![]() |
SUBSIM: The Web's #1 resource for all submarine & naval simulations since 1997 |
|
![]() |
#1 |
Silent Hunter
![]() Join Date: Dec 2004
Location: AN9771
Posts: 4,904
Downloads: 304
Uploads: 0
|
![]()
I'm sure we are all very curious about your video. But I'm pretty sure we are not waiting to download 60 Gigabytes!!
![]() 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 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. Last edited by Pisces; 08-31-15 at 03:47 PM. |
![]() |
![]() |
![]() |
#2 |
Navy Seal
![]() |
![]()
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.
__________________
Sub Skipper's Bag of Tricks, Slightly Subnuclear Mk 14 & Cutie, Slightly Subnuclear Deck Gun, EZPlot 2.0, TMOPlot, TMOKeys, SH4CMS |
![]() |
![]() |
![]() |
#3 |
Ocean Warrior
![]() Join Date: May 2007
Posts: 2,689
Downloads: 34
Uploads: 0
|
![]()
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.
__________________
"Enemy submarines are to be called U-Boats. The term submarine is to be reserved for Allied under water vessels. U-Boats are those dastardly villains who sink our ships, while submarines are those gallant and noble craft which sink theirs." Winston Churchill |
![]() |
![]() |
![]() |
#4 |
Watch Officer
![]() Join Date: Apr 2005
Location: massachusetts
Posts: 334
Downloads: 237
Uploads: 0
|
![]()
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. ![]()
__________________
Her gun crew had guts, however, for from her canting bow came a half dozen well-aimed rounds. How they pointed and trained their gun on that tilting platform will long remain a wonder, and their dedication in keeping up the fire until they went under would be a matter of pride to any nation. O'Kane, Richard. Clear the Bridge!: The War Patrols of the U.S.S. Tang |
![]() |
![]() |
![]() |
#5 |
Watch Officer
![]() Join Date: Apr 2005
Location: massachusetts
Posts: 334
Downloads: 237
Uploads: 0
|
![]()
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
__________________
Her gun crew had guts, however, for from her canting bow came a half dozen well-aimed rounds. How they pointed and trained their gun on that tilting platform will long remain a wonder, and their dedication in keeping up the fire until they went under would be a matter of pride to any nation. O'Kane, Richard. Clear the Bridge!: The War Patrols of the U.S.S. Tang |
![]() |
![]() |
![]() |
#6 |
Navy Seal
![]() |
![]()
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.
__________________
Sub Skipper's Bag of Tricks, Slightly Subnuclear Mk 14 & Cutie, Slightly Subnuclear Deck Gun, EZPlot 2.0, TMOPlot, TMOKeys, SH4CMS |
![]() |
![]() |
![]() |
#7 |
Grey Wolf
![]() Join Date: Aug 2005
Posts: 930
Downloads: 23
Uploads: 0
|
![]()
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? Last edited by tomoose; 08-13-10 at 07:48 AM. |
![]() |
![]() |
![]() |
#8 | |
Silent Hunter
![]() Join Date: Dec 2004
Location: AN9771
Posts: 4,904
Downloads: 304
Uploads: 0
|
![]() Quote:
__________________
My site downloads: https://ricojansen.nl/downloads |
|
![]() |
![]() |
![]() |
|
|