target speed: the eighty-ten method

[greyrider]

target speed, the eighty_ten method
in this tread im going to be introducing to all of you a technique
from the TFCM, and from the realm of imaginative tactics, that which is characterized by
or bearing evidence of imagination.
so if you want to advance your target speed determinations, to an advance level, your probably
going to have to pass threw this post, because no one has done this before, no one has shown this before, and the beauty is
it works great.
"
about a year and a half ago, i opened a tread called: "target speed, seaching for the magic bullet".
and in that thread i talked about a particular angular setup between a target and a submarine, and that if
this angular setup could be maintained, the AOB becomes predictable, and it didnt depend on seeing the target,
in fact the target could be at the maximum listening range of the hydrophones.
so with a closing target being held at a constant bearing, with a known AOB, the targets speed can be determined by using the
submarines speed.
the only tools i used on the submarine to determine target speed is:
submarine hydrophones (just listening and keeping target on bearing)
submarine knotmeter ( adjusting sub speed to keep target at constand bearing)
submarine timepiece (not really needed if target is held constant, but TFCM likes to time it for 2 to three minutes)
combat information mod for TM 2 (has the data to rate a targets speed versus sub speed)
and math formula: St= So*sin LA / sin AOB

where:
ST = target speed
LA = lead angle
AOB= aob of the target


By null at 2010-08-01


By null at 2010-08-01


By null at 2010-08-01


By null at 2010-08-01

whats not used are maps, plots, radar, sonar pings or ship length.
altho i have a movie to show you, its about an hour and one half long, i cant seem to find a site
to upload the movie to, filefront only accepts vids that are less than 2gb. the movie has 15 parts, each part has about has almost 4 gb,
so i cant even upload it in parts.
this movie shows the submarine holding a closing target constant on an 80 degree bearing,
with a ten degree aob, the submarines speed is 2 knots, so at the bearing and aob, the targets speed is 11 knots.
this speed was determined while the target was over 19nm away, and it took the sub almost 1 1/2 hours to close on it,it was hit with
all three torpedoes fired at it.
what i can do is give you the mission to practice with, i can give you the combat information mod for TM.
the combat info mod has two new charts, one has the data for the 8010 method, and the other is a chart for torpedo offsets, that is,
taking out two or three targets simultaniously, but i really need to make a handbook for the mod first, which explains how to use the charts and graphs.
so ill try to get that up later on, right now this is all im going to say about it.

[TabbyHunter]

That...is a very great tactic. You didnt make it yourself, did you?

[Rockin Robbins]

Now you have to demonstrate how you can determine AoB visually or any other way from 19nm! That is a stretch because they are well beyond the horizon at that point. If you're going to find the AoB by radar, then you might as well shoot by it and eliminate all the hocus pocus. I see smoke and mirrors here.

Since you cannot determine AoB from extreme range and you cannot determine target speed, your equation becomes a two variable expression with many solutions, not one. I don't think the problem is insolvable, but you're not there yet.

[greyrider]

continuing with the discussion on the 80-10 methed, one could ask, "how do you know your closing target aob is 10 degrees after leading it by 80 degrees".
theres only one way, and thats if the targets bearing remains contant at the 80 degree lead angle.
one thing i am seeing about this angular arrangment is that im begining to think of it as a reference bearing and lead angle, and that you can find the true aob
of the target, even if the target does not remain on a contant bearing.
for instance, take a look at this and see something, what if you set up this angular problem, and no matter how much you adjust the submarines speed,
the target will not remain contant. if that happens, thats a good indication the the aob is not 10 degrees.
this example asumes the target has a starboard aob, this is the same example used in this original post. now if the aob of the target is not 10 degrees,
no matter what, the target is going to advance in bearings,
in my original post, i held the target constant at bearing two eight zero, so it had a 10 aob.
what if it has an 11 degree aob, or more, well you will still certainly close on the target, you will see it when it comes over the horizon, and it will
still be a ninety or near 90 target track, but it wont be good for a accurate speed estimation
but watch this:
using the formula SS x sin LA / sin AOB
where:
ss = sub speed
la = lead angle
aob = target aob
watch what happens when aob other than 10 degrees are present on the target.
ask the sonar man the targets bearing a speed, he will usually tell you a few facts about the target such as bearing, closing moving away, slow med, or fast speed.
medium speed is from 8 knots to 11 knots.in the op, the target held contant at 280, sub speed keeping target constant was 2 knots, so target speed was 11 knots.
if the taqrget cant be held constant, aob is not 10 degrees, it could be more so, at
11 degree aob, plug in formula, do the math,
for an 11 degree aob, sub speed at 2 knots, target speed is 10.3 knots, still within medium speed tolorance
for a 12 degree aob, sub speed 2 knots, target speed is 9.7 still a medium speed.
for a 13 degree aob, sub speed same, target speed is 9.0 knots
14 degree aob everything the same, target speed is 8.3 knots. still within the medium speed tolorance, but as you can see, as the aob increases, the targets speed is decreasing,
so now if you try to plug a 15 degree aob into the formula, your target speed is now 7.8 knots, and now is below medium speed and would be rated as slow speed by the sonar man.
now you know that your target has anywhere from a 10 degree aob to maybe a 15 degree aob, if your sonar man rated the targets speed as medium.
now its just a play with numbers, or maybe a little mapping and plotting to find the targets real speed.
so from this angular settup between target and submarine, you can get either an extremely accurate speed estimation, or one very close.
more to come later.

