LouBoyd
Well-Known Member
- Joined
- Oct 15, 2007
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- 770
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- City & State/Province
- Patagonia Mountains, Arizona
The article by Bryan Litz "Fullbore Bullet Update" in the latest (Aug,1009) Precision Shooting magazine was very interesting. In Fullbore and Palma the rules regarding the bullet and cartridge have forced the bullet designs to become very similar for most manufacturers. That also indicates to me that little future improvment is to be expected in the way of new bullets.
In looking at the computer simulations of hypothetical matches one thing stood out clearly. Each simulation showed the errors were dominated by horizontal stringing which I assume was the result of the simulation programs using a typical statistcallly weighted amount of error in wind deflection estimation for each shot. Is that a correct assumption?
If that's the case then it would seem to me that the area that needs most attention in long range shooting is to improve the ability to determine the crosswind velocity over the range, or at least the overall effect of whatever crosswinds exist over the trajectory. No other error source is close!
The only device to measure downrange croswinds for shooting purposes I've seen was published in the Very High Power publicatioin of the FCSA about 15 years ago. It was an article by Israeli researches using a PC, a laser, and a couple of photodetectors. They claimed a demonstrated abilty to measure and supress croswind deflection by about 90% (stilll a 10% error in detmining the effect of the crosswind relative to making no correction) and stated that to be about equal to an expert shooter esitmating defelction from watching mirage. flags, or similar indicators. I've not found anyting on that work since from web searches.
There are some references to the aiming system used on the Abrams tank which uses some form of laser crosswind measurements but few details. There was a DOD "request for proposals" for a riflescope which woiuld have both drop and crosswind compensation a few years ago. That was on both some websites and a military laser trade journal. The result of that either came to nothing or became classified. I presume the latter.
There are companies selling commerical "scintillation anemometers" which measure crosswind velocity vs distance at ranges of a few kilometers. Most list applications such as predicting the movement of atmospheric contaminants for envronmental studies.
I'm seems to me that portable device capable of measuring crosswind speed (and it's corresponding bullet defelection) without the need for donnrange equpement is pracical which could work to at ranges to at least a mile. It should not have to be large or unreasonably expensive. I would expect it would have a higher wind speed capability and a lower air temperature limit than visual estimation does when mirage vanishes becaue of the movement of thermal air cells being to rapid or too weak for the human eye to follow. PC's, fast cameras, and lasers have improved a lot in price and speed since the Israeli article. The hardware in the article was crude.
This seems to me to be an area where a considerable imprvement in long range accuracy for hunters as well as the military could be made with modest effort. The range esitmation and drop cacluation in shooting has been mastered with the laser rangefinder. Crosswind measuement seems to me to be the only major problem still to addressed. A scintillantion anemometer can measure the crossswind's vertical component too. That's just a second axis to callculate in the software. The vertical component is rarely of concern except when shooting in mountainous terrain. The scintillation anemometer cannot measure head and tail winds. There are doppler LIDAR's which can, but they are much more complex and costly. Head and tail wind have a much smaller effect on bullet trajectories, and in most cases can be ignored.
questions to this group.
1. Would a a device wich works as binoculars, a rangefinder, and calulates wind deflection be of use? At what price? Assume it weighs 3 lbs and is the size of large binoculars. It could also measure lead for moving target. Later models might be contained entirely in the riflecope. I'm not trying to market one, but I'd like to stimulate some manuacturer to do so. Leica or Leupold have the technology. Perhaps Bushnell or NcStar...
2. Would it be legal for competiton. Palma, F Class, 1000 Yd Benchrest, etc?
3. Would it be "sporting" to use for hunting? ( assuming it works reliably).
4, Any arguments against why it shoudn't work? The concept is essentaily to measure the movement of air cells the way a human measures mirage, but use an infrared laser to produce a dot at the target wihch will backscatter to the receiver. The receive then analizes the returning light not unlike the way an optical mouse watches the movement of the light patterns reflecting off desktop.. The unit could emphasize the the movement near the receiver and at intermediate distances based on the objective lens focus. It could do that for multiple distances simultainously and apply the proper weighting. It woudn't be perfect, but It should be better than a human wth a spotting scope can possible do. The human eye and brain simply don't have the speed or brightness resoluiton of a ccd camera and microprocessor, nor does a human have the abllity to reduce the moving light patterns mathematically to bullet deflections in real time.
5. Does anyone konw of unclassified articles in the area of optical downrange wind measurement ? Perhaps references on the web or available books.
