E-Targets for F-Class

[Mudeat]

You have 8 sensors, but you only need 3. There are 56 unique combinations of 3 from 8. so you run the 3-input equation 56 times and take the average. A fair strategy for dealing with an over-defined problem. I do something similar. But these 56 values are not independent. Most of them are dependent on each other. You can't get something from nothing, you still only have 8 unique numbers to start with.

Here's an analogy. Flip a coin, and it comes up heads. That's one measurement. The other side is tails. Measuring the other side provides no value. It's determined by the first. Two sided coin, one degree of freedom.

If you have two coins, then you have two degrees of freedom, requiring two measurements. Not four. And so on.

There's no question that closed targets can be more accurate then open. But it's certainly not because 56 is bigger than 12, 8, or 4. It's because closed targets do not have to deal with physical movement. Which can be handled through frame construction and stability. The precision of the internal calculations is not important.

Well, right. Due to lack of understanding of physics, I have seen a few target frames built by well meaning guys that were made from 1/4 aluminum welded together and then solidly mounted to 3/4 inch solid building sheathing. These suckers transmitted bullet impact shock wave, through the solid media, faster and ahead of the air shockwave of the cone behind the bullet. Completely erratic results. But they thought it needs to be solid - based in hearsay.

 

[243Mendoza]

Well, right. Due to lack of understanding of physics, I have seen a few target frames built by well meaning guys that were made from 1/4 aluminum welded together and then solidly mounted to 3/4 inch solid building sheathing. These suckers transmitted bullet impact shock wave, through the solid media, faster and ahead of the air shockwave of the cone behind the bullet. Completely erratic results. But they thought it needs to be solid - based in hearsay.

There was an article in the Bulletin where a group of engineers used accelerometers to locate shots based on the vibrations of the target caused by the projectile hitting the target. These systems can detect rubber bands hitting the target (using appropriate sensitive target).

 

[KenOath]

I think for many of the Australians we have a hard time relating to the "Hype and Marketing" that seems to be held in high regard. A good website and high ranking google hits is not out measure of a good system. We are just ones to drink the Cool Aid and trust in what is written on a good website. In fact I think we throw up barriers to slow things down when something comes on strong.

What The??

 

[GeoffR]

You have 8 sensors, but you only need 3. There are 56 unique combinations of 3 from 8. so you run the 3-input equation 56 times and take the average. A fair strategy for dealing with an over-defined problem. I do something similar. But these 56 values are not independent. Most of them are dependent on each other. You can't get something from nothing, you still only have 8 unique numbers to start with.

Here's an analogy. Flip a coin, and it comes up heads. That's one measurement. The other side is tails. Measuring the other side provides no value. It's determined by the first. Two sided coin, one degree of freedom.

If you have two coins, then you have two degrees of freedom, requiring two measurements. Not four. And so on.

There's no question that closed targets can be more accurate then open. But it's certainly not because 56 is bigger than 12, 8, or 4. It's because closed targets do not have to deal with physical movement. Which can be handled through frame construction and stability. The precision of the internal calculations is not important.

Actually I agree with a lot of this. Which is why I haven't (to my detriment I suppose) bothered to adopt an 8-sensor (per plane) approach. Nor have I bothered to run two planes as I couldn't see any real need.

My comments were more to do with the virtues of one mathematical method (multilateration) versus another (trigonometry). Which method do you use?

I have had a phone call from a shooter that recently experienced the "shrinking group" phenomena when moving back to 1200 yards. Not on your target I wish to point out! Forget about why anyone was shooting on an acoustic target at 1200 yards in the first place The point is, or was, normally groups expand with distance. These didn't. Some days later however in identical conditions, on manual targets, the groups grew as expected. Apparently three very experienced shooters in addition to the one that called me noticed this but have no explanation for it. Great scores though. Is there a shooter in the world who will complain about a smaller than expected group - especially one that appears close to the centre?

Any ideas? Could it be to do with the method used to calculate the impact point?

 

[spclark]

These suckers transmitted bullet impact shock wave, through the solid media, faster and ahead of the air shockwave of the cone behind the bullet. Completely erratic results. But they thought it needs to be solid...

