This Spreadsheet Uses BfX Custom Functions Available Thru An Excel Add-in
Have you ever wanted to create your own custom spreadsheets to calculate out all those ideas you have about building the ultimate F-Class long range rifle?
If you are like most shooters (including me) you will just use a ballistic program and print off countless sheets comparing one calibre and bullet to another. Its gets the job done eventually but it will never provide the comparison that the above screen shot displays. This spreadsheet displays one easy to view, side by side, comparison of the calibre and projectiles of interest.
It would take a physicist or ballistician to work out the math involved for the displayed spreadsheet and math was never my strongest subject. Well I have good news for those of you that share my interest in calculating solutions and comparisons. I put together the spreadsheet on show and didn't get a headache or even raise a sweat. It is that easy that I want to share it with all interested shooters.
Let me introduce you to Robert Meijer who just happens to be a physicist (PhD) and also a professor in computer science. Don't be intimidated by his titles, this guy is a shooter with more than a passing interest in ballistics. He has a website that is dedicated to making ballistics available to anyone who can piece together a simple spreadsheet. He has written a very complete set of functions that can be used in Excel spreadsheets and installed as an "add-in" and are called BfX().
On his website he has available for download the add-in function along with an install application to load it into Excel. Most versions of Excel are covered from 2003 to 2010 (32 and 64 bit versions). His website can be found here: BfX Online
Robert is to be congratulated for making ballistics easy and available for free with his BfX functions. His website is a fascinating look into our sport from another perspective. He has made the math involved in ballistics as easy to use as filling in the blanks in a function. Any unit can be used or converted no matter if imperial or metric and they can even be mixed together in the same function.
The spreadsheet displayed above/below can be downloaded from here:Range Chart Using Any Units
The part of the spreadsheet shown below displays the units that can be used. All blue text in the spreadsheet is for data entry and unit selection. If wind deflection is shown in 'moa' then just changing the blue text unit heading to 'in' (inch) or 'mrad' (milli radians) will provide output in that unit. It really doesn't get any easier than this. Change the Range 'yd' unit heading to 'm' and the output recalculates for the range in metres instead of yards.
Its easier than entering data into a dedicated ballistic application that you would find online or buy. The BfX Online website has all the functions listed and many examples and help files. Enter the data as metric (SI) or imperial units or mix them together in any way you want to have the data displayed.
The idea of mine to compare 10 calibres/loads together side by side came from Bryan Litz's load comparison table in his book. The table was perfect for turning into a spreadsheet. It would not have progressed very far without the BfX functions of Robert Meijer. If you have a pet project that requires some ballistic number crunching and have a copy of Excel running on your PC then I recommend downloading Robert's BfX functions and putting your ideas into action.
I added a second revised spreadsheet as it provides a very flexible approach to using any listed unit type. I know that while I use mostly imperial units, I use temperature measured in degrees C and atmospheric pressure measured in hPa.
The revised spreadsheet is named 'Range Chart Any Units' for the obvious reasons. It is easy to use for range charts or to compare loads side by side. It includes a unit converter for converting metric to imperial or vise versa. It also has Miller's formula for gyroscopic stability and can calculate spin drift using Litz's equation. Download the BfX add-in for Excel and try it out!
kwk.us: Free Recoil (Like a rifle in recoil suspended from 2 strings)
Meijer: BfX Online
Original Spreadsheet: Drop+Drift+Recoil+Stability Calculator
Revised Spreadsheet: Range Chart Using Any Units
Ian Pavy for safclass.com.au (09-03-2011)