Zero gyroangle no-TDC attack [Archive] - SUBSIM Radio Room Forums

Mister_Spok

05-22-12, 12:26 AM

I also use TMO+RSRDC, and OTC as well.

The last and most impressive confirmation on this (My :)) methode I got yesterday. I was in the Slot, got radio messege that Japs will try to resupply their troops at Guadalcanal (Sep 1 1942) with high speed convoys. I set up patrol zig-zag through the straits and few hours later I pick up fast moving convoy on my radar (app. 30 knots). When I came closer I identified it as 10 Fubuki Destroyers. I came as close as I could, plotting their approximate course amnd speed with my A-scope (yeah, erly war radars had no PPI :)), dived to periscope depth.

Lucky me, I got them moving almost straight at my boat (AOB ~10 deg, bearing ~80 deg). So I went silent, using my periscope at first Fubuki, and plotted their course more accurately, and determined their true speed (app. 32 knots). So I turned my boad to go perpendicular to their course, calculated lead angle (~42 deg, and hey! who said that submariners had no tangens and sinus tables, or logarithmic rulers at their posession?).

I waited for first Fubuki to pass, waited a little, and let loose two fish at the second destroyer, one slight in front of his bow, secont - in the middle... First one missed in front of his bow, second one hit him in the engine room and he sank in the matter of minutes. Now that was a PERFECT hit on a target, that was steaming ahead at 32 knots! Without TDC, with torpedoes fired straight ahead! I love this game :)

P.S. I was on the S-boat. Few minutes later I surfaced and "eyeballed" lead angle on the other DD, that was searching for me. Two fish, one hit. Got second! :)

P.P.S. I play in on "Realistic" with only event camera turned on.

There are some nice stickies here that describe two techniques called "Dick Okane" and "Cromwell" with some very clear graphics.

It is weird and counter intuitive but for these types of attack, range literally does not enter the equation.

Took me a while to learn this.

I just had to do it myself :-)

Rockin Robbins

05-22-12, 10:16 AM

But Mr Spok, how do you actually perform these calculations? You are busily trying to make your game as realistic as possible, not using the TDC in a boat that most likely (some had them) did not have a TDC by making an electronic calculator necessary for the attack? Perhaps there is a slight disconnect there. Unless you have a slide rule with trig functions and know how to use it.

Or you could do as the real sub skippers did and use Nisgeis' vector analysis method (Nisgeis did not teach the real skippers:haha:). No trig. No tools outside the game itself. It's much faster than using your calculator, or even setting the TDC. It's idiot-proof, inspection validates the result.

http://i196.photobucket.com/albums/aa293/RockinRobbins13/Silent%20Hunter%204/VectorAnalysistargeting.png

Easier, faster, more accurate, self-validating, completely contained within SH4 with no outside tools. What's not to like?:D

Mister_Spok

05-22-12, 10:41 AM

Daniel Prates

05-22-12, 12:15 PM

Dear god, WW1 tactics!

Loudspeaker

05-22-12, 12:42 PM

Take a look at the vector analysis attack method actually carried out in these videos: http://www.subsim.com/radioroom/showthread.php?t=194687

Peronally I prefer to use TDC because... well, I am a bit of a technical freak and like to operate wheels and handles and stuff. I am ofcourse aware of the difficulties getting exact data such as speed, course and distance, but I accept the misses as well as the hits. In bad conditions I try to move within 1000 yards of the target. Here you can miscalculate both speed and range within certain limits (2-3 knots and about 10-20% range error) and still get a hit. Make sure to get at least the bearing right, though :D

Rockin Robbins

05-22-12, 02:08 PM

Lol, makes sense :) It IS actually the "graphic way" to solve that hypothetical attack. Only it doesn't force you to remember sinus and cosinus theorems and all that blow-your-head-off trigonometry (though I'm good at that :)).

Thanks!

Oh, the trig is awesome because it reveals just how much information is hidden in that little vector analysis!

Rockin Robbins

05-22-12, 02:14 PM

Dear god, WW1 tactics!
The S-Boat is a WWI boat! So it's a good fit and would be exactly how they did it, whether with a set of slide rules and a quick wrist or drawn on the chart.

They shot all torpedoes at a zero gyro angle because that's all the torpedoes had until the awesome Mark 10. Then they had a torpedo but no TDC.

Shooting with a zero gyro angle is much more error tolerant than with a steerable torpedo because any time you shoot with a zero gyro angle, if your target course and speed are accurate, range cancels out of the solution equation.

With curved fire, gyro angles non-zero, target range is critical to getting a hit. WWII practice was to consider all gyro angles under 15º straight fire and range no longer meant very much to the solution at all.

So it may be World War I tactics, but they were mighty effective.

Gangrene

05-22-12, 03:18 PM

I've got some pretty crazy trig I use to calculate speed and bearing of a ship. I'm going to have a video in my Let's Play about it. I'll show a hand method, a calculator method and a program to do it... I call it the Wagner Solution Method. For hand calculation you will need to make some of your own equipment for the job... I'll show that too.

Basically I take an observation and get their relative angle and distance... I wait and do it again...

then I use math

I get their distance traveled, speed, and bearing... I have everything I need.

all from two observations!!!

Rockin Robbins

05-22-12, 06:54 PM

Okay, why not just plot the two positions on a chart and measure the course and speed? Math is great, but it's like computers. We think that just because we know how to use it that math or computers are ALWAYS the best tool for the job.

I'm telling you that when you're slinging numbers around they're just numbers. They don't tell you when they're wrong. Every time to do a subcalculation there is a finite probability of an error and the effect is cumulative over the number of arithmetic steps you take until at some point the error probability becomes 1 or something very close to it.

Did you know that .99999... equals one? What's 1/3? .333... What's 2/3? .666...
.3333... plus .6666... equals .9999... which must equal one. Unless you convince me there's a 7 or a 4 out there somewhere. I don't think you can.

Math is a language just like English or German. As a language it is perfectly free to tell a lie as easily as it can tell the truth. Showing me an equation is true is not the same thing as proving that what you claim the equation represents is true. Did I say that right?

Graphical means not only come up with the solution, but they integrate all the intermediary steps of calculation into an elegant representation of the problem that is self-correcting. You can SEE when the graph of torpedo speed and direction, target speed and direction and impact point is wrong. You can measure and validate that the angles and velocities make sense. And so can your five year-old son, looking at the diagram say, "Hey, Dad, is the target supposed to be going faster then the torpedo?" or "The diagram says you're supposed to lead left, why are you leading to the right--behind the target?"

See numbers are too abstract and you can make dumb errors with them that you'd never make if you could visualize the problem graphically in your head. Graphic analysis makes up for any visualization deficiency, working much faster and more accurately than a hatful of numbers in a calculator.:D

merc4ulfate

05-22-12, 07:57 PM

TMO+RSRD

:ping:I do not know what is wrong with me maybe I'm insane but I just do not use math.

I captain the SS-200 Thresher, a Tambor class, without a deck gun YUCK!!. I had been defying my patrol orders for the past few days and instead of Patrolling south of Davao Gulf I have been patrolling around Truk.

I made a few successful kills on merchants entering the lagoon :yeah: and had gone down to Tulagi to reload and resupply my boat with fuel. On the 22nd of December I received an OP message that there would be an IJN group of ships 180 miles NNW of Truk on the 24 of December 1943. It read there destination was believed to be Truk.

I sailed to an area 180 miles NNW of Truk. Since there was no other information I plotted my best guess and sat all stop with the radar running. At 1229 on the afternoon of the 24th radar picked up a group of three ships moving fast towards the SSE.

By watching their radar position I estimated their course at 165 degrees. Speed estimated at 20. I was sitting SE of their location.

The weather was not my friend ... Overcast with heavy fog, wind speed 11 coming out of 056 degrees with 4 foot swells. I headed south west in order to get closer and could tell already my best speed was going to be to slow to match and shadow until the weather cooperated.

Knowing the main targets will mostly sit between escorts or supporting ships I decided to attack on radar bearings alone. They could not see me even at 500 yards but I, at least, knew their locations by radar. Visibility was no more than the length of my boat ahead of me.

