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Old 06-01-18, 11:56 AM   #1
greyrider
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Default Unites States submarines, the constant bearing firing method, plus part II

DISTANCE TO HORIZON.

distance to horizon really has a place in the tactical toolbox, it can do some functions or calculations that the tdc or radar is incapable of providing the answer to. there's two functions that it can do, it can give the range to the horizon, and beyond that, if there is something out there that has a known height, (like a ship's mast) and is fully or partially visible, and it can be identified, it can determine the range to that object thats out of radar and tdc range, (an abstract range) most of the time, a ship, or its highest points will become visual before seen by radar, sonar might pick it up about the same time if the player is manning the hydrophones, (not the AI sonarman). you must know your height of eye above sea level.

i have calculated height of eye at periscope depth with a fully extended periscope as a reference point for height of eye in a balao submarine only, becus that is what i have in my current campaign, but to calculate height of eye with fully extended periscope for other submarine classes, its pretty easy, the free camera should be activated for this, and the view of the periscope should be seen from outside the submarine. from the submarines periscope depth, raise the periscope until its fully extended, then, start sinking the submarine about two feet at a time, the periscope as seen from the outside camera will sink deeper into the water, until it just above water level, press the level the boat key on the keyboard (A), to stop when its just above the waterline, then go inside to the periscope and see the glass half full with water, and half full with sky, if you see that, then your line of sight is sea level, at the water line of the ocean, but the glass is still half full of sky, and so the periscope still has a small height above the waterline, look at the depth gauge, the depth is greater than periscope depth, add one more foot to that value, and then subtract periscope depth from that value, and you have the height of eye for that class of submarine when the periscope is fully extended.

in a balao, height of eye at periscope depth with fully extended periscope is 7 feet.( the games balao )

the formula for calculating distance to horizon is; 1.23 times the square root of height of eye = Distance to the horizon in nautical miles.

for a balao, this would be, 1.23 times the square root of 7 = 3.25 nm, or 6582 yards.

so, for a balao, at periscope depth with scope fully extended, and observing a ship that appears to be cruising on the horizon, the ship range would be 3.01 nm, or 6582 yards, that yardage can be easily computed with the tdc. in the series of two pics below, pic 1 shows what appears to be a ship riding the horizon, with auto tdc on, so range can be seen, at 6506 yards, about 76 yards short of the computed distance to horizon on low power, and the 2nd pic is the same accept its on high power magnification.





there is another way to use this same formula to determine a range if the height of an object is known. for this example, the object will be the yamato battleship. this ship has a height of 129.6 feet.

using the formula, it would be; 1.23 times the square root of 129.6 ft = 14 nm. (this means the ship highest points of superstructure or masts), will become visible at 14 nm, and that would be a known range, to be plotted on the map.

if there is a target thats partially visible with a known height, and hull down, its range can still be abstracted from the formula, the tdc cannot do this in hull down.

in pic 1 below, there is a yamato battleship out there, the scope magnification is low power, it hardly can be seen if at all. the second pic shows the same ship at high magnification. what can be seen in high magnification is partial superstructure, and a bit aft of the stack, that pinnacle to the rear of the smokestack in the ship rec manual. that looks about 1/3 of the total height of the battleship, so its estimated to be about 43.2 feet.

plugging 43.2 feet into the formula; 1.23 times the square root of 43.2 = 8.08 nm.

the sum of 8.08 nm gets added to the distance to horizon value of 3.25 nm, and so the range to target is 11.33 nm, or 22947 yards. ( 3.25 + 8.08 = 11.33).





(the pic below demonstrates that just like in real life, during some portions of the day, temperature, density, and haze at the horizon refracts light and that light bending can mask the range of a target, if you want to know if silent hunter imitates real life in that respect, it actually does. the pic taken below shows the same general direction as the two above, but the time is 12 noon, instead of 17 hundred, i can't see the yamato at all on high power.)





