Question for Gene Beggs--WakeTurbulence

R

ron collins

Guest
This question is about a post that Gene Begs had about shooting in dead calm conditions. He said WakeTurbulence may be one answer for the reason bullet POI is so erratick when the flags go dead. If this is so, does he see this condition in his wind tunnel? I would like to bring this topic back to the board. I have been in shoots where this has happened and my gun either goes completly out of tune or whatever is on the field is kicking butt. Can anyone shed some more light on this.
Gene does this happen in your tunnel? There is no wind to move this affect , does the vortex of the bullet stay there.
Do you have any info on this. Would you suggest
lowering the powder charge, go up, or if a tuner might help this.
 
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I don't know about Gene but I have heard from other folks with indoor ranges that this seems to be a real phenomenon.

A good friend of mine used to be a ballistician with Barnes Bullets and told me of the headaches in their underground 300 meter tunnel with still air, pushed air, and drawn air. They finally decided the drawn air method "sucked" out the previous bullet's turbulence best.

I related a story to him of a match I shot in back in October of 2008. We had steady 3 mph wind over the entire 200 yard course with mid 70 degree temps. My gun was really in tune and I was getting .3's and .4's quite consistently at 200 yards. In match#4, I shot a .191" which was a new range record. Then, in the last match, the conditions went dead calm. So calm that the dust kicked up off the burm behind the target frame didn't go up or down. It just hung there. It didn't even dissipate. The cloud of dust soon obscured the target frames and many people couldn't see where they were shooting! I was lucky enough to be able to see through it and my neighbor and I began our groups. The load and gun that had just shot a .191" minutes earlier now couldn't even get two bullets to touch! My target came back a .8" something and my neighbors was a .7" something. The only explanation for this was wake turbulence because the mirage was not strong enough to cause more than a half inch error in aim.

Then last week, I setup a video camera at about 95 yards and taped myself shooting flies off the 100 yard target frame. Upon reviewing the film, I noticed that there were several flies that I thought I drilled square but in reality, my bullet was off the mark maybe a bullet's width yet the fly still died. The only explanation I can come up with is that the bullet's wake of disrupted air must have still had enough force to partially splat a fly. Very interesting.

Good thread!:)
 
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Not sure about the vortex but as far as flies dying, the breaking of the sound barrier or sonic boom created by a bullet while very small in comparison is like the concussion from explosions in many ways. The concussion can kill people quite aways from the actual blast so it would be likely that it is the same.
Now maybe the vortex and and the sonic is the same, that I do not know.

I wonder if still air works like water.
They say the sound of the wake of a ship is detectable long after the ship has passed and the waters look normal on the surface.
 
ron collins said:
This question is about a post that Gene Beggs had about shooting in dead calm conditions. He said WakeTurbulence may be one answer for the reason bullet POI is so erratick when the flags go dead. If this is so, does he see this condition in his wind tunnel? I would like to bring this topic back to the board. I have been in shoots where this has happened and my gun either goes completly out of tune or whatever is on the field is kicking butt. Can anyone shed some more light on this.
Gene does this happen in your tunnel? There is no wind to move this affect , does the vortex of the bullet stay there.
Do you have any info on this. Would you suggest
lowering the powder charge, go up, or if a tuner might help this.
Click to expand...



Ron, I believe vortices created by preceeding bullets are responsible for some of the fliers we get when shooting in still air. And yes; this does happen in my tunnel.

I discussed this theory with Bryan Litz, the chief ballistician for J-4/Berger Bullets. Bryan says the wake turbulence behind a bullet is not the same as that created by the wingtips of an aircraft because a bullet does not create lift. This fact notwithstanding, I still believe there are significant air disturbances that rotate in place for quite some time in still air after a bullet passes at around mach 2.7. I think the disturbance is probably somewhat like smoke rings and rotate in place for quite some time.

