Testing E Target Accuracy

[243Mendoza]

The reference looks like it is for the case where the gas is moving over a stationary object (like an airfoil in a wind tunnel) rather than the case where the object is moving thru stationary gas (like a bullet thru air). It has been a long time since I worked with this sort of thing so I may be mistaken.

No difference in the results with a stationary frame of reference or reference frame moving with constant speed.

 

[243Mendoza]

...

Add air turbulence to the scenario (in open systems or closed once the membranes’ integrity has been compromised in use) how does one factor in the differences for what each sensor’s input shock experiences between moment of passage at array then at each individual sensor?

For external etargets, you probably cannot correct for this turbulence effect which will result in random errors.

 

[243Mendoza]

Im curious what the error is at a 300 yard mid range match after 60 shots by a 1/4 moa Dasher on the same F Class repair center on a conventionally scored paper target match.

Asking the NRA High Power Committee to establish certification standards, is very much like asking the FAA to certify UFOs. The requisite knowledge and competence to fully understand, comprehend, and then apply the science isn't held within the High Power Committee as a whole.

A potential path to follow...

1. Establish what the mean statistical error is of the current gold standard, a paper manually scored match. Obtain this data from either polling the high power/match directors of the high power community, or form a study group that obtains this data from the observation of actual matches. From there, an actual precision standard with a meaningful statistical mean can be determined. Paper matches are not able to meet the .25" standard 100% of the time, so a real world data derived # needs to be assigned to the current gold standard. First.

2. NRA Partners with industry. Despite what the threads on here may indicate, there's less than a dozen minds in the world that have the relevance and competence necessary to apply acoustic target technology to NRA High Power disciplines. Leverage the industry leaders of this tech, to develop proposed certification standards based off the capability of the technology.

3. Analyze the proposed certification pathways presented by industry, and compare with current paper match practices, to determine if the science behind the industry proposed certification pathways can meet/match/improve precision based on current paper match precision.

4. Keep in mind the charter of NRA comp shooting, by remaining true/faithful to history, past records, and the intent/practices behind current disciplines, and leveraging new technology to improve the shooter experience and grow the sport.

Excellent comments! I don't think that the NRA is willing to put serious effort into certifying etargets.

Here is a paper/study on how accurate is good enough for etargets which can be a starting point for the NRA.

This document shows if competitors who were in the top 3 or 5 in a match with paper targets would place the same top 3 or 5 with etargets.

The data for the SMT is based on the old 5-sensor system so the statistics need to be updated but nonetheless the methodology is good.

The Australians are pioneers in the development, testing and use of etargets and their methodology has not been bettered.

 

[GSS]

I don't think that the NRA is willing to put serious effort into certifying etargets.

Many of us are anxiously awaiting the release of the OFFICIAL NRA Rules Updates to see what the future holds for NRA E target certification.

All my NRA and CMP matches were approved this year stating ShotMarkers will be used.


Those of us that invested in ShotMarker or Silver Mountain will do well to be in contact with the NRA and CMP as the certification procedures are developed.

 

[243Mendoza]

Many of us are anxiously awaiting the release of the OFFICIAL NRA Rules Updates to see what the future holds for NRA E target certification.

All my NRA and CMP matches were approved this year stating ShotMarkers will be used.

I have no evidence of this. Just a hunch... but
I wouldn't put it past the Ferrarri dealer(s) that are not selling many units to lobby to get the Chevy's and Fords pushed out... just a hunch. Time will tell...

Those of us that invested in ShotMarker or Silver Mountain will do well to be in contact with the NRA and CMP as the certification procedures are developed.

I strongly suspect that the NRA will be in hot spot and will certify external sensor systems since so many are in operation.
They will have to not only increase the .25" requirement but have a more meaningful statistical standard.

My question is: what system will they use for the National Matches when/if they go etargets?

 

[sdean]

I strongly suspect that the NRA will be in hot spot and will certify external sensor systems since so many are in operation.
They will have to not only increase the .25" requirement but have a more meaningful statistical standard.

My question is: what system will they use for the National Matches when/if they go etargets?

Might be a moot point. Already had national matches on them

 

[Bindi2]

A .25" is too large an error for competition shooting.

 

[Rtheurer]

Yet if you shoot on Ranges like Ben Avery in Phoenix, Oak Ridge Tennessee, or others that have older Cantilever Target carriers in a conventional paper target/carrier . Those targets bob and weave a lot more than 1/4" in a windy condition they move more than you can imagine. So if your precicely aiming at the X or V bull and the wind bounces it over an inch left right or up down no one gives it a second thought...

 

[Warren Dean]

 

[Bindi2]

Not sure what you mean by two sheets. I coincide the virtual/acoustic and paper centers by removing the average error in x an y resulting in the random errors.

The actual shot sheet is one. Two is the shots plotted from the X Y on the monitor. Place two over the actual and move for best fit. Shows the real story because the acoustic centre is not X marks the spot which also decreases the random error to show how the target is actually working. The error will be consistent or as better explained repeatable ie the same with a slight increase the further the shot from the centre.

 

[Bindi2]

Yet if you shoot on Ranges like Ben Avery in Phoenix, Oak Ridge Tennessee, or others that have older Cantilever Target carriers in a conventional paper target/carrier . Those targets bob and weave a lot more than 1/4" in a windy condition they move more than you can imagine. So if your precicely aiming at the X or V bull and the wind bounces it over an inch left right or up down no one gives it a second thought...

You are very right. This is one of the problems that ET testing found here. Also the mounds or firing points not square to the targets. ETs have improved the accuracy of recording because we found how inaccurate the manuals were and had to address the situation.

