the recent purchase of an anemometer is proving to be most enlightening.
when the wind comes from the right (off the sea) on our range, such that the point of the flag is level with the bottom of flag at the pole, the machine reads 12 mph on the mound.
when it comes from the left (overland) with the flags reading the same, the machine reads 10 mph.
so either i am not using the machine the same, the machine has gone out of calibration, or the wind is the same speed at flag height, but not at ground level. i am pretty confident that i am looking at the same flag picture, although this could be another potential error.
at 800m, 2mph can be significant on the target.
bruce moulds.
wind, flags, & deadwind zero
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bruce moulds
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AlanF
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Bruce,
Is the Murray Bridge range dead flat like Lower Light? If not then its likely to be that the wind speed gradient is different from the left than from the right. So in your example, the velocity difference between flag and anemometer is 2mph less with a left wind. There are numerous ranges where I've seen sloping layers of strong wind, which can effect downwind flags before upwind flags. Someone said that smoke flares would be the best wind indicator in some situations - I tend to agree.
Alan
Is the Murray Bridge range dead flat like Lower Light? If not then its likely to be that the wind speed gradient is different from the left than from the right. So in your example, the velocity difference between flag and anemometer is 2mph less with a left wind. There are numerous ranges where I've seen sloping layers of strong wind, which can effect downwind flags before upwind flags. Someone said that smoke flares would be the best wind indicator in some situations - I tend to agree.
Alan
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ned kelly
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G'day all,
If you are measuring at a different point to the flag itself, you simply cannot compare unless the wind meter is at the flag itselfand the same height as the flag.
Anytime you you can walk the range you will feel different wind strengths against your body, measure the airspeed, then compare that to the flags behaviour. You will be surprised. So it simply is not that easy to correlate wind readings from the mound to flag behaviour. It is a very basic guide at best.
The best proof of all is for anyone to view the flag setup for a 100/200 yd BR match and carefully watch the flags, which are set up very close to the line of flight, many flags = many points of wind indication and you will see things that WILL blow your minds (no pun intended!), such as ribbons blown vertically, flags spinning 360 degrees around the pivot, flags showing direct opposite wind directions yet only placed a few metres apart, etc.
Also I believe the FB flags have too much weight (especially when they get wet!) and are slow to react to the given wind strength and direction changes, so much so that I rarely use them exclusively and rely much more on the mirage, it is much more meaningful in my experience. That and the fact the flags are nowhere near the trajectory of the bullet except perhaps a the the midrange point, but I dont reckon the bullets fly as high as some of the flag poles I've seen and the air usually is stratified and slower and more turbulent near the ground than at the height of the flags.
This turbulance of the air is created byany obstacle such as trees, safety mounds, buildings, butts, gully's etc. In fact the only true indication of what is going on is the impact point of the last bullet shot, and that is outdated info by the time the target frames are pulled, marked, scored and returned ready for the next shot.
If you could set off a smoke flare at the ranges at every distance you will see what I mean, especially if you use a different colour smoke flare at each distance and see how they interact and swirl..........
Anyhow this is some food for thought and if you can get to a 100/200 BR match its well worth watching!
Cheerio Ned
If you are measuring at a different point to the flag itself, you simply cannot compare unless the wind meter is at the flag itselfand the same height as the flag.
Anytime you you can walk the range you will feel different wind strengths against your body, measure the airspeed, then compare that to the flags behaviour. You will be surprised. So it simply is not that easy to correlate wind readings from the mound to flag behaviour. It is a very basic guide at best.
The best proof of all is for anyone to view the flag setup for a 100/200 yd BR match and carefully watch the flags, which are set up very close to the line of flight, many flags = many points of wind indication and you will see things that WILL blow your minds (no pun intended!), such as ribbons blown vertically, flags spinning 360 degrees around the pivot, flags showing direct opposite wind directions yet only placed a few metres apart, etc.
