ray porter
Member
mmmmmm
do you drink it or snort i? before or after a match?
do you drink it or snort i? before or after a match?
Wind Probe/Indicator
- Thread starter Chism G
- Start date
M
mks
Guest
Andy,
Interesting. I have heard of interferometry to measure machined surfaces, and in combination with Doppler to measure the velocity of planets, but never to measure wind velocity. Is this what you expect to measure? How does that work?
In principle, Doppler radar (like on the weather channel) could be used to map wind velocity across the entire range. But the cycle time for weather Doppler is 4-6 minutes. Talk about slow flags!
Thanks,
Keith
Andy Cross
New member
Interferometers are comparators
Interferometers are essentially comparators. They compare one signal with another. In this case the white light signal being reflected from the target with the - normally felt but not seen - thermal IR signal. This image was created by sending the combined and overlapped signals to a chip loaded with Nikon firmware used in a D700. So how it interpreted the data is anyones guess. But with specifically written software it could map the air currents induced by heat which is what generates the mirage. IF you were to record one static image from when the first shot was fired and compare it with a live feed for the remaining shots in combination with the flags it could help. Even when there doesn't seem to be any mirage this would pick it up and make it visible. I'll keep picking away at the project.
Andy.
Andy,
Interesting. I have heard of interferometry to measure machined surfaces, and in combination with Doppler to measure the velocity of planets, but never to measure wind velocity. Is this what you expect to measure? How does that work?
In principle, Doppler radar (like on the weather channel) could be used to map wind velocity across the entire range. But the cycle time for weather Doppler is 4-6 minutes. Talk about slow flags!
Thanks,
Keith
Interferometers are essentially comparators. They compare one signal with another. In this case the white light signal being reflected from the target with the - normally felt but not seen - thermal IR signal. This image was created by sending the combined and overlapped signals to a chip loaded with Nikon firmware used in a D700. So how it interpreted the data is anyones guess. But with specifically written software it could map the air currents induced by heat which is what generates the mirage. IF you were to record one static image from when the first shot was fired and compare it with a live feed for the remaining shots in combination with the flags it could help. Even when there doesn't seem to be any mirage this would pick it up and make it visible. I'll keep picking away at the project.
Andy.
Glenn that happens here in New Zealand also.......I hate shooting when the flags aren't showing anything, you're just about guaranteed a big group......Ian
Weird
Hi Ian,
Looks like it may be a World wide phenomenon. It gets even weirder. A hand full of shooters at the same match I described, drilled little dots. Usually,its not the top shooters.
Some of the experts caution against tuning your rifle in dead calm conditions,and I think it makes sense. However,I don't have any facts/experience to corroborate that opinion. I tuned my rifle,the day before the match, in what I call, light conditions. My rifle was shooting little dots. I went to bed Friday night feeling confident that I would not totally embarrass myself the next day. (Sound Familiar). At the start of the match on Saturday Morning,My wind flags were dead still. I saw nothing that explains why I ended up with a .500 group at 100yds. I definitely did not have a hang over and I paid close attention to bag handling. Something else is going on down at The Tomball Rifle range and around the Country that nobody seems interested in talking about. "SHOOTING WHEN THERE IS NO WIND"
Glenn
Hi Ian,
Looks like it may be a World wide phenomenon. It gets even weirder. A hand full of shooters at the same match I described, drilled little dots. Usually,its not the top shooters.
Some of the experts caution against tuning your rifle in dead calm conditions,and I think it makes sense. However,I don't have any facts/experience to corroborate that opinion. I tuned my rifle,the day before the match, in what I call, light conditions. My rifle was shooting little dots. I went to bed Friday night feeling confident that I would not totally embarrass myself the next day. (Sound Familiar). At the start of the match on Saturday Morning,My wind flags were dead still. I saw nothing that explains why I ended up with a .500 group at 100yds. I definitely did not have a hang over and I paid close attention to bag handling. Something else is going on down at The Tomball Rifle range and around the Country that nobody seems interested in talking about. "SHOOTING WHEN THERE IS NO WIND"
Glenn
Gene Beggs
Active member
Something else indeed
Hi Ian,
Looks like it may be a World wide phenomenon. It gets even weirder. A hand full of shooters at the same match I described, drilled little dots. Usually,its not the top shooters.