So what is the answer; what can we do about it? Well,, in the tunnel, we can exchange the air by turning the exhaust fan on high and open the air inlets. We can also slow the cadence of the shots. When shooting outdoors in calm conditions the only thing I know you can do is wait longer between shots and try to avoid 'doubling' with your neighbor.

I would not recommend changing the load in calm conditions. I don't believe what we are experiencing has anything to do with tune.


Gene Beggs
 
Gene

Have you every tried a smoke bomb or other source of smoke in the tunnel?
It could give you a visual like you said "smoke rings".
You could try small amounts of smoke in specific placements maybe in diff colors.

Of course you would have to use a rail gun with good return.
But you could try various rates of fire and the smoke could give you some indication as to what is happening to the air.
 
I think there may be more:

I think mirage is also a factor, albeit very subtle. I just fiished recounting to my traveling companion a match I shot in in which there were no conditions visable and what happened.

I shot my last five record shots in the absolute calm. I noticed that some of the shooters who shoot at that range regularly waited; sat there and just waited.

The second the flags just moved slightly they began to shoot. The end result was the two other shooters who were tied with me got exes and I didn't get any. I think the mirage shifted just enough with the flags to allow those guys an honest view of the target and I was shooting through a thin waterfall , if you will. The tails did not move at all during this entire match.

Heat rises, eh? Along with the heat is moisture, eh? Air movement moves the mirage, eh? I don't think this situation is unique to any particular range.

Patience and experience but most of all, memory; being able to remember why one wasn't successful in a particular condition inthe past. I have come to believe that the shooter with the best memory among a group of experienced shooters is the one who will win.
 
Gene Beggs said:
Bryan says the wake turbulence behind a bullet is not the same as that created by the wingtips of an aircraft because a bullet does not create lift. This fact notwithstanding, I still believe there are significant air disturbances that rotate in place for quite some time in still air after a bullet passes at around mach 2.7. I think the disturbance is probably somewhat like smoke rings and rotate in place for quite some time.
Gene Beggs
Click to expand...

Gene,

I'm curious if Bryan agreed with this theory?

This year at the Cactus, I was over on the east end of the range practicing on Friday morning. It was a very calm morning (the calm before the storm?) and the sun was just starting to shine in on us over the east burm. Down a couple of benches from me to the east was Don Nieslon who was also doing some shooting. At one point, with the sunshine behind him, Don fired several shots that I wish I would have had on video. Right from his muzzle came off a smoke ring about 2 feet in diameter and it shot right out from his muzzle about 10 feet. Then it would hang there in mid-air and spin for a couple seconds before dissipating. It looked just like that old smoke ring toy gun that they used to make. It made me wonder if he were to shoot another shot through the ring, or if a neighbor shot through the edge of the ring, what would the effect be on the target?

This phenomenon would be similar but distinctly different than a bullet's path wake yet could have similar results for a bullet fired next to, or along the same path.

As an ultra long range shooter too, I have seen the bullet's path of compressed or evaporated air commonly called the "vapor trail" be very large over the entire long trajectory of a given bullet. Sometimes, especially with heavy bullets in the .338 caliber, the diameter of the vapor trail looks like the size of a grapefruit or watermelon. With that kind of disruption in front and around the bullet, one would think that would have to have an affect on bullets fired near that same trajectory soon afterwards?
 
This reminds me of that thread on the effect of the weight of column of air in the barrel on the bullets flight. The mass of air set in motion by muzzle blast and bullet motion is certainly visible and lasts for a few seconds. However the weight or mass of that air is just not sufficient to keep it moving for more than seconds and having any significant effect on the bullet that follows it if more than just a few seconds elapse between shots. I would look for some other cause for erratic bullet flight rather than that "turbulent" air or "vortex", or even the smoke or vapor, left behind by the preceding bullet.
 
Vern said:
Have you every tried a smoke bomb or other source of smoke in the tunnel?
It could give you a visual like you said "smoke rings".
You could try small amounts of smoke in specific placements maybe in diff colors.