I angled in within around 500 yards of the lead ship at flank speed and slowed just a bit so the second ship could catch up faster with me. I am not as fluent in the game as some are so my thought was to turn the TBT on the bridge to 140. I set 3 stern fish to run fast depth 20. I under estimated my time between radar contact and fired when the ship was at 130 degrees. They all missed but as they were running I fired 4 more from the bow tubes and got four solid hits.

The fourth fish in the stern and the other two in the bow were homing fish and in the hopes that my four hits slowed them down I fired them as well. Two of the cuties hit my main target and one hit the trailing ship. I could tell by radar the trailing ship had been disabled, dead in the water.

What I could not believe was the fact that the center ship which had now been hit 6 times was sailing to starboard circling around and had not seemed to have lost much of her steam. I had no way of knowing what it was but I turned to port as I reloaded and at flank speed kept her within 1000 yards of me until I was reloaded. My next volley I increased my lead angle by 10 degrees and after a few misses I scored two more hits. I could see the explosions in the distance but still could not identify the ship in question.

Watching the radar for course and speed changes I noticed that the ship was slowing down greatly. The lead ship circled around looking for me but was always to far away to see anything especially with my course changes to keep up with my main target.

The target was now dead in the water. From the bridge I looked to try to see it. I was close enough to see the white flashing light from her bridge but I could not see the body through the fog. I set the bridge TBT right on the flashing light. I fired .... waiting .... wainting .... waiting ....

It had to miss. How could it?? ... I turned the TBT ten degrees to the port and fire again. Again another miss ... I sat and thought ... I had to be almost bow to bow with her or bow to her stern and the fish traveled on either side of her.

I went ahead slow and positioned myself 45 degrees from her and my previous position. ALL STOP!! I have two fish left and she has already taken 8 hits. This better work or I'll ram the damn thing. Fire 3 ... waiting ... wait- BOOM YES!! I was right FIRE 4 ... another hit and she began to explode like the 4th of July in December.

I could not resist cruising up to her as she now quickly sank and discovered one less YAMATO class Battleship!!

Sometimes sheer guts and a bit of Father Christmas luck is all that is needed. I also decided to thank Father Christmas for the fog ... I could not have done this if I had to submerge ... I was wrong ... the weather was my friend in deed this day. :ping:

Mark

Mister_Spok

05-23-12, 02:14 AM

Lucky you! :)

But, if you knew some attack tactics by that time, you would sink that Yamato (never encountered one myself) without using all you torpedoes stash :)

But I must confess that I myself often "eyeball" my targets, if they are within 400-500 yards from me.

ColonelSandersLite

05-23-12, 08:11 AM

The easiest most painless way is to use a lookup table. I've made some nice ones for all the us torps except the cutie (which is because the homing makes it pointless). Mk 14 Fast/Mk 14 Slow/Mk 18/Mk 10. The result is 2 double sided tables that give the correct lead angle for any zero gyro shot. It's honestly much faster than using a graphical method if you're going no tdc. I'll send them to anyone that wants them in both xls and bmp format. BTW, this is also going to be the historical method as well. No need to make a crew do the work during a combat situation when a mathematician and printer can do it years in advance.

Loudspeaker:
Thanks for the plug. Patrol 2 mostly done, but been to busy to finish. Hope to update this weekend. Lotsa action this time, including a convoy attack!

Spok:
I managed to get it done with one formula in excell, regardless of angle. I'm not going to retype it for readability but here it is:

=DEGREES(ASIN(AH1*SIN(RADIANS(AH2))/SQRT(AH1^2+B2^2-2*AH1*B2*COS(RADIANS(AH2)))))

I can't remember for sure which is which but ah1 and ah2 are intercept angle and target speed. Since I'm converting AH2 to radians here, I'm assuming it's intercept angle and ah1 is speed. B2 is torpedo speed.

Rockin Robbins

05-23-12, 01:28 PM

The Dick O'Kane method was the specific reaction to using a simpler lookup table and picking the wrong column by mistake. Again, numbers do nothing by themselves to tell you they are valid. Graphical means are intuitively self-checking. By inspection you can troubleshoot them and be sure you're not making a mistake.

When you are using a lookup table with 4 torpedoes, some with multiple possible speeds, differing target speeds, different AoB's etc, there are a lot of possible mistakes that will be made. Tables work, but people don't. Simplify! You'll get more hits.

The most foolproof methods are either to rely on the TDC to know what torpedo you're shooting at what speed as in the Dick O'Kane or John P Cromwell method, or using vector analyisis, where the solution is self-validating and can be verified by inspection.

Those tables contain the correct solution accompanied by a whole lotta (play Led Zeppelin here) wrong ones. The odds of picking the wrong one is 100%. It will happen. You just don't know when....

Gangrene

05-23-12, 03:59 PM

Any good mathematical system would have a self checking redundancy built in to reduce the chance of error to a minute possibility.

Mathematics if properly done, error free, will always be more exact than free hand or tooled drawing as there is slight variation in the decimal range that is unseen when drawn by hand. It's level of precision is limited to the analog systems of people. Of course this is to a minor degree.

Daniel Prates

05-23-12, 04:46 PM

So it may be World War I tactics, but they were mighty effective.

I know, I was trying to be funny (unefectively, as it seems).

It should be mentioned also that manual calculations with rulers as the 'banjo' were in standard use by then, regardless of the presence of the TDC.

ColonelSandersLite

05-23-12, 07:16 PM

razark

05-23-12, 08:28 PM

Unless you have a slide rule with trig functions and know how to use it.
If you don't happen to have a slide rule, you could always make one. The whiz wheel (http://www.hnsa.org/doc/attackfinder/index.htm) has a sine scale built in. I've used it to set up attacks using this method (http://www.subsim.com/radioroom/showthread.php?t=112765). I've also used a straight rule I borrowed my father, until I got a 1970s vintage slide rule.

There's just something about having an authentic tool in your hands to set up an attack with. (Plus, it's fun to watch the faces of people when you pull out the rule and start calculating with it. Bonus points if you get an answer while they're still messing with their calculator.)

Gangrene

05-24-12, 02:05 PM

One of these little bad boys could help as well... and it is 1940's tech!
http://www.youtube.com/watch?v=HYsOi6L_Pw4

Rockin Robbins

05-25-12, 12:08 PM

@ Robbins

True, but again, the s-boat doesn't have a tdc and it's faster to use a table than a graphical option in a combat situation and graphical options are limited in accuracy to the accuracy of the ingame tools. At the end of the day, you just gotta pick your poison.

The in-game tools are quicker and more accurate than a calculator. You don't even have to pause the game to use them.

All necessary tools are built into the nav map and are much more accurate than required.

ColonelSandersLite

05-25-12, 01:37 PM

The in-game tools are quicker and more accurate than a calculator. You don't even have to pause the game to use them.

All necessary tools are built into the nav map and are much more accurate than required.

I didn't say calculator, and I've had an in depth conversations with you where you complain about the lack of accuracy of the ingame tools so you know...

Anyways, here's an old addage for you. The proof is in the pudding. Check the first 2 vids in the video playthrough thread I'm doing.

The first Vid I use the graphical solution. Doing the work takes from 4:40 to 6:41 or 2 mins and 1 second. Could I shave that down to a minute or so if I was practiced at it again (and not talking at an audience)? Sure I could.

The second vid I use a lookup chart. Doing the work takes from 1:12 to 1:38 or 26 Seconds. And I wasted about 5-6 seconds there due to lack of practice and again, talking to the audience.

Worst case scenario for both with someone who was way out of practice: the lookup table was 1m 35s faster (or 465% faster).

Best case scenario for both with someone who actually remembers how the hell both work: the table is 40 seconds faster (or 300% faster).

Also worth noting, that my lookup table produces accurate lead angles to the nearest 10th of a degree. Sure it's overkill, but it eliminates a source of error from the final firing solution.

At the end of the day, am I saying that you shouldn't use the graphical approach? Hell no I'm not.

I don't necessarily agree that a graphical approach is faster than a calculator (I think an expert in both would be about as fast in both, unless you had programmed a function into a *nicer* calculator and just had to punch in 3 numbers, that's faster), but I personally reccomend against bringing digital instruments into the game for maximum immersion because they did not exist in the second world war.

