TDC

[captcrane]

Ahoy Guys. I have been using manual targeting for some time. But I have a question I was wondering if someone could clear up. My steps are as follows even before I see the target . #1 speed of target. #2 set periscope to 0 degrees. #3 Press L key #4 set angle on bow #5 Set range (dragging dial clockwise). The question is step 3 necessary? and my follow up question would be. If I turn the periscope say 25 degrees starboard then dragged the range dial would that change the course of the torpedo?

[Rockin Robbins]

Haw! Haw! You've come from U-boat land, haven't you! Well, from your point of view the American TDC is just screwey. The best thing I can tell you is to watch the Sub Skippers Bag of Tricks thread for a video which is presently in pre-production on Stadimeter Targeting Technique. But that doesn't exist yet.

Let me see if I can be of any help. Yes, the first thing I generally develop is the target speed and enter it into the TDC. When you turn the dial you must press the button with the triangle on it, the "send to TDC" button twice. That's done.

Now in the course of measuring the speed if you're using radar, you have two position points which can be extended to get you a target course. Now there's a sneaky trick to enter the course into the TDC in place of the angle on the bow and you'll see that in my video, but for now let's sit on that course determination to enter AoB.

We'll do that after we input the range. Hopefully he's too far away and using the stadimeter right now would be a joke. We don't have any tools to automatically send range from radar to TDC and no way to manually enter it. So much for realism in Silent Hunter 4, huh?

But we have a tool for directly entering range from long distance and that is the sonar. Have the sonar operator give you the bearing, then ping that bearing manually, then hit the send range to TDC switch and the send bearing to TDC switch. Done.

Now go to the nav map. With the protractor click on the course ahead of the target, then again on the center of the target, and finally on the center of your submarine. The angle you read is your AoB and the side of the target you can see from your sub is how you determine starboard or port. Enter that on the dial and press the send button twice.

Now immediately turn on your position keeper. Time for a little theory.

The German TDC works by pointing your torpedo at a point ahead of the target. When your target gets to your predecided shoot bearing you press the los button and the torpedo zips out there. This is like shooting at a duck by holding your shotgun pointed at a point and waiting for a duck to be the proper lead angle away. It's a timing shot.

Well the American TDC doesn't work that way, at least not when you're using the position keeper. It uses the equivalent of pointing the shotgun ahead of the duck and maintaining the correct lead angle at all times by sweeping across the sky ahead of the duck. The advantage is that you can shoot any time you want and hit your target.

If you go to the attack map, you can see the comparison between the real position of the target and where you told the TDC the target is. The position keeper also moves the artificial target on the course and at the speed you specified. Is the x superimposed on the target? If not, is it on a straight line between you and the target, very close to the target? That's a probable hit.

If you examine the end of the torpedo track you'll see a number, and that is the time of the torpedo run. To have a hit, the x marking the aiming point of the TDC must remain on the target for that length of time. If it won't do that you have to analyze what you see.

It could the that AoB is slightly wrong. In that case the x will move at the same speed as the target but drift to one side or the other. Go back to the plot, remeasure the AoB, set it on the dial and press "send to TDC" twice. You don't have to do anything with the position keeper button.

If the x is moving on the same course but lagging behind or forging ahead of the target your speed is wrong. Go to the TDC and add or subtract a knot from the speed, press "send to TDC" twice and go back to the attack map.

It should be much better now. It doesn't have to be perfect, just keep the x superimposed on the target for the time of the torpedo run. Get him under 700 yards. You can shoot at any time and hit the target. It's always good to check your solution just before you fire.

Remember, the American TDC has no automatic connection between periscope and TDC. If the TDC has information it's because you manually sent it there.

[captcrane]

Now that's a surprising answer and fast also. I have to rethink everything I thought I knew. I was under the impression that the position keeper and the stadimeter were intertwined. So I never (well not in awhile) used either of those. My ranges with the stadimeter were pathetic. Looks like I can add something new to my game. Currently I am in an S boat 3rd patrol. I have no surface radar but I can detect enemy aircraft. After I get SD radar I will change my game settings to no map contacts because that is pretty much how I am playing now. By the way I am always on the American side ex marine. When I get more proficient at the game going to try RSRD. I am also a citizen of England. Thanks for your input!

