SUBSIM Radio Room Forums - Intercept course?

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- - Intercept course? (https://www.subsim.com/radioroom/showthread.php?t=202812)

I'm talking on a more basic level, a very basic level. An intercept course as in your target is 500 miles away going 16 knots in a given direction. What do you need to do to reach this target to be able to attack or even track it? Intercept math is still very much necessary.

Also, if you are intercepting a track that is moving perpendicular to you, you will not be heading directly toward it to get it, you will be heading to the point where your two boats will be at a future time. How do you determine this point? You use trigonometry to set an intercept course. Remember, very very basic. Don't think about stand-off weapons versus heavyweight torpedoes or helicopters in the vicinity. We're taking away all those complex layers away to get to the root of the problem. Only then can you start adding those complexities back in.

(Due to the nature of my work, I can't think about a problem without tearing away complexities and I assume that's how everyone else thinks, as well. Apologies for any confusion)

Quote:

Originally Posted by Mike Abberton (Post 2444277)

You can estimate an intercept course with just range circles, assuming you know target course and speed. No calculators or outside references needed.

Time to Intercept Method:

1. Pick a desired time to intercept and draw a range circle around the target at a distance of Target Speed x Intercept Time. Draw an X on that circle where the target course intercepts it (cursor bearing from center of circle is displayed while you're drawing the circle). If you want a specific range other than zero at intercept, offset the X from the target course line at the desired distance (on your side of the course line obviously).

2. Draw a range circle from your sub that intersects the X, note the cursor bearing while it is on the X. That is your intercept course.

3. Intercept speed is the new circle radius divided by the Intercept time.

Speed to Intercept Method

Simplest method for this is to try different iterations of the Time to Intercept method, using shorter or longer intercept times, until you like the Intercept Speed calculated in Step 3. Once you do it a few times, you'll get a feel for where to start the iterations to speed up the process.

Admittedly, neither of these methods is likely to give the "exact" intercept course/speed for a given situation, but as others have said, with modern seeking weapons, you don't really need to be exact.

Mike

This is a good method. I hope to try it out. I do also still like my "bearing rate method" as it allows you to just go to a certain speed and "guide yourself in." However my method and I suppose yours to an extent require an accurate target track.

Quote:

Originally Posted by p7p8 (Post 2444281)

I know but first question is:

why you need method for interception?

In my opinion mainly for attack target. in that case, my points about weapon are also important.

I think "interception" isn't good word because in some cases better attack possition is far away from target (for example with SUBROCS). I think "attack possitons" is much better term than "interception".

Your premise is that contacts exist solely to be attacked. In the game this is mostly true. However sometimes you simply wish to get close to a target to identify with periscope. "You shouldn't kill a man without knowing for sure you ought to." In reality there may be other reasons as well, a submarine may rendezvous with a surface vessel without first giving an exact position, as to maintain the sub's discretion.

I agree that 1) an intercept course is not necessary with modern weapons and 2) an intercept course does not necessarily provide a good attack position for the aforementioned modern weapons.

Even still, suppose I am attacking a fast target with a TEST-71 torpedo. Autocrew and fire control does not seem to do a good job launching torpedoes on an intercept course and the TEST-71 has limited ability to catch a 30 knot target from behind. To be absolutely sure of killing my target I may wish to draw to within close distance ("no escape range") before shooting.

I know that all of this is for very, very basic model of situation. But this situations won't happend in 99% of scenarios.

Do you use "interception course" for P-3 Orion ASW operations? Do you know what I mean?

BTW: "tearing away complexities" is not always good method for solving every problem. Sometimes you have specific context that changing the same situation completly.

Quote:

Originally Posted by jadervason (Post 2444321)

sometimes you simply wish to get close to a target to identify with periscope. "You shouldn't kill a man without knowing for sure you ought to." In reality there may be other reasons as well, a submarine may rendezvous with a surface vessel without first giving an exact position, as to maintain the sub's discretion.

Quote:

Originally Posted by jadervason (Post 2444321)

Even still, suppose I am attacking a fast target with a TEST-71 torpedo. Autocrew and fire control does not seem to do a good job launching torpedoes on an intercept course and the TEST-71 has limited ability to catch a 30 knot target from behind

Even when you attack from bow, your target can turn back.

Quote:

Originally Posted by jadervason (Post 2444321)

To be absolutely sure of killing my target I may wish to draw to within close distance

TEST-71 have range only 8.1 nmi with max speed. That means, you should be 4-5 nmi before attack fast warship. Do you realy need "interception course" for this kind of attack? I think not.

Quote:

Originally Posted by rentacow (Post 2444196)

I use this: http://www.luizmonteiro.com/RA.aspx

Very handy tools on that website! :Kaleun_Salute:

Thanks for providing that link!

Quote:

Originally Posted by p7p8 (Post 2444329)

I think this is reasonable only for civilian units. Fast warship can detect you from "good periscope range". Other complication is, you can raise periscope up to 10 kts. So you can't visual track fast target.

Even when you attack from bow, your target can turn back.

TEST-71 have range only 8.1 nmi with max speed. That means, you should be 4-5 nmi before attack fast warship. Do you realy need "interception course" for this kind of attack? I think not.

Suppose my orders are to kill anything in a certain area. Suppose I detect a 25 knot warship in that area and determine with good confidence he is 20 miles away. Suppose I have a 35 knot submarine armed with TEST-71 torpedoes.

The gain rate of a 40 knot TEST-71 torpedo on a 25 knot warship is 15 knots. The run time of a TEST-71 torpedo is 12.2 minutes. 15 knots is 506 yards per minute, with 12.2 minutes available run time and a 15 knot advantage, the no-escape range of a 25 knot ship against a TEST-71 torpedo is about 6150 yards or 3nm. I can hit him from further if he does not evade but I want to be sure.

Target speed was 25 knots. Target bearing was 90. Target course was 180. Target distance was 20nm. Ownship best speed is 35 knots. Using the tool linked to above we achieve this intercept solution.

https://i.gyazo.com/01efc6d0aec8fada...7d1b19fe8b.gif

Calculated intercept angle is course 136 at 35 knots for 49 minutes. 49 minutes is a long time! You could easily waste a lot of time with a poor intercept angle. I would probably run course 139 or 140 so that I would eventually be in position ahead of him, that way I could listen once in a while and verify my intercept. Then I can use my very small 3nm torpedo range to good effect. I hope this illuminates why some of us are so interested in the question "how to intercept."

http://i.imgur.com/zRzxNaD.jpg

This is only example, but almost all attacks looks very similar

0) Only bearing and bearing rate

1) waiting for TMA data, identification
2) waiting for more TMA data, identification, you have course with medium error
3) you have range, course with medium error
4) you have speed with medium error and range/course with small error
5) you have speed without error (DEMON) and all data with small error
6) preparation for attack, you have all data

Like I said before, methods for ploting "course of interception" are crap in real situations.

I'm too dumb to do anything right.

I've read this guide 12 times. I've watched people plot a course across multiple videos. I've played the game UBOAT for 7 hours. I can't intercept anything. I can't hit any targets. I literally can't even SEE a ship anywhere. Can't get my money back bc I played it too long. Seriously just cannot understand any of this.

Quote:

I'm too dumb to do anything right

Karlbannsonr!:Kaleun_Salute:...remain dumb, only try doing it left! :yeah: