[Nikdunaev]

Originally Posted by derstosstrupp

I agree yeah seems odd, the numbering. My understanding was it was always early war scopes that had that integrated system. That system was developed after World War I. The C/2 I want to say came around in early 1940, at least that’s the earliest I see it being referred to in the KTBs. The type 21 had the C/2, as well, not sure about any of the other late war boats. Early war attack scopes looked like the one you have pictured. That scope can be seen today in the Vesikko submarine in Finland, a prototype of the Type II.

Sorry, what exactly are the KTBs?
You are saying that the stadimeter and the adjustable stand scope never actually coexisted in one unit, is that right?

I am curious, why could they not, say, take the boat one or two meters deeper, and use the normal, full length scope, with the same effect of it sitting low? Especially in quiet weather, when scope is most visible, but depth control is also easier and more precise...

Originally Posted by derstosstrupp

Speed calculations were typically by matching on the surface, or rough plotting. If they did not have the opportunity to follow the target on the surface, and had to dive quickly upon sighting, they fell back on either eyeball estimation or the fixed wire method, which we are familiar with, timing the target from bow to stern, but based on an estimate of the target length, since they never quite knew this exactly.

These guys simply just got very close, 500 to 1000 m. They were very skilled at eyeballing angle on bow, and range was mostly irrelevant because they shot at low gyro angles, so that whole unit was really redundant in practice.

Did they plot on the map? Maneuvering board? I assume they did not have a device similar in function to the allied dead reckoning tracer?

But plotting itself requires reasonably accurate ranges, right?
Did they get those from telemeter tables? Or was there some other way still?

And for the fixed wire, they did use U-Jagd, right?

I remember reading somewhere that they had tables, listing the linear, rather than angular, torpedo parallax, which allowed shooting at any angle without knowing range to the target, using the target length as a rough yardstick.

Originally Posted by Pisces

This particular statement: Yes, the speed computation is fictitious. I just came up with the idea of abusing the scales for that computation while OneLifeCrissis was making his GUI. I worked out the magic number for getting the calculation to work on the scales. And asked him to include a scratch mark on it as if it was carved in by the commander with a knife. Since then this was copied in pretty much every mod, and for different games, that included the RAOBF function.

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

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?

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?

As you said yourself, this version was reproduced pretty much everywhere.
No pressure, of course, just wandering.

Originally Posted by Pisces

As for centi- or mili-radians, this is not limited to the metric system! This applies equally well to the imperial system. It is just that in the imperial system height is usually measured in feet, and length or distance in yards. So you need to include a conversion factor of 3 in it. Or start measuring height in yards as well. Considering 2000 yards is close to 1 nautical mile (good enough for government work) this is not such a bad idea.

Essentially, centi-radians (or milliradians) means you are talking about a slope of 1 over 100 distance (respectively 1 over 1000 distance). So if something is 3 milliradians then it is 3 yards (or 9 feet) high at 1000 yards distance. Similarly, if it is actually 27 yards high, you are 9000 yards distant from it.
The same can be done in metric as long as you maintain the same system for both height and distance. 30 meters high over 2000 yards does not result in 15 milliradians. (though you will be close to within 10% error. ballpark quality)

Yeah, I understand that mils work in any units, as long as those units are consistent. But because of the foot vs yard thing, it is just not as convenient, I suppose.
According to the American Fleet Submarine Torpedo Fire Control manual, those scopes are marked in degrees, not mils, as one degree is 50 feet at 1000 yards. A rough approximation, sure, but something you can compute in your head.

I guess it is a matter of whether you prefer to multiply by two or divide by three.