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Vertical component of wind drift

 
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  #22  
Old 04-11-2003, 09:45 AM
MAX MAX is offline
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Re: Vertical component of wind drift

My nonexpert understanding of Robert McCoy's dissertation on the subject: For the .30 Ball at 2800 fps--.5"/10 mph rangewind at 600 yards. A minor concern I'd think.

I may not understand what he meant but my understanding is that he attributes vertical effect of crosswind to projectile jump, which I think is a result of gyroscopic precession as S1 said. I've had my head in the Rinker/Vaugh/McCoy trough for the last couple of months and I'll propably be catatonic and drooling anytime now. [img]images/icons/rolleyes.gif[/img] And all I wanted when I showed up here was to learn about long range shooting. [img]images/icons/grin.gif[/img]

Does anybody know how data is deduced or reduced from spark shadowgraph photos? I see no reference points.
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  #23  
Old 04-11-2003, 07:13 PM
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Re: Vertical component of wind drift

Max, what you saying McCoy suggests?

1/2" of what? Vertical Drift, or Wind drift.
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  #24  
Old 04-11-2003, 08:20 PM
MAX MAX is offline
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Re: Vertical component of wind drift

Vertical movement due to effects of head or tail wind(rangewind). .5" for that package at 600 yds. per 10 mph of wind. I understand only that he attributes vertical movement due to crosswind to projectile jump---I think. His stuff is a bit deep, my mind a bit slow.
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  #25  
Old 04-13-2003, 07:54 AM
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Re: Vertical component of wind drift

4mesh,

I finally had the time to read this thoroughly...not sure I understand everything you're saying. Your wiffle ball analogy is not relevant to this issue. Round ball aerodynamics have different rules at different velocities and with different diameters. It has a lot to do with Reynolds Numbers. As I understand it, the large magnus effect that causes baseballs to curve disappears for the most part at firearm velocities, as an example. I do not fully understand all(maybe most) of the science of external ballistics but I do know this: Vaughn pretty much knows his stuff. If you want to cross reference his "facts" try "Modern Exterior Ballistics" by Robert McCoy. Another fellow that knows his stuff. Oh by the way, get a scientific calculator if you want to follow the bouncing ball. It is "advanced", the $90 +/- pricetag a bargain. Luck to you.
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  #26  
Old 04-13-2003, 08:49 AM
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Re: Vertical component of wind drift

Brent...

The problem with that (top) picture is...
... in reality, the center of gravity in a match bullet is towards the rear of the bullet, and the center of aerodynimic drag (center of pressure) is in FRONT of the center of gravity... so if side air pressure were to be responsible for turning (it isn't), the bullet would turn left, instead of right (as shown in the drawing).

CatShooter.

[ 04-13-2003: Message edited by: CatShooter ]
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  #27  
Old 04-13-2003, 06:58 PM
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Re: Vertical component of wind drift

Cat,

I think you will find that the longitudinal balance point has little to do with the eventual line of drag as we are thinking of the air creating the drag and really it is the bullet that makes it's own. This is a crazy deal.

Max and S1.

OK. I said that I WOULD test this and attempt to rethink the idea if I could "See" something that would make me beleive I should entertain any other possibilities. Well, I have seen results that incline me to say that you and your cohorts are absolutely correct on the bullet flying to it's destination instead of being sent there.

I stand corrected.

Since the onset of this thread I have known that there is a tremendous difference between airodynamics and hydrodynamics, Air, Liquid and Solid physics. I simply could not see with my limited education on the subjects how the common sense physics do not apply. I tried to see it, but, till I got hit with it, it was foggy. Well, the main thing that Vaughn never points out that I did know ahead of time was that a wiffle ball travels through air and a bullet does not. Air, above the speed of sound is a solid. Or, at least it's dynamics for flight are treated as such. I think that Vaughn's statement of how fast the bullet turns into the wind is incorrect but that He most likely never expected anyone to care enough to actually test the theory while the bullet is still in the supersonic muzzle blast. You can affect the hell out of it shortly therafter.

Now, this afternoon I had the opportunity to test this at 1024 Yards, twice, and video'ed the effects. (actually the cause).

It's a most interesting discovery.

The most disheartening part of all this is that after all this ******* around, I still aimed 36" left and 10" high in order to center and was DEAD down the middle of the target. Now, If I could just fix my 20% issues, My infinite knoledge of this 1% issue might help me to win but I have many other problems to solve first and they cause me a lot bigger problem at this point.

No doubt, at some point very near in the future, my newfound understanding of this may come in handy. For now, wind blows my group all over hell and my gun problems compound this to where it's overwhelming. I cannot beleive that I have a gun that shoots as good as mine does, and have a gun that shoots as bad as it does.

I hope someone else gets something out of all this cause I have finger fatigue.
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  #28  
Old 04-13-2003, 07:34 PM
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Re: Vertical component of wind drift

[img]images/icons/confused.gif[/img] [img]images/icons/confused.gif[/img] [img]images/icons/wink.gif[/img]
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