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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Calculating BC with LabRadar. It works!
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<blockquote data-quote="entoptics" data-source="post: 1438781" data-attributes="member: 104268"><p>Picked up a LabRadar a couple days ago. It's a very nice machine.</p><p></p><p><em>Quick Review (though you've heard it all before).</em></p><p></p><p><em>Pros</em> - Easy to setup, appears very accurate (tested against ProChrono), can run two rifles side by side with a buddy without repositioning, amazing data collection, so far no problem reading 300 WM and 5.56 out to about 80 yds (sometimes 90-100).</p><p></p><p><em>Cons</em> - Stupidly expensive, needs a remote (wiggles when you press buttons, so you have to re-aim every string, and trying to control it from prone is just silly), no bluetooth to smartphone (yet), doesn't include MacDonalds straw for aiming, can't revisit a string to add more shots, and did I mention it's stupidly expensive?</p><p></p><p><strong>Anyway</strong><em>.</em> To the point in the title. You can absolutely calculate B.C. using the data it collects. And surprisingly accurately. Unfortunately, it's not as trivial as setting your distance points and plugging and chugging in JBM when you get home.</p><p></p><p>The machine records it's acquisitions in a CSV file. It appears to read every millisecond as the round travels downrange. It outputs a range, velocity, and signal:noise. I took that file and graphed stuff out, and noticed that sometimes there were obvious fliers, and minor scatter overall, in the data. This got me thinking.</p><p></p><p>Instead of taking the raw machine readings at two distances and plugging them into JBM, I fit a line to the data using Excel. I calculated theoretical "Near" and "Far" velocities and distances, using the fit line equation, and popped them into JBM. Suddenly out popped BCs that were scarily close to the manufacturer's advertised (Hornady 208 ELD-M and 212 ELD-X).</p><p></p><p>I only experimented with 2 shot strings, using atmospheric data from NOAA for a station 10 miles away, and <u>my calculated B.C.s were ≤ 5% from what Hornady quotes, and for a couple shots, within 0.5%.</u> Both G1 and G7 seemed to be darn close.</p><p></p><p>In summary, I'm thinking that with better atmospheric data (e.g. recorded on site with a kestrel/smartphone/weather meter/etc), and a half dozen shots for good statistics, one could get pretty precise BC results with the LabRadar.</p><p></p><p>I'll keep up the experiments, and potentially make an Excel template to distribute if anyone is interested.</p></blockquote><p></p>
[QUOTE="entoptics, post: 1438781, member: 104268"] Picked up a LabRadar a couple days ago. It's a very nice machine. [I]Quick Review (though you've heard it all before).[/I] [I]Pros[/I] - Easy to setup, appears very accurate (tested against ProChrono), can run two rifles side by side with a buddy without repositioning, amazing data collection, so far no problem reading 300 WM and 5.56 out to about 80 yds (sometimes 90-100). [I]Cons[/I] - Stupidly expensive, needs a remote (wiggles when you press buttons, so you have to re-aim every string, and trying to control it from prone is just silly), no bluetooth to smartphone (yet), doesn't include MacDonalds straw for aiming, can't revisit a string to add more shots, and did I mention it's stupidly expensive? [B]Anyway[/B][I].[/I] To the point in the title. You can absolutely calculate B.C. using the data it collects. And surprisingly accurately. Unfortunately, it's not as trivial as setting your distance points and plugging and chugging in JBM when you get home. The machine records it's acquisitions in a CSV file. It appears to read every millisecond as the round travels downrange. It outputs a range, velocity, and signal:noise. I took that file and graphed stuff out, and noticed that sometimes there were obvious fliers, and minor scatter overall, in the data. This got me thinking. Instead of taking the raw machine readings at two distances and plugging them into JBM, I fit a line to the data using Excel. I calculated theoretical "Near" and "Far" velocities and distances, using the fit line equation, and popped them into JBM. Suddenly out popped BCs that were scarily close to the manufacturer's advertised (Hornady 208 ELD-M and 212 ELD-X). I only experimented with 2 shot strings, using atmospheric data from NOAA for a station 10 miles away, and [U]my calculated B.C.s were ≤ 5% from what Hornady quotes, and for a couple shots, within 0.5%.[/U] Both G1 and G7 seemed to be darn close. In summary, I'm thinking that with better atmospheric data (e.g. recorded on site with a kestrel/smartphone/weather meter/etc), and a half dozen shots for good statistics, one could get pretty precise BC results with the LabRadar. I'll keep up the experiments, and potentially make an Excel template to distribute if anyone is interested. [/QUOTE]
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Calculating BC with LabRadar. It works!
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