[Rockin Robbins]

For some it will be difficult to understand the explanation above. Stay tuned for the video. I'll be asking questions afterwards to try to improve my explanations so everyone can understand just how the (insert appropriate curse word here) US TDC really works. The video and copy of the above explanation will be in my Sub Skippers Bag of Tricks (http://www.subsim.com/radioroom/showthread.php?t=221540) thread.

[ColonelSandersLite]

I thought I would try to word this another way, not saying that anything RR said is wrong though.

There are two major differences between the German TDC and the American TDC. In my book one is a major advantage and the other is a disadvantage required to make the other work.

In the american TDC, the AOB is not coupled to periscope bearing. Moving your scope will not change the AOB. I increased size and bolded there because this cannot be stressed enough. The typical german method of pointing your periscope at 0 and entering the track angle then just point the periscope at the target to get AOB does not work. This is a disadvantage.

In the american TDC, the optional position keeper tracks the target and your own subs movements and updates the torpedo gyro angle in real time, even if you are not tracking the target with any sensors at all. Again, cannot be stressed enough. This is clearly a major advantage.

[Rockin Robbins]

Interestingly, in real life the American periscope could automatically send data to the TDC and would work just like the German one if they so chose. So many things about the real TDC have been nerfed and dumbed down for the game. And radar range and bearing were also automatically linked to the TDC if desired. Plus there were two crewmen tasked with making sure the TDC data was accurate according to the plot and the data developed from sensors.

And ColonelSandersLite, those are the two sentences that will be on the test. Thank you.

[TorpX]

In the american TDC, the AOB is not coupled to periscope bearing. Moving your scope will not change the AOB. I increased size and bolded there because this cannot be stressed enough. The typical german method of pointing your periscope at 0 and entering the track angle then just point the periscope at the target to get AOB does not work. This is a disadvantage.



Umm. To clarify about this. The Germans couldn't do this in real-life. The automatic periscope connection did not exist. AoB data had to be manually input by a crewmember; meaning this mechanism is purely a game device, like 'locking' on a target with the periscope.

[ColonelSandersLite]

Didn't know that. Still an accurate statement as far as sh3 and sh4 is concerned though.

[TorpX]

Didn't know that. Still an accurate statement as far as sh3 and sh4 is concerned though.

Yes. I dare say most SH3 players don't know it, either. It kind of irritates me when they complain about how the USN TDC isn't any good, because it can't do what the German model does. :arrgh!:

[BigWalleye]

Umm. To clarify about this. The Germans couldn't do this in real-life. The automatic periscope connection did not exist. AoB data had to be manually input by a crewmember; meaning this mechanism is purely a game device, like 'locking' on a target with the periscope.




I don't know what your source is for this information, but it clearly conflicts with this site:

http://tvre.org/en/torpedo-calculator-t-vh-re-s3

The site is called Torpedoverhaltrechner Project, and includes an enormously detailed analysis of existing documentation for the Seimens T. Vh. Re. S3, the standard TVR installed on German subs from 1941 on.

A relevant quote:

"In the standard operating mode, after entering the target data by means of the knobs, the calculator (taking into account the current target bearing transmitted from the periscope/UZO and own course received from the gyro-compass) automatically calculated the torpedo triangle solution and the torpedo salvo spread angle." (emphasis added)

I have not found similar detailed analysis of the operation of earlier TVR's, but this source definitely claims that the S3 received target bearing and submarine heading data automatically. Perhaps your source refers to an earlier version. IAC, I would appreciate if you could post the reference. Thanks.

[Rockin Robbins]

A relevant quote:

"In the standard operating mode, after entering the target data by means of the knobs, the calculator (taking into account the current target bearing transmitted from the periscope/UZO and own course received from the gyro-compass) automatically calculated the torpedo triangle solution and the torpedo salvo spread angle." (emphasis added)

I have not found similar detailed analysis of the operation of earlier TVR's, but this source definitely claims that the S3 received target bearing and submarine heading data automatically. Perhaps your source refers to an earlier version. IAC, I would appreciate if you could post the reference. Thanks.
You read it wrong. Your quote doesn't say "automatically sent" it says "automatically calculated." And it says "current target bearing transmitted," which begs the question "Transmitted how?" It could be from the periscope directly, very, very unlikely considering the primitive nature of the U-boat compared to the fleet submarine, or, vastly more likely, transmitted manually and then entered manually or entered manually by an orderly at the scope.

