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91
Ballistics / Re: Vertical Deflection due to a Crosswind aka Aerodynamic Jump
« Last post by admin on April 30, 2014, 07:29:53 PM »
The problem with these matters is that assumptions are made "e.g bullet flies in the direction of the wind" and presented as facts.

Even they are somewhere along the trajectory true, there is a period they are not valid. What happens then.

Nevertheless, I have time to spare I will read better the article.

Robert
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Ballistics / Re: Vertical Deflection due to a Crosswind aka Aerodynamic Jump
« Last post by mman on April 24, 2014, 06:26:41 AM »
I just finished reading the article for the first time. I have to read it again and compare with other books to come to any conclusion. Basis of the crosswind vertical drift seems to be bit different from what I have red before. Still this article doesn't give tools to solve the actual drift like Litz does. Not taking position at this point if Litz's formula is accurate or not. However the article states to answer three questions.

A) The total bullet drift in a crosswind blowing from left to right is toward 4 o’clock.
This is obvious and explained by other references like McCoy and Litz. Article still gives good input on this one.

B) As the crosswind speed increases, the vertical drift of the bullet does not increase as rapidly as the crossrange drift.
I didn't catch the explanation for this one at all. Did someone else? I still wonder if this is even true...

C) Crosswind blowing from right to left produces a little more vertical drift than a crosswind blowing from left to right.
Author doesn't explain this at all. Just couple of guesses. Same thing goes for this one; I don't know if it is true or not.

All in all those crosswind vertical drifts are so small compared to other deflections that it is really hard to achieve hard facts empirically. Some target shooters tend to jump into conclusions too easily based on what they see on the target. For example very small vertical wind components could lead to conclusions like B and C.
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Ballistics / Vertical Deflection due to a Crosswind aka Aerodynamic Jump
« Last post by 375CT on April 13, 2014, 07:34:30 PM »
Hi there,

Just finished to read this paper by Mr. MacDonald (Sierra's ballistician) and it makes a lot of sense to me, indeed the formulation presented is much better than the usual "formula" by Mr. Litz (based on a curve fit and Sg)

Please check it out here

http://www.exteriorballistics.com/ebexplained/articles/article2.pdf

What do you think? ;)
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Member projects / Re: Ballistic_XLR a modification of the Jackson Rifles Workbook by Meccastreisand
« Last post by meccastreisand on March 17, 2014, 01:26:29 AM »
since it's you looking here's some useful info about how it works:

Ballistics Table 0 is the master calculation worksheet.
Ballistics Table <temp>_29 are for barometric pressure -1"hg calcs
Pocket PC input is the master input worksheet.
Everything else cascades down from there.
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Indeed, BfX does not work on a Mac.

In short I will have a look at your work!
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Member projects / Re: Ballistic_XLR a modification of the Jackson Rifles Workbook by Meccastreisand
« Last post by meccastreisand on March 16, 2014, 06:32:01 PM »
My latest version should have a full set of features for everyone in it but has a couple bits that I think will really affect you guys in a positive way. I've been scanning the BfX forum for things people were wanting and adding those features I didn't already have solved. I did try out the BfX add in and haven't been able to make big wads of it work on my Mac so my spreadsheet does not utilize BfX_xll, just standard Excel features. DO NOT try to open it with OpenOffice or variants thereof. It won't work and you'll call me names while you frustratedly cast about for a way to make it work.

Of particular value are the brand new Primary and Secondary functions tabs and the new Calc Form. With those 3 bits you can calculate proper solutions for highly complex shooting situations including shooting through different atmospheric condition zones, muzzle velocity variations induced by just about anything, predicting MVV based on weather and all sorts of similar things that complicate traditional ballistics solution calculation. The download link above still works.
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Member projects / Re: Ballistic_XLR a modification of the Jackson Rifles Workbook by Meccastreisand
« Last post by meccastreisand on March 15, 2014, 05:16:27 PM »
Guys, I'm looking to add additional features to the thing. Any suggestions?

svorog: glad that worked for you. If you need any support please ping me on Twitter @Ballistic_XLR .

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Member projects / Re: Ballistic_XLR a modification of the Jackson Rifles Workbook by Meccastreisand
« Last post by meccastreisand on March 08, 2014, 06:24:20 PM »
Hey chaps, I haven't been back here in a while. Sorry, been very very busy.

In any case there's a completely new version posted. 1.45.19 which simplifies and condenses the prior version. https://drive.google.com/folderview?id=0B2_BBw2VMf2-VUJZNXVTM0M1akE&usp=sharing is still the download link. You should watch my videos http://www.youtube.com/channel/UCSvqgqVNtzcLFuQkGxh-Egg as well for complete instructions.

If you put in correct data it should spit out correct solutions but you need to know how to integrate all the numbers and in which order. the new version makes this a lot simpler. You should probably at least glance at TiborasaurusRex's Sniper 101 videos too since I made the thing with his table designs and calc form designs.

http://www.youtube.com/user/TiborasaurusRex

If you experienced a bug in a prior version, please try this one and send me a message here or on Youtube or on Twitter (@Ballistic_XLR) and I'll get them dealt with.

The 1.45 branch is a massive upgrade and fixed all the bugs I'd found to date as well as introducing the most advanced version yet. Still free.
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Ballistics / Re: Spin Drift
« Last post by 375CT on March 06, 2014, 03:25:40 AM »
Mman & Richard,

Thanks for the feedback. Well put, next to impossible, unless done in a wind tunnet I guess.

The problem with PRODAS is, it's another approximation, yet sophisticated but not quite the "real" thing as far as I've been told so far.

Like you guys said, it's very easy to get SD lost in the background noise. >:(

For what it's worth, at least for the record, Litz's formula is surprisingly the same as the one published early bu a guy on the LRH forum...and nobody gave him the credit!
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Ballistics / Re: Spin Drift
« Last post by admin on March 03, 2014, 08:16:21 PM »
mman has a 1000m+ range in his backyard! Shall we  ask him?

The problem, of course, is to do the measurements.

In those measurements one has to vary some quantities that affect spin drift and other factors that affect horizontal displacement. Then there is wind and measurement errors. To single out to spin-drift effects one must trust the proper computation of all other effects that deflects the bullet. I would guess that only a professional organisation is able to do the measurements.

As far as I know, the US Army is the only institution that published measurements.

Brian did the best next thing. He used a proffesional 6DOF ballistic program - PRODAS - and fitted the spin drift of bullets.
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