Today, I had the opportunity to give back a little to FLOSS. I downloaded and installed the GNU Exterior Ballistics Calculator (gebc) to use with my hunting and target shooting. It took a bit of fiddling to install in Debian GNU/Linux because a file had a different name (case of letters). I was getting “file not found” during the build for fl_draw.h. On Debian GNU/Linux that file is fl_draw.H for some reason. Using
apt-file search fl_draw.h
I found that I needed to install libfltk1.3-compat-headers (“This package provides header symlinks with .h rather than .H extensions for compatibility with some older code that relies on the lowercase-h names.“) as well as libfltk1.3-dev and libhpdf-dev in order to build gebc.
The build procedure is typical. One downloads the source in tar.gz format, unpacks with
tar xzf filename and
cd gebc-1.07 to enter the directory. Then
./configure lists dependencies needed as error messages. In Debian GNU/Linux the header files are usually included in libxyz-dev packages. Once the configure script creates the Makefile, run
make and, as root, run
make install. Then
gebc starts the programme for any user.
The programme ran pretty well except for some crashes when storing to “memories”. Skipping that, I tried to run some data. The input windows included a field for “drag coefficient“. I usually use ballistic coefficients published by manufacturers of bullets but try as I might I could not enter drag coefficients and get reasonable results (Cd=k/BC). By examining the source code, I can see that the input field for drag coefficient should actually be labelled “ballistic coefficient”. Entering ballistic coefficients gives good results. I changed that string in two places, InputWindow.cpp and RangeWindow.cpp so the inputs and outputs are presented correctly. I tried to contact the authour, Derek R. Yates, but could not find any e-mail address. I could not leave a message on SourceForge. No “submit” button. By posting this perhaps Google will help others.
Beautiful, isn’t it? That’s for Hornady 180 grain RN bullets at 2600 ft/s under current atmospheric conditions. There are options to export results as PDF, spreadsheet, etc. Bullet makers from whom I usually buy include:
If you want the modified source code, download gebc-1.07a.tgz. Licence is GPLv3.