Kriegsmarine Angriffscheibe Handbuch

[jimmie]

Ok, again thank you for the tutorial.

I have little memory on trigonometry now but trying to beat my brain...
I'm also using a real sliderule to find out the target's speed by law of sine (unfortunatelly typical sliderules don't have "minute" or "knots" scales so it'll take more work other than finding speed by S scale..)

At the end of Example 6 you wrote that you could also calculate diverting tagert speed (via the formula on the tutorial).

I understand convergent course case (is it all angles in the triangle less than 90, right?) but I can't grahpically imagine the triangle and component for the diverting case. (I don't know the English name for the triangle which has an angle larger than 90 deg) I mean... in the converget course case, I imagine a triangle ABC, where A, B, C are angles and a, b, c are sides opposite to the same name angles. so, I imagine:

- uboat is on B, and angle B is scope reading (bearing to target)
- a is uboat speed
- target is on A, angle A is AOB and b is the target speed, found by the sliderule easily (in this case typical sliderule's C/D scale can represent knot because it's just a ratio problem without conversion).

Now, what's it's like for the diverting course triangle? I actually had problem finding out target's speed when I wasn't at collision course..

[klh]

Originally Posted by jimmie

Now, what's it's like for the diverting course triangle? I actually had problem finding out target's speed when I wasn't at collision course..

It helps me to draw a picture. Consider a target that is heading away from you on a constant relative bearing.



You are right that your course and the target's course no longer form a triangle. But if the target is remaining on a constant bearing, then you both would have occupied a single point behind you (think of a collision in the past). The lines from the stern do form a triangle. The problem is still workable, only we must now calculate the angles A' and B'. A'=180-A, and B'=180-B. Therefore, the target's speed is...

Target speed = Own speed [ sin (180° - B) / sin (180° - A)

In the above example, A=150, B=80, and the target is traveling at 3.9 knots.

Does that help?

[jimmie]

Originally Posted by klh

It helps me to draw a picture. Consider a target that is heading away from you on a constant relative bearing.



You are right that your course and the target's course no longer form a triangle. But if the target is remaining on a constant bearing, then you both would have occupied a single point behind you (think of a collision in the past). The lines from the stern do form a triangle. The problem is still workable, only we must now calculate the angles A' and B'. A'=180-A, and B'=180-B. Therefore, the target's speed is...

Target speed = Own speed [ sin (180° - B) / sin (180° - A)

In the above example, A=150, B=80, and the target is traveling at 3.9 knots.

Does that help?

YES!! Thank you VERY much! I will try this in the game to digest well!

I think you should include this somewhat "advanced" (?) example in the already well-written tutorial to make it yet better!

[klh]

Originally Posted by jimmie

YES!! Thank you VERY much! I will try this in the game to digest well!

I think you should include this somewhat "advanced" (?) example in the already well-written tutorial to make it yet better!

By the way Jimmie, either formula will work for convergent or divergent courses. Because the sine function is symmetrical around 90 degrees, we don't really have to subtract the angles from 180. It's just easier for me to visualize, and the attack disc calculator only goes up to 90 degrees.






In other words...

sin (Angle) = sin (180-Angle)

Therefore...

sin (AOB) = sin (180-AOB)
sin (TB) = sin (180-TB)

Target speed = Own speed [ sin (180° - B) / sin (180° - A) ] = Own speed [ sin (B) / sin (A) ]

In the above example:

Target speed = 2 knots [ sin (80) / sin (150) ] = 2 knots [ sin (100) / sin (30) ] = 3.9 knots

[jimmie]

Yeah, I just didn't realize I could just use angle values by subtracting from 180, and simply could put speed (sides) astern of the ship on the imaginary triangle, that is: if the target is remaining on a constant bearing, then you both would have occupied a single point behind you (think of a collision in the past) --- it doesn't matter ahead or beheind since the problem we're trying to solve is just ratio in the triangle.

Since I read this thread: http://www.subsim.com/radioroom/showthread.php?t=94608 I've been trying to use sliderule. After playing with virtual sliderules, I ended up getting a real Pickett 600ES (I should've gotten a longer one).