So your quote is conclusively inconclusive on the question at hand.:D

[BigWalleye]

You read it wrong. Your quote doesn't say "automatically sent" it says "automatically calculated." And it says "current target bearing transmitted," which begs the question "Transmitted how?" It could be from the periscope directly, very, very unlikely considering the primitive nature of the U-boat compared to the fleet submarine, or, vastly more likely, transmitted manually and then entered manually or entered manually by an orderly at the scope.

So your quote is conclusively inconclusive on the question at hand.:D

Fair enough. So I will add another quote from the same site:

"The current target bearing was entered automatically by means of selsyn links, however in an emergency, it could be set manually using the hand-wheel on the TDC. " (emphasis added)

A selsyn link is a pair of synchronous servo-motors wired so as to maintain the same angular rotation in both motors. The site has both pictures and circuit diagrams of the selsyn sets used in the TVR on U-995 and schematics of the overall system. The circuit disgrams and schematics were reverse-engineered from the existing hardware, which is datable to 1943. The schematics show the selsyns providing a direct link from the attack periscope and UZO stations to the TVR, via the selsyn sets.

Further information from the tvre.org site:

"The aiming and target bearing transmitting subsystem automatically transmits up-to-date target bearing data from a selected aiming device (UZO or periscope) to the torpedo data computer.

"The UZO and both periscopes were connected to target bearing transmitters (Torpedo-Ziel-Richtung Geber). They operated on the selsyn synchro link principle and transmitted the bearing directly to the torpedo data computer. Each target bearing transmitter consisted of two selsyn transmitters in order to achieve better accuracy. First, they transmitted the angle in the range of 0 – 360°, the second – in the range of 0 – 10°. The maximum transmitting speed was 12°/s.

"The aiming device (UZO, attack periscope, or sky periscope) used during the attack was selected (connecting the proper target bearing transmitter with the computer) by means of one of the two rotary switches located at the aiming subsystem control box that was installed in the control room (under the chart table)."

I can not claim to know the accuracy of the information which the tvre.org site presents, but it does clearly and repeatedly claim that, on U-995, which entered service in 1943, the target bearing and sub heading were automatically transmitted to the TVR. And it claims for the source of that information the hardware physically installed in U-995. The provenance of that hardware may or may not be verifiable. I assume that it is, and that U-995, being a military vessel, has reasonable maintenance records. But the vessel has been through several hands, so undocumented modifications might exist.

What is the source of the claim that WW2 vintage TVRs did not have automatic target bearing and sub course inputs?

[Rockin Robbins]

Ding! Ding! We have a weeeener! We have a weeener! I'll buy that for a dollar! The problem with a defeated nation is that we are often forced by lack of records to reverse engineer their capabilities. Sure would be interesting to know the history and development of their TVR, which was just as admirable a piece of engineering as the American TDC.

After all, it doesn't matter what hardware and software is used to create the music. It only matters if the final product rocks!

[BigWalleye]

Sure would be interesting to know the history and development of their TVR, which was just as admirable a piece of engineering as the American TDC.

Yes, it is interesting, and the tvre.org site provides quite a bit of that history and development background, going back to the first torpedo fire control systems developed to support the first "automobile torpedoes" (as they were styled). If you are actually interested in this topic, I think you would find the entire site worth reading. I can't vouch for the accuracy of the material. The site has extensive source attribution, but I haven't tried to cross-check those sources.

The tvre.org home page contains this "mission statement":

"The goal of the Torpedo Vorhaltrechner Project is to describe the development of the torpedo fire control systems used on submarines. The project evolved from an attempt to create a description of the German torpedo data computer that was manufactured by the Siemens Company and used on German U-Boats, known as a Torpedo Vorhaltrechner. Many incomplete and often inconsistent descriptions of this device can be found in books and on the Internet.

"During my research into this equipment I discovered the full scope of the torpedo fire control problem. For that reason, aside from a description of the German torpedo data computer, this project includes descriptions of similar American, British and Japanese devices as well as the history of the development of such systems - from the beginning of the torpedo weapon’s existence to modern times"

Unfortunately, I couldn't find the name of the site's author, so I can't give him proper credit. If anyone knows, please post it. He(she) has done a major piece of scholarly research.