And to Byran Litz. I just received your new book is great! It gives a lot of practical expanations to Robert McCoys book "Modern Exterior Ballistics". The sections on how error sources combine should be very useful to any long range shooter.
In looking at the computer simulations of hypothetical matches one thing stood out clearly. Each simulation showed the errors were dominated by horizontal stringing which I assume was the result of the simulation programs using a typical statistcallly weighted amount of error in wind deflection estimation for each shot. Is that a correct assumption?
If that's the case then it would seem to me that the area that needs most attention in long range shooting is to improve the ability to determine the crosswind velocity over the range, or at least the overall effect of whatever crosswinds exist over the trajectory. No other error source is close!
The only device to measure downrange croswinds for shooting purposes I've seen was published in the Very High Power publicatioin of the FCSA about 15 years ago. It was an article by Israeli researches using a PC, a laser, and a couple of photodetectors. They claimed a demonstrated abilty to measure and supress croswind deflection by about 90% (stilll a 10% error in detmining the effect of the crosswind relative to making no correction) and stated that to be about equal to an expert shooter esitmating defelction from watching mirage. flags, or similar indicators. I've not found anyting on that work since from web searches.
There are some references to the aiming system used on the Abrams tank which uses some form of laser crosswind measurements but few details. There was a DOD "request for proposals" for a riflescope which woiuld have both drop and crosswind compensation a few years ago. That was on both some websites and a military laser trade journal. The result of that either came to nothing or became classified. I presume the latter.
There are companies selling commerical "scintillation anemometers" which measure crosswind velocity vs distance at ranges of a few kilometers. Most list applications such as predicting the movement of atmospheric contaminants for envronmental studies.
I'm seems to me that portable device capable of measuring crosswind speed (and it's corresponding bullet defelection) without the need for donnrange equpement is pracical which could work to at ranges to at least a mile. It should not have to be large or unreasonably expensive. I would expect it would have a higher wind speed capability and a lower air temperature limit than visual estimation does when mirage vanishes becaue of the movement of thermal air cells being to rapid or too weak for the human eye to follow. PC's, fast cameras, and lasers have improved a lot in price and speed since the Israeli article. The hardware in the article was crude.
This seems to me to be an area where a considerable imprvement in long range accuracy for hunters as well as the military could be made with modest effort. The range esitmation and drop cacluation in shooting has been mastered with the laser rangefinder. Crosswind measuement seems to me to be the only major problem still to addressed. A scintillantion anemometer can measure the crossswind's vertical component too. That's just a second axis to callculate in the software. The vertical component is rarely of concern except when shooting in mountainous terrain. The scintillation anemometer cannot measure head and tail winds. There are doppler LIDAR's which can, but they are much more complex and costly. Head and tail wind have a much smaller effect on bullet trajectories, and in most cases can be ignored.
questions to this group.
1. Would a a device wich works as binoculars, a rangefinder, and calulates wind deflection be of use? At what price? Assume it weighs 3 lbs and is the size of large binoculars. It could also measure lead for moving target. Later models might be contained entirely in the riflecope. I'm not trying to market one, but I'd like to stimulate some manuacturer to do so. Leica or Leupold have the technology. Perhaps Bushnell or NcStar...
2. Would it be legal for competiton. Palma, F Class, 1000 Yd Benchrest, etc?
3. Would it be "sporting" to use for hunting? ( assuming it works reliably).
4, Any arguments against why it shoudn't work? The concept is essentaily to measure the movement of air cells the way a human measures mirage, but use an infrared laser to produce a dot at the target wihch will backscatter to the receiver. The receive then analizes the returning light not unlike the way an optical mouse watches the movement of the light patterns reflecting off desktop.. The unit could emphasize the the movement near the receiver and at intermediate distances based on the objective lens focus. It could do that for multiple distances simultainously and apply the proper weighting. It woudn't be perfect, but It should be better than a human wth a spotting scope can possible do. The human eye and brain simply don't have the speed or brightness resoluiton of a ccd camera and microprocessor, nor does a human have the abllity to reduce the moving light patterns mathematically to bullet deflections in real time.
5. Does anyone konw of unclassified articles in the area of optical downrange wind measurement ? Perhaps references on the web or available books.
And to Byran Litz. I just received your new book is great! It gives a lot of practical expanations to Robert McCoys book "Modern Exterior Ballistics". The sections on how error sources combine should be very useful to any long range shooter.