Also I believe the FB flags have too much weight (especially when they get wet!) and are slow to react to the given wind strength and direction changes, so much so that I rarely use them exclusively and rely much more on the mirage, it is much more meaningful in my experience. That and the fact the flags are nowhere near the trajectory of the bullet except perhaps a the the midrange point, but I dont reckon the bullets fly as high as some of the flag poles I've seen and the air usually is stratified and slower and more turbulent near the ground than at the height of the flags.
This turbulance of the air is created byany obstacle such as trees, safety mounds, buildings, butts, gully's etc. In fact the only true indication of what is going on is the impact point of the last bullet shot, and that is outdated info by the time the target frames are pulled, marked, scored and returned ready for the next shot.
If you could set off a smoke flare at the ranges at every distance you will see what I mean, especially if you use a different colour smoke flare at each distance and see how they interact and swirl..........
Anyhow this is some food for thought and if you can get to a 100/200 BR match its well worth watching!
Cheerio Ned
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bruce moulds
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john,
you could well be right,but i think both flags were dressed as similarly as possible.
alan what you say is most interesting and makes sense.
ned,
part of the pleasure of fclass for me is trying to maximize my potential with the tools at hand. you could be right about bullet height at the shorts, but i looked through my bore at 1000 yd once while the sights were on the target, & the angle of the bore was quite high.
i might have the opposite problem with my 45/2.4" blackpowder cartridge rifle - 550 gn bullets at 1300 fps going over the flags.
sometimes it is amazing how well the flags do predict bullet displacement if you can get in touch with the job. (rarely in my case)
there was a video of tony boyer shooting a group on 6br yesterday. for the life of me i don't know what he was shooting on with all those br windflags, but he seemed to know the deal. he even unloaded a group round and replaced it with a sighter. obviously if those bullets were jammed, the pre engraving on that projectile was of no concern to him, as he loaded it and shot it for score.
it looks like american palma shooters are using anemometers with compasses to give windspeed and direction on a screen on the mound. we are not allowed to do this.
bruce moulds
you could well be right,but i think both flags were dressed as similarly as possible.
alan what you say is most interesting and makes sense.
ned,
part of the pleasure of fclass for me is trying to maximize my potential with the tools at hand. you could be right about bullet height at the shorts, but i looked through my bore at 1000 yd once while the sights were on the target, & the angle of the bore was quite high.
i might have the opposite problem with my 45/2.4" blackpowder cartridge rifle - 550 gn bullets at 1300 fps going over the flags.
sometimes it is amazing how well the flags do predict bullet displacement if you can get in touch with the job. (rarely in my case)
there was a video of tony boyer shooting a group on 6br yesterday. for the life of me i don't know what he was shooting on with all those br windflags, but he seemed to know the deal. he even unloaded a group round and replaced it with a sighter. obviously if those bullets were jammed, the pre engraving on that projectile was of no concern to him, as he loaded it and shot it for score.
it looks like american palma shooters are using anemometers with compasses to give windspeed and direction on a screen on the mound. we are not allowed to do this.
bruce moulds
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Barry Davies
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Hi Ned,
Interesting post, particularly the reference to turbulance created by obstacles etc.
The worst range of those that we frequent would have to be Wellsford ( Bendigo )
Wellsford never used to be the unreadable range that it can be, prior to rebuilding the mounds. Prior to the rebuild it was just like any other range but now the exceptionally high mounds with the" skateboard park " like approaches create all manner of winds.
The honest ranges are like Horsham, Glenrowan, Warracknabeal, Rosedale etc -- all open to the elements and very flat.
Flags by necessity need to have some weight to cope with the high winds over the long distances experienced by FB shooters ( as distinct from BR shooters who shoot short range )
After having said that, without the wind ( and other atmospheric quirks ) FB shooting would be rather dull and boring. It is what it is -- fair to some, unfair to others.
Barry
Interesting post, particularly the reference to turbulance created by obstacles etc.
