U-Boot Periscope Telemeters

[Pisces]

Originally Posted by Nikdunaev

...
Oh, so you are the one who invented it?
Very interesting indeed. I think a lot of people now believe it is historical.

I am the one that invented the speed trick.
(from the old days: https://www.subsim.com/radioroom/sho...&postcount=135) And the other scratch mark just under 15 degrees, for magnification adjustment. If I was unclear, I am not the person that made the RAOBF mod. That was a collective effort of Hitman, JoeGrundman and OneLifeCrissis. They don't seem to be around here much. Unless they visit subfora that I don't visit.

Do you know why the whole device was simulated in Silent Hunter the way it was then?
Why the tick counting, instead of linking it to the stadimeter, which is simulated already anyway?
Why are the two marks and the Kurswinkel ring fixed?

I have no clue what modding difficulties they encountered while trying to make this. My knowledge is skin deep. But I'm sure this was motivated by that. Lack of available resources in modifying the GUI to move the way he wanted it/work like the historical device. It must have been the best way to replicate it.

How did the real thing function in terms of scope magnification?
Did you have to divide everything by four in low power, like with the American stadimeter?

Much of how it works can be learned on the following site. It is a gold mine if you want to know more about everything connected to target acquisition, tracking and torpedo guidance (from both sides of the war): http://tvre.org/en/ They have an English and a Polish language version.

Did you have to divide everything by four in low power, like with the American stadimeter?

As mentioned in my above first quote. The magnification trick uses the mark at 14.5-ish degrees. If you calculate the sine of that angle, you get 0.25. In other words, one quarter. If you line up the low-zoom size to the mark, you get the high-zoom size at the index at the top. For correction of the AOB width in low zoom it is a bit more complicated, and I actually forgot. Maybe you can find it in the archives if you search for my name in OLC's threads. The top link should be a start in the right direction.

https://www.subsim.com/radioroom/sho...&postcount=222
And finally: https://www.subsim.com/radioroom/sho...&postcount=263

!!! Be aware though, the precise values and steps relied on that older mod. For use in current RAOBF/GUI mods make sure to consult the documentation of the mod. It's scales may differ.

[Nikdunaev]

Sorry for the late reply

Originally Posted by derstosstrupp

Plotting was done on what was called millimeter paper, which is like graph paper on steroids.

Simple millimeter paper and no proper rangefinding device? Sounds like a big "ouch" to me.

Originally Posted by derstosstrupp

Probably not. U-Jagd means the hunting of subs, ASW. That watch was actually used by German ASW to plan depth charge approaches. Now, it just so happens that it is handy to use for this method, because the principles are the same, distance traveled over time. They had tables to help with this, but may have also used some form of stopwatch, there is reference made to that in at least one source.

U-Jagd is not a purpose made tool? Oh...
I honestly thought it was designed for this specific purpose. Those scales look very much like reasonable ship lengths and speeds...

What is the use for depth charging purposes? What do the scales represent in that case?

I am no expert in German, but the name, does it not stand for "unterwasser jagd" or "unterseeboot jagd"? Submarine hunting. Does it actually say if the hunting in question is for or by the submarine itself? I am curious.

By this point I am afraid to ask further. Does the Silent Hunter community actually use any historical tool correctly?

Originally Posted by derstosstrupp

The reticle was designed for 1.5x. In game you can multiply by 4 in 6x but IRL this was more complicated due to nuances in the optics. Rangefinding at 1.5x only was recommended.

Was it any different from the US optics?
Cause for the latter, as far as I know, multiply or divide by four was the "officially endorsed" method in real life. Both for the stadimeter and the telemeter scales.

The optical zoom, does it not change the angular field of view by that factor? 4 times in our specific case?

[Nikdunaev]

Originally Posted by Pisces

I am the one that invented the speed trick.
(from the old days: https://www.subsim.com/radioroom/sho...&postcount=135) And the other scratch mark just under 15 degrees, for magnification adjustment. If I was unclear, I am not the person that made the RAOBF mod. That was a collective effort of Hitman, JoeGrundman and OneLifeCrissis. They don't seem to be around here much. Unless they visit subfora that I don't visit.

