http://www.precisionworkbench.com/
this prog can do it, so anyone know the math? to toss in a excel?
this prog can do it, so anyone know the math? to toss in a excel?
Range Report calculating MV and BC from drop?..anyone know how?
- Thread starter Ring
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Re: calculating MV and BC from drop?..anyone know how?
No, not possible to calculate both. Need to know one or the other to calculate the other from drop.
No, not possible to calculate both. Need to know one or the other to calculate the other from drop.
Re: calculating MV and BC from drop?..anyone know how?
I'm new to this, so others please correct me if the following is in error.
Your best source for BC is Brian Litz's book, see:
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2475570&gonew=1#UNREAD
Assuming you have good data for all the other variables (temp, atmospheric pressure, humidity, etc.), you can then try different MV's in a ballistics program (JBM Ballistics is free to use on the web) to see if you can match the actual drops you saw at multiple distances.
The other alternative is to measure your MV using a coronograph.
This is not an error free process as there are errors/variability inherent in your drops, MV and BC. The idea is get "close enough" for your purposes.
I'm new to this, so others please correct me if the following is in error.
Your best source for BC is Brian Litz's book, see:
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2475570&gonew=1#UNREAD
Assuming you have good data for all the other variables (temp, atmospheric pressure, humidity, etc.), you can then try different MV's in a ballistics program (JBM Ballistics is free to use on the web) to see if you can match the actual drops you saw at multiple distances.
The other alternative is to measure your MV using a coronograph.
This is not an error free process as there are errors/variability inherent in your drops, MV and BC. The idea is get "close enough" for your purposes.
Re: calculating MV and BC from drop?..anyone know how?
It isn't recommended to derive BC's from drop. There are too many variables involved to obtain accurate measurements. There are ways and programs to make it happen but as with any experiment, the least amount of variables introduced the better. Knights Armament Bullet Flight program has a utility to compute BC from both muzzle velocity as well as bullet drop. Not knowing muzzle velocity will severely limit the effectiveness of the utility. Some will say that you can obtain muzzle velocity based on observed bullet drop, but this only proves true if you have a ballistically calibrated reticle or you have a definite, no BS grasp on what your turrets are doing.
Best bet, spend the small amount of money on Mr. Litz's book an have all the best BC's you'll ever need.
It isn't recommended to derive BC's from drop. There are too many variables involved to obtain accurate measurements. There are ways and programs to make it happen but as with any experiment, the least amount of variables introduced the better. Knights Armament Bullet Flight program has a utility to compute BC from both muzzle velocity as well as bullet drop. Not knowing muzzle velocity will severely limit the effectiveness of the utility. Some will say that you can obtain muzzle velocity based on observed bullet drop, but this only proves true if you have a ballistically calibrated reticle or you have a definite, no BS grasp on what your turrets are doing.
Best bet, spend the small amount of money on Mr. Litz's book an have all the best BC's you'll ever need.
Re: calculating MV and BC from drop?..anyone know how?
Did anyone actually read the 15 words in the post? He's not asking if you can, he's asking if you know how to do the math.
I don't know the formulas for trajectory calculations, but I'd suspect they're systems of differential equations, which I don't think is possible to do in Excel. If you're looking for an easy algebraic formula for accurate trajectory calculations, it doesn't exist.
Did anyone actually read the 15 words in the post? He's not asking if you can, he's asking if you know how to do the math.
I don't know the formulas for trajectory calculations, but I'd suspect they're systems of differential equations, which I don't think is possible to do in Excel. If you're looking for an easy algebraic formula for accurate trajectory calculations, it doesn't exist.
D
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Re: calculating MV and BC from drop?..anyone know how?
As for the BC you can with a known range but you have to be a superstar shooter. Still have to have a math constant for velocity. As for Precisionworks they state to determine MV before you can determine BC.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The default DK [personalized trajectory] of 0.5 is a good place to start and many have found that it suffices for all but the most demanding work. If extreme accuracy at extreme ranges is required, however, the user should take the time to compute a custom DK. CAVEAT: Do NOT, DO NOT, DO NOT change the DK from its default value until 1) the scope has been calibrated, 2) the scope has been zeroed, 3) a muzzle velocity has been obtained and verified via the POI method, and 4) a ballistic coefficient has been calculated. If the shooter tries to use DK to get agreement between the actual and calculated trajectories using erroneous muzzle velocities and ballistic coefficients, the program will produce a distorted, inaccurate trajectory. The DK was not intended for this purpose and will yield completely unusable data. Don’t do it.</div></div>
You have one variable that is bullet drop. Every operation you perform on one side of an equation must be performed on both sides of the equals sign. In order to do that you need math constant(s). Example 3x = 2x + 1. What you want to know is BC = BD [operator] MV or MV = BD [operator] BC. In order to calculate MV and BC based bullet drop would never be precise because of the unknown variables. Really, it is no different than asking if you can calculate BC based on bullet drops at different ranges. You would have to be a perfect shot and relates to Precisioworks personalized trajectory (DK). Anyway, here is a treasure trove of formulas related to external ballistics. Please post a solution if you find one. Thanks.
