Home Forums Hunting & Shooting Ask The Gunwriters Impact change with headwind?

He was responding to the clown BSA'.

I was being sincere. I have not experienced POI change in zero value winds. Whether they were 10 or 20mph. I have not experienced it.




Travis

I have--when the wind hits something in front of me and turns upward.

But this thread is turning into a real snarl, because the OP has modified his original question, and (per usual) many other posters haven't read the entire thread (including his posts), and others have simply wanted to impress us with their technical knowledge.

All of this is typical of the Campfire, and probably of the Internet in general. But the OP was NOT actually asking about the effects of a straight headwind. Instead he was asking about a headwind hitting a rise in the ground.

Now I'm confused.




Travis

You're right- time of flight, not distance. Regarding the way that shot angle effects are typically explained in gun magazines- it may appear that the writers get it wrong, but that's because they are not talking about absolute drop due to gravity- they are talking about how the bullet's initial angle relative to the force of gravity affects the trajectory curve, relative to a curve that is perpendicular to gravity. Using horizontal vs. LOS distance to the target is just a proportional way of describing gravity's perpendicular effect on the relative trajectory curves over time.

The affects of gravitational acceleration are less apparent in the bullet's trajectory shift as the magnitude of the bullet's initial vertical velocity component increases.

Ok John, point taken.
Have I seen the tails on my wind flag @ the 100 when shooting at the 2 go almost straight up when a headwind gust hit the back of the berm, Yes. Did it cause a change in POI? Absolutely.
Have I blown a shot 1/4-1/2" out of the group @ 100?
Yes again.
I am out of this one.

I'm with Travis. IME it takes a hellacious head wind to cause a 1.5 MOA shift at 100 yards. I'm also with JB. But we're talking about two different things- head wind vs. up draft.

At the very least this is entertaining...

That's the way I was taking the question too. If you're shooting downhill at 45 degrees at a target that's only 100-200 yards away and the wind is blowing up the hill parallel to the ground, it'll have practically no effect. The WIND effect would be the same as if you were shooting on level ground with a wind straight in your face.

Now if you're shooting on that same 45 degree slope with the wind coming upslope, parallel to the slope but you're shooting at a target that is only 10-20 degrees below the horizon, you're gonna see less drop. Kinda' like a crosswind in the vertical.

Check out exteriorballistics.com

Here are the three posts from the OP. Notice they continue to refine what he's asking:

Post 1:

Would a strong ( 20 mph) headwind noticableably affect point of impact at 100-200 yards? If so is the degree of change greater than just due to the (trivial) reduction in velocity as a result of the headwind?

I was shooting slightly downhill and into a strong headwind and found my POI higher than expected - just trying to figure out why.

Thanks.

Post 2:
I am aware of the effects of uphill or down hill shooting. I was shooting on a range that I use regularly.

I wondered if a very strong headwind blowing into a slight hill could create a "lift" great enough to cause a 2" higher impact than anticipated at 100 yards. Cartridge was a 300 WSM with 165 grain bullet. Load and rifle have been quite consistent which is why I questioned whether it could be a wind effect.

Thank you.


Post 3:

I was simply asking if a strong headwind blowing into a hillside could impact bullet elevation in such a fashion.

To be clear, I may have overstated the effect, it was closer to 1.5", the range is 110 yards, the bullet a 165 TTSX, velocity 2950ish.

Thanks

I probably shouldn't engage in this. And my responses probably won't be helpful.

I have tons of books here and some have the detailed explanations of angle shooting up hill and down hill. Some go into detail about the effect of wind on bullet drift. And there are some calculations about the amount of drift vs wind velocity. And some are so sophisticated and detailed in math and engineering that the average shooter probably has never even thought about all of the elements and conditions that go into external ballistics.

Not that long ago we were posting about 16" naval guns shooting over the horizon, out of line of sigh, and hitting targets 20 miles away.