USE THE TDC TO SIMULATE TARGET SOLUTION PROBLEMS. (training with the tdc)

the tdc can be used for training purposes, without a target. in the book clear the bridge, there are numerous passages that spoke of captain okane running simulated tdc torpedo targetting exercises while tang was on her way to a patrol area. he used an electric razor rubbing up against a microphone plugged into the hydrophones for propeller sounds, he had bought a metronome at a store to help his sonar operators count targets rpm's, everyone in the fire control party was involved in the training missions. he would plug values into the tdc, and as the tdc tracked the "target", the map plotters would plot, the tdc operators would operate, soundmen would listen, always designed to hone the crews skills to a higher level. before the war, okane was a sailor on private watercraft, if anyone new anything about propeller pitch, it would have been him. altho it seems that propeller rpm was important to him, nothing else is mentioned about how or if he used propeller rpms other than to know if ships were changing speeds.


"Some dives were scheduled , but others were not so that this training would approximate the expected operations off the Empire . In order not to slow the transit, fire control drills were held while we cruised on the surface , using sound bearings and propeller noises generated by Tang’s shaving brush - microphone method".

O'Kane, Richard. Clear the Bridge!: The War Patrols of the U.S.S. Tang (Kindle Locations 5156-5158). Random House Publishing Group. Kindle Edition.



so using the tdc for training gives the ability to set any value of speed, aob, bearing and range into the tdc, and then have the tdc "track the target", using the position keeper. this is fantastic for looking into the workings of the torpedo solution, an infinite number of values and conditions can be set into the tdc, plotted on the map, to work out torpedo solution problems.

to demonstrate this tdc capability, the set up of plate XVI diagram above from the TFCM will be used. the only value given in that diagram is the aob, which is 15 degrees true.

The sum of the measures of the interior angles of a convex polygon with n sides is (n – 2)180. for a triangle this would be (3-2)180 = (1)180 or 180 degrees.

and,

The measure of an angle of a regular polygon with n sides is (n - 2)180 /n, which for a triangle would be (3 - 2)180 / 3, or (1)180/3 = 60 degrees per angle, but this is wrong here becus one angle in the diagram already has an angle of 15 degrees, so 180 - 15 leaves 165 degrees to be divided between the other two angles, 165 / 2 = 82.5 degrees. each of the two remaining angles in the diagram are both 82.5 degrees, this triangle is isosceles, it has 2 base angles that are congruent, and the opposite sides of those angles are congruent.

plugging in 15 degrees into the tdc for aob, and plugging in 82.5 degrees for the lead angle, adding a random speed of 10 knots, a random range of 5000 yards, a bearing of 277.5 degrees, 360 - 82.5 = 277.5 degrees, clicking the red position keeper button, and now the torpedo problem plays out on the tdc, the range decreases, the angles change, the tdc begins to track the "target", without the target actually being there. the next series of pictures demonstrate this.

the following picture shows 4 views of the position keeper, from left to right; (1) set the aob to 15 degrees starboard, (2) bearing and range set to 277.5 degrees and 5009 yards, (3) target speed set to 10 knots, (4) position keeper set to track target.



the following picture shows the tdc tracking the target, own ship and target dials slowly spinning in relation to each other, at a 0 degree torpedo gyro angle; (1) torpedo gyro angle 0 degrees, (2) target aob at that instant is 75 degrees starboard, (3) bearing to target is 342 degrees.




lets see if anyone's home on bearing 342 degrees, up scope! the following picture confirms, there's no one home at bearing 342.