Of course you would have to use a rail gun with good return.
But you could try various rates of fire and the smoke could give you some indication as to what is happening to the air.
Click to expand...


Vern, I have not tried smoke in the tunnel but that's a good idea. Might reveal some real surprises.

Gene Beggs
 
Gene:

Hi Gene.

best make sure the barrels used are 18 yrs. old or older. Might get busted for selling to a minor:eek::D:D

Jeff
 
I have spent a few hours looking thru the scope on my rail gun, when
the flags are dead. It may be a mirage, but has no direction, it just
wanders . I'm sure its all optical
 
Pacecil, I made a big mistake,,

pacecil said:
This reminds me of that thread on the effect of the weight of column of air in the barrel on the bullets flight. The mass of air set in motion by muzzle blast and bullet motion is certainly visible and lasts for a few seconds. However the weight or mass of that air is just not sufficient to keep it moving for more than seconds and having any significant effect on the bullet that follows it if more than just a few seconds elapse between shots. I would look for some other cause for erratic bullet flight rather than that "turbulent" air or "vortex", or even the smoke or vapor, left behind by the preceding bullet.
Click to expand...


Yes sir,, I made a big mistake by referring to the 'column of air in the barrel' when I set out to explain how air density affects tune. Everybody got locked in on the miniscule weight of the air in the barrel and lost sight of the big picture and that is the ocean of air that surrounds us. :rolleyes: Okay, let's forget about the column of air in the barrel and confine our discussion to air density. Pacecil, I got a question for you. :)

Can we both agree that air molecules are more densely packed at sea level than at the NRA Whittington Center in Raton New Mexico where elevation is around 6000 msl? If we can agree on that, maybe I can get it across to you and everyone else what I'm talking about. How 'bout it?

Gene Beggs
 
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Everest

Gene I think you are absolutely correct and why not use the big boy for even better proof.
You even have to use bottled O to breath up there,,, because there are not enough air molecules:D
 
goodgrouper said:
Right from his muzzle came off a smoke ring about 2 feet in diameter and it shot right out from his muzzle about 10 feet. Then it would hang there in mid-air and spin for a couple seconds before dissipating. It looked just like that old smoke ring toy gun that they used to
make. It made me wonder if he were to shoot another shot through the ring, or if a neighbor shot through the edge of the ring, what would the effect be on the target?
Click to expand...
pacecil said:
This reminds me of that thread on the effect of the weight of column of air in the barrel on the bullets flight. The mass of air set in motion by muzzle blast and bullet motion is certainly visible and lasts for a few seconds. However the weight or mass of that air is just not sufficient to keep it moving for more than seconds and having any significant effect on the bullet that follows it if more than just a few seconds elapse between shots. I would look for some other cause for erratic bullet flight rather than that "turbulent" air or "vortex", or even the smoke or vapor, left behind by the preceding bullet.
Click to expand...
Pacecil - I used to have one of those vortex gun toys from way back when. We used to set up a house of cards across the 30' wide room and shoot the "smoke ring" at the cards. Well usually the ring would shed the "smoke" in 10' or 12' and everything would "look clear" - then about a full 60 seconds later the house of cards would implode as the remaining vortex "plowed" into it.
Point being that those toys had less power than even a 22 rimfire, but the effects hung around for minutes, not merely a "few" seconds.
 
Vibe said:
Pacecil - I used to have one of those vortex gun toys from way back when. We used to set up a house of cards across the 30' wide room and shoot the "smoke ring" at the cards. Well usually the ring would shed the "smoke" in 10' or 12' and everything would "look clear" - then about a full 60 seconds later the house of cards would implode as the remaining vortex "plowed" into it.
Point being that those toys had less power than even a 22 rimfire, but the effects hung around for minutes, not merely a "few" seconds.
Click to expand...



Thank you, thank you, thank you! ;) :D


Gene Beggs
 
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