Meantime, back on planet earth, long range shooters and snipers hit target 1,000 yards and more.

The wind is fickle, unpredictable, changeable - sometimes - over the course of a bullets path. What is a "head wind"? Dead on precisely aligned with the rifles barrel? Coming in at a slight angle, 5 degrees, 10 degrees left or right ??? The post above doesn't specify.

A head wind coming into the face of the bullet has the same effect as a head wind coming into an airplane *( And I am a pilot ). It slows the plane down. It will slow the bullet down too. But the bullets frontal square inches affected are really small. Side wind bears on the bullets side which is much more surface area. *( I really don't see any "lift" aspect of a bullets shape vis a vis an airplanes wing shape as discovered and invented by Wilbur Wright ).

If you want to get high tech and anal then consider atmospheric pressure, sea level or at what altitude? Also consider the humidity i.e., moisture in the atmosphere. *( And there is plenty of that ).

The opening question lacks too many parameters to answer scientifically with precision. At best the response will be a SWAG - *( Scientific Wild Axx Guess ).

Among my extensive repertoire of internal and external ballistic calculators there probably is one that could calculate the answer with significant precision. But it will probably be extremely time consuming and yield results that will be marginally accurate in any event.

So I'll take a pass, friends, and stay out of this one. Other than to say that a strong head wind will slow down a bullet and cause it to drop more than normal. The "how much" is the aspect that I'm not addressing.

With some kind indulgence let me say that I am "up there" in age, into the 8th decade. Looking back on my lifetime I am truly shocked at the comparison of what we were like in the 1930's and where we are today in technology and knowledge. Amazing advancements seeming to accelerate exponentially, that is to say faster and faster as time goes by.

Finally.

Someone at least got the sign correct.

The wind doesn't blow on the side of the bullet. The bullet
points into the wind. This makes a drag component that
points down wind. That is why bullets drift down wind. It
is also why high BC's drift less, and drift is proporti9onal
to velocity loss.

Agreed!


Think about this - a true head wind (not up or down in relation to the bullet travel is nothing more than increased air/fluid drag and eventually lead to a very minor addition to the drop of a bullet. Wind is just moving air - the bullet is already moving through air at ~3000fps, another 29fps effect (positive for headwind of 20mph) is only gonna increase the drag on the bullet by ~1.02% which will cause the bullet to drop ever so slightly more at the same distance. If the bullet is not tipping up/down due to the 3000fps of "wind" it's already experiencing, it ain't gonna tip up/down with another 30fps... The effect of a direct head wind would definitely not be noticeable in a hunting rifle at 100-200yds. A "rising" wind would cause some "lift" but not 1.5" at 100yd unless that 20mph was straight up the whole 110yds.

Apparently my post putting together all three of the OP's posts, which plainly state that he is NOT asking about the effect of a straight headwind, was also not read by anybody.

This thread has been what a friend calls a CF3 (clusterf*** cubed) from the beginning.

So go ahead, argue about the effects of a straight headwind. That should keep everybody busy for days.

Dang John, you might need a break from this place...

When does a discussion EVER stay on track here???

Maybe I shoulda just posted this...

"A "rising" wind would cause some "lift" but not 1.5" at 100yd unless that 20mph was straight up the whole 110yds."

Part of the problem is the OP kept changing the range conditions and results. He started with 100-200 yards and asked about an impact 2" higher, then went to 100 yards, then finally went to 110 yards and (maybe) 1.5" higher impact. Apparently he never did actually measure any of it, and may not have been sure in the first place, so discussing the effects of a straight headwind is probably more productive!

Strother Martin said it best, "what we have here is a failure to communicate."

Bullets are like airplanes. Only different.




Travis

Hawkins, apologies for my previous smart-aas remarks.

I agree with Tx, shooting down a slight incline won't produce a full value updraft and thats what it would take for that much drift. A canyon or steep dropoff might be different.

If I saw that much change in POI, I'd look for other sources.