[Pisces]

I'm sure we are all very curious about your video. But I'm pretty sure we are not waiting to download 60 Gigabytes!! for it. Surely there must be a way to compress it.

Your idea has merrit, however I think fixing your mind on a target AOB of 10d and a target speed of 11.3 knot if your sub is going 2 knots, well ... is just a too special case to be usefull in practise. If you manage to get the bearing to target steady over a long period, then you only know you are in pure intercept. However he could just as easily have had an AOB of 30d when moving at 4 knots. Or have 20d AOB when moving at 6 knots. And add to that the possibility of the target moving away, so the AOB could also be towards his rear.

Sure, you say, but the hydrophone operator can tell us what speed range he is in, or if he is moving away rather than closing to us. That helps narrowing it down. Well I really doubt if that could be done so quickly as in the game, the instant he hears it, or that he really could be so sensitive in real-life. What do I know, I have no real naval experience, I just find it hard to believe.

And I also would like to pose the question, how slow is constant? How long do you wait before you consider the bearing steady enough?

Let's generalize your idea. Because I certainly can see a use for it.

First of all, no need to fix your lead angle to 80. The sound on the 90 or 270 bearing is good enough, and get's that last percentage of use out of your speed. You can't expect the AOB to be near 10 degrees so why expect that you'll be crossing his bow perpendicular (which is what I expect you're expecting )

So, now I assume you set course to beam the sound bearing, so sound on 90 or 270. Now make a record of the starting position. Very important!!! Now, set whatever speed you need to keep that bearing steady. That means accelerating and decellerating a bit as the bearing changes 1 degree forwards or backwards. Since you are perpendicular to the sound you automatically will do this with the least speed neccesary. Avoiding excessive noise. Do not turn your sub but keep it steady on course. Eventually you should still have the bearing on your 90 or 270 after a long time. Infact you could do this the entire time until you are about close enough to fire. Now you figure out your average speed during this time, which could be really accurate if you do it right until the end. You've moved a certain distance over a certain time and calculate with whatever tool the average speed(authentic with a nomograph ) Ok, you may ask, but then I need to measure with the Super-Duper-GPS-Map-localiser. Surely that is not realistic. No, you are right in that, .... but ships can have a very simple speed measurement system that counts the revolutions of a small propellor as it flows through the water, known as a speed-log. If it is connected to a tachometer then you can sum up all revolutions and get a distance. Give or take a bit current-drift, but let's assume that to be equal to both vessels. Atleast, that's how I make it credible to myself.

Ok we measured our average speed, with the bearing kept steady, thus approximately in pure intercept. Let's now assume he has an AOB of 90 to the sound bearing (for lack of anything better), so we think he is going parallel to us. He probably is not, as he is probably faster and closing, but the rest of his speed is now pointed along the bearing and we can't measure that. But we do not need to either. He may come as quickly as he wishes, infact the quicker the better.

We are in pure intercept, but we want a torpedo to be in pure intercept.

In comes the intercept formula:

sine(ownsub_leadangle)= sine(targetAOB)*targetspeed/ownspeed

or how we are going to use it as torpedo-equivalent:

sine(torpedo_lead)=sine (assumed_targetAOB=90)*assumed_targetspeed/torpedospeed

Now you have enough data to setup the shot. Or feed the TDC. Assuming he is on a imaginary course perpendicular to the given bearing, and so appearing to move at the same speed as we did. (that's as much as a Blind's Man intercept can tell) And eventually being on top of us, so just a matter of waiting not too long with firing because of arming distance.