The worst range of those that we frequent would have to be Wellsford ( Bendigo )
Wellsford never used to be the unreadable range that it can be, prior to rebuilding the mounds. Prior to the rebuild it was just like any other range but now the exceptionally high mounds with the" skateboard park " like approaches create all manner of winds.
The honest ranges are like Horsham, Glenrowan, Warracknabeal, Rosedale etc -- all open to the elements and very flat.
Flags by necessity need to have some weight to cope with the high winds over the long distances experienced by FB shooters ( as distinct from BR shooters who shoot short range )
After having said that, without the wind ( and other atmospheric quirks ) FB shooting would be rather dull and boring. It is what it is -- fair to some, unfair to others.
Barry
Barry, I agree, without the ever changing variable of wind our scores would be dependent just on vision and equipment accuracy. We would need a Super Duper Centre to determine the winner!
Getting back to Bruce's comments about using wind speed instruments and relating them to flags. I say good luck to you Bruce because after using a Kestral instrument for a couple of years now I can say that if flags can be within 2mph when blown in opposing directions you have a particularly well tethered flag.
I have found that the wind speed rarely matches the drawings of flags used on plot sheets. I have also found that my Kestral is really only good for adding a measured amount of wind onto the scope for my first sighting shot. I wouldn't go to a range without measuring the wind before taking my first shot because flags give an inconsistent value range to range.
Then you need to consider trajectory or in particular the measure of bullet drop for the range you are shooting on. The bullet starts out lower than the line of sight to target, (scope mounting height) and arcs upwards while drag slows it and gravity pulls it down.
Lets take 2 examples, one at 500 yards and the other at 1000 yards. Bullet drop is indicated on ballistic charts with a negative number and is the point where the bullet crosses the line of sight for the second time. The first crossing is usually 10 yards of so in front of the muzzle (long range setup) and the second crossing should be when it hits the centre of the target.
At 500 yards your bullet will be around 2 feet higher than the muzzle but at 1000 yards the same bullet will go to 18 feet above the muzzle. If your trying to average wind with an instrument or using flags within a couple of mph then your a better man than me. I think it comes down to experience on the range and all thats gone before to predispose your mind to calculate a correct result.
Bruce, in your returned interest to the basics of shooting, you are making us all think about how it all fits together. An expert marksmen to my way of thinking is a man who has a complete understanding of ballistics but knows within himself that it is an art that requires constant practice. The more I understand shooting the more I realise that art (skill) and science are needed in equal quantities.
IanP
Getting back to Bruce's comments about using wind speed instruments and relating them to flags. I say good luck to you Bruce because after using a Kestral instrument for a couple of years now I can say that if flags can be within 2mph when blown in opposing directions you have a particularly well tethered flag.
I have found that the wind speed rarely matches the drawings of flags used on plot sheets. I have also found that my Kestral is really only good for adding a measured amount of wind onto the scope for my first sighting shot. I wouldn't go to a range without measuring the wind before taking my first shot because flags give an inconsistent value range to range.
Then you need to consider trajectory or in particular the measure of bullet drop for the range you are shooting on. The bullet starts out lower than the line of sight to target, (scope mounting height) and arcs upwards while drag slows it and gravity pulls it down.
Lets take 2 examples, one at 500 yards and the other at 1000 yards. Bullet drop is indicated on ballistic charts with a negative number and is the point where the bullet crosses the line of sight for the second time. The first crossing is usually 10 yards of so in front of the muzzle (long range setup) and the second crossing should be when it hits the centre of the target.
At 500 yards your bullet will be around 2 feet higher than the muzzle but at 1000 yards the same bullet will go to 18 feet above the muzzle. If your trying to average wind with an instrument or using flags within a couple of mph then your a better man than me. I think it comes down to experience on the range and all thats gone before to predispose your mind to calculate a correct result.
