Question for Gene Beggs--WakeTurbulence

Vibe, You've brought up something very interesting! The Vortex gun presents a really good illustration of what is happening here. It made me go and do a little "testing" rather than rely on science - and my gut feeling.

What I found using an air compressor and a nozzle was that I could in truth start air motion that would have effect several seconds later on a object 30' away. There was no way I could get it to have an effect 60 seconds later but I could get up to 8 seconds. That effect amounts to air moving about 1 mph at the 4 second point, so there could be effect on bullet flight if you get the second shot in within this time limit.

If I increased air pressure to simulate a gun firing then the effect would reach the object quicker and probably would travel farther. I suspect with the driving force you get out of a gun barrel, or a vortex cannon, you might have a blast of air that reaches the target by the time you fire the second shot.

I tried bouncing the air movement off walls, floor, and ceiling such as inside a tunnel and could never see maintenance of any significant air velocity. In fact I could never hold any velocity of air in the vicinity of where the second bullet might be traveling a few seconds after the first.

I tried swirling air around in a circular restriction to simulate turbulence and found I could maintain the circular motion for only about 1 or 2 seconds. I was using a path about a foot in diameter but I'm pretty sure if the swirls were less, say 2-3 inches then the mass of air would be less and the motion wouldn't last as long.

All things considered I still think you could only see air motion caused by the first bullet as having effect on the second one only if you fired at an interval of just a few seconds.
 
Harold Vaughn made a vortex board to show this effect. Although Harold doesn't get much credence here because "what did he ever win?" he was a bright guy.

al
 
Gene

In regard to the Vortex gun theory, Your tunnel try this. Set candles down range at varying yards like 20,40,60 and so.
Then shoot over them and see what happens and at what times if anything happens. We would be very interested in the results. If the Vortex gun theroy is correct, we should see a movement in the flames on the candles, This could be a major break thru in the mystery of The Calm.
 
I think it's pretty evident that these vortices are real and can be produced with much less force than what our guns are capable of. The vortex ring I saw come off Don's barrel in the early morning calm looked identical to these videos and it hung around just about as long. WIth the sun behind it, I could plainly see it and it was a darker gray color.

And the video link posted of the two vortices colliding was especially enlightening. Can you imagine 30 guys firing 5 to 10 bullets in the space of 7 minutes how many vortices are going to be produced and how likely it will be that any one bullet will pass through one of those vortices?

If this were an optical phenomenon, rail guns would be immune to it because they return to the same point of aim regardless of distortion of the target due to mirage. But, they are not immune. They suffer the same wild fliers in calm conditions because this is a physical, exterior ballistic phenomenon.

Makes a guy want to wait until the last 25 seconds to fire his group to see if by chance a little breeze will pick up and give him a chance to shoot!
 
pacecil said:
All things considered I still think you could only see air motion caused by the first bullet as having effect on the second one only if you fired at an interval of just a few seconds.
Click to expand...
LOL. I have to laugh. You do "testing", using completely non-analogous, methods and then tell me that there is no way that I could have seen what was clearly apparent, even to children. And we still read your posts? :D
 
I'm with vibe here...


I've fiddled with these "vortex guns" some. Used to make them from Quaker Oats cartons, then larger pistons, now my kids have several called Airzooka's > http://www.airzookatoys.com/ < which work quite well to ruffle hair or knock over cups across the room........ I think the operative principle dictates that the higher the rotational velocity of the ring itself, the longer it will last and typically the slower it will traverse a room. In other words you gotta' POP the ring, vet it spinning rapidly. It doesn't necessarily travel very fast at all.

In this light, I have to agree, rings or blasts made with an air compressor in no way relate to the high-speed vortexes in question. The passage of a 3000fps bullet through still air creates ring-like whirlies completely unlike those from a compressor.

pacecil, here is where you go astray :)

Your statement "If I increased air pressure to simulate a gun firing then the effect would reach the object quicker and probably would travel farther." indicates a poor understanding. In fact the FASTER the passage of the driving pop of air, the SLOWER the ring actually travels. When we made air cannons we didn't use a compressor, we used a drum. Picture this, you cut a hole in the middle of a drum head and then whack the opposing side quickly, it's the quickly that gets 'er done......... quickly means the vortex forms very solidly and strongly yet due to inertial effects actually travels through the air slowly. A good vortex will indeed last 15-20 seconds from a pretty small pop. I've Airzooka'd people, SET THE GUN DOWN and resumed conversation before the vortex swept their empty styrofoam cup off the table or popped the word leaving their lips.