I do agree that using the graphical approach is certainly faster than using slide rules though, even knowing exactly what you're doing with them.

At the end of the day you have 3 historically available options (precalculated table, slide rule, graphical trig) and while some are faster than others, they all have their merits and it comes down to a matter of taste.

Edit: Actually, if you want to use a period correct calculator to do the job, it's available on all post s class submarines. It's a damn big hunk of steel called a tdc. Ya might have heard of it :D...

Rockin Robbins

05-25-12, 04:16 PM

Edit: Actually, if you want to use a period correct calculator to do the job, it's available on all post s class submarines. It's a damn big hunk of steel called a tdc. Ya might have heard of it :D...

And that is what the Dick O'Kane technique is. It was born when I was using one of those tables, but simpler than the ones you use. I picked the wrong page or column, heck they're only baskets of number arrays--lots of wrong answers on every page--and missed of course.

That got me to thinking: how can I save time and NEVER have to use one of those <insert colorful insult here> tables AGAIN! And I though as you just did, that there is a marvelous calculator on board, also all possible firing tables cooked into one nifty TDC unit. It knows which torpedo you're using and what speed setting without you having to remember a thing. It works if you thought you picked slow speed Mark 14 but set for fast by mistake!

So I cooked up the rules of thumb for picking a ballpark firing bearing, knowing that anything under a 15º gyro angle is considered straight fire and range still doesn't matter. I can guess within a couple of degrees, so my rule of thumb is five times more accurate than it needs to be.

I decide to fire 10º before the zero bearing for a 7 knot target, set the AoB for 80º starboard or port depending on which way the target is coming from, speed 7 knots, range who cares, stab the send to TDC button and I'm ready to fire. The TDC will figure out the actual lead angle of the torpedo and send it down the correct bearing, within a couple of degrees of zero, to get a perfect hit on my aimed position on the target. Each torpedo is individually aimed for it's own separate impact point on the target.

Takes much less time than a table even. Now all I have to worry about is positioning my boat at 90º to the target track in range of the torpedo. I've set the TDC up to an hour before I fired. Whenever that happens, all the work is already done. All I have to do is open torpedo tube doors and shoot.

I've been the champion of this method even over the vector analysis method because it is so easy and foolproof. The advantage of the vector analysis method over Dick O'Kane and the lead angle tables is that it works at any AoB/TTA. Unless you have a book the thickness of War and Peace you can't do that with tables.

You're always giving up flexibility for simplicity or giving up some simplicity for flexibility. There's no free lunch. However, the potential for error in the tables far outweighs their usefulness in speeding up the targeting process. The most important and neglected part of any targeting procedure is error mitigation.

ColonelSandersLite

05-25-12, 11:18 PM

The advantage of the vector analysis method over Dick O'Kane and the lead angle tables is that it works at any AoB/TTA. Unless you have a book the thickness of War and Peace you can't do that with tables.

Not sure what you mean by tta (Target Track Angle?) but my chart handles all AOBs from 0 to 180 at a speed range from 0 to 30 knots on one page. Well, really 2 double sided sheets. 1 side per torpedo. Here, see for yourself:

Edit: Note that due to photobucket stupidity, these images are low quality. I'll upload a high quality printable archive version soon. I think I'll even do a usage walkthrough video to go with them.

http://i3.photobucket.com/albums/y91/ColonelSandersLite/mk10torpedochart.jpg

http://i3.photobucket.com/albums/y91/ColonelSandersLite/mk14slowtorpedochart.jpg

http://i3.photobucket.com/albums/y91/ColonelSandersLite/mk1423torpedochart.jpg

http://i3.photobucket.com/albums/y91/ColonelSandersLite/mk18torpedochart.jpg

Rockin Robbins

05-26-12, 01:47 PM

So there you have it: the very reason to not use the tables. And the very reason TO use the tables. If your eyes don't swim around in frustration looking at that spreadsheet from hell like mine to, and if you believe that under severe time pressure you can pick the correct torpedo page, target speed, AoB and corresponding lead angle very time without error, then that chart is your baby.

Then if you don't want that minefield, you can do a quick Dick O'Kane without any of that, or a vector analysis attack using three lines drawn on the in-game navigation map.

There you go folks! Use your own judgement on what and who makes sense. That's all the evidence I need......:ping:

Decent spreadsheet design by the way. You've made it as easy as possible to choose the correct solution from one of four pages with 90 rows and 31 columns apiece for a total of 2700 solutions per page, of which you must pick one correct number. In spite of good design, it's still extraordinarily too probable to pick the incorrect solution. There is nothing self-validating about the method, therefore its effect will be to produce error. Lots of errors.

To be error tolerant procedures must be simple, their answers unambiguous, clear and uncluttered. Lots of stuff works. Very little works well. Less is more.

Suggestion on the tables: A decimal point in an angle shot from a submarine is meaningless. Why not bin the solutions rounded to the nearest degree? Not only would that result in many fewer columns and rows but the resulting uncertainty would still be WAY under the error contained in your measurement methods. Too many significant figures is impressive to the ignorant but amuses the experts. Your real accuracy of result is limited to the least accurate of all your inputs. That restricts you to whole degrees.

Loudspeaker

05-27-12, 07:43 AM

Thanks, colonelsanderslite. Your tables are very welcome here. As an occasional player I tend to forget the intercept angles, and I am tired to draw them over and over again, when attacking a poor japanese bastard who is only trying to make a living. :arrgh!:

Respectfully, Rocking Robbins, I agree with the colonel that the tables will make the work easier. The only fault is that players now can carry out precise attacks without knowing the theory behind it. Thus, the time I have spent so far, drawing and drawing, was not a waste.

Now that I have been trained (by RR, btw), I think it's time for me to make use of the tables. :know:

P_Funk

05-27-12, 08:36 AM

I think the charts are just too complicated. They give you too much information. The goal is to balance information with necessary detail to effectively operate.

If you notice how little the lead angle changes based on intercept angle you can cut down significantly by limiting the blocks to Lead Angle every 10 Degrees since the difference every 10 degrees is acceptable for most applications. Instantly you've trimmed it down. Next you nix the 0 and 180 portion of the table. Start only at 170 to 10 because any shot lower than that is basically straight down the throat.

With that criteria you end up with a chart that is 30 by 17. If you want to be even more austere you can chop it down to the preferred firing angle which is within about 60 or 70 degrees and 100-120 degrees.

I'm a firm believer in putting more energy into the approach than the firing solution. Better to spend your time getting into position ambush a man from spitting distance than to spend all your energy trying to make a perfect shot from an impossible position.

Here's what I refer to in my personal 0 Degree Gyro tables for SH3:

For 30 Knot torpedo @ 90 degrees

Target Speed / Lead Angle
1 / 2
2 / 4
3 / 6
4 / 8
5 / 9

And this continues to 20 or 30 knots. Simple, clean, informative to the point necessary. You can even slap a multiple torpedo speeds in columns parallel if you please or just keep it limited to a single torpedo speed.

The problem with information overload isn't the information, its how its presented. The most concise and important information is useless if you can't read it. Make it legible and its just as good as anything.

If you put the time in to plot the target accurately, if you put the time into getting into a favorable position, then relying on a table for the moment of firing is easy because you've done the hardest work getting into a position that affords you the luxury of a clean little reference sheet.

Here, Makman knows how to do it:

http://i965.photobucket.com/albums/ae138/sphere94/15.png

Rockin Robbins

05-28-12, 01:19 PM

Even there the tenths position is meaningless clutter. All angles should be rounded to the nearest degree to reflect the true accuracy of the procedure. We kill ourselves working with absolutely false precision. Your answer is accurate only to the number of significant figures in your least accurate input.

Therefore, if you can only measure bearing to the nearest degree, you can only measure lead angle to the nearest degree. You can specify decimal places out to hell, but they're all a lie.

False precision isn't...

Rockin Robbins

05-28-12, 01:24 PM

Not sure what you mean by tta (Target Track Angle?)
Here you go, the US Navy Submarine Torpedo Fire Control Manual of 1946 (http://hnsa.org/doc/attack/index.htm). Read it. Learn it. Learn the nomenclature, it's important. It reflects on your credibility, if you have no better reason to read it. TTA is important because it is central to deriving the most tolerant solution to changes in target course and speed. There are some really interesting (and baffling!) graphs in there relating to that relationship.