Kinda like engineers thinking buildings’d better withstand earthquakes if build to resist movement, huh? So maybe there’s something to be gained in ‘tuning’ target structures to work with ETS (Electronic Target Sensors) in a manner similar to how we ‘tune’ load profiles to vibration harmonics & barrel movement in our rifles?

With my (admittedly obsolete Gen II SMT five-mic) system I get consistent results (at least for practice) from a backer built from wood & foam. Maybe there’s something to its sensors being mounted in an elastic medium too rather than a more rigid construction?

At WGC there may be an added benefit to the sensor masts arrayed in front of the aim point target carriers, decoupling potential for sensor feedback ‘noise’ associated with bullets impacting targets.

 

[Bindi2]

Kinda like engineers thinking buildings’d better withstand earthquakes if build to resist movement, huh? So maybe there’s something to be gained in ‘tuning’ target structures to work with ETS (Electronic Target Sensors) in a manner similar to how we ‘tune’ load profiles to vibration harmonics & barrel movement in our rifles?

With my (admittedly obsolete Gen II SMT five-mic) system I get consistent results (at least for practice) from a backer built from wood & foam. Maybe there’s something to its sensors being mounted in an elastic medium too rather than a more rigid construction?

At WGC there may be an added benefit to the sensor masts arrayed in front of the aim point target carriers, decoupling potential for sensor feedback ‘noise’ associated with bullets impacting targets.

My SMT gen2 target is 1200mm square. I am more than happy with the accuracy of 1mm at 900 yds on still days. I use coreflute with the aiming mark glued to it. I doubt that I have secondary impact noise problem. I adjust my scope so I don't shoot out my aim point or the middle. Shooting for group not score. I think the small size has a lot to do with its performance.
I have noticed that the smallest sized Kongsberg targets perform better to a much higher shot count before degrading than the larger targets.

 

[adamjmac]

Is there a shooter in the world who will complain about a smaller than expected group - especially one that appears close to the centre?

Any ideas? Could it be to do with the method used to calculate the impact point?

If I had to guess, I would guess it was a SMT 5 mic and the low left chrono is crooked. This leads to incorrect on target velocity and scales the results accordingly. Is more significant when velocity is lower.

 

[243Mendoza]

If I had to guess, I would guess it was a SMT 5 mic and the low left chrono is crooked. This leads to incorrect on target velocity and scales the results accordingly. Is more significant when velocity is lower.

The angle of the bullet may be significantly higher?

 

[GSS]

Regarding catching the crossfire shooters, I had a situation at the recent SWN where I sent a round downrange, my target goes down then comes up with 3 spotters on it. This was a first for me so I paused and looked back at my scorekeeper, but not a single shooter or scorekeeper on either side of me claimed to be missing a shot. So, my scorekeeper recorded the highest value spot and I continued...

Honest, diligent, and attentive human scorekeepers will continue to be an important part of the sport even with ET's in my opinion.

Archer,
Excellent point.
What you did is the correct thing by rule to do.

Hopefully now with velocity indicated on target for each shooter E Targets may helps sort that out.

If I knew I fired and my target didn't go down and I saw an adjacent target come up with more than one marker in it ( proving I crossfired ) I would know I did it and my scorer should know I did it. Even if my scorer was asleep and missed my crossfire I would insist that a Miss be recorded for that shot on my scorecard.

George

 

[Bindi2]

Archer,
Excellent point.
What you did is the correct thing by rule to do.

Hopefully now with velocity indicated on target for each shooter E Targets may helps sort that out.

If I knew I fired and my target didn't go down and I saw an adjacent target come up with more than one marker in it ( proving I crossfired ) I would know I did it and my scorer should know I did it. Even if my scorer was asleep and missed my crossfire I would insist that a Miss be recorded for that shot on my scorecard.

George

Many don't

 

[spclark]

Many don't

But that's not the target system's fault! That's simply ignorance of the rules in play; when hasn't taking the high value for multiple spotters been the right thing to do?

At WGC here in Wisconsin it's accepted practice in the event of 'spurious impacts' to ask a Range Officer to intercede. They have log-in privileges enabling access to target info that shows the velocity of spurious shots, making it a relatively simple task to discern whether in fact a cross-fire has occurred or not.

