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#1 esldude

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Posted 11 April 2007 - 10:27 PM

http://www.benchrest...mp;d=1136598479

Would you fellows with experience reading wind say the effects pictured in this link are about correct?

#2 Gary Lemons

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Posted 12 April 2007 - 05:05 AM

In a perfect world where the wind is constant in velocity and direction all the way from the muzzle to the target, the rosette will give the directon of the bullet's movement. Since it's rare to find a time when the wind patterns are textbook perfect, use the rosette for an educated guess on hold-off for the sighter shots and use what the sighters tell you for the record shots.

Gary

#3 patriot

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Posted 12 April 2007 - 06:37 AM

http://www.benchrest...mp;d=1136598479

Would you fellows with experience reading wind say the effects pictured in this link are about correct?

Yes, for target (subsonic) 22 RF I've come to believe the chart. When you have time try shooting without changing the zero once set. Check the wind flags and mirage, call your shot, recheck the wind flags and mirage, then check the results. Don't worry about score just cause and effect. This should speed up your learning curve.

Go to the range on bad wind days. Try one where it is clocking from 2 to 4 and another from 5 to 7. Also note the direction and velocity cycles. I've had thermals when shooting at 1000 yds that took the direction 360 degrees as they passed over the range.

Mark

Edited by patriot, 12 April 2007 - 06:46 AM.


#4 Tom R

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Posted 14 April 2007 - 10:20 AM

Hi,
I have the identical wind rosette tacked above the bench where I shoot.
According to physics,and in a perfect world,Yes that is where the bullet Should go.
BUT my Flags LIE,
I look for a repeating condition with my flags.Then shoot on the sighter,that is were the bullet will really go
then Run and Shoot the condition,with the proper adjustments.
Wind Probs also lie.
Tom R

#5 Carl

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Posted 14 April 2007 - 11:51 AM

Go to the range on bad wind days. Try one where it is clocking from 2 to 4 and another from 5 to 7. Also note the direction and velocity cycles.
Mark



You gotta' be kiddin'... 2-4 or 5-7??? is that MPH?... those are dead calm where I shoot... try 10-15 on a good day and 20-30 on a bad day. Maybe it's no wonder I can't shoot a group without having 1 or 2 flyers almost every time :angry2: !! Wednesday started out as a good day, maybe gusts to 8-10mph, but by the time I really got dialed in and into shooting groups, it had gone to 10 mph with gusts to 15 or so. Also it changed directions a few times... and we thought that was a good day. We have trees that cause the wind direction to change through the range as the wind speed changes.... it makes it real tough to figure out. I'm trying to learn to read wind flags, but it's like beating my head against a wall. In 50 yds., sometimes the wind changes to 3 different directions. I've sat there for a 2 or 3 minutes just watching the flags and some have gone 360 degrees in that time. I have tried using the rosette and another wind direction gage that is pretty much the same, but what do you do with more than one direction. A lot of people say the one closest to the muzzle has the most effect, but if the others are pointing a different direction, what is the effect farther down range?
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#6 patriot

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Posted 14 April 2007 - 12:33 PM

You gotta' be kiddin'... 2-4 or 5-7??? is that MPH?...

... but what do you do with more than one direction. A lot of people say the one closest to the muzzle has the most effect, but if the others are pointing a different direction, what is the effect farther down range?

Clocking: 2-4 o

Edited by patriot, 14 April 2007 - 12:36 PM.


#7 Carl

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Posted 14 April 2007 - 01:57 PM

Sorry, guess I misunderstood the direction vs. velocity (2-4 or 5-7).

It's not unusual to have a 180 degree change or more in direction as the velocity varies. The way our range is laid out with the trees and shooting past the end of the 25 yd. berm, the wind is seldom the same at the bench as it is two or three other places down range. It curls around the trees and berms and it's hard to pick a condition that repeats. Last time I was out (Wed.) I only put one flag out... about 3 yds. in front of the bench, to see if that made a difference... didn't worry about farther out. "Most of the time" it made a difference when I picked out one condition to watch, but I believe the conditions were not the same farther out. Problem is, to try waiting for one or two conditions when other flags are the same, and you wait forever. Then, it seems with my target rifle that if I wait too long, I need to shoot whether or not the conditions are right, so I need to shoot another sighter. then while reloading and re-sighting, I miss the correct condition. sometimes if the condition stays for 10- 20 seconds, it is best to shoot 2 or 3 fast before it changes and you need to wait gain.