THE CONSTANT BEARING FIRING METHOD (shooting)

So far, everything discussed above was either setting up an instrument, or techniques for data collection and setting conditions for the tdc, the items needed for shooting. this last section deals with shooting, shooting the constant bearing method, pretty much the most popular firing method by U.S. submarines in world war II, as i have learned it. it matches the description of the actions and observations noted in the torpedo fire control manual of the method, and also the attacks by tang in the book, "clear the bridge". there is only one action the tdc operator does in the constant bearing method that we as players aren't able to do, and thats what i call, (keying the tdc), we as players can't do that.
i think there is a work around for it, but with or without the ability to "key" in either case , it has no affect on the actual method, so in the end, it really wasn't needed anyway, it hits "WHERE" its aimed at. its active shooting, to aim means you have to move the scope to different points on a moving object, its not just waiting for targets to cross the vertical wire. moving to different aiming points and shooting kind of gives the feeling of what it must have been like behind that periscope, it can be fast and intense, actually its fun to. i dont think it was just an american thing, the U.S. had the position keeper, that made it easy, but i think the germans knew the method also, tho they didnt have a position keeper, they did have the ability to set different offsets on each torpedo, that would make up the difference lacking a position keeper (alot more math and timing of shooting). in U.S. submarines, if one torpedo is set with an offset, they all are, and all will have the same offset value, the position keeper itself would put the offset on the torpedo gyro.


Spreads

the constant bearing method can be fired in two ways, with a longitudinal spread, or a divergent spread, its clear from his book captain okane used the constant bearing method in a divergent spread, and also along with morton in wahoo, i'd bet they all did.


divergent spreads, if i hold my hand out front , palm down, and spread my 4 fingers and thumb slightly, i look at my fingers as the torpedoes or wakes of torpedoes in a divergent spread, thats what it looks like in the water, all fingers pointing to different points, (offsets set by the position keeper) as opposed to just putting out one finger and firing down that bearing shot after shot, that is called a longitudinal spread, its always the same with longitudinal spreads, but there are different combinations to use in firing torpedoes with a divergent spread, the combination of firing torpedoes from aft to forward creates the most divergence, according to the tfcm, its very difficult to avoid.

The constant bearing method was one of three firing methods taught to the submarine crews in the torpedo attack, the 3 methods are:

(1) Check bearing method
(2) Continuous bearing method
(3) Constant bearing method

i write this only to show that all three were different methods, yet they all had something in common, which was a bearing, and more than that, it is the firing bearing, submarine captains had to know on what bearing they would fire on. when firing a longitudinal spread with this bearing, the bearing is held constant until all the torpedoes are fired as the vessel crosses the vertical wire, the torpedo gyro angle stays the same thoughout the firing process, but in a divergent spread, this firing bearing is the bearing they pivoted from, to shoot at different sections of the vessel as submarine captains moved the vertical wire, not necessarily firing on that bearing, the tdc operator will match the periscope bearing to the generated tdc bearing and stop the generation (keying the tdc), fooling the tdc into thinking the periscope bearing is the firing bearing, it is the firing bearing, but with the tdc offset, after the torpedo fires, the tdc operator restarts the generation, which applies a new offset because of target advance and tdc keeps tracking, the generation is stopped again and a torpedo fired, and the relative hand crank on the tdc is released, then starts the generation again, the position keeper still keeps tracking, and as the target advances, the tdc is applying an offset, its stopped again, the torpedo fired, and this happens each time a torpedo is fired until the amount of torpedoes specified in the spread is fired. the tdc fires from the base firing bearing, with tdc offsets to the left and right of the base firing bearing, about 7 offset bearings in all, 3 bearings before the firing bearing, four bearings after the firing bearing, and down where the torpedoes will impact the target, the range is constant. as players, we dont have the luxury of having a relative bearing hand crank, but keeping an unlocked scope will serve as our hand crank. this explanation might be wrong, or not wrong, but this is what i see when i use the method, in the game, the scope is unlocked, and i pivot off the firing bearing, i place the wire of the scope ahead of the firing bearing, which will be ahead of the desired point of aim, an example; if the firing bearing is 15 degrees, i place the scope on bearing 18 degrees,(ahead of the firing bearing and ahead of the desired point of aim), the vessel begins to cross the vertical wire, i wait until the stern of the vessel is on the vertical wire, when it is, i fire the torpedo on bearing 18, i then move the scope to the left, and aim for the midsection of the target, this might be bearing 14 degrees, when the vessels midsection is on the vertical wire, at 14 degrees, the torpedo is fired, the scope is then moved to the left again, and aimed to shoot at the bow or forward part of the ship, this bearing could be bearing 12 degrees, the torpedo is fired when the bow crosses the vertical wire, this is how its played out in the game, the wire is being placed ahead of the desired point of aim, the torpedoes fired are in a divergent spread, becus tdc tracking applies the angle between generated and observed bearing. the range of the shooting sequence is between 11 degrees and 18 degrees, and all the bearings between them, 7 in all, shooting outside this range means a miss, once the target crosses, in this example bearing 18, as captain okane wrote in his book, the vessel is a dead duck!


