Frontal wind, veritical poi change

[foxx]

Yea, Therm, I really don't know. Fred thinks so. I have often thought so, to a point. My reasoning is it gets pushed up the way a Frisbee would when bucking the wind and angled upwards. Not sure if a bullet would. I think the wind pushes at, so it probably counters some gravity effects.

my brain hurts tinkingabout i

[earl39]

You can't compare a bullet to something with wings. The physics are not the same. One has wings. One travels really fast. I'll let you decide which does what.

[foxx]

You can't compare a bullet to something with wings. The physics are not the same. One has wings. One travels really fast. I'll let you decide which does what.

I'm guessing you are hinting that he bullet travels fast and is not affected the same way a wing is. :)

My next bet is the head wind still has an up/down affect on the bullet, but probably negligible.

Negligible, unless, of course, you're as good a shooter as I am! :) ;)

[Cat 64]

I was actually playing around with my scope calc earlier http://spoton.nikonsportoptics.com/spoton/spoton.html#Index:94 kinda fun to play with. So I fudged some data for you as simple example.
300 win mag, Fed 180 gr woodliegh weldcore sp, 3100 fps, 200 yrd zero, 1000 yrd target, dead 0 wind -356.64", head wind 10 mph -359.82, 20 mph -363.07", 30 mph -366.40, Tail wind 10mph -535.54, 20mph -350.5", 30 mph -347.52". Keep in mind this is just a calc and if you put the zero to 1000 yrd and target at 1000 yrd it will show 0 difference for head and tail wind.
That is exactly the opposite of the quote above "head wind...bullet up, tail wind ...bullet down"

[foxx]

Regardless, at 500-1000 yards, a strong headwind MUST slow down your bullet enough so that it will drop further than it will without a headwind. Just like trying to swim upstream as opposed to downstream.

[earl39]

It all depends on the angle the wind hits the bullet. If the bullet flys thru a wind that is going up the bullet will go up and if the wind is coming down the bullet will drop. Same goes for the direction the bullet is going. In a straight and level head or tail wind if the bullet is rising in its arc in a head wind the bullet will rise more. If it is falling in a head wind it will fall faster. In a tail wind it is not as pronounced but it does just the opposite. You just have to experience it to believe it.

[foxx]

It all depends on the angle the wind hits the bullet. If the bullet flys thru a wind that is going up the bullet will go up and if the wind is coming down the bullet will drop. Same goes for the direction the bullet is going. In a straight and level head or tail wind if the bullet is rising in its arc in a head wind the bullet will rise more. If it is falling in a head wind it will fall faster. In a tail wind it is not as pronounced but it does just the opposite. You just have to experience it to believe it.

That's gotta be it!!! Thanks. :)

[sharpshooter]

I've been shooting competitions for the last 30 yrs, and I would take a tail wind anytime over a head wind.

[thermaler]

You guys with practical long distance shooting know far more than I do--but I'm going to go way out on a limb and throw some ideas out for the sake of discussion ; ).

If you consider a bullet's basic design--it is optimized to reduce friction--and lift induces friction (actually--it produces what's called "boundary layer separation"; in the case of a bullet the vortices produced by this separation "meet" at the trailing surface, just as they do off an aircraft's wing--a reason the popular boat-tail design helps reduce the effect of this trailing vortices). An aircraft flying through the air basically doesn't "see" a crosswind component as long as it's speed is greater than the velocity of the wind hitting it. In practical terms--the velocity of a bullet so vastly exceeds the speeds of random winds that it is virtually inconceivable that it could actually cause a bullet to go up or down as a result of the wind "hitting" the bullet surface. If this were true, than we would likely see instability in the bullet's flight--and the bullet would be "pushed" into yawing/tumbling.

Here is the somewhat "cosmic" part that's a bit hard to explain. Air itself can have tremendous mass when it moves in large areas. That is what I mean when I say the actual bullet trajectory changes little if at all as a result of wind velocity alone--it's the over-all "big box" of the ambient air parcel the bullet is traveling in that "moves" the bullet's path.