 

[243Mendoza]

The actual shot sheet is one. Two is the shots plotted from the X Y on the monitor. Place two over the actual and move for best fit. Shows the real story because the acoustic centre is not X marks the spot which also decreases the random error to show how the target is actually working. The error will be consistent or as better explained repeatable ie the same with a slight increase the further the shot from the centre.

THis will be difficult since one is paper and the other in on the computer screen. So you would have to take a screen shot of the etarget and a picture of the paper target which will have some distortion due to perspective and you need to to do some fiddling on scaling to get a decent match on size and after all this you only get a visual comparison. I prefer actual measurements and as I said, I match the acoustic center with the paper center.

 

[Bindi2]

THis will be difficult since one is paper and the other in on the computer screen. So you would have to take a screen shot of the etarget and a picture of the paper target which will have some distortion due to perspective and you need to to do some fiddling on scaling to get a decent match on size and after all this you only get a visual comparison. I prefer actual measurements and as I said, I match the acoustic center with the paper center.

No fiddling you plot the shots from the x y of each shot onto the clear sheet two which is overlayed onto the actuals on sheet one, moving sheet two for best fit. This shows the true error if any. The true error will be the same for each shot . It will also show that the acoustic centre is not X marks the spot but is actually is a small area. The quadrant lines on the two sheets will show this.
Best Fit. . Best Fit. We have some targets that come very close to pin point but most show a small repeatable error that is in the shooters favour. A quarter inch accuracy is not acceptable here in closed sound chambers.

 

[243Mendoza]

No fiddling you plot the shots from the x y of each shot onto the clear sheet two which is overlayed onto the actuals on sheet one, moving sheet two for best fit. This shows the true error if any. The true error will be the same for each shot . It will also show that the acoustic centre is not X marks the spot but is actually is a small area. The quadrant lines on the two sheets will show this.
Best Fit. . Best Fit. We have some targets that come very close to pin point but most show a small repeatable error that is in the shooters favour. A quarter inch accuracy is not acceptable here in closed sound chambers.

OK, understood about the overlays. But the complete error will not be a constant; once you have centered the virtual with the paper center to the best of your ability, there remains random error.


An error of .25 may not be acceptable but not attainable with external targets. Have no experience in testing closed chamber targets.

 

[Bindi2]

OK, understood about the overlays. But the complete error will not be a constant; once you have centered the virtual with the paper center to the best of your ability, there remains random error.


An error of .25 may not be acceptable but not attainable with external targets. Have no experience in testing closed chamber targets.

Random error on my SMT is the environmental effects. I have tested the SMT on very good still days to be as accurate as the Kongsbergs with the same pattern of true error. I don't know if the error is in the frame build or the programming after all the range defects have been eliminated. There is true error( in built ) and then there is the random. We identified the random fixed them then found there is a true error which we accepted as it was constant. If the target is repeatable it is good to go regardless what the error is because the shooter makes adjustments to record Xs.

 

[243Mendoza]

Random error on my SMT is the environmental effects. I have tested the SMT on very good still days to be as accurate as the Kongsbergs with the same pattern of true error. I don't know if the error is in the frame build or the programming after all the range defects have been eliminated. There is true error( in built ) and then there is the random. We identified the random fixed them then found there is a true error which we accepted as it was constant. If the target is repeatable it is good to go regardless what the error is because the shooter makes adjustments to record Xs.

What was the true error and typical random error on the SMT? What did you do to fix random error?

According to the Aussie tests, random error was decreased with increasing terminal bullet speed which is not an environmental effect (or could it be that faster bullets are less affected by the environment?).

 

[Bindi2]

I got down to 1mm @ 900yds. The random I gave up on as I was not shooting for score. Bullet shape seem to have a bearing on things but finding days without wind when you live on the coast is almost next to fairy dust on the top shelf. Early mornings can be ok. My target is small 1200mm square so altering the H W to correct the X Y of the shots was not hard. Once I had that I knew the target was working the random was caused by something else which in my case the wind was picking up time to go home for breakfast. I have used the target during windy days knowing the groups are more compact than what is being shown.
10+mm was not uncommon at times as load development was carried out. The actual groups were better than the recorded ones. 9 groups per 300m aim centre. The further back I went so the recording differed. I am happy using it for what I need. For big comps no, social club shooting where results are more about who buys the first beer yes. The 8 mics are a new ball game to me. We are running out of pit workers which meant we were losing shooters because of the pit work. So ETs were the answer just had to solve the issues.

 

[243Mendoza]

1mm is a amazing! I never go below .25" but I was testing over the whole 6'x6' frame.

Not sure what you mean by "The random I gave up on as I was not shooting for score."?

How does altering H W correct x y of the shots since H and W are measurements of the sensors and they to the nearest mm?

 

[Bindi2]

1mm is a amazing! I never go below .25" but I was testing over the whole 6'x6' frame.

Not sure what you mean by "The random I gave up on as I was not shooting for score."?

How does altering H W correct x y of the shots since H and W are measurements of the sensors and they to the nearest mm?

When you measure the shot hole to find the x y and the monitor x y is different to the actual change the H or W to correct. You will arrive at a setting that will not get you any closer to the actual. What this shows is the true error which will be constant across all shots. Random is an error greater or different placement to that.

 

[243Mendoza]

When you measure the shot hole to find the x y and the monitor x y is different to the actual change the H or W to correct. You will arrive at a setting that will not get you any closer to the actual. What this shows is the true error which will be constant across all shots. Random is an error greater or different placement to that.

This is totally confusing.

H and W are not variables to change error, they are the sensor location which do not change unless you move the sensors, is that correct? I may be misunderstanding what you mean by H and W.