al
 
This is exactly why...................

small civil aircraft are cautioned not to cross the wake of a jetliner for some time after its passage. Gene, if you want to see a very significant demonstration of this, take a .17 Remington and fire it downrange on a calm day, even in your tunnel, and hold position after discharge, the amazing sights are such that I've never witnessed after firing a .22 or 6MM centerfire. When you think about it, the bullet becomes a segmented, toothed wheel spinning downrange, pushing the air out of the way as a result of its passage, and "gripping it to assist in the movement of the air in creating its vortex.
 
goodgrouper said:
Gene, I'm curious if Bryan agreed with this theory?
Goodrouper,

Yes, Bryan Litz is probably the ONLY one who agrees with me on this and understands what I'm trying to say. I understand it perfectly; it's as simple as night and day but I'm having trouble getting it across to others.

I wish I was a better writer; my choice of words has caused a lot of confusion. Instead of the word "Drag" I should have used "Resistance" when referring to the force the bullet experiences as it accelerates down the bore. Oh well. :rolleyes:

Gene Beggs
Click to expand...
Click to expand...
 
It would seem reasonable to me that there is some relationship between the diameter of he vortex and the size of the object or jet of high speed air producing it. It may be that in calm conditions, that our bench spacing affords us some protection from vortexes produced at adjacent benches, and that there is an issue of timing where if a bullet leaves before or after the adjacent shot that the force has sufficiently dispersed to no longer be a factor. If one is concerned about ones own vortexes, under perfectly calm conditions it would seem that you would be shooting through the hole in the doughnut, and that where there is a breeze it would be rapidly disbursed. Also, is this phenomenon distinct from the initial shock wave produced when a rifle is fired, that gives rise to concerns about doubling? What effects have you seen, at the target that you might attribute to the interaction of vortexes and bullets? In short, is this a real problem, or just an interesting phenomenon?
 
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.
Gene Beggs
Click to expand...

attachment.php


Bryan is correct. The turbulent vortices in the wake of a bullet are energetic, but are small (smaller than the bullet itself), and break up into even smaller vortices rotating in random directions. You can seem them in the image above (the specks trailing the ball). The wake also spreads out, but by doing so, loses its velocity and energy density, and its ability to influence the motion of any subsequent bullets. Bullets do not create ring vortices.

On the other hand, the jet of combustion gases that exits the muzzle after the bullet passes can create a ring vortex. I've seen it at the range in humid conditions. This jet is analogous to a shot of air from an air hose, though obviously at much higher velocity.

Cheers,
Keith
 

Attachments

  • shock10.gif
    shock10.gif
    185.9 KB · Views: 419
mks said:
attachment.php


Bryan is correct. The turbulent vortices in the wake of a bullet are energetic, but are small (smaller than the bullet itself), and break up into even smaller vortices rotating in random directions. You can seem them in the image above (the specks trailing the ball). The wake also spreads out, but by doing so, loses its velocity and energy density, and its ability to influence the motion of any subsequent bullets. Bullets do not create ring vortices.

On the other hand, the jet of combustion gases that exits the muzzle after the bullet passes can create a ring vortex. I've seen it at the range in humid conditions. This jet is analogous to a shot of air from an air hose, though obviously at much higher velocity.

Cheers,
Keith
Click to expand...

A round ball will produce different shock waves than bullets.;) That being said, as a wake spreads out and dissipates, it obviously loses its energy and it's ability to influence bullets. But how much is needed to cause a bullet to deflect? What's the cut off point? And wouldn't the supersonic shockwave also have influence? And if the only vortex is being produced is the one from the gases leaving the muzzle, wouldn't it stand to reason that this would also be affecting the nearby bullets and to a greater degree on target since the bullet would have more time of flight off in that imparted direction?
 
Last edited:
goodgrouper said:
A round ball will produce different shock waves than bullets.;) That being said, as a wake spreads out and dissipates, it obviously loses its energy and it's ability to influence bullets. But how much is needed to cause a bullet to deflect? What's the cut off point? And wouldn't the supersonic shockwave also have influence? And if the only vortex is being produced is the one from the gases leaving the muzzle, wouldn't it stand to reason that this would also be affecting the nearby bullets and to a greater degree on target since the bullet would have more time of flight off in that imparted direction?
Click to expand...