The area closest to the ground is the area that experiences the greatest friction of the wind upon the surface of the earth. This results in mechanical mixing of air-masses and to further complicate things the ground itself is convectively heating (heating by the sun). What you have is a pretty dynamic smorgasbord of airmasses doing all kinds of movement. In terms of a head or tailwind, I suspect the greatest effect on the bullet's path is not so much the direction/velocity of the wind as it is an increase or decrease in air density (drag).

Just food for thought!~ LOL

[earl39]

You guys with practical long distance shooting know far more than I do--but I'm going to go way out on a limb and throw some ideas out for the sake of discussion ; ).

If you consider a bullet's basic design--it is optimized to reduce friction--and lift induces friction (actually--it produces what's called "boundary layer separation"; in the case of a bullet the vortices produced by this separation "meet" at the trailing surface, just as they do off an aircraft's wing--a reason the popular boat-tail design helps reduce the effect of this trailing vortices). An aircraft flying through the air basically doesn't "see" a crosswind component as long as it's speed is greater than the velocity of the wind hitting it. In practical terms--the velocity of a bullet so vastly exceeds the speeds of random winds that it is virtually inconceivable that it could actually cause a bullet to go up or down as a result of the wind "hitting" the bullet surface. If this were true, than we would likely see instability in the bullet's flight--and the bullet would be "pushed" into yawing/tumbling.

Here is the somewhat "cosmic" part that's a bit hard to explain. Air itself can have tremendous mass when it moves in large areas. That is what I mean when I say the actual bullet trajectory changes little if at all as a result of wind velocity alone--it's the over-all "big box" of the ambient air parcel the bullet is traveling in that "moves" the bullet's path.

The area closest to the ground is the area that experiences the greatest friction of the wind upon the surface of the earth. This results in mechanical mixing of air-masses and to further complicate things the ground itself is convectively heating (heating by the sun). What you have is a pretty dynamic smorgasbord of airmasses doing all kinds of movement. In terms of a head or tailwind, I suspect the greatest effect on the bullet's path is not so much the direction/velocity of the wind as it is an increase or decrease in air density (drag).

Just food for thought!~ LOL
That is fine thinking but saying the air really has that small an effect leaves you open to attack with "well how do you explain a bullet being pushed sideways with a crosswind" type of question. One must remember that air has mass and as such will affect things it touches no matter how small or fast they might be. Without air the bullet would only be affected by gravity and would impact at almost the same velocity it started at.

[thermaler]

That is fine thinking but saying the air really has that small an effect leaves you open to attack with "well how do you explain a bullet being pushed sideways with a crosswind" type of question. One must remember that air has mass and as such will affect things it touches no matter how small or fast they might be. Without air the bullet would only be affected by gravity and would impact at almost the same velocity it started at.It's the air's mass that affects the bullet's flight mostly--not the actual wind velocity per sae... is my argument. In the case of a head or tailwind--it's not the additional or "subtractional" wind component that is going to "push" the bullet around aerodynamically (as if the bullet had "control surfaces" that caused it to rise or fall as the result of a very slight change in apparent wind) so much as the air mass density increasing or decreasing the effects of drag upon the bullet--and the over-all entire air mass movement that "drifts" a bullet's path in the case of a crosswind.

When you think about it--if these slight changes in wind really did push a bullet around--it would be almost impossible to reliably predict where a bullet's path would go.

[foxx]

Okay, Them, I gotta believe what you say is true, but it's a matter of degree or significance. Clearly a bullet does not have wings, so it will not be affected by a head wind like a plane is, but there's got to be some affect. It's conical shape obviously helps, but it's there nonetheless. Consider a bullet "flying" through water... if it's traveling 500 yards upstream, it will be slower at its final destination than if it's "flying" downstream. Whatever the difference, however slight, will allow gravity a bit more time to affect it's path. Also, if the bullet is angled a bit up or down, the headwind will push against it a little differently than if there was no wind. If there's a difference, then the bullet's path will be affected, if only a little bit. Again, it's a matter of degree. Is it perceptible to the average shooter such as myself? Probably not. To the top shooters at 500-1000 yards? I gotta think so.

BTW, just in case there's any doubt... I am enjoying this :)

[foxx]

Here's my best example of my point: Consider a football. A perfectly thrown spiral pass into a headwind will travel a different path then the same pass would travel without a head-wind. Yes? No?