“ Ten degrees to go , ” called Fraz . This would be a new one for me . I could get the “ Constant bearing — mark ” off handily , but the “ Fire ” on a separate exposure might be too early or late . I considered firing on generated bearings , most submarines did , but with only two torpedoes , I’d stick with our bow - and - arrow method . “ Constant bearing . ” Jones raised the scope on the generated bearing . I swung it ahead to amidships and called , “ Mark ! ” Jones dunked the scope and raised it immediately . “ Fire ! ” The mainmast had passed the wire , but the after well deck was still on . The torpedo went out with a whine . The second double dip was more accurate , and our last torpedo was on its way for her foremast , its whine fading out in a few seconds . The range was 900 yards , the gyros near 180 , the same as near zero for a bow shot .

O'Kane, Richard. Clear the Bridge!: The War Patrols of the U.S.S. Tang (Kindle Locations 4776-4784). Random House Publishing Group. Kindle Edition.



below i copied what the tfcm has to say about the constant bearing method.

(page 7-5 of the TFCM)

703. CONSTANT BEARING METHOD:

(a) The Approach Officer having previously announced SHOOTING WILL BE BY CONSTANT BEARING METHOD he then, when in all respects ready to fire, announces FINAL BEARING AND SHOOT UP SCOPE.

(b) A designated member of the Fire Control Party orders STANDBY FORWARD (AFT).

(c) The periscope is placed ahead of the desired point of aim as soon as the top of the periscope breaks water. The Approach Officer announces BEARING MARK.

(d) The TDC Operator matches the generated and observed relative bearing on the center section of the TDC and stops the generation by holding this value constant He then announces SET.

(e) The Assistant TDC Operator announces SHOOT when the following conditions have been met:

(1) Correct solution light on
(2) Gyro matched light on

(f) the Approach Officer orders FIRE one when the point of aim crosses the vertical cross wire at the periscope which has been left on the original relative bearing. The TDC Operator then releases the relative bearing hand crank and allows the TDC to generate.

(g) This procedure is repeated for each desired point of aim, unless a longitudinal spread is being fired. In this event, the original bearing is held constant throughout the salvo.

(h) The Firing Key Operator fires each torpedo on the order of the Approach Officer.


from the viewpoint of physics and mathematics, the definition of the word constant as a noun is:

Physics. a number expressing a property, quantity, or relation that remains unchanged under specified conditions.
Mathematics a quantity assumed to be unchanged throughout a given discussion.

so if something's unchanged thoughout a given discussion and a relation remains unchanged under specified conditions, then it must be linear, and the constant bearing method can be translated into a linear equation.

assuming a 90 target track.


y = Mx + b


where y is a base firing bearing slope = y2 - y1 / x2 - x1 = -3--4/15-14 = 1/1 = 1
M is the slope of the line
x is the offset value slope = 1
b is the y-intercept b = 18



equation for a firing bearing of 18 degrees is:

y = Mx + b
y = 1x + 18

x y
-------------
-4 + 18 = 14
-3 + 18 = 15
-2 + 18 = 16
-1 + 18 = 17
0 + 18 = 18
1 + 18 = 19
2 + 18 = 20
3 + 18 = 21

so, in a nutshell, if the base firing bearing is 18 degrees, torpedoes can be fired on bearings 14 to 21 degrees. the relationship remains unchanged over 7 bearings, its the same with any firing bearing.