I'm not saying this is accurate, because you have no idea how far he is, so if you fire too soon you're probably going to miss. (As objects in the distance look much smaller angularly than when they are near) Also, the gyroangle is probably significant and you need a range figure to correct for parallax aiming error. But if you let him get close enough his length makes him vulnerable anyhow. Anyway, the geometry of the speed triangle should be correct. What you are really interested in is matching the speed vector components that are perpendicular to the bearing, so inside the triangle, as in this image:



You just have to have patience when matching your speed to the steady bearing, and hope your batteries last that long.

[Rockin Robbins]

If you let him get close enough you don't need the mumbo jumbo. And just because you are on a collision course does NOT mean his AoB is 10º. As Pisces said, it could be just about anything. The only thing we know is that it is under 180º! We do know whether it is port or starboard also.

I'm coming up with a brainstorm but I can't quite put my finger on it. Pisces' diagram is the beginning of it though...

The only problem is that I'm coming up with another visual or radar technique, at least partially. You do have to know whether the torpedo can reach and you really should shoot well under 2000 yards for your average merchie.

Once I get my software back in order I'll work on it.

[joegrundman]

sure, using the sonar man to get a rough speed estimate significantly reduces the range of possible aobs.

But in fact, greyrider, all due respect, this is broadly speaking a rehash (and a limited one at that) of what i was writing about 3 or 4 years ago.

And in any case, the USN more or less already solved the problem from the other way round(for finding speed, when AOB is known, and in reality being able to eyeball AOB is a skill that is more or less assumed to come with practice)

OK you can do it without markings on the map, whereas the thing i wrote about several years ago used markings to help the procedure.

This is the article i wrote several years ago, but it took advantage of the speed omnimeter side of the ISWAS tool:

http://www.subsim.com/radioroom/showthread.php?t=115587

it was rewritten better subsequently, can be downloaded from my ff, but in fact someone else rewrote it again even better.

But a better idea is to read the original USN document detailing the use of the ISWAS, written between the wars, when such techniqes were a staple of submarine attack doctrine, before PKs and radar appeared. Has the advantage over conventional plotting in that the operation occurs while making a normal approach.

http://www.hnsa.org/doc/attackfinder/index.htm

Still, if you want to popularise the method, that's cool with me.

[greyrider]

if you have been reading this post, you know that a good speed estimation can be obtained by using the angular arrangment of 80-10, miles before you even see the target.
we can also get a fix on the targets course, and know pretty much what course the target is on as well. theres only one problem tho, because we wont know the range of the target,
we might know the course its on, but we wont know just where it begins, how far away it is, unless we are able to estimate range with the hydrophones, and that im going to try to show you is possible.
after listening to the sonar training records of the naval historical society, i have identified at least 2 ways sonarmen estimated target range by passive sonar.
one is by the loudness of the targets propellers, and the other way by the width of the targets sound signal, which i will show in another thread at some point.
but getting back to target course, once you have set up the 80-10 arrangment between target and submarine, if you worked with the AOB trainer, there was an explanation with it that described
how to determine target course, from either a visual contact, or sound contact.
to determine target course in the 80-10, you must remember that the target course is relative to the submarine. so using the original example, in the 80-10,
we have a target bearing 280, relative to submarine, since the targets bearing is 280, its more than 180 degrees, so you subtract 180 degrees from 280, and you
have a general direction now of the targets course. but we havent factored in the aob yet. so lets figure that in as well, so we can have a somwhat accurate target course line.
the target has a starboard aob, and since its a starboard aob, we have to subtract the aob, after subtracting 180 from the 280 target bearing, if the target is
being held constant at 280, it has a 10 degree aob, so we subtract 10 degrees from 100 degrees, and the result is the targets course relative to the submarine, 100 - 10 = 90 .
so the target has a 90 degree course relative to submarine, the only problem tho is what i stated at the begining of the post. it really doesnt matter tho, because if you keep the 80-10 arrangment, and continue to close the target,
your going to see it anyway, but i just wanted to show you that.
even if the aob is not ten degrees, you can still get target course, just like speed because you only have only a few courses that the target can be on, in the 80-10.

joe, i have download your info, i will check it out later, thanks

one thing joe, im a lazy captain, i dont wanna plot, i love it and hate it all at the same time, and becuse im lazy, i just want to drive the submarine to the target, shoot it, and then go away.