I just picked the round ball picture because it had a better image of the turbulent wake. ;)

The shock waves of round balls and pointed bullets look different near the bullet that created them, but have the same character several feet away, where it might influence another bullet. The pressure difference across a shock wave can be large, so it is easy to believe that it could deflect another bullet. But remember that shock waves travel with (or more accurately, emanate from) the bullet, so for the wave to have an effect, the second bullet would have to be shot after the first and travel at the same speed and, therefore, stay in the wave, or be shot later and travel at a higher speed and, therefore, pass through the wave to be influenced. Shock waves travel at the speed of sound, and so don't hang around long.

I have had flyers happen when I doubled with a neighboring bench, but since I put some shoulder into my 30BR, I can't honestly say whether they happened because of an aerodynamic effect, or because the blasts startled me. But free recoil shooters also see flyers, so the shock wave may be the cause.

The point I didn't make too well about the turbulent wake is that all those little vortices are moving in random directions, so another bullet traveling through the wake would experience small pushes in different directions that don't effect its overall trajectory. Sort of like flying through turbulence - it's a rough ride, but you emerge still going in the same direction.

A large coherent vortex, on the other hand, pushes in a consistent direction. It seems plausible that a bullet passing through a ring vortex from the muzzle of another rifle could cause some deflection. As you recognized, the effect would happen close to the bench, so if the bullet were deflected by a small angle, the effect at the target could be significant.

Cheers,
Keith
 
mks said:
doubling



...............But remember that shock waves travel with (or more accurately, emanate from) the bullet, so for the wave to have an effect, the second bullet would have to be shot after the first and travel at the same speed and, therefore, stay in the wave, or be shot later and travel at a higher speed and, therefore, pass through the wave to be influenced.........

..........have had flyers happen when I doubled with a neighboring bench,


Cheers,
Keith
Click to expand...

This is why I love this forum! :)

I had never even considered that this may be a rational explanation for "doubling."

interesting

to me :)

al
 
Remembering back

When I was around 10 years old, my father had a wildcat he called the 44x2". It was a 30-06 case cut off at the shoulder. The case looked like a rimless 444 Marlin, and headspaced off the case mouth. His load out of a bolt action was 48gr. of 2400 behind a 250gr bullet for 3000fps.

Dad and I had gone on a walk hunt. We spotted a small buck down in a draw. I was below dad on a ledge when he touched off a shot. The top of my head was about even with dad's feet, and a couple of feet in front. I remember the force of the blast feeling like a sack of potatoes being dropped on my shoulders.

I have no doubt that this force from a neighboring bench would change the path of a bullet, either by hitting the side of a bullet that has just exited the muzzle, or by changing the point of aim, if the bullet was still in the barrel.

Michael
 
I hope

mturner said:
When I was around 10 years old, my father had a wildcat he called the 44x2". It was a 30-06 case cut off at the shoulder. The case looked like a rimless 444 Marlin, and headspaced off the case mouth. His load out of a bolt action was 48gr. of 2400 behind a 250gr bullet for 3000fps.

Dad and I had gone on a walk hunt. We spotted a small buck down in a draw. I was below dad on a ledge when he touched off a shot. The top of my head was about even with dad's feet, and a couple of feet in front. I remember the force of the blast feeling like a sack of potatoes being dropped on my shoulders.

I have no doubt that this force from a neighboring bench would change the path of a bullet, either by hitting the side of a bullet that has just exited the muzzle, or by changing the point of aim, if the bullet was still in the barrel.

Michael
Click to expand...

We can accept some of this antidotal evidence. This one seems to me a great one to explain what many of us see and feel; could explain the "Doubeling" situation more than the concussion behind the muzzle.

Pete
 
Last edited:
Pete

Just another Thought.

When the bullet first exits the muzzle, the pressure of the expanding gases is still somewhere between 5000 to 10000 psi. A large amount of those gases turn 90 degrees since the base of the bullet forces the gases to make this turn. This would make it seem to me that boat-tail bullets would generate less concussion to each side than flat base bullets. In the case of doubling, the guy shooting boat-tail bullets (at short ranges) could actually be aiding his neighboring shooters more than himself.

Michael
 
You must log in or register to reply here.
Back
Top