[thermaler]

Here's my best example of my point: Consider a football. A perfectly thrown spiral pass into a headwind will travel a different path then the same pass would travel without a head-wind. Yes? No?A football is traveling a bit slower than a bullet : ) so it will in fact be subject to "pushing" by a significant head or tailwind--in addition to being "floated" by the general airmass drift. At the speeds a bullet is traveling, the relative density change of the airmass (hence change in drag) is likely going to have far more effect than any change in the apparent wind. Apparent wind is a reference to the "felt" wind the object encounters as a result of it's movement--so if you are walking 2 miles an hour into a 10 mile an hour headwind--then the apparent wind you are "feeling" is 12 mph. Point being--as the projectile's velocity approaches that of the head/tail/cross wind--the more vulnerable it will be to the direct force of the wind acting upon it. In terms of a flying aircraft, going slowly makes it more vulnerable to stall and consequently inability to fly--inn terms of a bullet a loss in stability means yaw/tumble or worse.

BTW--this is all just hypothetical conjecture on my part as it relates to my understanding of flight--so I'm not claiming this is necessarily the gospel truth. But I have trouble seeing why these basic concepts of flight would not also apply to a bullet's flight. : )

[foxx]

BTW--this is all just hypothetical conjecture on my part as it relates to my understanding of flight--so I'm not claiming this is necessarily the gospel truth. But I have trouble seeing why these basic concepts of flight would not also apply to a bullet's flight. : )[/QUOTE]

I am no expert on either subject, so everyone has to put up with me more so!

If I dare say you are having trouble with what I believe to be true, it is because your practical and scientific knowledge of flight is interfering. Bullets do not fly. A plane FLIES due to its wings that are airfoils. Airfoils produce lift. therefore a plane has features/virtues that allow it to overcome minor, almost insignificant forces like the gentle push of a breeze. Those virtues are, primarily, an engine and wings. My football example shows that a football must be thrown harder if it is to reach its intended target if thrown into the wind because the wind will act as a force against it. That force will slow it down. That same force is present and affects the path of a bullet for the same reasons, but to an obviously lesser extent. Practically speaking, it won't matter much. But if you're trying to hit a dime at 500 or 1000 yards, it will make a difference. I am guessing 15-20 mph head wind at 1,000 yards will make quite a bit of difference. Maybe a few inches. Certainly that is only a fraction of what a cross wind will do, but a difference nonetheless.

[thermaler]

If anything--an aircraft would be FAR more vulnerable to crosswinds/headwinds etc because in general they are flying slower than a bullet and present far more surface area to generate drag. A modern bullet is truly a work of aeronautical art--and it is because of it's remarkable design and performance that enable them to largely "evade" the environmental effects of winds.

I think now would be a good time for a true bullet ballistician to step in--somebody who actually designs bullets for hornady, sierra, berger etc. I'm saying that the majority of the effect on a bullet's trajectory in a head or tailwind is due to increase or decrease in drag in the ambient airmass--not a mere increase or decrease in winds physically exerting enough force to alter the bullet's path. I would love to be told my illusion is wrong--if it is! : )

[Cat 64]

BTW--this is all just hypothetical conjecture on my part as it relates to my understanding of flight--so I'm not claiming this is necessarily the gospel truth. But I have trouble seeing why these basic concepts of flight would not also apply to a bullet's flight. : )

I am no expert on either subject, so everyone has to put up with me more so!

If I dare say you are having trouble with what I believe to be true, it is because your practical and scientific knowledge of flight is interfering. Bullets do not fly. A plane FLIES due to its wings that are airfoils. Airfoils produce lift. therefore a plane has features/virtues that allow it to overcome minor, almost insignificant forces like the gentle push of a breeze. Those virtues are, primarily, an engine and wings. My football example shows that a football must be thrown harder if it is to reach its intended target if thrown into the wind because the wind will act as a force against it. That force will slow it down. That same force is present and affects the path of a bullet for the same reasons, but to an obviously lesser extent. Practically speaking, it won't matter much. But if you're trying to hit a dime at 500 or 1000 yards, it will make a difference. I am guessing 15-20 mph head wind at 1,000 yards will make quite a bit of difference. Maybe a few inches. Certainly that is only a fraction of what a cross wind will do, but a difference nonetheless.[/QUOTE]

Foxx and Therm,

I truly believe that you both bring very practical/logical/supported conjectures as to our debate. Could we, for the sake of somewhat arriving to an unanimous conclusion, draw a line and sum up our findings? What do we believe/agree to be true…what is the effect of the wind (cross, head, and tail) to a bullet in flight? What does a shooter need to be aware and make amends for when pulling the trigger? What is he looking for when the information down range is telling him that the wind is increasing/decreasing in intensity either form the front or rear (or sideways)?

