Labrabaco: a G7 BC calculator from Labradar tracks

ptosis

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Following up on this interesting thread -- https://www.longrangehunting.com/threads/calculating-bc-with-labradar-it-works.202475/

I have put together some code to calculate G7 ballistic coefficients from Labradar tracks. The tool is available here: https://bc.geladen.ch/labrabaco/labrabaco.html

It all runs in your browser, there is nothing to install, and it's free and open source.

Some bits of additional info are here: https://geladen.ch/en/labrabaco-v-0-5-beta-is-out/
and here: https://geladen.ch/en/tips-to-set-up-labradar-for-the-most-awesomest-results/

My deepest gratitude goes to entoptics, who provided absolutely precious data for design and calibration of the algorithms.

That is what can be expected:

Bulletref BCBC srcvalid tracksbaco BCdiff, %
GP90 (Fass90)0.166CH armee150.1670.7%
GP110.274CH armee160.270-1.4%
RUAG BALL 8.60.312vendor [*]70.3161.1%
Lapua Scenar-L 7.62 155gr0.230vendor160.2300.1%
GP90 (SG-553-LB)0.166CH armee140.166-0.1%
Hornady ELDM 6.5 147gr0.351vendor160.332-5.4%
Berger EOL 6.5 156gr0.347vendor40.3521.3%
Hornady ELDM 5.56 73gr0.200vendor50.2063.0%
Hornady ELDM 6.5 147gr0.351vendor50.337-4.1%
Hornady ELDX 6.5 143gr0.315vendor40.312-1.0%
Hornady ELDX 7 175gr0.347vendor190.3531.6%
SMK 223 69gr0.169Litz [**]100.167-1.1%
Hornady ELDX 6.5 143gr0.315vendor70.315-0.1%
Hornady ELDX 7 175gr0.347vendor220.3511.2%
[*] from trajectory data
[**] Applied Ballistics For Long Range Shooting, 2nd ed.

"Ref BC" is a known good G7 BC from "BC src". "Baco BC" lists the values calculated by labrabaco from radar tracks.

Gory details will follow in a separate article. In short, the software uses a 5th order polynomial regression weighted by SNR (absolute, not dB) on all data points for V(t), then runs an actual 3DOF ballistic engine in reverse to iterate to the best-fitting BC.

You're welcome :)
 
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I have also checked most of the tracks I provided to Ptosis, using a regression spreadsheet I created (as seen in the thread linked above), and entering the values into JBM Ballistics B.C. calculator. My results match very closely to what Ptosis's tool gives, but requires quite a bit of tedious clicking and typing.

Dragging a zip file into a web browser is sweet!
 
v.0.7 is out, now available:


The major change is noise filtering. Most people who have plotted Labradar tracks in spreadsheet software, must have seen occasional tracks of this shape:

1637532265064.png


The tail of the graph -- beyond 60 ms -- is obvious noise; there is no way speed can increase downrange. Now Labrabaco can detect and eliminate such data points, and make sense even of very dirty signal, and make better sense of clean signals too.

Special thanks go to entoptics for his excellent suggestions and observations!

Also, a bug has been fixed: for those who care, Labrabaco now understands tracks recorded with "ft" distance units (did not try it myself, but should work ok).

In the works for future v.0.8: BC calculation for G1 and GL standard models, interface cleanup, indications of data and results quality, etc.

Enjoy.
 
v.0.8 is out, now with the taste of RA4, G1, and, while I was at it, G8.
(The default is still G7.)

Still at the same place: https://bc.geladen.ch/labrabaco/labrabaco.html

All you ever wanted to know about long-range ballistics of your rimfire trainer...

JBM and Strelok Pro (probably some others too) understand RA4 BCs.
Coming soon to Plan 33 (alas, not for the metric-impared).

Caveat: I did not test RA4 model results very extensively; would very much appreciate any feedback, especially from those who use Lapua ammo.

Enjoy.
 
Thanks for your work on this. I hadn't followed your progress for some time. Will take look at the provided links when I'm able.
May have some questions as I try to sort thru your program(s).

Edit:
Well I can't run your program since my LabRadar SD card is 4000 miles away from my winter residence. So it won't be until February, 2022 when I can play with your .html program.
 
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