Range prediction, fast fire solution.

[NavyUSA]

Originally Posted by Pisces

I don't in SC or DW really. Back in the beginning I made bearing history charts to plot it. But lost interest in this arduous task. Also, I didn't really know how to use this plot effectively.

Then some years ago I figured out I could used the TMA ruler to estimate the fraction of a bearing to a 10th degree by setting the course of the TMA ruler to the degree before and after the bearing line, and then measuring/eyeballing the ruler-tip distance to the bearing line. This provides much better accuracy than the 1 degree resolution of the bearing readouts. But is still quite arduous, and not very useful in tense combat situations. It takes too much time for me to be comfortable.

It is easier to calculate the angle between two bearing (in LAG los)with the pocket calculator :
angle = arctan((So*2/60)/(length segment bearing from ownship and the intersection point))
Br= angle/2 [DEG/min] ''always approximated for defect''

Originally Posted by Pisces

So, I still just fumble around trying to get the ruler to lineup with the bearings after enough zig-zags. Just like everyone else, with only a faint idea of what I'm supposed to do with the TMA dotstack. I still let the Auto-TMA do most of the work also. In other words, I suck at it.

Zig-zags method is useful when target is very far. Allen Schrader in his video show a TMA solution of one target (civil) at range 35 nm. In this situation there is insufficient relative motion between the two platforms and is necessary to move along three/four legs (LAG and LEAD) with 4/5 bearings for leg, exactly Zig-zags.
So, this is a unusual scenery. Method inefficient for target range less then 11 nm (probable scenery).

Originally Posted by Pisces

In SH3 and SH4 though, I rely much more on the graphical methods of determining course and speed based on bearing alone. (search subsim for 3 bearing and 4 bearing method) And my self-created 3-bearing AOB finder sliderule disk. Unfortunately the drawing tools in SC and DW leave much to be desired to be able to do this effectively in the game. (no ability to plot lines on the map, only during mission editing)

Plotting Procedures in Dangerous waters aren't necessary, but certainly in the Second World War

[Pisces]

Originally Posted by NavyUSA

It is easier to calculate the angle between two bearing (in LAG los)with the pocket calculator :
angle = arctan((So*2/60)/(length segment bearing from ownship and the intersection point))
Br= angle/2 [DEG/min] ''always approximated for defect''

Sure, a pocket calculator does make it easier. I didn't find that much math though in that document that you suggested. Or it is hidden in the Italian text. Do you have any other suggestions where I can find how this formula is used and explained? Feel free to make us a tutorial.

Zig-zags method is useful when target is very far. Allen Schrader in his video show a TMA solution of one target (civil) at range 35 nm. In this situation there is insufficient relative motion between the two platforms and is necessary to move along three/four legs (LAG and LEAD) with 4/5 bearings for leg, exactly Zig-zags.
So, this is a unusual scenery. Method inefficient for target range less then 11 nm (probable scenery).

Well, speed changes only also helps to change the bearing rate. But not as much as a lag-los. I can't comprehend this method that you suggest in the first message, so I can't really say anyting about it's preference for short range TMA.

Plotting Procedures in Dangerous waters aren't necessary, but certainly in the Second World War

Until you frequently patrol close to the bottom and near to the shores. Then you'll like to do a bit more depth contour-plotting by yourself. It's a shame it isn't possible during play really, as the code is obviously built into the engine. If I can plot circles and crosses, why not lines? Time comparison between modern and WW2 eras is just no excuse. I'm sure real life operators would have this function.

I know there is MoBo, the electronic manoeuvring-board application. But it is external to the game.

[NavyUSA]

Originally Posted by Pisces

Sure, a pocket calculator does make it easier. I didn't find that much math though in that document that you suggested. Or it is hidden in the Italian text. Do you have any other suggestions where I can find how this formula is used and explained? Feel free to make us a tutorial.

The formula is not mentioned in the manual, also the table of the first post is not in the manual. I mentioned the manual (by cristian) just to recommend a precise method for Br calculation.

About formula: (simple trigonometry)
With the law of sines you can calculate the angle § = arcsin( B/L*sin(w)) , w lower angle between B and bearing at time 0.
B/L << 1 therefore § is approximately equal to §* = arctan(B/L) OR §* = arcsin(B/L) [error=<10^-2] ''more easier to calculate''. In the example B is SpeedOwnship/60*2. For obtain L is sufficient bring the cursor on intersection of the bearings when the bearing appear on TMA display.

[Pisces]

Oh ok, I remember having seen that drawing. Yep, in chapter 10 of some US Navy tracking training guide (Operations Specialist, Volume 1 NAVEDTRA 14308).

Not sure anymore where or how I found it. I think I can share it to all that are interested, as the frontpage says " Approved for public release; distribution is unlimited."

I guess I'll have to read that again.

[NavyUSA]

Originally Posted by Pisces

Oh ok, I remember having seen that drawing. Yep, in chapter 10 of some US Navy tracking training guide (Operations Specialist, Volume 1 NAVEDTRA 14308).

Not sure anymore where or how I found it. I think I can share it to all that are interested, as the frontpage says " Approved for public release; distribution is unlimited."

I guess I'll have to read that again.

Yes, the image is taken from that document.
Do you understand how to calculate simply the Br?
Just a clarification: the cited formula is fine for a single calculation of the Br, for a Br historian use the cristian's method plotting on navmap.

Now you can use the ekelund range or tables for range predictions, understand if the target range is decreasing or increasing, apply the Spiess graphical method, ecc.
The bearing rate is essential for an efficient TMA.

[Pisces]

Yes, using that picture your earlier posts start to make sense. Also the requirements for near 90 degree relative bearing. But if you use a calculator then you might as wel correct for different relative bearings.

...
Just a clarification: the cited formula is fine for a single calculation of the Br, for a Br historian use the cristian's method plotting on navmap.

I don't think you meant this one:

http://en.wikipedia.org/wiki/Cristian's_algorithm

[EDIT]Nevermind, different Cristian. You meant from the Italian forum.

[NavyUSA]

Originally Posted by Pisces

Yes, using that picture your earlier posts start to make sense. Also the requirements for near 90 degree relative bearing. But if you use a calculator then you might as wel correct for different relative bearings.


I don't think you meant this one:

http://en.wikipedia.org/wiki/Cristian's_algorithm

[EDIT]Nevermind, different Cristian. You meant from the Italian forum.

Are you kidding me?