EDIT: And I still hope that someone (TorpX?) will post a reference for the TVR description which indicates that it does not have automatic input for taget bearing and sub heading. Because this source is likely describing an earlier version of the TVR (pre-1941, when the S3 went into service), and it would be nice to have more information about those earlier versions. Anybody help?

[ColonelSandersLite]

Thanks for those links walleye. I'll definitely want to read them in detail later.

So far, I've read most of this page http://www.tvre.org/en/development-of-torpedo-fire-control-systems-for-the-kriegsmarine and this http://tvre.org/en/torpedo-fire-control-system-on-german-u-boats and noticed a couple of interesting things.

Re u-boats not automatically sending bearing to their tdc. I'm not 100% sure as I need to do more reading in detail, but I got the impression that what we're talking about here isn't actually directly related to the tdc, but rather the fire control systems it was connected to.

I.E. the TRW and T.Vh are separate but related topics.


It's off topic, but I also saw in the first link that prewar, the germans where firing spreads by turning the boat while firing. I want to try that soon, but to me that sounds absolutely horrible and I don't really see any logical reason to do it. Wouldn't it be easier and just as effective to use time for spread rather than an actual turn?

[TorpX]

Ok, about the automatic link from the UZO/periscope to the TDC. I can't give you the source; I read it some time ago and I don't recall details. My memory is that it was more procedure oriented than mechanical/technology oriented.

Based on what you quote, what tvre.org says, and what I remember, I'll go with the idea that there was a automatic link. However, I don't think it operated in real-time. That is to say, continuously; so to have a valid/updated firing solution a crewmember had to perform some action (press a button?) so that the TDC would receive the new input. This would have to be done on command, or else how would he know the skipper wasn't just looking to see if there were any escorts nearby.

I would not say it was done automatically, just that they were mechanically linked. In any case, it doesn't make sense to me to have the bearing automatically fed into the TDC all the time, as the UZO/peri. would be rotated a lot in normal searching to maintain situational awareness, and to have the TDC always fed changing bearings might 'burn up the gears', so to speak.

[ColonelSandersLite]

That's probably a good point, but it probably would be a simple button. Maybe push and hold to send. That being said, I don't know where that button would be and might have been just s simple toggle on the periscope.

Take a look at this video, particularly the first few clips showing the captain at the periscope and notice where his hands are:
https://www.youtube.com/watch?v=WMYlbnhtVDs

In the second clip showing the captain, notice that his right hand is holding something down. I don't have a good source for german operation (hopefully someone does), but could it be that what he's doing there is providing periscope bearings to the tdc?

If it's actually as simple as a button to turn sending on and off, I'm pretty well satisfied as to the functionality of the german tdc in this regard in sh3 and 4. Though I think I might like a button press to turn on bearing sending, with it being off the rest of the time.

[BigWalleye]

Ok, about the automatic link from the UZO/periscope to the TDC. I can't give you the source; I read it some time ago and I don't recall details. My memory is that it was more procedure oriented than mechanical/technology oriented.

Based on what you quote, what tvre.org says, and what I remember, I'll go with the idea that there was a automatic link. However, I don't think it operated in real-time. That is to say, continuously; so to have a valid/updated firing solution a crewmember had to perform some action (press a button?) so that the TDC would receive the new input. This would have to be done on command, or else how would he know the skipper wasn't just looking to see if there were any escorts nearby.

I would not say it was done automatically, just that they were mechanically linked. In any case, it doesn't make sense to me to have the bearing automatically fed into the TDC all the time, as the UZO/peri. would be rotated a lot in normal searching to maintain situational awareness, and to have the TDC always fed changing bearings might 'burn up the gears', so to speak.


Another quote from tvre.org:

"Between the compound dial and the electric motor was a relay which was controlled by means of a follow-up switch (Blauschalter (http://tvre.org/en/torpedo-calculator-t-vh-re-s3?id=48#blau-schalter)). If released, the relay interrupted the connection between the dial and the electric motor – the current target bearing from the periscope/UZO did not alter the calculator settings. When the order “Follow-up the target” (Folgen!) was issued, the follow-up switch was triggered and the relay connected the dial with the electric motor, thus the current target bearing was entered into the calculator. This feature made possible updating the target bearing (when the follow-up switch was in the “Folgen!” position), but when it was needed to scan the whole horizon – to not alter the correct calculator settings – the order “do not follow-up target” (Blau! Nicht folgen!) was given and the follow-up switch was released, and the relay disconnected the electric motor from the dial."