I have no clue what modding difficulties they encountered while trying to make this. My knowledge is skin deep. But I'm sure this was motivated by that. Lack of available resources in modifying the GUI to move the way he wanted it/work like the historical device. It must have been the best way to replicate it.


Much of how it works can be learned on the following site. It is a gold mine if you want to know more about everything connected to target acquisition, tracking and torpedo guidance (from both sides of the war): http://tvre.org/en/ They have an English and a Polish language version.

As mentioned in my above first quote. The magnification trick uses the mark at 14.5-ish degrees. If you calculate the sine of that angle, you get 0.25. In other words, one quarter. If you line up the low-zoom size to the mark, you get the high-zoom size at the index at the top. For correction of the AOB width in low zoom it is a bit more complicated, and I actually forgot. Maybe you can find it in the archives if you search for my name in OLC's threads. The top link should be a start in the right direction.

https://www.subsim.com/radioroom/sho...&postcount=222
And finally: https://www.subsim.com/radioroom/sho...&postcount=263

!!! Be aware though, the precise values and steps relied on that older mod. For use in current RAOBF/GUI mods make sure to consult the documentation of the mod. It's scales may differ.

Thanks for all the links!

Actually, http://tvre.org/en/ is where I got most of my questions from.

The scope and ring pictures above are theirs.
That article mentions that the device could be used for either magnification in real life, but does not give any detail.
So, given that there is no Optische Länge scale on the thing, and the two pointers work differently as well, in real life... I started wondering how it was supposed to work.

Why the two different eyepieces on the scope?
Does this have anything to do with magnification?
Apparently the ring could be mounted on either:


Also what is the purpose of the big knob in the lower left corner of the ring? I can not find any references to that one in the text of the articles, even though it is numbered in one of the photos.

[derstosstrupp]

Originally Posted by Nikdunaev

Sorry for the late reply



Simple millimeter paper and no proper rangefinding device? Sounds like a big "ouch" to me.





U-Jagd is not a purpose made tool? Oh...
I honestly thought it was designed for this specific purpose. Those scales look very much like reasonable ship lengths and speeds...

What is the use for depth charging purposes? What do the scales represent in that case?

I am no expert in German, but the name, does it not stand for "unterwasser jagd" or "unterseeboot jagd"? Submarine hunting. Does it actually say if the hunting in question is for or by the submarine itself? I am curious.

By this point I am afraid to ask further. Does the Silent Hunter community actually use any historical tool correctly?



Was it any different from the US optics?
Cause for the latter, as far as I know, multiply or divide by four was the "officially endorsed" method in real life. Both for the stadimeter and the telemeter scales.

The optical zoom, does it not change the angular field of view by that factor? 4 times in our specific case?

Correct, U-Jagd was the term used for hunting of subs, not by. We have the service manual for German ASW as part of the Crush Depth project (in my sig). The word “Annäherung” means “closure” - it’s for timing closure rate most likely, probably to assist in depth charge pursuits. The concept is the same though, distance in m converted to knots.

To your question about there being anything realistic used by the community, yes, these concepts are all historical, it’s just sometimes the devices that are used to get there are a little different than what they actually used. The recognition manual is overused though, that didn’t have that kind of data that these games have, so that’s probably the biggest diversion. And using the manual assumes that the very good vision we have out of the periscopes in game was how it was, and it certainly was not. Viewing a target with the head of a periscope just at the waterline, with fogging, and waves etc. was apparently very difficult. Hence the emphasis on gathering data on the surface while overtaking.

Multiplied by four is correct for 6x, however, there was something with the optics that made that not so straightforward. To the extent that the commander’s handbook recommends rangefinding only at low power.