I have been waiting for very low wind conditions to check 6 lot#s of Eley this spring and it just hasn't happened. A buddy and I split these lots of ammo and he went out and shot his, but I don't know if he really learned anything do to the other variables, mainly the wind. I'm waiting to at least reduce that problem, but it may be the middle of the summer at the rate things are progressing.
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#8 tim s

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Posted 18 April 2007 - 07:07 AM

Sorry, guess I misunderstood the direction vs. velocity (2-4 or 5-7).

It's not unusual to have a 180 degree change or more in direction as the velocity varies. The way our range is laid out with the trees and shooting past the end of the 25 yd. berm, the wind is seldom the same at the bench as it is two or three other places down range. It curls around the trees and berms and it's hard to pick a condition that repeats. Last time I was out (Wed.) I only put one flag out... about 3 yds. in front of the bench, to see if that made a difference... didn't worry about farther out. "Most of the time" it made a difference when I picked out one condition to watch, but I believe the conditions were not the same farther out. Problem is, to try waiting for one or two conditions when other flags are the same, and you wait forever. Then, it seems with my target rifle that if I wait too long, I need to shoot whether or not the conditions are right, so I need to shoot another sighter. then while reloading and re-sighting, I miss the correct condition. sometimes if the condition stays for 10- 20 seconds, it is best to shoot 2 or 3 fast before it changes and you need to wait gain.

I have been waiting for very low wind conditions to check 6 lot#s of Eley this spring and it just hasn't happened. A buddy and I split these lots of ammo and he went out and shot his, but I don't know if he really learned anything do to the other variables, mainly the wind. I'm waiting to at least reduce that problem, but it may be the middle of the summer at the rate things are progressing.

Carl, as you've stated and Gary implied, often the challange is to discover the "primary" wind condition when several flags are doing different things. Shooting often in wind will ultimately teach you more than shooting in calm once you have a gun that you know shoots and is in tune. Figure a couple thousand bucks worth of ammo. :o

Edited by tim s, 18 April 2007 - 07:08 AM.


#9 Amos

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Posted 29 April 2007 - 10:20 PM

First flag physics - An object in motion will remain in motion unless acted upon by a net force (Newton).

A bullet pushed by the first flag will continue in that direction until offset......

In a simple sense, a wind at the first flag would result in greater displacement than the same wind at the second flag. An equal, offsetting wind at the fourth flag does not return the bullet to zero, it just stops the lateral movement where it is. If the first five yards only of bullet flight felt a force of X wind to the left and then some point later in flight the bullet felt an equal force of X wind to the right, the point of impact will be left.

wind.jpg


Concerning competitive benchrest shooting, toss that "Rosette", all related information and any thoughts of having advanced knowledge of wind drift. Such matters may be of value to a prarie dog hunter or a sniper but of little use to precision paper shooting. Said differently, at best the rosette offers a guess and that ain't going to win a benchrest match. A guess is almost always a miss.

Finally, you don't have to know anything at all. In fact, the less you know the better. Pick a condition and shoot a couple or three sighters. If the sighters ain't pretty, pick another condition. If you can't find a suitable condition, pick another rifle.

#10 Brad Clodfelter

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Posted 29 April 2007 - 10:45 PM

Gary is correct.

The best way to learn to shoot in the real wind world is to go out and do it.

No graph will let you see all the different winds that can be seen on real gun range with several windflags on a twitchy wind gusty day. Shooting in these conditions will make you learn real quick what different winds will will do to a bullet by watching the flags to what they are doing while you are shooting each shot. You will learn when not to shoot when shooting over windflags and when to shoot. It just takes practice and trial an error.

Brad

#11 Doug

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Posted 07 June 2007 - 03:12 PM

That wind Rosette is not even close!! :blush:
Visit "The Wind is Not Your Friend" for a lot better wind rosette - Not as pretty but better plus a ton of good information. :rolleyes:
http://team40x.com/wind/index.html
You will find that as the wind gets close to 6:00 or 12:00 the POI moves very little!
Doug

#12 patriot

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Posted 07 June 2007 - 07:38 PM

What is interesting to note is that the POI is starting to rise
above the horizontal after 1:00 and
a pure head and tailwind (12:00 & 06:00) have
very effect on POI


Ah, so a head or tail wind does not change the point of impact elevation? That sure isn't my experience with a RF at 100yds. Reading his rule number 4 there seems to be a discrepency with the chart:

"... Care must be exercised, however, to watch for elevation changes with a corresponding horizontal drift. In general, the change in elevation is to 4 oclock for a wind from the left and to 10 o'clock for a wind from the right. A rule of thumb for any given horizontal correction, take 1/2 the correction in elevation..."

