About btrakr
         
   btrakr runs on the Amiga computer, and given appropriate input
information, will attempt to predict the landing location of a
weather-balloon type package.  Such a package is flown by Amateur
Radio balloonists, with various kinds of radio gear, experiments,
and photographic equipment on board.  The package is lifted by
a rubber balloon of the type used to fly the dozens of weather
balloons sent up by the National Weather Service in the USA
each day.

   The version of btrakr associated with this file is:  0.4
A separate version of this program runs on MSDOS computers,
and has the same functionality as does the Amiga version.
Get in contact with the author if you need the MSDOS version.
   
   This version of btrakr will only work west of the zero meridian,
and north of the equator.  More specifically, I have not made the
math work all over the world, only in North America.  If you have
the need to run btrakr elsewhere, let me know, and I will get to
work on the changes.  

   A Frequently Asked Questions file about Amateur Radio ballooning
is on the World Wide Web.  See:
http://www.usa.com/~rickvg/pubs/faqloon.htm

   The program btrakr will accept upper air wind data from either the
keyboard or from a file.  To get an appropriate file, from the WWW,
key in the URL:
http://www-das.uwyo.edu/upperair/sounding.html

   You will need to grab the text version of the SKEW-T file
appropriate for your balloon.  A sample file is included with
the btrakr archive.  The only part of the file actually used
is the wind data at the very beginning.  The program needs that
specific format to properly read data from a file.  If you don't
have the data in that format, use the keyboard.  If you find
wind data in a different text format, let me know and I can add
a routine to the program specifically for that new type of wind
data file.  Note that wind speeds in the text file are specified
in knots (nautical miles per hour) and altitudes are recorded in
meters.  

   When you start btrakr, you will have to key in your own launch
coordinates, by latitude and longitude.  The default coordinates
are for a real launch location used by the Kansas Near Space Project,
near Manhattan, Kansas.  The KNSP URL is:
http://www.ksu.edu/humec/knsp
   If you wish a customized verson of btrakr, with your launch 
coordinates as the default, just send me email with the coordinates.
I will recompile the program with your numbers.

   You may also change the default climb rate of the balloon, as well
as the rate at which it descends on its parachute.  The program allows
you to change the expected altitude at which the balloon will burst.
The highest balloon flight I have personally experienced (so far)
is 111-thousand feet.  The program allows burst altitudes of up to
150-thousand feet.  The default burst altitude is 90-thousand.

   The output from btrakr starts with an estimate of the time in
minutes for the balloon flight, from launch to touchdown, and then
a predicted landing site coordinate pair, latitude and longitude,
and a distance (range) from the launch site in miles, followed by
a bearing from the launch site in degrees. 

   As of this writing, I have had the opportunity to test the program
with only one real flight.  The program predicts the landing location
of the 07 June 1997 KNSP flight within about six miles of where it 
actually landed, which seems *very* good for a first effort.  Some of
the math routines in the program are, at best, suspect.  I don't fudge
calculations, but I do some really simple calcuations when more 
complicated math might be appropriate.  I need more data for testing.
   If you have balloon data, I would like to see it.  I need the 
latitude and longitude of the launch and landing points, and the 
wind data from the nearest weather service site at the time nearest
your balloon launch.  That will usually be the data for 1200 Z.
   Please send such data to:
   bobdavis@cadvantage.com
   
   The files you will find in this archive are:
   btrakr             (the balloon prediction program)
   btrakr.info        (the associated .info file)
   btrakr.text        (this text file about the program)
   top1200_07         (the upper air wind text file from
                       Topeka, Kansas at 1200Z on 07 June 1997)
   btrakrxx.readme    (the readme file required for aminet)
   
   This program is EMAILWARE.  If you use it, please send to me
an email and feel free to include comments or suggestions.

bobdavis@cadvantage.com