Bruce, in your returned interest to the basics of shooting, you are making us all think about how it all fits together. An expert marksmen to my way of thinking is a man who has a complete understanding of ballistics but knows within himself that it is an art that requires constant practice. The more I understand shooting the more I realise that art (skill) and science are needed in equal quantities.
IanP
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ned kelly
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G'day all,
The main points I wanted to make are the current flags do not respond immediately to direction changes as is often witnessed by changes in mirage direction. This is due to the weight of the flag material. An interesting experiment would be to use a lighter material similar to that used in yacht sails.
Also, air is a fluid just like water and you only have to watch a creek to see the back currents, eddy's and how the water speeds change so frequently around obstacles, etc. Especially if you muddy the water to see where the silt is carried. The issue with air is you cannot really see this happening. It is definately not static or even remotely linear unless the range is wide open and "honest" - a good term Barry!
Now considering the behaviour of a fluid, from the muzzle to 1000yds; a single point sample of wind speed and direction, either from a flag or wind meter simply cannot give you the whole picture of what is happening down range. Walking the range to the targets helps, you can feel WHERE the air movement is different, ask WHY, look at the terrain, vegetation, buildings etc. So would more responsive flags along either side of the range, perhaps even allowing personal competitor flags (no I am not seriously going there again!) Flags that do not accurately show the wind speed and direction will lead to flyers that do not correlate to the flags positions. You must use the mirage for a more accurate means of wind indication.
An example of this was Darren White at Castlemaine some years ago using a 6ppc 1:14' twist BR rifle and 70gn SMK's not exactly a FO cartridge nevertheless he had a solid 300yd score, at 500yds he was burned by the flags NOT showing the wind changes, unlike the mirage which was going with the spotter postion on the target (I was observing through a spotting scope). however he came back hard at 600yds by ignoring the flags, only watching the mirage to come back hard to come 2nd overall. I can't recall the scores but I seem to recall it was a low 90's at 500, and a high 90's at 300 and 600. Against shooters who had ballistically better cartidges and more experience and it was his first ever OPM...............
Also one more point, a stronger wind seems to reduce a lot of turbulance that lighter winds seem to have, I call it "blowing the crap off" the range to make it more honest, regardless of whether it is F class or 100/200 Benchrest. It probably concentrates it rather than allowing it to spread out in gentle winds and have a greater effect. So IF the flags agree with the mirage, I'm fairly happy to shoot, but always looking for the mireage to catch the flags out in a lie!
More food for thought
Cheerio Ned
The main points I wanted to make are the current flags do not respond immediately to direction changes as is often witnessed by changes in mirage direction. This is due to the weight of the flag material. An interesting experiment would be to use a lighter material similar to that used in yacht sails.
Also, air is a fluid just like water and you only have to watch a creek to see the back currents, eddy's and how the water speeds change so frequently around obstacles, etc. Especially if you muddy the water to see where the silt is carried. The issue with air is you cannot really see this happening. It is definately not static or even remotely linear unless the range is wide open and "honest" - a good term Barry!
Now considering the behaviour of a fluid, from the muzzle to 1000yds; a single point sample of wind speed and direction, either from a flag or wind meter simply cannot give you the whole picture of what is happening down range. Walking the range to the targets helps, you can feel WHERE the air movement is different, ask WHY, look at the terrain, vegetation, buildings etc. So would more responsive flags along either side of the range, perhaps even allowing personal competitor flags (no I am not seriously going there again!) Flags that do not accurately show the wind speed and direction will lead to flyers that do not correlate to the flags positions. You must use the mirage for a more accurate means of wind indication.
An example of this was Darren White at Castlemaine some years ago using a 6ppc 1:14' twist BR rifle and 70gn SMK's not exactly a FO cartridge nevertheless he had a solid 300yd score, at 500yds he was burned by the flags NOT showing the wind changes, unlike the mirage which was going with the spotter postion on the target (I was observing through a spotting scope). however he came back hard at 600yds by ignoring the flags, only watching the mirage to come back hard to come 2nd overall. I can't recall the scores but I seem to recall it was a low 90's at 500, and a high 90's at 300 and 600. Against shooters who had ballistically better cartidges and more experience and it was his first ever OPM...............