P_Funk

05-29-12, 03:57 AM

Even there the tenths position is meaningless clutter

All angles should be rounded to the nearest degree to reflect the true accuracy of the procedure. We kill ourselves working with absolutely false precision. Your answer is accurate only to the number of significant figures in your least accurate input.

Therefore, if you can only measure bearing to the nearest degree, you can only measure lead angle to the nearest degree. You can specify decimal places out to hell, but they're all a lie.

False precision isn't...

You seem to forget the way that a periscope dial is not a digital display with only rounded whole numbers. It has spaces between the marks, more than enough that you could reasonably estimate a 10th. If its inaccurate, its off by about a 10th, whereas a rounded whole number could be off by as much as a whole half of a degree. Its wasting the accuracy of the available tools to ignore that space between marks.

I think you're just fighting to keep a sinking ship afloat at this point.

You had a point, then you got greedy. Classic internet mistake. :|\\

Diopos

05-29-12, 10:05 AM

To strive for an 1/10 of a degree of accuracy for a lead angle because you periscope accomodates it has no meaning if you don't have a corresponding accuracy on the target's speed, course and your own sub's heading. My game play tactics are based on zero gyro angle shots AND a close range to the target (1500-500 m). The close range eliminates my lack of precise knowledge of the targets speed or course. BTW my periscope has devisions for every 5°. And I am quite happy with the results. If I used the same "set up" to hit a target at 8000 m I would probably fail. In fact the more "relaxed" approach RR suggests is probably closer to what WWII skipers actually "tolerated" as adequte data to solve their torp firing problems (either via tables, slide rules, TDC or "eyeballing the situation).

.

Rockin Robbins

05-29-12, 10:24 AM

So you're saying our bearing is good to a tenth of a degree? Our range is good to a tenth of a yard? Our AoB is good to a tenth of a degree? Our target speed measurement is good to a tenth of a know? All these have to be good to one significant figure past the decimal point for our answer to be truthfully rendered to a tenth of a degree.

Otherwise all those numbers after the decimal point are pointless fiction. Surely you've studied this? You MUST have studied this if your position is that I've taken my position too far. After all a baseless position is worth nothing. And you would NEVER present a position from a position of ignorance, would you?

Therefore, my position remains. Lead angles are only good rounded to the nearest degree. If you want to split the difference between two degrees, even that makes no sense because you don't know whether the lack of precision in your measurements cancel each other out or are additive.

Especially if you are using the <insert derogatory term here> stadimeter to derive range instead of radar, any claims of accuracy to a tenth of a degree are merely comedy, not worthy of anything short of contempt.

That's my story and I'm sticking to it. It's an opinion based on mathematical certainty. That's pretty solid ground.

The concept of significant figures it this: the number 1 is not an exact number. It is the set of all numbers between .5 and 1.5 Similarly, the number 1.5 is not exact either, but is the set of all numbers between 1.45 and 1.55. Thus the way numbers are expressed reflects an accuracy claim inherent in the number of significant figures presented. The answer to a calculation is only accurate to the extent of the least accurate input to that calculation and the answer must be rounded to the correct number of significant figures to be a truthful result.

Therefore 1 <> 1.0 because 1= the range between .5 and 1.5, where 1.0= the range between .95 and 1.05. Kapeesh?

Rockin Robbins

05-29-12, 10:26 AM

To strive for an 1/10 of a degree of accuracy for a lead angle because you periscope accomodates it has no meaning if you don't have a corresponding accuracy on the target's speed, course and your own sub's heading.

.
HERE's a guy who understands the targeting process. It contains errors. We don't know what magnitude those errors are, so we mitigate those errors using appropriate tactics. Diopos gets lots of hits as a result.:D

P_Funk

05-29-12, 09:35 PM

To strive for an 1/10 of a degree of accuracy for a lead angle because you periscope accomodates it has no meaning if you don't have a corresponding accuracy on the target's speed, course and your own sub's heading.
Thats a fair point to make, however, why is the rounded whole number any more correct than the decimal place? If I assume that I'm being "casual" or just procedurally incomplex and accepting that methods are never 100% accurate enough to say with certainty that this or that decimal is right, then why the romanticism over whole numbers? Because its easier to work with? Alright.

But what if I know that given a whole rounded number in every other category of the Target Triangle the correct lead angle is in fact correct as say 12.5 rather than 13 degrees? If my calculations should happen to be spot on wouldn't I be incorporating a deliberate error into the solution if I rounded that result-?

Lemme ask you, if you get a speed read out of 5.5 knots after making numerous speed/time calculations acquired from plotting over lets say 30 minutes, and every time it comes out that its 5.5 knots, are you going to procedurally round up to 6?

My point is that there's no logical reason to assume a rounded whole number is any more accurate than one with a decimal in it. If you make a measurement that produces a whole number with a decimal its just as inaccurate as the rounded number, the only difference is that the rounded number is cleaner. Its easier to manage intellectually.

If my TDC or my periscope has the capacity to handle the decimal places then I'll use it if I have it. Using the closest thing to the pure results is better in my opinion if you can than creating a 'cheat' number. Cheat numbers are for instance calculating speed by multiplying by 2 rather than 1.94. Its good enough to plot an intercept, but if your target is going faster than 10 knots the compounding error from that .06 could easily add to the existing error that comes from inaccuracy in estimation and the overall limitations of the equipment. In my head? Yea multiply by 2, but if I have the means to multiply by 1.94 from a calculator or a slide rule or a reference sheet no logical person is going to use the short hand version unless absolutely necessary.

My point, well belaboured by now, is that there are enough inaccuracies, but the on paper math is one of the things we can know with absolute certainty. If you dumb down the math enough along with inherently inaccurate observations then you're just adding another error variable into the equation. Every additional variable that limits accuracy compounds the overall accuracy of the result. Math we have a luxury of knowing, especially if you can do much of it ahead of time or refer to it.

Thats a lot of talking to justify using one decimal place. But I stand by my logic. The only proper counter argument here is that the decimal place adds a potential for confusion. So I say, which do you prefer risking be confused? The person dialing in the TDC or the Torpedo? Only one can correct himself once he's made a mistake. :hmm2:

Therefore, my position remains. Lead angles are only good rounded to the nearest degree. If you want to split the difference between two degrees, even that makes no sense because you don't know whether the lack of precision in your measurements cancel each other out or are additive.
So if we know none of this how can we confidently incorporate a rounded figure with the same level of certainty? If your numbers are in fact accurate without your knowledge you're adding another error after the fact.

The point isn't whether it doesn't make a difference or not, the point is why not?

You've gone on this tangent about subjective accuracy but your primary argument was that incorporating a decimal is confusing. If someone can manage to not be confused, what advantage does rounding have? What disadvantage does using a decimal have?

This is just a semantics debate now. If most of this ends up being gut instinct and experience, who's more right when it comes to evaluating the subjective accuracy of their own fire solutions? There had to have been real fire solutions used in the war to hit a target that had a decimal in it.

Rockin Robbins

05-30-12, 08:51 AM

Thats a lot of talking to justify using one decimal place. But I stand by my logic. The only proper counter argument here is that the decimal place adds a potential for confusion.
Your premise is wrong. Your premise is that if you measure speed, you are getting a precise number and your mathematical bent wants to treat that number as a precise quantity.

However, as I told you above, that "precise" target speed is subject to the imprecise components used to calculate it. Your range is not precise, it is accurate to within ten yards or so at best with radar, much worse if range is from any other method. So you already have lost the tenths position with your first input.

Your very concept that numbers are precise is fatally flawed. As I explained above 1 is not equal to 1.0. 1 is the set of all numbers between .5 and 1.5. 1.5 is the set of all numbers between 1.45 and 1.55 therefore the number 1.0 contains 10% of the range that 1 contains.

Let's do an elementary school addition problem in engineering think. 1+1=?. Now we know that 1 equals the complete range of values between .5 and 1.5. So the result of 1+1 is a bit different than we think. The answer has a minimum and maximum value, AND a probability of each value between that range.