That kind of sounds like the z pattern. Maybe his chart was for a short distance or a high power round.

Mark

Edited by patriot, 07 June 2007 - 08:57 PM.


#13 DonMatzeder

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Posted 07 June 2007 - 08:32 PM

The problem with the wind rosettes is that they are for one wind speed. Vector analisis (sp) will give you the concept better as to what happens. The first vector is in the direction of the wind and with a magnitude proportional to the wind. The second vector is up or down based on the side of the bullet that the wind is "touching". Adding these to vectors together will give you bullet displacement. With low velocity of wind from say 7 oclock, the lift that you get may not equal the drop from the left to right touching of the bullet by the wind and the bullet will show some drop. More velocity from the same place and you have more lift from the wind than drop from the rotation and the bullet goes up. This drove me crazy until I put the rosette away.

#14 patriot

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Posted 07 June 2007 - 08:55 PM

I agree that the magnitude will change with the wind direction and velocity. A polar diagram would be appropriate. But the change should be constant for a given distance, bullet (drag & inertia), bullet velocity, bullet trajectory, spin rate (lift & gyro effect), density altitude, wind speed and direction.

Mark

Edited by patriot, 07 June 2007 - 08:58 PM.


#15 steve b.

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Posted 08 June 2007 - 01:32 AM

Wow, good thread.

1st, Amos really does a good job about discussing wind effects on bullet flight - well done Amos.

2nd, Head and tail winds are difficult to estimate in terms of influence, but they sure do move bullets around on the target. Side winds are easy, it's those 11 to 1 and 5 to 7 winds that really screw you up. Mark is right on with this, and it strikes me that Mark and I have been in the same bind with a head or tail wind that punishes scores.

3rd, the wind rosette is generally not worth the paper it's printed on. It does not take into account for the thermodynamics of heat rising and cold air falling. It may be a decent guesstimation tool, but you gotta shoot sighters and from what I have seen only half of the sighters follow the wind rosette.

4th, Consider wind to be just like water (just not a dense - ha!), the bullet surfs along it's path, it does not jump from condition to condition (or from flag to flag). If the flags don't match, you got a swril or substantial shift in any three planes of direction. Again, this is where the wind rosette won't help you out.

#16 Carl

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Posted 08 June 2007 - 06:31 AM

Wow, good thread.


4th, Consider wind to be just like water (just not a dense - ha!), the bullet surfs along it's path, it does not jump from condition to condition (or from flag to flag). If the flags don't match, you got a swril or substantial shift in any three planes of direction. Again, this is where the wind rosette won't help you out.





I didn't stop to think about that when people are using 5 or even more flags. I was watching my 2 flags and sometimes the wind rossette was right on and sometimes it was almost the exact opposite... however, watching more than 2 or 3 flags for an old goat like me is going to make it work. I didn't retire to get another job :D !! I'm beguining to think I may just use one flag close to the bench where the wind direction/speed will have the greatest effect and to H*** with the rest... well, maybe another a little farther out, JIC.
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#17 mntnwillie

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Posted 08 June 2007 - 08:34 AM

... or to add a note of heresy to this discussion ... you could find yourselves in the position of everyday shooters, either hunters or Prone/Position competition shooters, ( You know - the ones who actually hold their rifles in their delicate little paws ! ), who don't have the "artificial luxury" of a rigid concrete bench and unlimited wind flags, "droop indicators", etc.

At many major competitions, including the Nationals at Camp Perry, your only indicator of any use might be the one you are allowed to plant immediately in front of the muzzle ... or, like me, the feel of the breeze through my chin whiskers. The Perry wind flags are huge streamer affairs set almost a mile away on the shores of Lake Erie ... or 50 yards behind[i] you in the parking lot.

But I digress ... in a perfect world - or set of conditions - the wind effects diagram that started this thread is absolutely correct in its' orientation - at least for a rifle having a RH twist to its' rifling. The vertical offsets would reverse for a LH twist barrel. Some years ago Stacy Kunz prepared, and published on his old Tennessee Smallbore website, more exact wind rosettes for typical target velocity ammo indicating both the lateral and vertical come-ups for specific wind conditions. Of course they were only of value as general guides ... in 70 years of competition I cannot ever recall experiencing winds of that uniformity all down the range - lol !