[greyrider]

http://www.filefront.com/user/greyrider
ok, well to put all doubt to rest about 8010, the link above is the original mission i used to test out the 8010.
if your going to try the mission, as soon as it starts, make sure you put 2 knots on the sub knot meter, and dont do any turns,
this is a real easy misssion, in order to see how the 8010 works, all you will have to do is make the sub go forward at 2 knots asap after the mission starts..
since i cant upload the movie, and no one wants one that large, youll will have to prove to yourselfs that it works.
one thing i wont do is make a claim, without proof, so here it is.
im kinda surprized by you rr, calling this smoke and mirrors, i thought if anyone could understand the trig involved in this, it would have been you,
no matter tho, prepare to eat those words rr,
just an added note to all the newer guys looking for a way to get a targets speed, you can still use this method even if your using auto tdc.
and if you are able to grasp the concept, and apply it correctly, you will be doing one of the most advanced techniques to date here at subsim.com, and be among the elite,
i dont care if you started playing this game last week, learn this, and no one can put you down.
the formula is from the torpedo fire control manual, but the concept for 8010 is mine, i still havent worked the handbook for the cic mod, so im attaching the chart for the 8010 here, for now.
caution: you will collide with the target if you dont shoot it first.



Submarine Speed Lead Angle Target AOB Target Speed|
.05 knot 80 10 2.8
.06 knot 80 10 3.4
.07 knot 80 10 3.9
.08 knot 80 10 4.5
.09 knot 80 10 5.1
1.0 knot 80 10 5.6
1.1 knot 80 10 6.2
1.2 knot 80 10 6.8
1.3 knot 80 10 7.3
1.4 knot 80 10 7.9
1.5 knot 80 10 8.5
1.6 knot 80 10 9.0
1.7 knot 80 10 9.6
1.8 knot 80 10 10.2
1.9 knot 80 10 10.7
2.0 knot 80 10 11.3
2.1 knot 80 10 11.9
2.2 knot 80 10 12.4
2.3 knot 80 10 13.0
2.4 knot 80 10 13.6
2.5 knot 80 10 14.1
2.6 knot 80 10 14.7
2.7 knot 80 10 15.3
2.8 knot 80 10 15.8
2.9 knot 80 10 16.4
3.0 knot 80 10 17.0
3.1 knot 80 10 17.5
3.2 knot 80 10 18.1
3.3 knot 80 10 18.7
3.4 knot 80 10 19.2
3.5 knot 80 10 19.8
3.6 knot 80 10 20.4
3.7 knot 80 10 20.9
3.8 knot 80 10 21.5
3.9 knot 80 10 22.1
4.0 knot 80 10 22.6

[Rockin Robbins]

greyrider, you cannot establish an 8010 relationship without seeing the target, either visually, with active sonar or radar unless you cheat in your mission setup and build it into the situation.

[tomoose]

I don't get it either. I've read the above but there seems to be a leap of faith involved plus "situating the estimate" (as RR has implied). Getting a good AOB is a bit of an art at the best of times using the VISUAL method! Despite the method described above I still can't see how one can possibly "assume" the 10D AOB just by placing the target at 80D when the target is completely out of sight with range/speed unknown and given that the degree of error varies with the range (i.e. the further away the target the greater any error or assumption will compound the situation, if you get my meaning).

I'm trying to understand the method but can't get past the distance and AOB aspect. For example; as indicated above, I detect a target at 120D starboard, range unknown, and sonar says he's closing, fine. I turn my boat to put the target at 80D bearing. Target is still closing. I adjust speed to keep target on 80D. Target is still closing but regardless of my speed, how do I know he's at an AOB of 10D? He could be at 0D AOB and proceeding at .5knots or at 25D AOB proceeding at 4knots (I'm exagerrating to make my point). I can adjust my speed to keep him at 80D but I don't see how that means he's definitely at 10D. He's still closing and depending on his approach angle to me it would take quite some time to determine his speed but that would still not give me his range (which 'could' be 19nm but then again could be 25nm etc ad naus). With a lot of sonar hits I should be able to determine his course (over time) which in turn would give me a rough AOB but I'm still not sure how that could definitely be 10D!?!?
Perhaps some still map shots with the trig etc could clarify things?

[Armistead]

In theory, if all variables are correct, maybe it's possible, but I see too many issues where it is impossible to get correct data. Plus, there are too many easier ways to go about it.

