


                          ABOUT BULLET FLIGHT 1.20

     First, the formalities:

     DISCLAIMER
     ----------
     I have made a thorough effort to "debug" this program and to make
     sure that the information produced by it is reliable. However, since
     I am only human and could possibly have missed something, please
     pay careful attention to the following:

     This program is provided 'AS IS' and I specifically disclaim all
     warranties, expressed or implied, including but not limited to
     implied warranties or merchantability and fitness for a particular
     purpose. In no event shall Donald B. Arp be liable for any loss
     of profit or any other damage, including but not limited to special,
     incidental, consequential or other damages.
                             Donald B. Arp, Author


     And now that the formalities are out of the way, let's take a look
     at BULLET FLIGHT 1.20.

     My goal in writing this program was to produce a program which would
     produce ABSOLUTELY PRECISE results in its final calculations.  To
     accomplish this, BULLET FLIGHT uses a numerical integration technique
     in its calculations.  Results are calculated at EACH YARD out to the
     maximum range you specify.  Naturally, this takes more time than 
     some other methods.  But, if precision is the utmost consideration,
     then the few seconds delay should be worth the wait.   On the
     80286, AT-compatible computer on which this program was written,
     a full set of calculations out to a maximum range of 1000 yards took
     about six seconds.

     My second priority was to write a program which would produce
     PRACTICAL information for the shooter.  Consequently, BULLET FLIGHT
     is not full of "bells and whistles".  No graphing functions is
     provided.  Why?  Because trajectory graphs all look pretty much the
     same.  (The only things that change much are the figures on the X and
     Y axis of the graph.)  And I wanted a program which would run on
     anybody's computer, regardless of the graphics interface they are
     using.  No accomodation is made for saving the results to a file.
     Why?  Because it is just as easy to recalculate a set of data as it
     is to reload it from disk.  Besides, that keeps the program simpler.
     And the less the program has to access your drive, the less chance
     there is for something messing up.
          So what DOES a shooter need to know?  He needs to know where
     his bullet will be at any practical range, how much "knock-down-
     power" it has left, how much to adjust his scope to rezero for extreme
     ranges (unless he is a pretty good judge of "holdover"), how the wind
     will affect his bullet, where to zero at close range to get on-paper
     at long range, and maximum bullet rise above line-of-sight.
          Other considerations only come into play when you compare one
     cartridge to another.  Things like recoil, time of flight, and
     downrange velocities are useful here.
          I make no apologies for limiting the maximum range of BULLET
     FLIGHT to 1000 yards.  The only reason that I set it THAT far is
     because there are 1000-yard competitive shooting events.  As for
     myself personally, I consider 400 yards to be the PRACTICAL limit
     for shooting.  And that is true ONLY if you can get "sandbag" steady.





     This program was written to produce a black-and-white screen display
     without any graphics.  This was done intentionally to insure that it
     would run on any IBM-compatible computer, regardless of monitor type
     or graphics interface.   The only requirement is that your monitor
     run in 80-column mode.

     This program uses the G1-Drag Function to calculate velocity losses
     which result from air drag on a bullet.  A lot of calculating has to
     be done for the program to figure all the variables it calculates. The
     greater the maximum range you specify, the greater will be the time
     necessary for the program to perform its calculations.  This time
     interval will depend on the speed of your particular computer.

     The figures calculated by this program are, for all practical
     purposes, identical to the figures contained in the Speer Ballistics
     Tables (which are also based on the G1-Drag Function).  However, with
     this program, you are not limited to a certain zero-range, nor are
     you limited to a 500-yard maximum range (1000 yards is the limit).  In
     addition to remaining velocities and trajectory points, this program
     also calculates kinetic energy (ft/lbs), scope adjustment to obtain
     new zero, the bullet's time of flight, bullet drift in a crosswind,
     close-range zero range, maximum bullet rise above line-of-sight, free
     recoil, and optimum zero ranges (explained below).  It will also
     standardize ballistic coefficients to conditions other than sea level.
     Also, the program will produce a printout for any interval you choose,
     even down to EVERY YARD in the range.

     There are some pieces of information which you will have to look
     up, probably in a reloading manual of your choice.  These are:  the
     ballistic coefficient of the particular bullet you are using, the
     muzzle velocity of that bullet, and (if you want recoil information),
     the weight of the powder charge for the cartridge.

     The Trial Version of this program is intentionally limited.  It
     only allows a Maximum Range of 200 yards, prints results at 50-yard
     intervals only, does not calculate close-range zero range, maximum
     bullet rise or recoil, does not provide for hardcopy printout, and
     does not allow you to standardize the ballistic coefficient to
     conditions other than sea level. 

