tkBallistic v1.3, Copyright (C) 1999,2000,2001 Joshua Weage

This program comes with ABSOLUTELY NO WARRANTY!
It is licensed under the GNU General Public License, see the
file 'COPYING' for details.

INTRODUCTION

tkBallistic is a Python/tk port of the program Small Arms Ballistics, and
since I like using a GUI better than ncurses, it currently has more
features than S.A.B.  Actually, development has stopped on S.A.B.

S.A.B. was derived from smallball, which was written
by Ole-Hj. Kristensen <okh@edeber.nta.no>.  I have pretty much rewritten
the entire program, but smallball got me started.  All major trajectory
calculations have been implemented, and a variety of bullet drag models
are available.

The tkBallistic homepage is at
<http://members.xoom.com/joshua_weage/ballistic/>

See the file INSTALL for installation details.

CONFIGURATION OPTIONS

Unit System - English or Metric unit operation.
Drag Model - The drag function used to calculate projectile deceleration,
	see the DRAG MODELS section below.
Maximum Flight Time - The projectile flight is calculated using a time
	stepping integration routine.  This is the maximum simulated flight
	time.
Integration Points Per Second - The number of integration steps per second.
	Values as low as 10 (!) seem to produce good data.  1000 was used in
	the smallball program, however python is much slower than C, so
	the default is set to 100.  

DRAG MODELS

The deceleration of a bullet is calculated using standard drag models.
These models were produced by firing a standard projectile at a range
of velocities and recording its performance.  The ballistic coefficient
relates any bullet to the standard model.  However, only projectiles
shaped exactly the same as the standard will match the model's performance.

ATTENTION: For good accuracy, recalculate the ballistic coefficient using
your chosen drag model.  The majority of manufacturers report the B.C. 
using the G1 model, for other drag models, the ballistic coefficient
will be different.  The best way to calculate the ballistic coefficient
under a different drag model is to use G1 first, then take two range/
velocity points and calculate the new B.C. based on those two points.

Ingalls - Based on Krupp data of 1881
British - Based on British 1909 data
G1 - Standard drag model (similar to Ingalls)
G5 - Moderate boat tails - 7 degree 30' tail taper with 6.19 caliber
     tangent nose ogive.
G6 - Flat base, spire points.  6.09 caliber secant nose ogive
G7 - "VLD" boat tail.  Long 7 degree 30' tail taper with
     10 caliber tangent nose ogive.

For .22LR use the G1 model.  The G1 is good for blunt nose,
exposed lead bullets with a velocity less than 1400 ft/s.

SELECT BULLET

I have included a datafile of bullets which was taken from PCB by
Odd Harvard Skevik.  <http://www.stud.ntnu.no/~oddske/ballistikk.html>

The first two lines of this file are skipped.  If you add more
entries, just follow the format and position of the current entries.

CALCULATION PARAMETERS

Bullet Name - Intended for future functionality
Buller Diameter - Not used in current calculations
Ballistic Coefficient - Projectile ballistic coefficient.
Bullet Weight - Projectile weight in grams or grains.
Muzzle Velocity - Initial velocity of projectile

Bore-Sight Distance - Distance between the line of sight and the bore.
Zero Distance - Sight zero distance.

Vital Zone - Diameter of the target vital zone.  This value is used
	in the maximum point blank range calculation.
Firing Angle - Elevation angle of the shot.  The Path output in the 
	trajectory table is calculated relative to the distance along the
	line-of-sight, not horizontal distance.
Wind Velocity - Velocity of the wind.
Wind Angle - Direction of the wind source.  0 deg. is from behind
	the shooter, 90 deg. is from the right, 180 deg. is directly in 
	front of the shooter, 270 deg. is from the left.

Starting Range - Starting distance listed in the trajectory output.
Ending Range - Last distance listed in the trajectory output.
Step Size - Range increment used for the trajectory output.

TRAJECTORY TABLE OUTPUT

Here are the details of the trajectory output table.

Range - The horizontal distance to the projectile location.  For calculations
	with a non-zero firing angle, the Path values are given for the range
	along the line of sight, not the horizontal distance.
Velocity - Absolute projectile velocity.
Energy - Projectile kinetic energy.
Mom. - Projectile momentum.
Path - Actual projectile flight path in relation to the line of sight.
Zero - Projectile flight path for a horizontal, zeroed shot.
Drop - Amount of drop if the projectile is fired perfectly horizontal.
Drift - Horizontal drift due to wind.
Time - Flight time of projectile.

CALCULATE B.C.

This function calculates the projectile ballistic coefficient based
on the input data and the selected drag model.

INFO SOURCES

There are several sites on the web that have good information on
ballistics, these are the ones I recommend:

http://www.snipercountry.com/ballistics/index.html
http://www.lascruces.com:80/~jbm/

BUGS / SUGGESTIONS

Probably a few, but I haven't noticed them yet.  You may get strange
behavior if you input very large or small numbers, but typical values
work fine.  If you find any, please email me at weage98@yahoo.com.
Any suggestions for features are welcome also.


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