As I wrote in the above, a typical sliderule doesn't have "knot" nor "minute" scale so things like (ship length/seconds)*1.944 cannot be done in one no-brainer operation like in Hitman's circuler sliderule, but law of sine method is just fine


BTW, I like your rec book very much! I want one Using lots of external physical material gains immersion a lot. You can gather all information except range with real tools (have a stopwatch?).

[klh]

Originally Posted by jimmie

BTW, I like your rec book very much! I want one Using lots of external physical material gains immersion a lot. You can gather all information except range with real tools (have a stopwatch?).

You can find the recognition book on Terrapin's website (http://ubrsdlc.realsimulation.com/), but it appears to be down right now. If we can get his permission, I would be glad to put it up on FileFront. It takes some work to put together, but it adds a tremendous amount to realism. I've also got some printouts of real Kriegsmarine maps (not the gamey one that came with SH3) that add a little bit to the realism.

And no, I do not have a mechanical stopwatch yet. I can't seem to find one for a reasonable price.

As for range, I'm hoping to find the time to create a table or whiz wheel that allows you to calculate range knowing mast height and degrees in the periscope/UZO (by counting the ticks in the reticle).

[jimmie]

Is the rec book mentioned new one? I remember someone made printable rec book about a couple of months after the release of SH3. What ships are included in it?

Hey I missed the chance to get the "official" rec book when it was included in the US pre-order of SH3, and I remember Neal gave us as a pirse at some time at subsim.com for some contest or even at SimHQ Teddy Bear gave it us at some occasion when he was the moderator of Naval/SilentHunter forum...

The monstrous package of hyped GWX version 2 has great numbers of new ships (actually I don't remember how many ships in the original except torp-worth merchants) and moreover, aren't we impatiently anticipating iambecomelife's merchant ships
So I guess I anyway need to create one by myself if I want the catalogue of all avail now.

As for range, back then someone made a simple table and I found it in my harddrive. But it's limited to "generic" ships (mast height 10.5m or 25m and C2/C3 cargo). Performing a calculation with some sliderule may be better way for this...

BTW, I excavated this thread: http://www.subsim.com/phpBB/viewtopic.php?t=46693 in my SH3 folder (I seem to saved don1reed's what_is_track.jpg which seems to be missing now, it's a table of AOB and distance)

[Puster Bill]

Originally Posted by klh

By the way Jimmie, either formula will work for convergent or divergent courses. Because the sine function is symmetrical around 90 degrees, we don't really have to subtract the angles from 180. It's just easier for me to visualize, and the attack disc calculator only goes up to 90 degrees.

One of the neat things about the American version (SACF/IS-WAS) is that the wheel with the Sine scale on it had 4 of them to cover the entire compass:

006 to 090 degrees
096 to 180 degrees
186 to 270 degrees
276 to 360 degrees.

You don't have to do any conversions in your head or on paper. You just read them off the wheel. That helps quite a bit when using it to find the AOB of a ship that is greater than 90 degrees.

[joegrundman]

I have three things to say here:

You want a whiz wheel to hand work out range? - try the very thing available in the U-jagd tools mod or the OLC-GUI which incorporates said tools.

Secondly, the U-jagd tools 1.3, which will be released soon, includes a 3 wheel circular slide rule. I chose to model it on the American one for the reason that Puster Bill mentions.

Thirdly, klh, are you by any chance near completing the updated manual that you mentioned to me you were planning to do? I would like, if I may, to include your manual with the U-jagd 1.3 download. Alternatively, I'll just link to it.

Joe

[jimmie]

Mine is this: http://www.antiquark.com/sliderule/s...lide-rule.html

Well, not virtual, real one. Yes, since its S scale is 6 - 90, I need to perform simple subtraction for anything beyond 90 but that won't hurt much; it's maybe alternative to "Brain Age" on Nintendo DS :p And knot - km conversion is simple... the most fundamental usage of sliderule is multiplication and division, anyway

[klh]

Originally Posted by joegrundman

Thirdly, klh, are you by any chance near completing the updated manual that you mentioned to me you were planning to do? I would like, if I may, to include your manual with the U-jagd 1.3 download. Alternatively, I'll just link to it.

Joe

Joe,

I am almost finished with my update. I corrected the issues you noted, as well as adding a few more uses (such as calculating distance to track, and best speed for a firing solution). I hope to get it done this weekend, and you are welcome to include or link, whichever you choose.