[foxx]

Cat 64, to answer your question: No, I can't !!! LOL

I think, as Therm said, we need more help from a ballistics expert. Personally, I think Sharpshooter and Earl have answered your question, but Therm doesn't agree and I am just goofing around trying to explain what I believe is the basis for their opinions. Apparently they have better things to do or just aren't gonna try to explain what they believe (know?) to be true. :)

It's been fun, but I've exhausted my arguments/reasoning and I am not capable of understanding everything Therm is using for his reasoning.

Seriously, I'm just a "wannabe" long range shooter that likes to argue, debate things. I would really like to see a ballistic expert get in here, for sure. Until then, I'm right, Therm is wrong. JUST KIDDING!

[earl39]

You guys have to remember that except for a very small fraction of a bullets flight when fired at extended (read 600+ yards) range a bullet is pointed either up or down and is not flying a level path. If you were to the side and could see it in relation to the line of sight is what i am saying. As such you have a surfboard type action of the bullet riding the air. You have to make minute adjustments for mirage which is also a type of air movement where the moving air moves the light around making your target swim.

Therm if you take your plane and get it flying in a perfectly straight and level path in a no wind situation and lock the controls and hit a headwind odds are the plane will fall or rise. A cross wind will blow it off course. Now i don't fly unless someone else is driving but i am just trying to put it in terms you will understand. To use the bullets path in a plane you have a slight nose up with lets say a 100 ft per minute climb at 200 knots and hit a head wind and the only change is to increase power to maintain the 200 knots. You should find yourself at a faster rate of climb due to the added lift. If you make no changes to the controls you will find yourself not only going slower (ground speed) but your climb rate will change also and not always in a predictable way. Updrafts and downdrafts play a big part in all this. Wind coming up a mountain or dropping down over the crest of a mountain is a good example.
Like i said earlier you just have to get out on the same range and shoot in a no wind, a head wind and a tail wind to see the difference and something like a 223 or 308 at 1000 yards will show the effects pretty dog gone good. Sometimes book learning doesn't jive with practical application.

[foxx]

Thanks, Earl. I did find this online that corrects some of my misconceptions. (but confirms there is an effect.) :)


To summarize this subsection: A wind from any direction can be resolved into at most three components, a horizontal headwind (or tailwind) component blowing along the line of sight between the shooter and the target, a cross-wind component blowing in a horizontal direction across the shooter’s line of sight to the target, and a vertical wind component blowing upward or downward across the shooter’s line of sight to the target. Headwinds or tailwinds generally have a quite small effect on bullet trajectories, unless the wind is very strong and the range is very long. Crosswinds and vertical winds, however, have serious effects on bullet trajectories. The effect of each component wind can be analyzed separately, and this approach gives insight into wind effects. However, to get accurate calculations of the wind’s effects from any direction, all three components must be analyzed simultaneously, because the wind effects interact, primarily by changing the time of flight of the bullet to the target. Infinity can be used to calculate the effect of any wind component, or to calculate the effects of all components acting simultaneously.

There is a common misconception among shooters that a wind “blows” a bullet off its course as it travels downrange. It is very important to realize that a wind does not “blow” a spin-stabilized bullet off its course. Rather, because of its spin stabilization a bullet turns to follow the wind if the wind direction is perpendicular to the line of sight between the firing point and the target. This will be described in greater detail in Section 4. In the case of a headwind or tailwind, the moving air simply changes the drag on a bullet, because drag depends on the speed of the bullet relative to the air and not the ground. A headwind will increase the drag a small amount, in turn increasing the time of flight and causing the bullet to shoot low. A tailwind will decrease the drag a small amount, in turn decreasing the time of flight and causing the bullet to shoot high.