What happens with a convoy with many ships and escorts in a protecting zig pattern?

[greyrider]

guys, your just not seeing it, thats all i can say, but ill tell you this, i have been doing this since the earliest days of sh3,
this is the point and shoot method i always wrote about.
did anyone download this mission and try it out yet?
because if you did, you would see that it works.
its a mathematical relationship, of proportions, and keeping those proportions intacct, while closing on the target, and you only need to keep those
proprtions long enough in order to calculate speed, as i said, the torpedo fire control manual asks that you time it for 2 to 3 minutes.
then you can do what you want, if you want.
its mathematical trueism, please dont take my word for it, im invited all doubters to try it, if you dont, then your really talking out of your hats, with all due respect to you guys, you should keep an open mind.
dont be close minded, because you miss things that could help you, in my posts above, i told you guys how you could verify a 10 degree aob,
this method is only for closing targets, targets moving away is not what its for.
this mission to test is anaseptic, i build it to test the formula, but i have keep the target constant on a 80 degree offset many many times with sh3 and sh4,
only i didnt get speed this way, because i didnt know the formula until about a year and a half ago, i always got speed in other ways, then i tried this, and it does work.
working with this formula and angular arrangment, i was able to change a variable into a constant, because of the mathematical relationship of the 8010, and that variable is a constant now,
when the target is held constant at a bearing, and does mot advance or decrease in bearings.
pieces brought up somethings such as using other bearings like 270 or 90, if someone were to do that, and try that way, their going to find the target going behind them instead of in front of them, and now will have to turn again,
and start over.
as far as convoys are concerned, im going to make the claim that you can still do it, and i could tell you how, and i will at some point.
i have done it!
just because someone doesnt know how to do it, doesnt mean that it cant be done, all you have to do is learn.
you cant see the wind, but you know it exists right?
try the mission, see how it works, you guys are the captains of your own submarines, once you see it works, its up to you to verify, from what i wrote, if the target has
a 10 aob.
remember the verification process to determine 10 aob is a constantly held bearing, if the bearing of the target advances no matter how much you adjust sub speed, its not 10, if it decreases in bearings, its going to go behind you, and you
will have to turn and readust the bearing to 80 offset.
not only did i learn this from experience, its also in the TFCM.
the whole point of this post is an attempt to take the concepts of the TFCM, and apply them to the game.
to say that a varible can only be a variable at all times is wrong, because it can be changed to a constant, under certain conditions, this is one of them,
and ther could be more, i havent worked them, so i cant say.


im also not twisting anyones arm to try it, that decision is up to you to either use it, or drop it and count it as useless.
but if you dont use it, im the only one who knows, and im one up on you, you can change that status
but i did show not only how to determine speed in the 8010, i also demonstrated that you could know AOB, and target course r to sub, using this method,
whats left? only range, and you have all four parts of a torpedo solution

i didnt write this to keep to myself, i wrote it to share with all of you.

[Armistead]

I'm all for learning any new method that would help me with contacts off. I tried the single mission. If I played with it enough I think I could get it to hold close, the problem for me is all the variables, but the bigger issue is I seldom attack singles, usually let them go unless a biggy. It also seems very limiting for faster ships, plus taking a lot of time tracking.

The other issue is it's just more work than needed for me. Maybe I'm use to easier methods. The bigger issue is sonar, why it may have some success with a single, can't see how you work it with a convoy. Not only that, often sonar won't pick up a ship until you can see it, unless you listen yourself and then you have no clue if it's coming or going.

For me as of now the better tool is the new radar mod. I can perfectly track ships far behind visuals.

When you desire, would love to hear the convoy explanation.

[greyrider]

np amistead, ill get that up for you soon, im going to have to play the campaign, to come in contact with a convoy, and then ill show you. im not going to make it a movie, ill do pics this time.

just a general explanation, i have done this before so i know, when a convoy is approaching, before the sonarman tells you he has contact, the contacts in the hydrophones will all be writeen on the notepad as unkowns. this is when your able to do it, point the hydrophones at the unkown that is on the far right, that has merchants screws, ask the sonar man to id it, he will id the target as merchant, then turn to get that merchant word on the notepad to the 80 degree offset, all others contacts will still be unknown, track the known merchant, and get its speed before the other contacts become identified.

thats it in a nutshell

only one or two minutes constant bearing needed to get convoy speed is needed

ask the sonar man to follow the contact as you turn, until its on 80 offset