CompCalc - The Trajectory Compensation Calculator For Handheld Organizers

The following screen images show Palm and Sharp handheld organizers (computers) and the CompCalc main compensation screen.  See text below for program capabilities.  True sizes are: Palm M100 = 3.1x4.7x.7 inches, Sharp OZ730 = 6.3x5.7x.8 inches open and 6.3x3.2x.8 inches closed.

The CompCalc program lets the user take BalCal 6.2 trajectory data for multiple loads into the field on handheld devices and interpolate (calculate) exact hold over, wind compensation, and moving target lead for input conditions.  Specifically, the CompCalc program allows the user to:

1. Select which load (firing data set) to use from all that were downloaded.  1-99 firing data sets can be stored on the organizer to cover various combinations of rifle, load, location, climate, and altitude conditions.

2. Enter distance, wind velocity, wind direction, up/down hill angle, and target speed.  For each variable entered the CompCalc program will calculate and display the proper holdover, wind compensation, and target lead.  These compensation values will be displayed in inches(or cm), clicks, and mil dots as shown in the above images.  The input values will also be written to a file so if the organizer is turned off and then turned back on the latest values will be used for initialization.  Condition change calculations will take about 3-5 seconds on the M100 Palm which has a 16 Mhtz processor.  Newer, more expensive machines will probably run much faster.  On the Sharp Wizards with their 10 Mhtz Z80 chip but much simpler operating system and screen I/O the calculations are done in about 2 seconds.

3. CompCalc can switch between metric and english input and output.

4. Do mil dot ranging calculations by entering observed mil dot spans and the size of the targets spanned.  Output is in yards and meters.  The most recent distance calculated can then be used to generate a new set of compensation values.

5. Change the mil dot to MOA relationship so a variable power mil dot scope not set on its calibrated power can still be used for mil dot ranging.  This requires the user to know how many MOA a mil dot spans at its various power settings.  The best way for the user to establish the MOA to mil dot relationship for various power settings is to put out a target at exactly 100 yards that has a line of alternating black and white squares that are 1 inch on a side.  The user can then run the power setting up or down and observe and record the number of 1" (1 MOA) squares that are spanned by a 1 mil dot span.  Hint, just get a cheap wooden yard stick and carefully blacken every other inch with a magic marker.

Currently the supported handheld organizers (computers) are:

a. Palm/Handspring/other PDA's using the Palm OS.  The CompCalc program has been tested with a variety of emulator/rom combinations with 3.0 or newer Palm OS's and the CompCalcV2 is for use with older hardware and OS's.  This code was developed using NS Basic on an M100 Palm with the 3.5 OS.  Other possible Palm OS type machines are made by IBM, Sony, Handspring, Acer, AlphaSmart, Gramin, Kyocera, Samsung, Symbol, and Handera.

b. Sharp Wizard OZ-730/750/770 series and probably the very similar ZQ-7xx machines.  This code was developed on a Sharp Wizard OZ-730 using their SharpSDK basic.

Other related notes:

a. The usefulness of a compensation interpolator depends on the tactical situation.  You must have a free hand and enough time to enter the conditions.  A solitary sniper has to do everything by himself while keeping one eye on his area of concern.  A two or three man sniper team has a lot more flexibility and can both observe an area while another member of the team can be doing mil dot ranging calculations and compensation calculations.  Atmospheric conditions also have to be reasonable, these devices work in certain temperature ranges and too much water on electronic devices renders them useless.  It is also possible to put these devices in very clear zip lock bags and operate them thru the thin plastic.  Devices can also be carried in pockets close to the body to keep them warm enough for short term usage out of the pocket in extreme cold conditions.

b. Effects of head and tail winds are figured into the elevation compensations in CompCalc.

c. Vertical effects on 22 LR rounds from side winds are also figured into the compensations for these loads.  See the BalCal 6.2 help information to learn more about this effect.  This effect plus that of head/tail wind effects on elevation make competitive smallbore shooting very technical and one of the best possible training venues for anyone that wants to call themself a rifleman.  Many of the very best long range shooters started out firing 22 LR ammo at outdoor smallbore targets.

d. Obviously you will need a copy of BalCal 6.2 to produce the trajectory data files needed by CompCalc.  We can solve that problem for you!

e. CompCalc was intentionaly developed for the low end versions of handheld devices so the cheapest and most expendable devices can be utilized.  The more expensive models tend to run faster, use batteries quicker, and may well be more fragile.  Before purchasing a handheld device for use with the CompCalc program consider the following tactical usage parameters:

    1. Required ruggedness and anticipated operating conditions.

    2. Size and weight of the unit.

    3. Type of battery and consumption rate.  Can the batteries be replaced or recharged in the field without losing installed data and programs?  Are the batteries readily available AA or AAA or expensive other types?

    4. Processing speed of the device versus tactical needs.  See the speed notes above.

    5. Availability of screen backlighting for usage in low light conditions (many devices have this feature).

    6. Possible usage of satillite email type communications to and from a situation/detachment commander as a backup to normal radio communications in SWAT/sniper operations.

    7. Possible GPS functions for far ranging snipers/lrrp-recon/hunters who need to communicate with a base unit or other users in the field.

    8. Which pocket you will carry it in.  If you have to 'hit the dirt' quicky you don't want to land on top of the device and smash it.  For right handers a pocket on the front of the left shoulder or back of the right thigh or calf might be the best place to carry it.  Visualize your expected usage situations and you should get a good idea on how to carry the device into the field.  Check out the waterproof containers from Otterbox.  The box dimensions given are outside not inside (subtract about 1/2" from each dimension) and you will probably have to add some more padding.  Also, will your usage situations permit its use?

    9. Possible usage in conjunction with a handheld laser range finder.  In field usage a CompCalc equiped device could be taped or glued onto the top or side of a range finder or spotting scope to provide quick compensation data when a spotter is making an area range card.

   10. Other standard built-in features not related to hunting/sniping (memos, addresses, phone numbers, schedule, to do lists, expenses, clock, calendar, calculator, email, wireless internet, GPS, & whatever).  Actually memos could contain notes on firearm zeroing, firing test results, locations of observed enemy personnel or emplacements, radio codes, observed bomb/artillery strikes, and other types of recon info.

   11. Still have questions?  Contact Constant Force Products for more info.  Simply click on the email link below and type away!  We try to answer every email within 24 hours or less (usually a lot less).

Click on the following links to:
View sample Palm screens.
View sample Sharp screens.

Email Constant Force Products with questions or whatever.

What does CompCalc cost and how do I order a copy?

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