Also one more point, a stronger wind seems to reduce a lot of turbulance that lighter winds seem to have, I call it "blowing the crap off" the range to make it more honest, regardless of whether it is F class or 100/200 Benchrest. It probably concentrates it rather than allowing it to spread out in gentle winds and have a greater effect. So IF the flags agree with the mirage, I'm fairly happy to shoot, but always looking for the mireage to catch the flags out in a lie!
More food for thought
Cheerio Ned
Ned, air is a gas not a fluid but I understand what you are saying about eddies and swirls like water in a river.
Air is compressible and atmospheric pressure plays a role in altering the ballistics along with temperature, humidity and wind. Air density is difficult to calculate without a Kestrel type weather meter.
Different ranges are at different altitudes which affects air density. Here in SA at the lower Light range the altitude is only 4 metres above sea level whereas at Mt. Barker range its 406 metres.
Who said shooting was easy?
IanP
Air is compressible and atmospheric pressure plays a role in altering the ballistics along with temperature, humidity and wind. Air density is difficult to calculate without a Kestrel type weather meter.
Different ranges are at different altitudes which affects air density. Here in SA at the lower Light range the altitude is only 4 metres above sea level whereas at Mt. Barker range its 406 metres.
Who said shooting was easy?
IanP
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ned kelly
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G'day all,
you can get a better understanding of airflow as a fluid if you read any basic aerodynamics book.
I suggest the following "Mechainics of Flight" by A C Kermode which is a text book for all budding aircraft mechanics such as myself and Dazza, including chapters on air & airflow - subsonic speeds", airfoils at subsonic speeds, flight at transonic speeds, flight at supersonic speeds.
All fairly relevant to movement of ANY object through air regardless whether you are shooting a bullet or flying an aircraft.
You will learn that supersonic flow is a different beast to subsonic airflow too.
If you are after something a bit more advanced on why a plane is built the way it is try "The Anatomy of the Aeroplane" by Darrol Stinton it is more of an engineering tome rather than fluid dynamics, but it does cover aerodynamics and the design considerations and shape of the aircraft/wing etc i.e. drag vs lift etc.
Read either book and you will see the similarities to why bullets are shaped the way they are, much like an aircraft, they both "fly" through the air, and get moved by wind, need a high BC for efficiency etc.
Cheerio Ned
you can get a better understanding of airflow as a fluid if you read any basic aerodynamics book.
I suggest the following "Mechainics of Flight" by A C Kermode which is a text book for all budding aircraft mechanics such as myself and Dazza, including chapters on air & airflow - subsonic speeds", airfoils at subsonic speeds, flight at transonic speeds, flight at supersonic speeds.
All fairly relevant to movement of ANY object through air regardless whether you are shooting a bullet or flying an aircraft.
You will learn that supersonic flow is a different beast to subsonic airflow too.
If you are after something a bit more advanced on why a plane is built the way it is try "The Anatomy of the Aeroplane" by Darrol Stinton it is more of an engineering tome rather than fluid dynamics, but it does cover aerodynamics and the design considerations and shape of the aircraft/wing etc i.e. drag vs lift etc.
Read either book and you will see the similarities to why bullets are shaped the way they are, much like an aircraft, they both "fly" through the air, and get moved by wind, need a high BC for efficiency etc.
Cheerio Ned
Thanks for that Ned, I'm betting its interesting and technical. My father was an aircraft fitter stationed in Darwin during WW2. I read fluid but interpreted it as liquid, my mistake.
If anyone is interested in weather meters Kestrel make really good ones and info for them can be found here: http://www.nkhome.com/kestrel/
IanP
If anyone is interested in weather meters Kestrel make really good ones and info for them can be found here: http://www.nkhome.com/kestrel/
IanP
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