Minimum value of 1+1 is .5 + .5 (actually this value does not include .5, .5, an infinite number of zeroes and a 1 at the end is the actual minimum value. Note that 1 = all the values BETWEEN .5 and 1.5) If both ones equal not quite .5 then the answer to 1+1 is 1.infinite number of zeroes with a one at the end. This is just a smidge over one.

Maximum value of 1+1 is if both ones are 1.5 (actually 1.499999999... not quite 1.5) equals 2.9999999... almost 3.

Now the actual values of the two measured ones are assumed to be random, not within our ability to measure. We have measured as accurately as we can so intuitively you can see that values toward the middle, 1.0, are more likely than either extreme. And in order for the answer to be at high or low limits, both measurements would have to have an error in the same direction of maximum extent. This is much less likely than a situation where the errors cancel each other out and our value comes out very close to 1.0.

You end up with the classic probability bell curve. Our answer could be 1.000001 or 2.99999. but the probability is very low. There is more than a 50% probability that our answer is 1.0 and most likely 75% that it is between 1.2 and .8. You see where this is all going.

Your most accurate answer, closest to the set of every possible real result is going to be approximated as 1.0. That way you are splitting the difference of all possible errors. That is why the rounded whole number would be more accurate than a number with a fictitious decimal place, answering your objection to Diopos above.

The TDC does this automatically. If you attempt to input 5.5 knots into the TDC it sees 5 knots. If you attempt to enter 340.5 bearing it sees 340 or 341, not where your scope is pointed. You cannot have a gyro angle between 1 and 2 degrees.

Guess what? It works! If you were right you couldn't hit anything using the TDC. You would have to have the "precision" of the tenths position.

You see, you have been laboring all your life under a misconception about what numbers mean. You think they are like counting numbers: precise. One torpedo does not equal a torpedo and a half!

However when you are measuring quantities, you must incorporate another concept of what numbers mean and you just aren't there.

Now I've been talking about significant figures in a non-specific and general sense. The actual concept is more complex and of course more complete than I have presented.

Here is a fine very technical tutorial on the proper use of significant figures from the University of South Carolina (http://www.chem.sc.edu/faculty/morgan/resources/sigfigs/index.html). http://en.wikipedia.org/wiki/Significant_figures has a non-technical still but more complete statement than I have presented in this thread. These explain the idea of what significant figures are and how they MUST change how you conceptualize numbers when used for measurement, not counting. They are in complete agreement with me that any digits after the number of significant digits in the least accurate measurement in your calculation are all fictitious and of no value whatever.Like I said, I didn't make it up. These are not fantasies I'm talking about and I am not a raving lunatic despite the unfamiliar and quite strange concepts.

Using insignificant digits beyond the true significant data in your calculation does not add precision to anything. They are garbage to be discarded.

When you disagree, you are not disagreeing with me. It is not my idea. It is the proven work of thousands of mathematicians and engineers for well over 100 years. If you wish to continue to espouse contrary ideas, I suggest that educating the University of South Carolina might be a good start. Find the defects in their course material and become famous.

JohnnyCarwash

05-30-12, 09:29 AM

The TDC can be set to speeds other than whole numbers. While the PK display will show 6,7,8 etc, you can input fractional speeds using the attack data tool.

Rockin Robbins

05-30-12, 09:58 AM

The TDC can be set to speeds other than whole numbers. While the PK display will show 6,7,8 etc, you can input fractional speeds using the attack data tool.
Doesn't work. Input what you want, the TDC changes everything to whole numbers. How about a video explaining what the attack data tool is? Are you talking about the TDC input dial? Let's avoid renaming all the instruments on the submarine, OK?:D

P_Funk

05-30-12, 10:42 AM

Guess what? It works! If you were right you couldn't hit anything using the TDC. You would have to have the "precision" of the tenths position.

You see, you have been laboring all your life under a misconception about what numbers mean. You think they are like counting numbers: precise. One torpedo does not equal a torpedo and a half!
You are an unpleasant and arrogant person. Congrats, you won the argument. How about some self indulgent insult to my intellect to top it all off? They didn't cover magnanimity at UNC?

I always hated people in the math club, and this is exactly why.

Rockin Robbins

05-30-12, 11:13 AM

Well the point is that what is intuitively correct often is dead wrong. It was as much a surprise for me to learn it as it is to you. It felt as if someone had redefined the word "bathroom" and a couldn't ask where it was any more.

We're taught that numbers are discrete quantities, when they are actually different sized bins of lots of different possible quantities. If you love the precision of math, as you obviously do, and as I do, it wrecks your day at first.

The concept of significant figures proves that often we're just torturing ourselves with fictitious precision: I as well as you! Then the difficult part begins.

Error has to be assumed and its magnitude mitigated in any solution. Okay, I am within +-1º of my result. The MOT of my target will be somewhere between 340º and 342º. So I'll send the torpedo up the 341 bearing to split the difference between the possible errors.

Now, at what range is 1º less than half the length of the target? Because if I am within that range then any error in my calculation due to lack of precision in my inputs will result in a guaranteed hit.

This will be a nicely distant range to comfortably shoot, that's for sure. You know there is error. You know how large it can be. You've made sure that it doesn't matter. Further precision is a waste of time.

That's all I'm saying. Keep it simple. Complexity is not equal to precision.

You are the one who went beyond talking about ideas and brought personality into this discussion when you very wrongly said, "I think you're just fighting to keep a sinking ship afloat at this point. You had a point, then you got greedy. Classic internet mistake. :|\\" At that point I had no choice but to lower the boom as you questioned my credibility. I don't make claims lightly. I am always subject to correction on points of accuracy, but not personal dismissal as a credible source of reason.

Rockin Robbins

05-30-12, 11:44 AM

JohnnyCarwash

05-30-12, 03:14 PM

Doesn't work. Input what you want, the TDC changes everything to whole numbers. How about a video explaining what the attack data tool is? Are you talking about the TDC input dial? Let's avoid renaming all the instruments on the submarine, OK?:D

The attack data tool is explained in the manual that comes with the game.

P_Funk

05-30-12, 03:31 PM

An important addition to my treatment of significant figures. Suppose you decide that your least accurate measurement is to three significant figures. The doesn't mean that you round ALL inputs before doing your calculation.

You use all available precision during the calculation process to avoid rounding errors. It is only the final result that is rounded to avoid invalid digits. All you spreadsheet jockeys will already know this one.
And that is the particular distinction that lead me to challenge your position since you were entirely vague in the process of describing why you were right. You at no point until now stated that rounding errors should be avoided in the process of calculating, which is one thing I was about to bring up after reading about that specifically.

In fact I mentioned at least in concept the idea of rounding errors when I stated that if you rounded everything you end up potentially skewing results far more than they need be.

Now I'm not going to dispute the logic of your proof, its solid, however you've done a poor job at times of representing it, instead substituting fact with condescension or even worse offering fact married to an intellectual insult, something thats well below someone who purports to have such a decent level of education.

Essentially you posses knowledge and understanding, I just found your method of disseminating it rather obnoxious. Math is something I admire but have struggled with in the past. I have not taken engineering courses but your statements failed to, until the final addendum, account for the creeping suspicion of something being amiss. Effectively, someone with a relatively incomplete mathematical knowledge could still smell that the simplicity of what you were saying wasn't complete. On reading more on the concepts you brought up I found just that: qualifications you didn't bother to incorporate as you were bombasting down at the inferior student of mathematics.

I more than anybody appreciate the enlightenment of a more learned party, but I respectfully refuse to accept it with the qualifying of humiliation that comes with that arrogance. We all get carried away in arguing but it just annoys me how easily when someone has the clinching argument they feel the need to "rub it in".

Besides, I don't think I was entirely off. As you say, and as I've read, nothing in the principles of significant figures states you must round to a whole number. As I've noted the periscope affords an angle which is able to be interpreted in decimals. While the Fire Computer may not allow every variable (Im not sure which ones or if its all of them) to be inputted with decimals I can say that at least as far as observation goes utilizing decimals seems perfectly valid, in that you should use only as much precision (ie. decimal places) as the instrument is able to measure. In the case of the periscope you can measure 10ths of a degree.