THE BATTLE

"hypothetical reaction to contact"


Alittle before 4 in the morning

Captain to the conning tower..... we have radar contact sir, enemy formation outbound from Rabaul, 3 large ships in column, 3 escorts, one at the point, the other two providing flank security sir, tending to the rear of the formation..... Whats its relative movement line? dont know sir, looks like northwest...no wait!... sir, ships are turning to a more westerly direction. okay, here we go, ahead flank, left full rudder, set course to close on the target track at a ninety, dont think we can make the distance to cover in time, but we're gonna try. what if we can't make it to critical range sir, what do you have in mind? If we can't, then we will turn to starboard, parallel the enemy's course at full speed and open up the range between the enemy and us most importantly first, the night will give us concealment and time to close the target once we have everything we need for the torpedo solution, by getting into a parallel course to the enemy, we will know the enemy course and set the conditions for the TDC to use its angle solver to give us an accurate value of AOB of the target ship.....Visual sighting sir! two large funnels, masts forward and aft! Damn!!!...Damn enemy is moving fast! alright, right full rudder, set course to parallel enemy course at full speed.... Maneuver done sir, ship is parallel to enemy course. what is the enemy course and how far abeam are we to it?

enemy course is two seven nine true sir, 8000 yards abeam, navigation has plotted courses for us and the enemy, they are heading for open waters in the bismarck sea and the northern coast of New Guinea, possible destinations are Wewak or Jayapura sir....hmmm, long voyage, these ships could be troop transports either picking up or dropping off a regimental or brigade size Japanese army unit, some 1800 to 3600 lives... The captain climbs the ladder into the cool night air on the bridge, lights and puffs his cigarette gazing up at the southern cross and the pointers of Alpha Centauri, pauses.... alright, this is a priority target, we know the enemy course, we can attack at any point along the course line, the overall plan is to attack every transport ship in the formation until its wiped out, for the sake of our ground troops fighting in New Guinea, we will attack using the constant bearing method in a divergent spread, rig for the inevitable counterattack, surface when we can, chase them down again, attack once more, as needed until we send every one of them to the bottom, we will attack this time just before dawn, turning toward the southern cross, this operation could be over a few days, make sure the men get as much rest as possible when not on duty, lets go to work.
aye aye sir!


the radar screen had been watched continuously since the taking of the speed value, radar detected the enemy had slowed down in preparation of a course change, and in fact made a course change that would put Wewak as the destination, about 8 degrees to port for them, the submarine continued on course 279T at 18 knots, allowing the enemy to settle into its new course. when the enemy course stabilized, the submarine changed course to 271 degrees true, again to parallel the enemy course, at 18 knots. the radar was watched to see if enemy speed would remain the same, or would there be a new speed? they speeded back up on the new course, to 18 knots by watching a constant bearing on them over time, it held, they maintained speed at 18 knots, but now the range of the enemy course line had opened up to 12000 yards abeam, the 2nd and 3rd ships in column are zig-zagging, the 1st maintains base course, escorts retain their place in the formation. in order to attack the enemy, the submarine would have to move closer to the enemy course by shifting laterally while at the same time having vertical distance applied until a good firing position could be gained, or just, when ready, to dart right in at a right angle at flank speed, toward the enemy course.


split pic below shows enemy course changing and map course after course stabilized, destination Wewak. the submarine turned perpendicular to the enemy as morning light was good enough to see masts, at 05:56, running fast and at flank, enemy range about 15000 yards.