http://www.jbmballistics.com/ballistics/downloads/downloads.shtml
EDIT: Also, Litz's book is nice. But people that recommend his book for questions like the OP are ignoring Litz himself or have not actually read the book.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Page 1: I felt there was a great need for a book that could explain the science of external ballistics to average shooters in layman's terms</div></div>
Litz repeats this philosophy throughout the book. So, instead of recommending an entire book for a simple formula question just properly quote Litz and the page number to help the OP understand that the formula is beyond a simple answer.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Page 25: If you measure: muzzle velocity, range to target, atmosphere, and have a known zero at some range, you can (in theory) determine the BC of the bullet based on bullet drop. As with many things, the simplest way stands to be the least accurate. <span style="font-weight: bold">The biggest problem with this approach is the rifle's ability to group precisely.</span></div></div>
The OPs other variable is MV. Litz's quote above is still relevant in regards to that variable as well since it is the other side of the formula being requested.
As for the BC you can with a known range but you have to be a superstar shooter. Still have to have a math constant for velocity. As for Precisionworks they state to determine MV before you can determine BC.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The default DK [personalized trajectory] of 0.5 is a good place to start and many have found that it suffices for all but the most demanding work. If extreme accuracy at extreme ranges is required, however, the user should take the time to compute a custom DK. CAVEAT: Do NOT, DO NOT, DO NOT change the DK from its default value until 1) the scope has been calibrated, 2) the scope has been zeroed, 3) a muzzle velocity has been obtained and verified via the POI method, and 4) a ballistic coefficient has been calculated. If the shooter tries to use DK to get agreement between the actual and calculated trajectories using erroneous muzzle velocities and ballistic coefficients, the program will produce a distorted, inaccurate trajectory. The DK was not intended for this purpose and will yield completely unusable data. Don’t do it.</div></div>
You have one variable that is bullet drop. Every operation you perform on one side of an equation must be performed on both sides of the equals sign. In order to do that you need math constant(s). Example 3x = 2x + 1. What you want to know is BC = BD [operator] MV or MV = BD [operator] BC. In order to calculate MV and BC based bullet drop would never be precise because of the unknown variables. Really, it is no different than asking if you can calculate BC based on bullet drops at different ranges. You would have to be a perfect shot and relates to Precisioworks personalized trajectory (DK). Anyway, here is a treasure trove of formulas related to external ballistics. Please post a solution if you find one. Thanks.
http://www.jbmballistics.com/ballistics/downloads/downloads.shtml
EDIT: Also, Litz's book is nice. But people that recommend his book for questions like the OP are ignoring Litz himself or have not actually read the book.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Page 1: I felt there was a great need for a book that could explain the science of external ballistics to average shooters in layman's terms</div></div>
Litz repeats this philosophy throughout the book. So, instead of recommending an entire book for a simple formula question just properly quote Litz and the page number to help the OP understand that the formula is beyond a simple answer.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Page 25: If you measure: muzzle velocity, range to target, atmosphere, and have a known zero at some range, you can (in theory) determine the BC of the bullet based on bullet drop. As with many things, the simplest way stands to be the least accurate. <span style="font-weight: bold">The biggest problem with this approach is the rifle's ability to group precisely.</span></div></div>
The OPs other variable is MV. Litz's quote above is still relevant in regards to that variable as well since it is the other side of the formula being requested.
Re: calculating MV and BC from drop?..anyone know how?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Ring</div><div class="ubbcode-body">http://www.precisionworkbench.com/
this prog can do it, so anyone know the math? to toss in a excel? </div></div>
There are 3 variables and 3 equations at play here. You really need to know two of the variables in order to solve for a third. Through iteration you could get a combination of MVs and BCs that would give you the drop you measured. However, they would only work for the range/distance at which they were developed; they could not be used at any other range.
That software only adjusts a DK value once you have a really good idea what the MV and BC are.
Check out Bryan Litz book for more details.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Ring</div><div class="ubbcode-body">http://www.precisionworkbench.com/
this prog can do it, so anyone know the math? to toss in a excel? </div></div>
There are 3 variables and 3 equations at play here. You really need to know two of the variables in order to solve for a third. Through iteration you could get a combination of MVs and BCs that would give you the drop you measured. However, they would only work for the range/distance at which they were developed; they could not be used at any other range.
That software only adjusts a DK value once you have a really good idea what the MV and BC are.
Check out Bryan Litz book for more details.
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