The 90 degree 0 gyro angle firing table, the thing which started us on this merry jaunt through math and insult, uses known whole numbers (target track angle and target speed) as a means to fix the third (lead angle). If the result of those two whole numbers, rounded once calculation is completed, produce a lead angle that measures in 10ths of a degree, then why is it incorrect to use that with the primary instrument concerned with the lead angle, namely the periscope, which can in fact measure to the same degree of precision as the reference table records?

The torpedo is firing at 0 degrees along own ship's longitude, the ship is pointed at the best accurate estimate of 90 degrees to the target's track, all this tells us to point the periscope at a degree of say 12.5 and to fire once we've observed the target cross this point.

If I can observe 12.5 degrees in my periscope then how is the decimal place inappropriate? As far as I can tell the rules of precision dictate that if I have 10th of a decimal place measurable then I should use that decimal place. The TDC's limitations to rounded whole numbers need not apply as this is a non TDC operation, and as such with all other variables in the solution being whole numbers how can the observed lead angle required rounding? Why would it be false precision if the periscope can guarantee that degree of precision?

I accept that you have more knowledge and experience int his field, but I still cannot find a reason why the above statement is flawed. Feel free to enlighten me, but if I have a peri that can see to a 10th, then how can I not use it to a 10th?

You are the one who went beyond talking about ideas and brought personality into this discussion when you very wrongly said, "I think you're just fighting to keep a sinking ship afloat at this point. You had a point, then you got greedy. Classic internet mistake. :|\\" At that point I had no choice but to lower the boom as you questioned my credibility. I don't make claims lightly. I am always subject to correction on points of accuracy, but not personal dismissal as a credible source of reason.
I call Bullcrap on that. I got cheeky, and you could have easily said "no I'm using something I learned in university math which I've as yet not bothered to give in any detail". You were speaking with a sense of self assurance that was not buoyed, at least publically in the conversation, with any fact, just your own assumption of fact. I said I think you're arguing for ego, you could bother to enlighten, as you did. Personal insult has no place, and frankly you punched pretty low below the belt on that one.

I much prefer purely analytical arguments Lets leave the alpha male BS to UFC forums shall we?

Rockin Robbins

05-30-12, 04:27 PM

I much prefer purely analytical arguments Lets leave the alpha male BS to UFC forums shall we?Arrrrrr!:arrgh!: Agreed in full there. Sorry if I came off insulting. I include myself in those who were instructed with an entirely wrong idea of what numbers represent and it is no crime to follow good horse sense, even when the horse sense leads you wrong.

Brighter folk than we have been mislead by things that just should be true. Aristotle taught that since gravity pulled stronger on heavy objects than on light ones that the speed they fall would logically be proportional to their weights. For a thousand years all of humanity believed that until that imp Galileo started his meddling with balls and inclined planes, later upping the ante with his demonstration of dropping two greatly varied weights from the top of the bell tower at the Cathedral of Pisa.

When he was in 5th grade, I proposed to my son that he reproduce Galileo's inclined plane experiments without disclosing that the experiment came from Galileo. He built a five foot long inclined plane with a release on top that would release a 2" ball bearing and a ping-pong ball at the same time. By listening to the balls strike a wall at the bottom you could judge which was the winner.

Turned out his instructors decided the whole thing was stupid. Of course the ball bearing would slaughter the ping pong ball and what would that prove? So when my son released both balls and they made a single tonk against the end barrier they accused him of rigging the device. These were college educated teachers!

Which leads me to muse. Which universally accepted truths that we know are completely wrong?:woot:

doulos05

05-30-12, 07:43 PM

Besides, I don't think I was entirely off. As you say, and as I've read, nothing in the principles of significant figures states you must round to a whole number. As I've noted the periscope affords an angle which is able to be interpreted in decimals. While the Fire Computer may not allow every variable (Im not sure which ones or if its all of them) to be inputted with decimals I can say that at least as far as observation goes utilizing decimals seems perfectly valid, in that you should use only as much precision (ie. decimal places) as the instrument is able to measure. In the case of the periscope you can measure 10ths of a degree.

The 90 degree 0 gyro angle firing table, the thing which started us on this merry jaunt through math and insult, uses known whole numbers (target track angle and target speed) as a means to fix the third (lead angle). If the result of those two whole numbers, rounded once calculation is completed, produce a lead angle that measures in 10ths of a degree, then why is it incorrect to use that with the primary instrument concerned with the lead angle, namely the periscope, which can in fact measure to the same degree of precision as the reference table records?

The torpedo is firing at 0 degrees along own ship's longitude, the ship is pointed at the best accurate estimate of 90 degrees to the target's track, all this tells us to point the periscope at a degree of say 12.5 and to fire once we've observed the target cross this point.

If I can observe 12.5 degrees in my periscope then how is the decimal place inappropriate? As far as I can tell the rules of precision dictate that if I have 10th of a decimal place measurable then I should use that decimal place. The TDC's limitations to rounded whole numbers need not apply as this is a non TDC operation, and as such with all other variables in the solution being whole numbers how can the observed lead angle required rounding? Why would it be false precision if the periscope can guarantee that degree of precision?

I accept that you have more knowledge and experience int his field, but I still cannot find a reason why the above statement is flawed. Feel free to enlighten me, but if I have a peri that can see to a 10th, then how can I not use it to a 10th?

Because only 1 of your inputs goes to the 10ths place. Your speed arguably doesn't go to the 10ths place and your distance definitely doesn't go to the 10ths place. Therefore any precision to the 10ths place hides potential errors in the other two inputs.

Rockin Robbins

05-31-12, 11:53 AM

The attack data tool is explained in the manual that comes with the game.

Sorry. I always use terms from the US Navy Submarine Torpedo Targeting Manual of 1946 for clarity. It's been a long time since I read the manual. I'd have to take it out from under the short leg of my desk to read it!

I'll take your word that it says that. Most of us have thrown that useless thing away ages ago. I kept it because I found it useful for the short leg of my desk.:har: So THEY were the guilty ones renaming the instruments on a submarine!http://i196.photobucket.com/albums/aa293/RockinRobbins13/smileys/clueless.gif

Okay, then we WERE talking about the same thing. Yes you can set the dial between two numbers. Then the TDC takes one number or the other and uses it. I believe the true TDC was a true analog computer which would accept partial degrees or partial knots from the input dials and calculate accordingly.

In the digital age, our game works differently. As explained previously that does not introduce error into the calculations and you'll hit just as many (and miss just as many) as a result.

In the conning tower, crewmembers used slide rules. Those always dropped a slew of real significant figures because you couldn't interpolate accurately between two closely spaced lines. Many approach officers swore by them and if there was a disagreement between the slide rules and the TDC they either didn't shoot or believed the slide rules.

P_Funk

05-31-12, 12:51 PM

Because only 1 of your inputs goes to the 10ths place. Your speed arguably doesn't go to the 10ths place and your distance definitely doesn't go to the 10ths place. Therefore any precision to the 10ths place hides potential errors in the other two inputs.
That doesn't explain why in a tool which derives percision to a 10th we must use the rounded whole number.

The error is assumed to be there, therefore we assume that all derived values from our calculations are inherently inaccurate to some degree. There is to be assumed a built in +/- (the same thing you see when they show statistics being accurate to +/- 5% or something).

Now, I'm saying that given the fact that a periscope reticle can measure angular deflection to the 10th of a degree why is the decimal place considered irrelevant? Why is the whole number somehow considered more accurate? Why is rounding it necessary? Why are we not saying that 12.5 or 9.2 or whatever is +/-(x) accurate and adjusting it one way or another?

My point is that why does everything fall to whole rounded numbers in this case? As I've read after being pointed to it by Robbins, nothing in the principles of significant figures dictates that the assumed error requires us to settle everything onto the whole number. It says that you use the precision of the instrument available, and in the case of a periscope you can have 10ths, in fact the return on a bearing is more often between whole numbers than its on the whole number as you watch a target move across.

So, I'm acknowledging there's an inherent inaccuracy, but how does the fact that previous parts of the equation being rounded off mean that the final result must also be?

When you take a rounded speed and a rounded Track Angle the math for a Lead Angle does not give you a whole number. Why does that have to be rounded as well? Why is it not 4.7 +/- .5 meaning you make it 5.2 or 4.2?