My own basic practice for the non-bench style shooting is to "know" the zero-wind sight settings for the rifle sights in use before heading to the competition. Then, where possible before the match, try to determine the overall wind patterns across the range as a whole. On some ranges this is comparatively simple ... for example during CMP Sporter "O" Class at Perry in 2004, the wind fluctuated all day from 1 to 3 o'clock at 20-25 knots with gusts in the 40-45 knot range. This indicated a need to physically reset my open sights to produce 50 yard zero-wind POI's some 6-7 inches right and 1-2 inches down from that "known" zero before the practice/sighting-in period. Then from spotting of intial sighter shots the amount of "aiming-off" - or "shading" as it appears to be called in this country - could be ascertained for actual scoring shots. At a range like Chattanooga Smallbore such a technique is virtually impossible due to the constantly swirling conditions. There one must use the sighter target to evaluate the overall spread of shot under as many conditions as possible and adjust sights to a "median" position .... observations of the minimal flags, grass motion and mirage then dictate the degree of aiming-off. I realise that this is far from the precision that the bench-rest fraternity desire but the principles still hold true ... or you can click the knobs with each shift until your finger tips wear out ... your choice !

Regards,
Mick - The Fuzzy Limey :rolleyes:

Edited by mntnwillie, 08 June 2007 - 08:39 AM.


#18 steve b.

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Posted 08 June 2007 - 09:07 AM

Carl, if you want to see this in 3-D, get a bubble wand from the toy or grocery store, the one where you dip a plastic wand in the soap mixture and blow bubbles, and take it to the range. When the wind is very calm, or a bit switchy, blow some bubbles and watch where they go.

Right after you do that you will really get a shock as to what the wind actually does.

#19 mntnwillie

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Posted 08 June 2007 - 10:00 AM

Excellent tip Steve ... I have used it in my rifle tuning/ammo testing work over the years ... ! At one time I had several home-made bubble-machines, running on low pressure air, spread along my 50 yard range to produce wind trend patterns. Another "visual" which generally occurs only on extremely light fluky days are long spider-web filaments floating though the air 5~10 feet above the ground/water ... observation of these filaments often gave me the calm weather edge in my Olympic sailing dinghy-racing days.

Regards,
Mick :rolleyes:

#20 patriot

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Posted 08 June 2007 - 08:15 PM

... observation of these filaments often gave me the calm weather edge in my Olympic sailing dinghy-racing days.

Regards,
Mick :rolleyes:


Ah, a fellow dinghy sailor. I raced Interlakes, Lightnings, and Lasers around midwest puddles. Nothing like light air with rain to bring out my best. The most useful wind indicators were those on the other boats' mastheads. :-) I'm sure you know why.

Mark

Edited by patriot, 08 June 2007 - 08:15 PM.


#21 mntnwillie

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Posted 09 June 2007 - 07:56 PM

Hi Mark,

Yep ... had a long run at that game ... Swallows and National 12's before WW2 ... Fireflies, International 14's, Snipes and Airbornes after WW2 ... then over here, Fireflies, (Was North American class Commodore for several years), Finns, Snipes, Int.14's, Int. Canoes, Highlanders, Thistles, Lightnings, Dutchmen, 505's, Jolly Boats, Shearwaters, 12-Metres, Dragons, Force 5's ... basically whatever anyone wanted me to skipper or tactician for them.

Gave up on dinghy racing in late 70's and settled down to lead-bottomed stuff .. my final boat was a Beneteau Idylle that I brought over from France ... used to be 'old man' Beneteau's personal cruiser .... re-fitted it as our retirement home before moving back ashore 10 years ago.

Onset of Vertigo in my old age brought me to this mountain top instead ... still miss the water though !

Regards,
Mick :rolleyes:

#22 patriot

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Posted 09 June 2007 - 10:54 PM

Wow, I've won my class a few times but nothing at your level.

I did spend a little time in Thistles and Highlanders when other skippers needed ballast that could trim the jib, fly the spinnaker and call the shifts.

I've done very little blue water. The first time off Florida my wife saw fins swimming up astern and thought sharks were attacking. Luckily the "sharks" only wanted to play on the bow wake.

My wife keeps suggesting we buy something to sail overnight. But, I've held off until we can retire to water large enough a windward beat wouldn't feel like a match race to the first mark.

Fair Breezes,
Mark




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