I can answer the second part of your question to Pisces, only because I know the answer at the ready about the multiple oculars. So the one on the left, with the wire going out of it, inside of that one there was apparently a depiction of the torpedo triangle in colors. This allowed the user to visualize the lead angle. It was linked, at least by my understanding, to the AOB finder, since AOB is an angle in the torpedo triangle (gamma). The only other critical pieces of information are target and torpedo speed, and I’m not clear on how those were entered exactly. The ocular on the top inside of the RAOBF I believe was how the prisms were viewed for the stadimeter.

These sound like great features, and they are very innovative, but with the TDC it’s easy to see how they are somewhat superfluous.

[diego_gut]

"Multiplied by four is correct for 6x, however, there was something with the optics that made that not so straightforward. To the extent that the commander’s handbook recommends rangefinding only at low power."


The zoom and field of view had different ratios, perhaps that made it impossible to calibrate the graticle for both.

[Hitman]

Ignore the film footage, those were overlays added on post-production to the film. When you looked through teh scope the reticles were noting like what you see in Youtube or Das Boot.

[John Pancoast]

Originally Posted by Hitman

Ignore the film footage, those were overlays added on post-production to the film. When you looked through teh scope the reticles were noting like what you see in Youtube or Das Boot.

I was wondering if you'd chime in. Hope all is well.

[Hitman]

Yes John all is OK thanks God

I check daily here but I don't usually have much time to read or reply.

[John Pancoast]

Originally Posted by Hitman

Yes John all is OK thanks God

I check daily here but I don't usually have much time to read or reply.

[derstosstrupp]

Hitman is the reason I ventured down the path of wanting to learn more - his research back 10 years ago or so was what got me initially curious. Thanks Hitman!

[Nikdunaev]

Originally Posted by diego_gut

The zoom and field of view had different ratios, perhaps that made it impossible to calibrate the graticle for both.

Sorry, I am not sure I understand what you are saying

The optical magnification in telescopes is increasing the apparent angular size of an object by a certain factor, compared to what would be seen by the naked eye.
The decrease in field of view, looking through the same eyepiece, is a direct consequence of that, right?

So, it seems that zoom and field of view are proportionally linked to each other by definition.
If not, than the magnification power number is just meaningless.

[Nikdunaev]

Originally Posted by derstosstrupp

Crush Depth project (in my sig).

That one looks really amazing...

A highly detailed and accurate, historically and physically, submarine simulation, representing the actual particulars of the boat, as they functioned in real life?
Yes, please!

Originally Posted by derstosstrupp

I can answer the second part of your question to Pisces, only because I know the answer at the ready about the multiple oculars. So the one on the left, with the wire going out of it, inside of that one there was apparently a depiction of the torpedo triangle in colors. This allowed the user to visualize the lead angle. It was linked, at least by my understanding, to the AOB finder, since AOB is an angle in the torpedo triangle (gamma). The only other critical pieces of information are target and torpedo speed, and I’m not clear on how those were entered exactly. The ocular on the top inside of the RAOBF I believe was how the prisms were viewed for the stadimeter.

Visualize the lead angle? How was it different from setting the lead angle on top of the bearing ring on the scope tube? The one visible in the "bubble" when looking through the scope?

Or was it automated, with TDC-like functionality?

So, the stadimeter prisms were only visible through one eyepiece, but not through the other, is that right?

Why not just align the ghost image, or move it all the way out of sight, when not being used?

In the scope photo on the first page, the ring sits on the bottom ocular, whereas on the photo above, it sits on the top. Otherwise they seem to be pretty much identical. Is there any significance to that, in terms of functionality?

Originally Posted by Nikdunaev

Originally Posted by Nikdunaev

[Pisces]

@derstosstrupp and Nikdunaev:

You are both talking about this image?
http://www.tvre.org/images/02_fot_07.jpg

[Nikdunaev]

Originally Posted by Pisces

@derstosstrupp and Nikundeav:

You are both talking about this image?
http://www.tvre.org/images/02_fot_07.jpg

Yes, exactly

[derstosstrupp]

That whole unit rotated, so you could simply rotate the ocular with the RAOBF down.

As to the eyepiece with the lead angle inside of it, I don’t know much more than that unfortunately. I only have documentation of StaSr but not the older scopes.