It seems to me that rounding this figure is as much a flawed idea as assuming the decimal place is accurate. So basically if the entire prodocut of our calculations is inherently inaccurate how does making it rounded off somehow change anything? Its not false precision to have a decimal becuase the tool has the capacity to measure that level of precision.

I don't understand why the decimal is any more or less inaccurate than the whole number everyone keeps saying you should just round to. :dead: And since you can observe the target to a 10th through the periscope you can choose to fire at the point of a bearing measured to a 10th.

I don't know if people understand what I'm saying here or not. :doh:

Rockin Robbins

05-31-12, 01:31 PM

Well, first of all, when you are using the TDC an integer value for the bearing is input, not any partial degrees. Secondly, when you are setting the torpedo gyro angle you are restricted to whole degrees. So there is no way to shoot a torpedo up the 23.1º bearing as the chart might say, because you can't set that gyro angle.

Now 1º at 57 yards is a 1 yard length on the target. So at 570 yards it would be 10 yards, 30 feet. If you are quibbling over a tenth of a degree, you are wasting a great deal of effort to make a 3' difference in where the torpedo strikes. Is it too much to realize that a tiny error in target speed, an incorrect stadimeter range, a couple of degrees error in target track would likely make a much larger difference?

And since all these things are happening at once, what if the torpedo hit amidships instead of a quarter of the way back from the bow? Is there any way to separate the factors that resulted in this difference between impact point and aiming point? I don't think so and who really cares?

You just use whole measurements, realize that you are possibly off by as much as a whole degree. Then you close the range so that a 1 degree error in either direction still ends with a boom.

We know that at 570 yards one degree one way or the other means that your torpedo can hit 30' one side or the other of your aim point, with greatest probability toward the middle.

We'll take a small target, the Atami Gunboat, 45.3 meters long, a skoash over 148' long. If you're sitting 1140 yards off, that is double what we were figuring before, 1º is going to be a 60' possible error either direction from your aim point. If you aim at the middle of target, you have 74' of target on both sides of your aim point. Since 60 is less than 74 YOU ARE getting a nice satisfying boom at the end of the procedure.

So remember! One degree is one unit (pick one, feet, yards, meters, furlongs) wide at 57 units away. Real submariners did it, I stole it from the Run Silent Run Deep trilogy. Then you can do some quick and dirty mental math to figure what your expected error looks like in target length. Then you know right away if you are likely to get a hit, certain to get a hit or less likely.

Or toss all that lousy math out the window and remember that we've just proved that at 1000 yards shooting at a small target a hit is practically guaranteed if you have not made any mistakes and if the torpedo operates correctly. I like to shoot under 750 yards.

JohnnyCarwash

05-31-12, 01:31 PM

Sorry. I always use terms from the US Navy Submarine Torpedo Targeting Manual of 1946 for clarity. It's been a long time since I read the manual. I'd have to take it out from under the short leg of my desk to read it!

I'll take your word that it says that. Most of us have thrown that useless thing away ages ago. I kept it because I found it useful for the short leg of my desk.:har: So THEY were the guilty ones renaming the instruments on a submarine!http://i196.photobucket.com/albums/aa293/RockinRobbins13/smileys/clueless.gif

Seeing that the game does not replicate a full TDC, what difference does it make what you call a "gauge" the game provides, that never existed in the real world, to simulate part of the TDC? Anyway, the term you used to inquire what I was referring to does not seem to show up the manual you referenced either. Probably because the attack data tool has no analog in the real world, and so could not be accurately described by the Navy document from decades ago.

Sheesh. :salute:

Rockin Robbins

05-31-12, 01:48 PM

You want photographs? The input dials exist and they are part of the TDC, thus TDC input dials. Man, I wish they had done true justice to that incredible piece of mechanical computer.

Also check out the US Navy's manual on the Torpedo Data Computer Mark 3 (http://hnsa.org/doc/tdc/index.htm) It will make you pine for the real thing! The dials in the game although they are separated from the machine itself are a decent representation of the appearance of the originals. Of course they didn't have send to TDC buttons or switchable interfaces for different functions. They had separate sections to input target speed, AoB/target course and bearing.

http://i196.photobucket.com/albums/aa293/RockinRobbins13/Silent%20Hunter%204/Sub%20Manual%20Stuff/TDCPhoto.jpg

You can see our familiar dials in the black sections at the top of the position keeper/sound bearing converter module and toward the middle of the angle solver module. Just below the gauges are the cranks that were actually used to input and move those dials to the proper positions to reflect your inputs. Like I said, what we have in the game are decent representations of the dials without the cranks and we directly move the dials around. See how they had more dials than we have, and so, even more information than we are allowed in-game? I drool over that teasing eye candy there! It deserves to be replicated on a computer.

JohnnyCarwash

05-31-12, 01:55 PM

Friend, I'm well aware of the TDC dials. But when you mix in the stadimeter gauge, which is also part of the game's attack data tool, it's hard to call it a TDC input dial. That part did not exist on the TDC.

Also, I think quite a few of those are knobs, BTW. :haha:

I can't believe this is an important issue to anybody, so I suggest if just get dropped.

P_Funk

05-31-12, 06:05 PM

Well, first of all, when you are using the TDC an integer value for the bearing is input, not any partial degrees. Secondly, when you are setting the torpedo gyro angle you are restricted to whole degrees. So there is no way to shoot a torpedo up the 23.1º bearing as the chart might say, because you can't set that gyro angle.
Except that the 90 Degree 0 Gyro Angle method, which the table that started this all is made for, involves a Torpedo firing perfectly striaght along the longitudinal axis of own ship's course, firing at a perpendicular target track angle.

This is a no TDC method. The only tool used to fire the weapon is the observed lead angle in the Periscope/UZO/TBT. As such the above has no bearing on this.

Now 1º at 57 yards is a 1 yard length on the target. So at 570 yards it would be 10 yards, 30 feet. If you are quibbling over a tenth of a degree, you are wasting a great deal of effort to make a 3' difference in where the torpedo strikes. Is it too much to realize that a tiny error in target speed, an incorrect stadimeter range, a couple of degrees error in target track would likely make a much larger difference? But after all this talk about math and precision and now we're talking about accepting an error saying it means nothing overall?

Given all the known error we're going to be running into why would I accept more for the sake of forgetting a meek little decimal place? If its 30 feet after 570 yards then what if you take a shot at a farther range? at 1500 yards thats 90 feet off. If you're firing a spread of torpedos, aiming 2 or 3 at forward, middle, aft, then that could easily be the difference between 1 2 or 3 hits.

My point is that you go all this way to convince me that that decimal place isn't accurate, then you tell me that even if it were, who cares. :rotfl2:

Rockin Robbins

05-31-12, 07:23 PM

And you might add to your top part there that the submarine is not constrained by whole degrees in its course. As a matter of fact our compass is nerfed so we really can't tell within a half degree what our course really is. The real gyro compasses had digital readouts, we should too! Our dial is too small, we don't have a lubber line and we don't have digits. That's not good.

To your bottom point, because the error doesn't matter if you've mitigated it, using tenths of a degree or tenths of a yard or tenths of a knot just don't make sense. That has been my constant point throughout. Using whole knots, whole degrees and whole yards is perfectly acceptable and you won't lose a single hit by doing that and keeping it simple.

I was objecting to a table where the correct answer (but to more precision than is ever useful) is hidden among, what was it? 2,700 other possible solutions, each of them wrong, except for the one. And there were not just one but several pages of them, with 2700 solutions (if my memory serves me correctly) per page.

There's one secret to success. Keep it simple. Complexity is suicide, especially when the pressure's on.

I've told you how to calculate error tolerance. I've told you how to relate that to hits on a target. So long as you quantify your possible error and then close the range so the error range still results in a hit you're all good.

Is there some precision in that? Maybe in the initial calculation, but what results is one of my famous rules of thumb: shooting from inside 1000 yards guarantees hits on just about any small ship and becomes ridiculously accurate for much larger targets. Don't forget my example was about the smallest warship in the game, smaller than any of the merchies except for the sailboats.