     If you want to obtain a Registered version of this program, send your
     name and address with a registration fee of $15.00 to:

          Don Arp,  1214 Irwin Avenue,  Maryville, Tennessee 37804

     If you should find an error in the results which BULLET FLIGHT
     produces or if the program should malfunction somehow, please feel
     free to let me know.  If you have any suggestions which would make
     this program more beneficial to you, let me know that too.  I won't
     guarantee that I will USE every suggestion I get, but you can rest
     assured that I will CONSIDER every suggestion you send me.    















     To start the Registered Version, type BF120 <Enter> at the DOS
     prompt.  To start the Trial Version, type BFT120 <Enter>.

     When the program starts, you will be asked to enter several pieces of
     information.  Although most of this information is not printed out
     on-screen (in order to conserve screen space), it is printed as a
     header when you ask for a printout to your printer.

     1. HEIGHT OF SIGHTS.   This is the distance (in inches) of the
     centerline of the gun's sights above the centerline of the gun's bore.
     Most "open" sights are located about .75 inches C-C above the bore. 
     Scopes (due to the particular mounting hardware) are usually located
     at 1 to 2 inches C-C above the bore.  Note:  This is the distance from
     CENTERLINE TO CENTERLINE of sights to bore.

     2. BULLET WEIGHT.  This is the weight of the bullet in GRAINS.

     3. BALLISTIC COEFFICIENT.  This is a DECIMAL NUMBER which represents
     the air drag capability of a bullet.  You can look this up in any of
     the reloading manuals available for the particular bullet you are
     using.  Values of .01 to 1.0 are acceptable to the program.

     4. MUZZLE VELOCITY.  This is the speed in feet-per-second at which the
     bullet leaves the barrel.  This information is available in reloading
     manuals.  The minimum allowed is 250 ft/sec, maximum is 4365 ft/sec.

     5. MAXIMUM RANGE.  Here you tell the program what maximum range (in
     YARDS) you want it to calculate to.  For instance, if you want
     trajectory information out to 500 yards, enter 500.  The Registered
     Version of the program will calculate to a maximum of 1000 yards,
     but the Trial Version only allows a maximum of 200 yards.

     6. ZERO RANGE.  This is the range (in YARDS) at which you want to zero
     your gun.  You cannot exceed the Maximum Range selected above.

     7. YARDAGE INCREMENT.  This tells the program which ranges (in YARDS)
     that you want it to print information for, out to the maximum range
     you have selected. For instance, if you want to know what your bullet
     is doing every 25 yards, enter 25.  The smallest increment you can
     choose is 1 yard. The largest is the maximum range you chose.

     8. RECOIL INFORMATION.  If you want to know how hard your gun "kicks",
     enter "Y" (for yes).  You will then be asked to enter two other pieces
     of information.--The weight of the powder charge in GRAINS, and the
     weight of your gun in POUNDS. (Don't forget to add the weight of your
     scope & mounting hardware, sling, and ammunition in the magazine when
     you figure your gun's weight.)   If you don't want this information,
     enter "N" (for no).

     9.  STANDARDIZE COEFFICIENT.  Ballistic coefficients as listed in
     the reloading manuals are almost universally calculated at sea-level
     conditions.  However, you may want to find out what your bullet will
     do at conditions other than sea level.  Altitude, temperature, and
     barometric pressure all affect the density of the air. And the
     denser the air, the greater will be the resistance to the bullet
     passing through it.  If you choose to standardize the coefficient,
     you will be prompted to input the conditions you want.  The Standard
     temperature and barometric pressure for the altitude you select
     are printed in parenthesis.  You can use them or put in whatever
     value you prefer.  If the value you want is above the cursor, just
     press ENTER. You can select any altitude from 0 to 15000 feet (even





     feet only), temperatures from -100 `F to 150 `F, and barometric
     pressures from 15.00 to 35.00 In/HG (inches of mercury).

     10. CROSSWIND SPEED (MPH).  This is the crosswind velocity which you 
     want the program to use in calculating bullet drift.  Any value
     from zero to 50 is acceptable.
     
     11. VERIFY.  The last question asks you to verify all the data which
     you have entered with the question "Is all data correct?  Y/N". 
     If you want to change something, enter "N" (for no).  If all the
     data is correct enter "Y" (for yes) or simply press ENTER.  Also,
     read "RE-ENTERING DATA" below.

     On any piece of information, if you should enter a value which is
     out-of-range or invalid, the program will reject your input and
     require you to re-enter that piece of information. 