at 06:05, submarine is closing perpendicular to enemy course, enemy range decreasing, the enemy course line about 5000 yards dead ahead.




this post gets pic heavy at this point, the events leading up to the firing sequence, the views of the torpedo wakes, the aiming points used, the look of a divergent spread in the water, and the points on the target ship where the torpedoes were fired at, all best understood by the pics, some will have split views to cut down on the amount.

split pic below is first look at the enemy thru binoculars, they are approaching in what looks like a good perpendicular course, torpedoes were set for magnetic influence, depth 26 feet, 46 knot mk-14 torpedo.



pic below;
from the combat information mod, a target steaming at 18 knots, for a 46 knot torpedo, the firing bearing is 339 degrees in a perpendicular course, bearing 339 is the firing bearing, which means in the constant bearing method, that shooting can begin at bearing 336 and stopped at bearing 343, all bearings between 336 and 343 are shooting bearings, bearing 339 is the pivot bearing, and a shooting bearing.



in the pic below, i know the submarine is perpendicular, and so i can pick out a bearing that i will take range and bearing estimation with the stadimeter, i also know, if the target is on bearing 320 degrees in the perdendicular, then the aob here will be 40 degrees starboard, so the aob is set and sent to the tdc.



pic below is speed of 18 knots set and sent to the tdc.




in the attack, the second ship in column has been selected to be the target, becus i reckon the first ship is highly alert for torpedo wakes, the second ship might feel alittle bit more secure knowing the first is alert, and their lookouts might be alittle more lazy.

in the following two pics, the target ship has reached bearing 320 degrees, where it is ranged by the stadimeter, the range and bearing sent to the tdc and the position keeper button set to "on", to track the target.

range and bearing measured




range and bearing sent, position keeper turn on to track.



pic below is the escort on the right flank heading toward the submarine unaware of its presence at this time, but there is no way to avoid the counterattack, and its going to be bad, all three escorts are subchasers, that never seem to run out of ammunition, persistent in stalking, and are great hunters.




the pic below:

in this pic, the periscope bearing is placed on bearing 336 degrees, the first firing bearing, which is ahead of the pivot bearing of 339 degrees, and ahead of the aiming point.




in the following pic, the target as crossed the vertical wire, when the stern of the target is on the vertical line, the first torpedo is aimed and fired at the stern.



from here, it would be difficult to change torpedoes, fire them, and take pictures at the same time, what was done is, after the first torpedo was fired at the stern, the periscope was rotated to bearing 338 or 339, to fire the second torpedo at the targets midship section, after the second torpedo was fired, the periscope was rotated again to bearing 342, and a torpedo was fired at the bow section of the target. the last torpedo was fired at 343 or 344, if 344, it probably will miss, but i tried to get 4 torpedoes off, so that the divergence of the spread could be seen clearly. pics of the torpedo wakes coming up clearly show the torpedoes fired on different bearings, the question is, will the torpedoes hit where they were aimed at.


in the pic below, all four torpedoes are zinging their way to the target, the bow and stern wakes of the target ship still showing the target is not slowing down or turning, the divergence of the torpedoes is clearly seen by the torpedo wakes.




the following pic shows the target has spotted the torpedoes approaching, and has slowed down to avoid them, the bow and stern wakes of the target have diminished, but its to late, there's nothing it can do, its a dead duck, as captain o'kane said.



the pic here shows the torpedoes approaching the target, the first torpedo in approaching the stern stack, on its way to the stern where it was aimed at, the other 3 following in a beautiful divergent spread, the ship is doomed.




the following pic shows the first torpedo exploding at the stern, where it was aimed at.




the pic below shows the second torpedo exploding midship of the target, where it was aimed at.




the following pic shows target destroyed message, and just the beginning explosion of the third torpedo hitting the bow section.




the following pic shows the third torpedo hitting the target ship at the bow, where it was aimed at, the ship has been destroyed.