Some of the experts caution against tuning your rifle in dead calm conditions,and I think it makes sense. However,I don't have any facts/experience to corroborate that opinion. I tuned my rifle,the day before the match, in what I call, light conditions. My rifle was shooting little dots. I went to bed Friday night feeling confident that I would not totally embarrass myself the next day. (Sound Familiar). At the start of the match on Saturday Morning,My wind flags were dead still. I saw nothing that explains why I ended up with a .500 group at 100yds. I definitely did not have a hang over and I paid close attention to bag handling. Something else is going on down at The Tomball Rifle range and around the Country that nobody seems interested in talking about. "SHOOTING WHEN THERE IS NO WIND"
Glenn, your thread has been most interesting, lots of good discussion here. There were two things you said that sent up a red flag to me:
1. "I tuned my rifle the day before the match,,,,"
2. "Something else is going on that nobody seems interested in talking about."
If you tune your rifle the day before the match it will most likely be done in the heat of the afternoon when temperature is much warmer than it will be early next morning. If you tune the rifle when temp is 90 degrees and preload for the first match tomorrow morning when temp is 70 degrees, you will be completely out of tune when you go to the line. Unless you have a tuner installed, you're stuck with twenty rounds that are loaded about .6 grains too light. That's one of the advantages of a tuner; you can correct for an out of tune condition during the match at the line before going to the record.
In (2) above you mention there is something else going on that nobody seems interested in talking about. Darn right there is; it's called wake turbulence.
Wake turbulence?
There are actually three components to the wake turbulence we shooters are faced with;
1. Ring vortices created by the muzzle blast. (This has nothing to do with the projectile.)
2. The wake left behind the supersonic bullet.
3. The column of extremely hot gases that are blasted into the much cooler atmosphere.
Bear in mind that all this commotion is blasted right down the flight path of all succeeding shots, and if conditions are dead calm, it will hang there and rotate for a surprisingly long time.
"So,,, what can be done about it?" you ask.
Well, for one thing, you can wait; wait for a little breeze to come along and drift the stuff out of your way.
The other option is to wait longer between shots. (This is one time when you don't want to 'machine gun' your record shots.)
Discussion?
Later,
Gene Beggs
Lets Discuss
Hi Gene,
Thanks for joining this discussion. You offer a viable explanation as to what may be happening on those cool mornings at Tom Ball,Tx. Your background in Aviation/physicis places you heads above my simple approach to the Sport. After thirteen years, this stuff is still a learning experience for me. As the Old Folks used to say,You're never too old to learn. I wouldn't have it any other way. Having said that. I'll share my personal experience(s) with the forum in hopes that the competitors who are more experienced than me will sort out the Physics,Which you have so eloquently done.
I seldom preload for a Match. When I do,its usually on Saturday afternoon in preparation for the early start (8:00AM) on Sunday. I know that I may have to change something after the first match on Sunday morning. I say" may",because there are times when I start off with a good group,with preloaded ammo. Especially when I'm shooting my favorite lot of 8208. VT-133 is a whole different story.I never know what to expect. In my thirteen years of addiction with this Sport,I have found few absolutes. It could be because I haven;t paid that much attention. Too busy having fun. Wouldn't have it any other way.
I recognize "Wake Turbulence" as something that occurs while flying Airplanes. I used to hear some of my Co-workers(Pilots) talk about it on my old job. I had no clue how much this phenomenon would affect bullet flight. My contention has been,if the flags aint telling you what's going on in front of the bench,you're just SOL. I'm not a good Mirage reader. Thanks for the explanation.
We recently held the UNL(10 shot) and HV at the NTSA(Denton,Tx). I took my newly acquired Rail Gun up to Denton on Friday and by late afternoon,I found a Tune that was shooting little bitty five shot groups.
The first Match on a cool Saturday morning,with the same load(Preloaded),in calm conditions, I shot a .166 ten shot group. Won the small group award for the UNL phase of the match. I shot em as fast as I could,which is not record breaking,but fast. There was plenty of turbulence out in front of the benches from the Rails blasting away. Maybe I just got lucky, Don't know. I went down hill after shooting that screamer. I own a couple of tuners but haven't learned how to use them.
I,however,accomplished my goal,of having fun and hanging out with some fun people.
Good to see you posting.
Glenn
Hi Gene,
Thanks for joining this discussion. You offer a viable explanation as to what may be happening on those cool mornings at Tom Ball,Tx. Your background in Aviation/physicis places you heads above my simple approach to the Sport. After thirteen years, this stuff is still a learning experience for me. As the Old Folks used to say,You're never too old to learn. I wouldn't have it any other way. Having said that. I'll share my personal experience(s) with the forum in hopes that the competitors who are more experienced than me will sort out the Physics,Which you have so eloquently done.
