SUBSIM: The Web's #1 resource for all submarine & naval simulations since 1997 
080317, 04:55 PM  #1 
Grey Wolf
Join Date: Jan 2014
Location: 50.1° N, 14.4° E
Posts: 832
Downloads: 73
Uploads: 5

Real navigation  Perfectly controlled approach
With this, you should start to love real navigation target approaching because this turns real nav into real kingdom!
Aaaand... i know i am probably 1 millionth kaleun who started to use this so i really know that i haven't found out operation parkenshlag Just believe me, its just about to repeating one or two simple equations all over again and its relevant to every situation in navy! The reason for this is i became really lazy in years as i play TWOS, so i stopped to find out distance by target motion analysis and so even target speed, because i never used this to something more, than just to justify this really works in TWOS (and thus SH5 itself). 99% of targets will move between 68kts and for proper targeting you always have to analyse it via periscope anyway, so i stopped to get anything but course. And from the books, i found out real kaleunen mostly used really simple rules by head.. There are just 2 requirements to have to use this: 1) You have to know target course + 10 degrees 2) Target cannot change its course (as always in ww2 navy) + for the very newbies, please accept your targetting is not "mapposition" relevant, its just relevant to your relationship to target, you could draw this situation to mediteranean as good as to north pole while you really are near south America, it will be always the same.. So lets start: As i wrote before, you can calculate target future distance, where it will be before you with perpendicular Angle on bow (AoB)  90° in advance. While the target moves to you, its easy to calculate it. It is just its current distance(d) * sine(current AoB). So if it has current AoB=30°, it is current distance*0.5 Now let me tell what is approach about Approach is of course to reach out our "sweet spot" for perfect firing position. Lets just clarify, that perfect position for firing is directed to target where it will have perpendicular course to your's (90°AoB) with optimal distance to fire. Optimal distance to fire would be depending on how defended the target is. ~700m it is for non defended target (yes the holy grail), 5km is for heavilly defended convoy (battleship..). And you could of course have different preference, this is just something like rule of thumb.. So, to be short, what we mean by approach is to get into proper point near of our target track and to turn our sub to heading which will be perpendicular to target track. Thus our bearing will be its course  90° if we will attack its starboard, or its course + 90° if we will attack its port side. So , what we want is to know where our sweet spot is. How to find out just by current AoB and distance?  By the rule of sine To be simple, the rule of sine says that, if we will stop here, the target distance from us in the moment when it will have AoB90° will be its current distance * sine(current AoB). So what this all is about is just to control 2 things from distance  current AoB and distance!. Lets demontrate on example 1) Your sub here is the point C The target is the point B Target is moving bofore you with course 70 and you are moving with course 347 into its track. These two courses are your only input here, you can imagine this triangle, but thats not important, its just for you to have overview. Everything what we need here, is to get its current distance and AoB, mission accomplished! how to control the distance you know. (just dont be exact, if you can see the smoke, lets just say its about 1015km, you'll have enough time to calibrate in periscope depth submerged...) How to control current AoB? By the rule of triangle interior angles! If you know our courses, we know angle A  here we will calculate it as 70(target course)+360347(our course)=83. Its always about subtracting two courses from each other, remember, if you are going to get into negatives, just add 360 to the first.. You are always turning in circle of 360 (if you are thinking this is just too complicated, just look to triangle and you will know how many degrees its between the courses..) Angle C is simple, its just 347(our course)293(bearing which we see our targets smoke at the horizon)=67. And the 3rd angle? Always 180two others  1806783=30 So we now know the targets AoB and thats the key to everything.. Just go into the triangle example, drag angle C and move it closer to angle A to simulate your quick approach to firing position. Can you see? The sum of inner angles is always 180 no matter what you wil do... + if you imagine yourself at tower of that ubote approaching to target track you can see here how the ship at the horizon will be moving to the left in your optic. So right now, we know, that if we would stop, the target would be just its current distance * sine(current AoB) > distance * sine(30) = distance*0.5! 2) But this is just a beginning, now it will be just better for us, we know even that if we would get them to 6 AoB, their distance would be 1/10 when we would just wait for them here!!! How to get them to AoB=6? By being so quick to move the target to see it at our bearing 269!!! Why bearing 269? Because its 180836=91 (83 is our current angle of tracks  angle A at image and 6 is our desired AoB)  if you will look by periscope or uzo to 360 (just before you) and move 91 degrees to the left, you will end at 269. So you just could pick how many times closer you want them, check sine table to get angle and calculate where it will be at your bearing in relation to your course, thats really all. If you want their AoB to be 1° smaller, you just have to move them 1° more to the side at the bearing you see them. As you may see, our position to target just moved and we was just waiting until we will see their smoke at 269, so we now know we are at position where they will move before us in 1/10 distance then they have now from us, because their current AoB is 6° and sine(6°)=0.1 What more we know? We know even our perfect firing bearing is 340, because its their course90°. So! We just need to have as high enough speed to see, they are moving at our bearing to the left and just wait until they will be at 269. .. And then just turn to course 340, stop the engine and submerge to periscope depth, no guessing, you are pretty set to have them at your 360 with perfect 90° AoB  sweeeet!!!! Just wait until you will be able to confirm perfect firing solution to TDC optically Please set TDC more preciselly by optical input from closer range, this is really just for perfect approach, not to set TDC! Final recapitulation to show you how easy this whole process is: 1) get course of target from distance by 4 bearing method or different way 2) set your course to cross target's track in way you profit most (i recommend you for most of situations angle of track 3060°) 3) subtract your courses to get angle between them (angle of track) 4) calculate angle between your course and bearing to target (how many degrees from your 360 you see the target) 5) subtract them both from 180 to get angle on bow 7) alter AoB of your target by moving forward the way you want (if you want to have AoB of target 26° smaller, just move forward to see target 26° more to the side of you)  This is very simple and comfortable way how to control your relationship to target! If you calculate 0° AoB you are directly in its track! Thats all. No more guessing ever! 8) change your course to your firing course (course of your target /+90) and wait for him here. ..Repeat over and over again, because its so boringly simple, you will loose any mistery behind navigation This pattern is most comfortable i found in years of playing TWOS, its pretty satisfying and easy to repeat over and over again. And this all you can very easily calculate in head. (+i can confirm this very quickly recover your skills which were lost by using smartphones ) And as always kaleunen Gutte Jagd
__________________
Check my mods (Downloads tab) uboats documentaries 1) Real navigation  target motion analysis cheatsheet 2) Real navigation  Perfectly controlled approach 3) Real navigation  How to prepare torpedo Attack with basic trigonometry Really needed: Learn RAOBF optical targetting Last edited by palmic; 112322 at 07:44 AM. 
Thread Tools  
Display Modes  

