Declinating the M2A2 Aiming Circle
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- Опубликовано: 21 авг 2020
- A demonstration of how to use a declination station to declinate an M2A2 Aiming Circle and produce a Declination Constant that can be used to establish grid azimuths via Mag Check.
Excellent block of instruction, Devil Dog! I was an 11C at Benning and GE. Made it to Check Computer. nobody trusted me to do this shit. I don’t blame them. 😂. Truly appreciate!
EDIT: I found your other video on setup, plumbing the tripod, and leveling the aiming circle which explained everything I mentioned below. That was a great video, except for the minor mistake of using "45°" and "1600 mils" interchangeably. (I decided to leave my original comment here, if for no other reason than to draw attention to the procedures and your other video)
I was a Fire Direction Chief in a 4.2" Heavy Mortar Platoon in both Germany and South Korea. Your demonstration, and procedures were spot on; however, I think it would have been helpful if you would have explained more about how to set up and determine that the tripod was plumb with the declination station. Some people may not know what "plumb" means during this calibration. Also, I think you should have included the very important step of leveling the instrument after it has been mounted on top of the tripod base by using the three "leveling screws". It is very important to know that when using the leveling screws that you always turn the screws with your thumbs in the proper direction, i.e. both thumbs moving towards each other, or away from each other. This technique makes it much easier to center the bubble in the circle of the leveling window.
I understand. The video is meant displayed after a several hour long PowerPoint presentation. For someone trying to learn off of these videos alone, I could see that being a potential issue.
That being said, these videos could easily be an hour+ long each. I had to make these videos in my free time and didn't have much of it at the time. I wish that I still had some of the gear so that I could remake the videos.
On my Wild G10 it has a calibration screw for "Declination". I thought that it maybe used for setting the magnetic declination of a known area. Here on Van Isl I set my Brunton to 16° 22' East and I thought that I would convert that angle to mil and set it with the declination screw on the instrument. I see your method works great in the ball part, but in the field there would be no known aiming points unless the engineering team had set them up prior to setting up the guns. Your videos have brought me closer to what I want to know. Now you just got to give me the book, lol.
I sent you an email
Hey your idea of using a known magnetic declination is clever but you have to account for the fact that magnetic declination can actually vary a lot in a given area (by more than a few mils). The instrument you're using also produces some inacurracies from manufacture or wear that the method shown in the video mitigates.
I set up my instrument on a clear night and took a star shot on Polaris and made a reference point on a building 0.5 Km away. The next morning I sighted on that point and set my compass to North.
@@wojtekimbier You have to redec if you move more than 25 miles from where you dec it from
I keep metal away from the AC and it rode home in my lap after it was done at the declination station
How could you have a trig list or a known point?
Does this take curvature of the Earth into account in any way?
Cowboys round up, in the artillery we "artillery express"...
How does one create Quadrants for my known point? What I did was using GPSS Set up a base station over another known point. Set Up an S7 Theodolite over the point I wanted to make a Dec station over. Then walked with the GPSS Rover to a point I could sight in on, I used the side of a building, a fence pole, a power pole, and a roof corner. Then after recording the points with the GPSS I measured Topo from The S7 point to Quad 1 Quad 2 Quad 3 and Quad 4 to get the Azimuths for my trig list. Is this the right method? Also what would you say one should do if survey recovery hasnt been done on known points in roughly 8 years.
Fantastic questions. The quadrants for a Dec station need to be at least 300 meters away from the OS and higher than a 5th order grid azimuth accuracy. The quadrants also need to be placed as follows in reference to Grid North: (quad 1 = 0 to 1600 mils, quad 2 = 1600 to 3200 mils, quad 3 = 3200 to 4800 mils, quad 4 = 4800 to 6400 mils).
The form of RTK that "we" conduct produces a positional accuracy of up to 4th order, BUT, the azimuthal accuracy is usually considered Hasty accuracy if conducted using the "COGO" > "compute azimuth and distance" method. This is because no post processing occurred to verify the accuracy ratio of the data.
Therefore, if you oriented off of an azimuth that was considered a hasty accuracy. Then proceeded to turn one position angles to the following quads. The entire survey as far as directional control could be considered hasty. You can still save it with minimal effort though while retaining the bulk of your work.
If you already know the mean angles between all of the quadrants, then all you have to do is conduct something like a 4th order artillery astro to the quad that you originally oriented off of. Then use this new azimuth as the "orienting azimuth" in your recordings and apply the mean angles to it to find the new grid azimuth to the 3 remaining quads.
If that was too much to take in via text, you could just give me a ring sometime. Dm me if you do not have the number saved.
As far as survey recovery, it probably wouldn't hurt. You could key in the points that you are checking and conduct rtk to see how far they have shifted and go from there.
Hey I am not exactly familiar with the US procedures and terminology. But the topo azimuths calculated using coordinates obtained via GPS positioning will be accurate to the order of about 5 mils (depending on how far away the sighting points were from your theodolite-I used 400 meters in my calculation). You will of course get more accurate results by averaging multiple measurements
Is the method of M2A2 same as PAB2AM from Bulgaria?
I do not know. The method I used is just what the US military settled on as the "correct" method. If you can apply the M2A2 method to the PAB2AM, (and it meets your accuracy requirements) then I'd be interested to hear about it.
I can say that the calculations differ from country to country but the result is the same. Method shown in the video can be used with a PAB-2
ita ll the same becouse its same type of instrument, PAB-2AM its part of PAB-2 - soviet's army artillery bussole.
I want to buy this but i don't no how i buy online which website. Any one please recommend me.
Have you checked Ebay?
@@mrjoeyeo8993 thanks for quick reply. Yes I search on eBay. But I can't find out.
I hate this thing
How could you have a trig list or a known point?