I seldom preload for a Match. When I do,its usually on Saturday afternoon in preparation for the early start (8:00AM) on Sunday. I know that I may have to change something after the first match on Sunday morning. I say" may",because there are times when I start off with a good group,with preloaded ammo. Especially when I'm shooting my favorite lot of 8208. VT-133 is a whole different story.I never know what to expect. In my thirteen years of addiction with this Sport,I have found few absolutes. It could be because I haven;t paid that much attention. Too busy having fun. Wouldn't have it any other way.
I recognize "Wake Turbulence" as something that occurs while flying Airplanes. I used to hear some of my Co-workers(Pilots) talk about it on my old job. I had no clue how much this phenomenon would affect bullet flight. My contention has been,if the flags aint telling you what's going on in front of the bench,you're just SOL. I'm not a good Mirage reader. Thanks for the explanation.
We recently held the UNL(10 shot) and HV at the NTSA(Denton,Tx). I took my newly acquired Rail Gun up to Denton on Friday and by late afternoon,I found a Tune that was shooting little bitty five shot groups.
The first Match on a cool Saturday morning,with the same load(Preloaded),in calm conditions, I shot a .166 ten shot group. Won the small group award for the UNL phase of the match. I shot em as fast as I could,which is not record breaking,but fast. There was plenty of turbulence out in front of the benches from the Rails blasting away. Maybe I just got lucky, Don't know. I went down hill after shooting that screamer. I own a couple of tuners but haven't learned how to use them.
I,however,accomplished my goal,of having fun and hanging out with some fun people.
Good to see you posting.
Glenn
Last edited:
Butch Lambert
Active member
Glenn,
We found a good place to eat in Arkansas didn't we.
We found a good place to eat in Arkansas didn't we.
Andy Cross
New member
These mysteries visualised
Hi Ian,
Wake turbulence?
There are actually three components to the wake turbulence we shooters are faced with;
1. Ring vortices created by the muzzle blast. (This has nothing to do with the projectile.)
2. The wake left behind the supersonic bullet.
3. The column of extremely hot gases that are blasted into the much cooler atmosphere.
Gene Beggs
These are the types of mysteries the interferometer would pick up and display. Being able to see the condition the flags probably don't respond to and find out how they affect a bullet will be a big learning curve. But you can't do that without the tools.
Andy.
The "Poor Horse Grill". It was better last year. They must have changed cooks. If I had to vote on the best place to eat in Arkansas,it would be the food that match director John Henry's wife Remy lays out for lunch at the Range.
It don't get too much better than that.
Glenn
DeltaBravo
Member
Gene, Glenn, Andy,
Is there any consistency to the effects of these gun/bullet-induced turbulences or vortices? If I have an absolutely DEAD day, no wind at all, flags just sitting there, can I expect my bullets to be deflected one direction only, or is it random? If I wait long enough for the initial turbulence to go away, will my bullet deflection repeat in direction and magnitude?
Is any of the turbulence related to rate and direction of twist? I can imagine that the hot gases being ejected behind the bullet would corkscrew in alignment with the rifling - clockwise for a right hand twist for example - but have no proof. More for a fast twist, less for a slower twist?
Geez, you guys really know how to scramble someone's brain cells!
Dennis
Is there any consistency to the effects of these gun/bullet-induced turbulences or vortices? If I have an absolutely DEAD day, no wind at all, flags just sitting there, can I expect my bullets to be deflected one direction only, or is it random? If I wait long enough for the initial turbulence to go away, will my bullet deflection repeat in direction and magnitude?
Is any of the turbulence related to rate and direction of twist? I can imagine that the hot gases being ejected behind the bullet would corkscrew in alignment with the rifling - clockwise for a right hand twist for example - but have no proof. More for a fast twist, less for a slower twist?
Geez, you guys really know how to scramble someone's brain cells!
Dennis
Dead calm works a little better here in the Left than elsewhere I think...... SOMETIMES I can shoot little ones in the calm here in WA.
Other times you'd best just wait until the wind blows......if it's dead calm and there's air in the group??? Just walk away!
Also, I can and do shoot 24-7 and 365 here at the house and can state that shooting at night under lights is a complete waste of energy in the calm and shooting over snow in calm is a waste day or night IME.
Now if it's calm and raining or snowing, you're golden rain and snow may be the best windflags.
al
Other times you'd best just wait until the wind blows......if it's dead calm and there's air in the group??? Just walk away!
Also, I can and do shoot 24-7 and 365 here at the house and can state that shooting at night under lights is a complete waste of energy in the calm and shooting over snow in calm is a waste day or night IME.
