used.
Unit System -> Pressure
When selected, HGDT uses bars as the unit of measure for pressure input and
output. When not selected, pounds per square inch (guage) are used.
Unit System -> Linear Dimensions
When selected, HGDT users centimeters for all linear dimensions and derrivatives thereof
(ie, square centimeters for area, cubic centimeters for volume). When not selected,
inches are used instead. Output does, however, vary a small amount. When the input
dimensions are centimeters, meters may show up in the output screen. Similarly, feet
will show up when inches are the input unit of choice.
Unit System -> Projectile Mass
Another option with three choices (pick one of the radio boxes). The mass of the projectile
can be expressed in grams, ounces, or - for those with very light projectiles - grains.
Environmental -> Chamber volume definition
For various reasons, some people like to define chamber volume by the length of the chamber
(and diameter) of the chamber. Others like to define it directly by inputing a volume.
Still others prefer to fix it as a ratio of the barrel's volume. Which type of person are
you? Make your choice here.
Environmental -> Altitude
Atmospheric conditions (read: pressure and density) have a small but noticable effect on gun performance.
At the same time, they have a huge effect on ballistic trajectories. With this in mind, HGDT accepts
launch point elevation (above sea level, of course) as an input. The atmospheric model goes up to 90km, so
feel free to see what your gun would do if that pesky atmosphere would only get out of the way!
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