so thats it, thats the constant bearing firing method as i have learned it, it certainly matches the descriptions of the torpedo attacks in the book "clear the bridge".


just a note, at any time before the firing sequence, if it had been decided that a longitudinal spread would have been the better of the two spread patterns, it could have been switched from divergent to longitudinal by just placing the unlocked scope on the firing bearing, and shooting as the target crosses the wire, the torpedoe gyro's with all be the same.

happy hunting!
grey
__________________
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

Last edited by greyrider; 06-02-18 at 10:27 AM.
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Old 06-04-18, 08:02 PM   #2
stork100
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Thank you very much for these highly detailed and informative posts. Really excellent.
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Old 06-05-18, 09:50 AM   #3
greyrider
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thank you Stork, if you have any questions, feel free to ask, and i will help, but if you learn the method, and you shoot in the divergent spread, your actually in elite company.
at the begining of the post, i said it was the most popular method used by submarine captains, i have to take that back now, after rereading a passage from clear the bridge.

reexamining this quote from clear the bridge:

“ Ten degrees to go , ” called Fraz . This would be a new one for me . I could get the “ Constant bearing — mark ” off handily , but the “ Fire ” on a separate exposure might be too early or late . I considered firing on generated bearings , most submarines did , but with only two torpedoes , I’d stick with our bow - and - arrow method . “ Constant bearing . ” Jones raised the scope on the generated bearing . I swung it ahead to amidships and called , “ Mark ! ” Jones dunked the scope and raised it immediately . “ Fire ! ” The mainmast had passed the wire , but the after well deck was still on . The torpedo went out with a whine . The second double dip was more accurate , and our last torpedo was on its way for her foremast , its whine fading out in a few seconds . The range was 900 yards , the gyros near 180 , the same as near zero for a bow shot .


"I considered firing on generated bearings , most submarines did"

captain okane is telling us that most us submarines were firing on the generated firing bearing, if thats the case, then they were firing a longitudinal spread, and not a divergent spread, so if thats true what he said, only a very few u.s. skippers fired the constant bearing method with divergent spreads, okane was one of them. he called it his " bow and arrow method".
__________________
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
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Old 06-05-18, 07:58 PM   #4
stork100
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Very cool. I only got SH4 literally a couple of days ago, but as a veteren of SH3 and manual targeting enthusiast, every bit of information on how they really did it is like gold to me. No doubt O'Kane was the master.
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Old 06-06-18, 07:15 PM   #5
greyrider
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your going to be fine here stork, i was over at the sh3 forums when the game came out, so its good to see you here, just the position keeper is the only difference really, sh4 is really sh3 underneath. i have started a german career in sh4, a couple of days ago, so i can work out the constant bearing method with german submarines, and then post it in the sh3 forums, i cant get sh3 to work anymore.


anyway, any questions, feel free to ask.



found a reference to distance to horizon in the torpedo fire control manual,
page 5-6




this


(6) At extreme ranges it must be remembered that the waterline is below the horizon. This necessitates estimating the position of the waterline.
__________________
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
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Old 06-30-18, 12:58 PM   #6
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So I'm tracking on most of this, however I got lost on a few things.

How is it determined what the range of acceptable shooting angles is? In the example you have I understand determining 339 as the correct angle for an engagement with a longitudinal spread (or a single aimed fish for that matter). However where I got off track was figuring out the spread of bearings one can fire on.

So in your example of the pivot bearing being 18, why is the lower bound 14 degrees and the up bound 21 degrees?

I thought with the TDC engaged it generated a bearing and set the gyro angle for it regardless of where the scope was pointing? So do I need to send a new bearing and range to the TDC with each torpedo?

Also as I only recently re-installed SH4, does this work with stock 1.5 or do I need to add some mods to get things up to snuff?

Thanks!

Last edited by jenrick; 06-30-18 at 01:24 PM.
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