Now if it's calm and raining or snowing, you're golden
rain and snow may be the best windflags.al
Safe at home.
Jerry...This looks like some type of wind flag. How does it work? If you can talk about it.
Glenn
"Turbulence"
I've shot some small groups,at a match,where the air in front of the benches was turbulent from gun blasts. I have also had some unexplained flyers in the same conditions. Some of them "Where did that come" shots. It's gotta be something that the traditional flag designs are not indicating. As explained by Gene and Andy.
A Turbulence Story: I was on a shuttle flight from Washington,DC to New York City back in the 80's. It was about a 45 minute flight from Washington National to Laguardia Airport. Due to the short flt time,we(passengers) only had time for coffee,juice,etc. I ordered a big coffee. The flight was bumpy when we took off from National Airport. Real Bumpy. It was so quite in the cabin of that aircraft,you could hear a mouse fart at a Rock Concert. About half way through the trip,the airplane suddenly dropped what felt like 200 feet(Guessing)
All of The Coffee came out of my cup and suspended in midair. The Aircraft came back to level and the coffee and other liquids sprayed throughout the cabin. I heard blood curdling screams,my suit was messed up from coffee stains and I did not have an extra. Swore I'd never fly again.
On a smaller scale,imagine what turbulence can do to bullets fired at a benchrest match. If your flags don't tell you its there, You're,literally just pissing in the wind.
Glenn
I've shot some small groups,at a match,where the air in front of the benches was turbulent from gun blasts. I have also had some unexplained flyers in the same conditions. Some of them "Where did that come" shots. It's gotta be something that the traditional flag designs are not indicating. As explained by Gene and Andy.
A Turbulence Story: I was on a shuttle flight from Washington,DC to New York City back in the 80's. It was about a 45 minute flight from Washington National to Laguardia Airport. Due to the short flt time,we(passengers) only had time for coffee,juice,etc. I ordered a big coffee. The flight was bumpy when we took off from National Airport. Real Bumpy. It was so quite in the cabin of that aircraft,you could hear a mouse fart at a Rock Concert. About half way through the trip,the airplane suddenly dropped what felt like 200 feet(Guessing)
All of The Coffee came out of my cup and suspended in midair. The Aircraft came back to level and the coffee and other liquids sprayed throughout the cabin. I heard blood curdling screams,my suit was messed up from coffee stains and I did not have an extra. Swore I'd never fly again.
On a smaller scale,imagine what turbulence can do to bullets fired at a benchrest match. If your flags don't tell you its there, You're,literally just pissing in the wind.
Glenn
Jerry H
Different Drummer
Smartflag 4 is a speed sensor (anemometer) feeding a direction sensor (vane) using a similar non-linear effect of actual ballistics (small direction change near 90 means nothing while it means a lot near null). This electro-mechanical combo of a speed and direction signal is the resultant relative displacement from center expressed as a DC voltage.
Apollo
Jason Stanley
A couple things to keep in mind when shots don't go where they are supposed to in a properly tuned, mechanically sound rifle:
1. Mirage. Mirage trumps windflags and does not always go in the same direction the flags are showing. One thing that I look for when there is mirage: wait for the mirage to be different than the flags - then watch for the first flag to follow mirage. That flag is pretty important. (not implying that they are not all important - just that is a "must hit" flag.
2. Assuming you use 4 flags at 100 yds. Each flag is roughly 1/8" thick, but let's say they are turned sideways and call it a foot. 4x12" = 48" If you are looking only at flags you are only seeing 48" of 100 yds or 48" in 3,600"= 1.3% of the range. Flag placement is critical. One thing I like to do is walk the range and just feel when there is a wind change. Drop a pole there and continue on down the range. Make needed adjustments from there.
Stanley
1. Mirage. Mirage trumps windflags and does not always go in the same direction the flags are showing. One thing that I look for when there is mirage: wait for the mirage to be different than the flags - then watch for the first flag to follow mirage. That flag is pretty important. (not implying that they are not all important - just that is a "must hit" flag.
2. Assuming you use 4 flags at 100 yds. Each flag is roughly 1/8" thick, but let's say they are turned sideways and call it a foot. 4x12" = 48" If you are looking only at flags you are only seeing 48" of 100 yds or 48" in 3,600"= 1.3% of the range. Flag placement is critical. One thing I like to do is walk the range and just feel when there is a wind change. Drop a pole there and continue on down the range. Make needed adjustments from there.
Stanley