     ---------------------------------------------------------------------

     The program will take the information you have entered, and will
     proceed to calculate several items for you.  (A great deal of
     calculating has to be done, so this takes a few seconds.)  The
     printout includes the following:

     1. RANGE.  Distance in yards at each yardage increment you selected.

     2. SPEED.  Bullet velocity in feet-per-second at each range.

     3. TRAJ.  Abbreviation for "TRAJectory".  Most people think of this as
     "drop". This is the location of the bullet above or below the
     line-of-sight at each range.  A positive number means that the bullet
     is ABOVE the line-of-sight.  A negative number means that the bullet
     is BELOW the line-of-sight.

     4. ADJ.  If you are using a scope, this is the amount of ADJustment
     (in INCHES, not clicks) that you would need to dial in to adjust your
     zero to the range in the RANGE column.  A positive number means that 
     you would need to move your scope adjustment UP.  A negative number 
     means that you would need to move your scope adjustment DOWN.   For
     instance, if your gun is zeroed at 100 yards and you want to re-zero
     to 200 yards, look up the ADJ value listed in the 200-yard data line.
     Then move your scope up/down adjustment the number of inches you found
     in the 200-yard ADJ line.  Remember this is INCHES, NOT CLICKS.

     5. FT/LBS.  Most people think of this as "knock-down-power".  This is
     the kinetic energy of the bullet, in foot/pounds, at each range.

     6. TIME.  This is the bullet's time-of-flight (seconds) at each range.
     Why include this in the chart?  This is the absolutely reliable way
     to determine which bullet shoots the flattest.  The quicker the
     bullet gets there, the flatter its trajectory.  When comparing two
     bullets, the one which crosses the finish-line first is the flattest-
     shooting of the two. It is surprising how much difference just a few
     hundredths of a second will make in the drop of a bullet at 500 yards.
     
     7. DRIFT.  This is the number of INCHES your bullet will drift to the
     left or right at the crosswind velocity you selected.  This crosswind
     is considered to be at a right angle to your line-of-fire.

     In addition, the program will calculate a CLOSE-RANGE ZERO for you. 
     This is the close-up range at which to zero your gun in order to get





     "on-the-paper" at the longer zero range you specified. However, if
     you specify a zero range which is relatively close to the muzzle,
     the Close-Zero Range and Zero Range will be the same. Also, the
     program calculates the maximum bullet rise (in inches) above the
     line-of-sight, and tells you at what range this maximum rise occurs.
     If the bullet is still rising when it reaches the maximum range you
     selected, the printout on-screen will tell you.

     Once the program has calculated the trajectory information for you,
     you can get an OPTIMUM ZERO RANGE.  To use this feature, you simply
     enter the maximum height (in inches) above line-of-sight that you
     want, and the program will tell you at what range to zero your gun to
     get it. (If the height you choose would result in a zero beyond the
     Maximum Range specified, the program will give you an error message.)
     For instance, if you want to zero your gun so that the bullet will
     never be more than 2 inches higher than your line-of-sight, simply
     enter 2 when the program prompts you to enter Maximum Rise.  Then, by
     pressing "R", you can have the program to re-figure the trajectory
     chart based on this new zero range.  To save a multitude of
     recalculation and quite a bit of time, this Optimum Zero feature
     uses a shortcut method to figure the zero range.  Although this
     method is not as accurate as a full-blown analysis, it is accurate
     to within a few yards, and is certainly more than accurate enough
     for all practical purposes.   And it saves a BUNCH of time.

     Also, you can select a NEW ZERO RANGE.  Only the portion of the
     calculations which pertains to trajectory will be recalculated,
     which requires about 1/3 the time of a full set of calculations.


     GETTING A PRINTOUT
     ------------------
     If you want to print the information to your printer, you will be
     prompted to enter two other pieces of information.  These are used
     in a header for the hardcopy printout.
     
     1. DESCRIPTION OF GUN.   Here you enter whatever description you want
     of the particular gun you are calculating information for.  For
     instance, 30-06,  7mm Magnum, .243 Winchester, etc.  This can be
     worded however you want it, up to 35 characters in length.

     2. DESCRIPTION OF BULLET.  This is a description of the bullet you are
     using, worded however you want it, up to 35 characters in length.

     When printing is finished, the chart will be re-displayed on-screen.


     RE-ENTERING DATA
     ----------------
     The program stores all information which you enter.  Therefore, if you
     want to go back and change some portion of the information you
     originally entered, it is not necessary to re-enter the whole thing
     again.  The information which you have previously entered will be
     printed at each prompt.  For each entry which you DO NOT want to
     change, simply press ENTER.  The program will use the value which
     you entered before.  For instance, if you only want to change the
     Muzzle Velocity, the only new figure you will have to enter will be
     the new Muzzle Velocity--just press ENTER on all other prompts.


