Field
Firing Solutions© runs on a
small, hand-held PDA and is used
to obtain a real-time firing solution in the
field based upon current atmospheric and
target data.† The trajectory computation
engine is the same as used in the desktop
programs, but has output limited to the specific
information needed for a complete firing
solution: elevation, windage, lead, and hold-off.
Elevation is given in terms of an MOA
adjustment and actual turret solution; windage is output in terms MOA for
scope adjustment and Mils for a wind correction hold-off with a mil-dot scope; lead is the
hold-off correction needed for a moving target
given in terms of MOA or Mils for use with a mil-dot
scope; and hold-off which is the combined value
of windage and lead correction in terms of MOA
or Mils.
Compliments the desktop program -
The desktop program is used create the profiles
that can be used on the PDA. While it is
certainly possible to input all of the data
needed to compute a firing solution, it is very
convenient to simply load "profiles" that will
populate the various data requirements
automatically. To load atmospheric data,
simply click on the atmosphere profile that
contains pressure, temperature, humidity, wind
speed and direction; click a bullet profile and
load the bullet caliber, weight, muzzle
velocity, ballistic coefficient, deceleration
constant; click a turret profile and select the
specific turret to use and get turret specific
elevation solutions. All of these files are created
on the desktop and copied to the PDA for use in
the field.
Metric or English - The program
may be used in either English or metric mode.
Trajectory table - The PDA
program also outputs a trajectory table that
will start at the range and in increments
selected by the user to the target distance.
The output columns are Range, Turret, Elevation,
Windage, Lead and Holdoff - only those data used
in arriving at a firing solution.
Session continuity - Like the
desktop programs, upon exit the PDA version
saves all current setup data and reloads this
setup when the program is restarted. In
the field, this means that after the program
environment, bullet and target presents are
input, turning off the unit does not mean a loss
of this data. Powering up the unit brings
the program to the same state it was at last
usage - no loss of time re-inputting data.
Mil-Dot ranging - Integrated in
the program is a mil-dot ranging dialog box that
permits target size input in inches, feet, yards
or meters and the mil size of the target.
The resulting range that is calculated is
automatically input into the target range window
for immediate firing solution calculation.
Coordinate ranging - The program
also allows the user to calculate target range
by inputting the shooter's Latitude/Longitude coordinates
in a variety of formats or UTM coordinates, and the target's coordinates. The
program will then calculate the range of the
target, its bearing and the shot angle. The latitude and
bearing will also be used by the program to
calculate Coriolis effects. Input may be
accomplished via coordinates directly from a map
or by GPS signal. Please see the FFS
manual for a full explanation.
The angled shot - Shooting either
up or down from level effects the elevation
solution for the shot. The PDA program, as
well as the desktop programs, will correctly
calculate the proper elevation solution and
therefore permit angle input.
Multiple target table - Given the
ability to store FFP and target locations, it
only makes sense to create a table of possible
targets for instant selection. Looking
back at the opening display above, you will note
a button labeled "Target." Pressing this
button will produce the following:
The
FFP drop-down list shows all of the FFP which
the user has saved in terms of map coordinates.
Below that list is a window that lists all of
the target cites. The next screen shows
that FFP Alpha
has been selected.
Note that the program has calculated the range,
bearing and shot angle for each potential target
from FFP Alpha. In order to reduce the
size of the list, the user can use the Target
Filter box as shown below:
Here,
we've selected only those targets with a target
ID starting with "A." To select any
target, simply double tap the target ID.
The Target Range Card will close, the data will
be input into the opening window and the firing
solution calculated. This way, multiple
targets may be engaged by tapping "Target",
double tapping the target and reading the
solution. The number of FFP and/or target
locations that can be shown is limited only by
the available memory.
Wind Zones - Have you ever seen the wind
flags flying in different directions at
different parts of the range at the same time?
It is a vexing problem to try to figure out an
average wind vector to compute how much wind
drift to compensate for. To deal with this
issue, the program has the ability to configure
up to three separate, contiguous wind zo
nes
and then calculate where the bullet is at any
point along the trajectory. For instance,
here is a problem taken from an actual
competition: at the 1000 yard firing line,
the wind was 5 mph from 9 o'clock; at about the
600 yard line the wind had switched to a 2 mph
wind from 3 o'clock. The data window for
this problem would look like the screen to the
right.
After
the data is input, click OK and return to the
solution page. Note the solution of 1.5L;
in the absence of the 2 mph wind from the other
direction for the last 600 yards, the windage
necessary would be 4.0L - a substantial
correction.
Here
is what the trajectory looks like on the table.
You can see that at 400 yards the bullet had
been pushed 1.2 MOA to the right (for a 1.2L
correction.) At that point, the bullet
entered into the second wind zone. While
the bullet continues to move right, its rate
begins to slow until at 800 yards it begins to
move back towards the left. At the target,
the bullet is still further right than it was at
400 yards, but in the absence of the
counter-wind, the bullet would have continued to
move further right even if the wind completely
died at the 400 yard line. According to
the program, if the 5 mph wind completely ceased
400 yards down range and there was no other
cross-wind, the correction would have
been 2.2 MOA left.
† -
Important note:
This software is designed to run on the Windows
CE, the Windows operating system for mobile
devices, because of the demands the software
places on the operating system and CPU.
Currently the program has been tested on a Viewsonic V37 with the Pocket PC
2002 and Pocket PC 2003
operating systems and a iPAQ hx4700 running
Windows Mobile 2003, 2nd edition.
This
program is not designed to run on Palm products
or PDAs that use the Palm operating system.