But you got it right. If the decimal point DID mean anything valid, all it would mean was that the shot hit 3 feet one way or the other from where you aimed. All those extra calculations for nothing! Your last statement is 110% correct!:up:

We aren't talking about getting more hits, we're talking about whether they hit the 10th or 11th stanchion back from the bow. You're never gonna count 'em anyway! And they're all going to blown to smithereens so you can't check afterwards.:D

P_Funk

06-01-12, 12:17 AM

doulos05

06-01-12, 01:09 AM

Well thats one of the nice things about SH3 GUI mods. I believe OLC Gold and definitely MaGui have a little compass reader that tells you where in between the course you are. So in that regard there are some ways that modders have helped to mitigate the errors we've been forced to live with.

At this point we're arguing semantics but you are totally right about the under 1000 thing. I always prefer to put my energy into getting into a great position so that the firing solution need not even be laboured. All the work is in dodging the escorts and getting that ideal shot.

Indeed, and honestly I find the approach to be more fun than planning the shot (though I do love the boom at the end). I think the best part is definitely matching wits with a Japanese escort and then laughing maniacally as you sail away on the surface while he depth charges the wrong side of the convoy almost 14,000 yards away.

My last convoy, I thought I'd blown the approach, but he mis-read my position by over 2,000 yards. It was tense because there was no thermal layer to get below, but sending his two biggest charges to the bottom was great. Especially when the shots that sent the second one to the bottom passed just 500 yards astern of him. Not sure how he didn't figure out from that he was DCing the wrong spot.:doh:

Rockin Robbins

06-01-12, 09:13 AM

TorpX

06-02-12, 12:43 AM

Interesting discussion about the significant figures. I read RR's posted link and I can go along with the concept up to a point, but I think it would be legitimate to speak of significant figures and rounding rules as more of in the nature of being useful guidelines than hard and fast rules.

Here are links which speaks about this:

http://www.angelfire.com/oh/cmulliss/

http://en.wikipedia.org/wiki/Significance_arithmetic

Here is a brief quote from the later:

Significant figures are used extensively in high school and undergraduate courses as a shorthand for the precision with which a measurement is known. However, significant figures are not a perfect representation of uncertainty, and are not meant to be.

Significance is not the same as significant digits. Digit-counting is not as rigorous a way to represent significance as specifying the uncertainty separately and explicitly (such as 1.234±0.056).

Here is an example of what I mean. Say your crew is tracking a merchant a estimate its speed at 10.5 +/- .5 knots. Later they estimate the speed at 9.5 +/- .5 knots. In your calculations, the first figure has three significant figures, while the second has only two. But, aren't they equally precise?

In any case, I calculate firing solutions to a tenth of a degree. I know they are not accurate to .1 deg., but rounding to a whole deg. would be too coarse, and rounding to quarter degrees would be more work.

Well, first of all, when you are using the TDC an integer value for the bearing is input, not any partial degrees. Secondly, when you are setting the torpedo gyro angle you are restricted to whole degrees. So there is no way to shoot a torpedo up the 23.1º bearing as the chart might say, because you can't set that gyro angle.

I'll admit I didn't know this. I am somewhat horrified, actually. This is something else Ubi botched. I know the RL TDC could compute angles to a quarter degree. O'Kane mentions this.

doulos05

06-02-12, 02:14 AM

1000% agreed with both of you. Success comes primarily from how the approach is executed and a poor secondarily from the exact procedures used for targeting your shot.

Actually, I'm a believer in the "Bag of Tricks" philosophy. If you're a one-trick pony and always rely on my Dick O'Kane procedure, similar to Fast-90 on a U-Boat, but a bit less flexible and modifiable on the fly, you'll get your fist shots off just fine.

Then with the booms, you'll have additional opportunities during the chaos, which you'll miss if you do not have conventional stadimeter/position keeper procedures under your belt. They don't rely on a single relationship between own course and target track. They don't require a zero gyro. Sure, they're less accurate, but much less accurate is the shot never taken because you lack the tools to make it happen.

One thing about the real captains that continues to amaze me. Like a basketball player, they were perfectly willing to take a low percentage shot when the potential reward was great. I think we sometimes get too tangled up in our "no misses!" thought processes.

Hear, hear for the bag of tricks. I missed a shot on two beautiful carriers earlier today because I did a classic Dick O'Kane approach and got picked up by the lead escort because I was only 1,000 yards off their track and perfectly broadside to them. That would have been a time to take the shot from 3,000 or 4,000 yards at radar depth and deal with the errors using a shot spread of 120% of target length or so. Oh well, live and learn. at least I dodged the escorts...

Rockin Robbins

06-02-12, 10:41 AM

Here is an example of what I mean. Say your crew is tracking a merchant a estimate its speed at 10.5 +/- .5 knots. Later they estimate the speed at 9.5 +/- .5 knots. In your calculations, the first figure has three significant figures, while the second has only two. But, aren't they equally precise?A great observation. Although there is a difference in the number of significant digits, there is an equality in the implied error.

But that is easily resolved by discounting the whole numbers and only looking at the accuracy of the fraction, which is what separates our evaluations of accuracy. We are talking absolute accuracy, not accuracy expressed as a percentage of the measured quantity, which is usually best estimated by counting the significant figures.

To use an example, 9.1 and 91 both have the same number of significant digits, 2, and the error percentage of each is the same, .1/9.1 =1/91. So we have to be careful whether we are concerned with absolute error (this value is accurate to _+ half a knot) or relative error (this value is accurate to +_1%)

So, in your example, 9.5 knots is a bin containing all possible values between 9.45 and 9.55 knots for an uncertainty of 1 knot. The concept of significant digits says that there is doubt about the last digit provided and that uncertainty is arbitrarily deemed to be half the value of that digit because it is assumed that we have no real idea how accurate we are, only that there is uncertainty. This is a one size fits all concept. Sometimes that is the way science works.

Our 10.5 knot measurement implies a bin containing all possible values between 10.45 and 10.55 knots, again an uncertainty of 1 knot, same as above. So we can demonstrate that my observation is correct, that the relative accuracy of the value can be evaluated by the number of significant digits after the decimal place.

Now it is possible to specify an accuracy different from what the number of significant digits represents. For instance if you say your speed is 9.5 knots +_1 knot, you have overridden the +_.4999... knot error that is inherent in the number.

By doing that you have accomplished two things: you specify that the uncertainty is centered on the half knot per hour instead of a whole number. Secondly you have specified that the size of uncertainty is twice what the number would imply by itself.

There is no reason to explicitly state that your accuracy is higher than that implied by the number because you could merely write the number with another digit, 1.50 instead of 1.5, saying that the value is confidently within 1.495 and 1.505 by using the zero.

Edit: there's a GLARING error above. Somebody find it and whack me!

I'm goin' down

06-02-12, 09:45 PM

Or you could do as the real sub skippers did and use Nisgeis' vector analysis method (Nisgeis did not teach the real skippers:haha:).

If Nisgeis had taught them, we would have won the war in '41 ('42 at the latest.)

Rockin Robbins

06-03-12, 12:52 PM

There's a real STINKER of an error in my last post! Somebody find it and whack me good!:D

TorpX

06-03-12, 08:42 PM

Edit: there's a GLARING error above. Somebody find it and whack me!

Our 10.5 knot measurement implies a bin containing all possible values between 10.45 and 10.55 knots, again an uncertainty of 1 knot, same as above. So we can demonstrate that my observation is correct, that the relative accuracy of the value can be evaluated by the number of significant digits after the decimal place.

Should be .1 knot? Do I win a cookie?

With the significant figures the last figure can be in error by more than one. That is, both 12.2 +/- .1 and 12.2 +/- .3 would both be written 12.2. Another reason not to rely on this too much.

But getting back to the original question about tables, I agree compact and short tables are to be prefered over large/long ones. Personally, I'm not a big fan of tables. That was something I didn't like about the Celestial Navigation mods. Too many tables.

I guess it depends on what you want the tables for. Sometimes they are only desired to produce a "good enough" answer, sometimes they are intended to produce a result of maximum accuracy. Ordinarily, I think it is better to arrange things so the math does not add to the errors in the data, so I frequently carry over to an extra digit in calculations (not neccessarly in SH 4), even if it is not strictly justified.