And it's not always from adjacent firing points either! It's happened from as far as ten line assignments away from the target where this has been noted that I'm aware of.

 

[sdean]

I would hope that somebody shot 10 targets over was asked to leave.

 

[Jdne5b]

I would hope that somebody shot 10 targets over was asked to leave.

Its possible to do at a range like Ben Avery if your gun bounces on recoil.

If scorers pay attention and crossfires arent an issue.

 

[sdean]

Its possible to do at a range like Ben Avery if your gun bounces on recoil.

If scorers pay attention and crossfires arent an issue.

I didn’t say impossible. He was talking about Wisconsin, well maybe to many assumptions. I know if I had a gun jumped that much I sure would be paying attention to which target I was shooting at.

 

[David101]

How much the nuts and bolts cost is largely irrelevant. Is your time worth nothing? There has been a development R&D, manufacturing for ten years most of it with more than just one person. There is a website that can do real time competition scores. Your score are stored and easily retrievable from the website at any time.

Most importantly you can ring Hexta any time (respectively working hours) however over the phone support and online computer sharing out of hours I have had more than once when I just wanted to learn the intricacies of the system more thoroughly. 24/7 customer support costs money. Website hosting and software cost money, Its not about how much one sensor costs *4

 

[rardoin]

How much the nuts and bolts cost is largely irrelevant. Is your time worth nothing? There has been a development R&D, manufacturing for ten years most of it with more than just one person. There is a website that can do real time competition scores. Your score are stored and easily retrievable from the website at any time.

Most importantly you can ring Hexta any time (respectively working hours) however over the phone support and online computer sharing out of hours I have had more than once when I just wanted to learn the intricacies of the system more thoroughly. 24/7 customer support costs money. Website hosting and software cost money, Its not about how much one sensor costs *4

All very true. However economics does come in to play in the majority of the e-target market. A Ferrari is an amazing piece of engineering with much capability and many features, aesthetics aside. A Toyota Camry is very reliable, no frills but will get to to work and back. I understand the costs behind a Ferrari and the limitation of a Camry. But, they both will get me to and from work. Only a small percentage of the market will be able to afford to purchase and maintain the Ferrari. The Camry, with it's limitations, is the one with the highest sales rate.

I have shot on the Hexta system and appreciate the dedicated display and the connectivity abilities. When it came time to buy a target for myself I chose a much cheaper option that is 'getting me to and from work' reliably.

Robin

 

[Erud]

I would hope that somebody shot 10 targets over was asked to leave.

Why would they be asked to leave? I’d say that 10 targets off is the 3rd most common crossfire after 1 target off and 2 targets off. It’s really easy to do at ranges like Camp Perry, Camp Atterbury, and Ben Avery where only every 10th target has the full target number on the number board. Particularly for sling shooters with iron sights, those number boards at 1000 yards can be pretty hard to read with zero or .5 magnification.

 

[jkl]

You would have to drive a bus to carry the shooters from Ben Avery that have shot 10 points off. It has happened many more times than you imagine. With 100 points I have seen people shoot more than 10 points off before. At the SWN I know I was fired on from 10 points off twice on Saturday.

John

 

[sdean]

You would have to drive a buss to carry the shooters from Ben Avery that have shot 10 points off. It has happened many more times than you imagine. With 100 points I have seen people shoot more than 10 points off before. At the SWN I know I was fired on from 10 points off twice on Saturday.

John

I stand corrected. The original I quoted was in Wisconsin I figured a smaller range. A 10 target spread on 10 firing points compared to a hundred is not the same to me.

 

[GeoffR]

If I had to guess, I would guess it was a SMT 5 mic and the low left chrono is crooked. This leads to incorrect on target velocity and scales the results accordingly. Is more significant when velocity is lower.

So the point is, an incorrect terminal velocity (Vt) can greatly affect the resultant calculated impact point. No? I guess you're saying on a 5-sensor SMT system it will be. Is a false or incorrect Vt not going to affect your system in the same way?

So if you you can eliminate that risk by not requiring an accurate Vt, you're ahead. No?

Multilateration requires no Vt so that is one factor - and risk - removed.