Barnes Calculates Ballistics Using Doppler Radar Speed Data
How do you build better (more precise) ammo drop tables? With radar, that’s how. Barnes Bullets is using Doppler Radar to develop the drop tables for its new Precision Match line of factory ammunition. The Doppler radar allows Barnes to determine actual velocities at hundreds of points along a bullet’s flight path. This provides a more complete view of the ballistics “behavior” of the bullet, particularly at long range. Using Doppler radar, Barnes has learned that neither the G1 nor G7 BC models are perfect. Barnes essentially builds a custom drag curve for each bullet using Doppler radar findings.
Use of Doppler Radar to Generate Trajectory Solutions
by Barnes Bullets, LLC
Typical trajectory tables are generated by measuring only two values: muzzle velocity, and either time-of-flight to a downrange target, or a second downrange velocity. Depending on the test facility where this data is gathered, that downrange target or chronograph may only be 100 to 300 yards from the muzzle. These values are used to calculate the Ballistic Coefficient (BC value) of the bullet, and the BC value is then referenced to a standardized drag curve such as G1 or G7 to generate the trajectory table.
This approach works reasonably well for the distances encountered in most hunting and target shooting conditions, but breaks down rapidly for long range work. It’s really an archaic approach based on artillery firings conducted in the late 1800s and computational techniques developed before the advent of modern computers.
There is a better approach which has been utilized by modern militaries around the world for many years to generate very precise firing solutions. Due to the sizeable investment required, it has been slow to make its way into the commercial market. This modern approach is to use a Doppler radar system to gather thousands of data points as a bullet flies downrange. This radar data is used to generate a bullet specific drag curve, and then fed into a modern 6 Degree of Freedom (DOF) [ballistics software program] to generate precise firing solutions and greatly increase first-round hit probability. (The 6 DOF software accounts for x, y, and z position along with the bullet’s pitch, yaw, and roll rates.)
Barnes has invested heavily in this modern approach. Our Doppler radar system can track bullets out to 1500 meters, recording the velocity and time of flight of that bullet every few feet along the flight path. Consider the graph below showing a bullet specific drag curve referenced to the more common G1 and G7 curves:
Neither of the standard curves is a particularly good match to our test bullet. In the legacy approach to generating a downrange trajectory table, the BC value is in effect a multiplier or a fudge factor that’s used to shift the drag curve of the test bullet to try and approximate one of the standard curves. This leads to heated arguments as to which of the standardized drag curves is a better fit, or if multiple BC values should be used to better approximate the standard curve (e.g., use one BC value when the velocity is between Mach 1 and Mach 2, and a different BC value when the velocity is between Mach 2 and Mach 3.) Barnes’ approach to creating trajectory tables is to generate bullet-specific drag curves, and use that data directly in a modern, state-of-the-art, 6 DOF ballistics program called Prodas to generate the firing solution.
Story tip from EdLongrange. We welcome reader submissions.Similar Posts:
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- Lapua Releases Doppler Radar Data for Lapua Scenar-L Bullets
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Tags: 6 DOF, ballistics, Barnes, bullets, Doppler Radar, Drop Chart, G1, G7, Precision Match Ammo, Software
Will they do the same for their LRX, TTSX, TSX?
That’s more like it. Proper ballistic instrumentation
Two Infinition Doppler radars by the look of it. One 10.525 GHz (X-band) BR-29015 and one 35.5 GHz (Ka-band) BR-3503. The former for long-range work, the latter for in-bore (yes measurements of the velocity within the barrel) and smaller projectiles. I’ve used both types (but not make) many, many times. Wonder if they have the spin analysis software? You can get the projectiles spin rate from the Doppler signal too if the projectile is modified suitably, or just wobbles. I managed to get the spin off a unmodified 5 mm (.20) airgun pellet, well slug, quite often.
http://www.infinition.com/site/index.php/us/products-us/10-ghz-en-us/br-29015-en-us
http://www.infinition.com/site/index.php/us/products-us/35-ghz-en-us/br-3503-en-us
It is great news that Barnes is doing actual drag measurements. Hopefully they will make the results available in a format that can be used by exterior ballistics programs (as Lapua did).
6DOF programs like PRODAS are nice, but they require many more bullet parameters than radar drag data. These can only be obtained in a spark range. A better service to the shooting community would be making the drag data available.
Real drag functions usually is better than cool pictures.
Didn’t Bryan Litz do this 3-4 years ago for 100’s of bullets. I don’t think he made the data available to the public, but it is in my Kestrel w/ Applied ballistics for sure. I heard the list is over 500 bullets now. Out here in west Texas we shoot long range all the time and the Kestrel AB is spot on to some ridiculous ranges, 2000+ meters super rare to have more than 1 Moa vertical dispersion w/ horizontal being on me and my wind calling ability. Does Barnes even have any Aerospace Enginners or qualified ballisticians. Hopefully so, all the fancy pictures and cool high tech gear is useless unless you. Know how to use it and then analyze what it is telling you. Looking forward to giving there data a try at long range. One more thing not saying there bullets are bricks, but you can build a trajectory for a flying brick, that doesn’t make it any better of a bullet just because you can predict it.
Just opened up one of Bryan Litz books, this article reads nearly verbatim from his book, even the graphs look super similar. I am just a Texas cow punching cowboy but that would get you shot here. If you are going to be bragging and talking up how something is all that, you need to at least be original or give some credit where it is do at minimum. That kind of behavior makes me question a lot of things about this article. Don’t know if things are different for the folks out east, but when you catch a guy branding over yours, he is a no good skunk! And nothing he says after that is worth a plug nickel.
They didn’t say no one had ever done this before ! They are gathering the data for themselves and are going to use it in their manuals ! Then it will be available to the the public. In that form. If they were branding over they would have just stole litz’s data ! And maybe they are the first to use dual Doppler radar for data to be used in a published loading manual