The circuit diagrams at tvre.org show the "Folgen" switch triggering a relay which engages/ disengages the selsyn motor circuit from the target bearing transmitter at the selected 'scope to the receiver motor in the TVR target bearing calcullator section. When the selsyn circuit is disengaged, target bearing can be entered by hand. When this circuit is engaged, the target bearing input to the TVR is slaved to the target bearing transmitter at the selected 'scope, and follows all horizontal rotation of that 'scope, with resultant continuous calculation of the torpedo firing solution by the TVR and continuous updating of the gyro setting in the selected torpedo. (Continuous updating of the torpedo gyro could also be turned off by a separate switch on the TVR.)

Notice that the "Folgen" capability was not a matter of transmitting a single-point target bearing, but of switching between a continuous-update mode and manual entry mode. This is also exactly how the TVR model is implemented in SH3. There is a command "Toggle_TDC_autoupdate" which toggles between automatic continuous updatingof the target bearing from the 'scope/UZO and manual input. According to tvre.org, that is exactly how the Siemens TVR S3 on U-995 operates.

So any german submarine fitted with the Siemens T. Vh. Re. S3, the standard KM issue from mid-1941 onward, had the ability to continuously transmit 'scope bearings to the TVR, which would then calculate a firing solution and transmit the calculated gyro angle to the selected torpedo in its tube, all in real time without human intervention. This claim assumes that the analysis of the Siemens S3 hardware presented at tvre.org is correct and that the Siemens TVR onboard U-995 today is an authentic, unmodifed unit. If those two assumptions are correct, then the TVR modeled in SH3 implements this capability exactly as the historical prototype did.

Now, it is not fair, or even relevant, to compare the German TVR and the US TDC. The TVR was strictly a torpedo fire director. To the extent that SH3 accurately models the TVR, it appears very intuitive and easy to use. The TDC, in addition to providing a fire control solution, also was an approach aid, through its Position Keeper section. Use of the PK to project target position during a submerged approach, minimizing the need for frequent periscope exposure, was an important element in USN doctrine, and the TDC was used for that purpose in every first-person account I have ever read. The TDC also integrated target data from sonar and radar sensors. The TVR had no comparable capabilities. Is a motorcycle "better" than an SUV?

EDIT: Reference to blue indicator lamp for TVR manual update removed. Blue lamp is from a mod, not stock SH3.:oops:

[TorpX]

After reading your quotes, and skimming the material on the site, it looks like TVR is substantially better than what I had been led to believe. I don't see any reason to doubt what tvre.org has stated; they go into quite a lot of detail.

If Ubisoft got it right here, that's one point for them. I wished they had given all the other areas of the SH series equal attention.

[ColonelSandersLite]

Interestingly, in real life the American periscope could automatically send data to the TDC and would work just like the German one if they so chose.

OK, so here's a thing. Ive seen you say or at east imply a couple of times now that the US tdc could be set up to receive constant bearing updates from the periscope, which would automatically calculate aob once course was entered.

If you (or someone else) can show me good proof of that, I might have an idea of a way to make that work in game.

I don't even want to try without knowing for sure though as the temptation to use it anyways would be pretty strong...

[BigWalleye]

Interestingly, in real life the American periscope could automatically send data to the TDC and would work just like the German one if they so chose. So many things about the real TDC have been nerfed and dumbed down for the game.

Was it possible to get the TDC to calculate a deflection angle and include that in the gyro angle setting? The in-game TDC requires that you estimate your own lead angle, just as if you were duck hunting. That's a learned skill.

Lest you think that gives the U-boats points for technical excellence, the U-boat periscopes did not have a stadimeter. Range measurement was done with a scope graticle and the Mark 1 human eyeball! That's one Ubi didn't get right. (Source here is also existing U-boat on exhibit.)

[Rockin Robbins]

Was it possible to get the TDC to calculate a deflection angle and include that in the gyro angle setting? The in-game TDC requires that you estimate your own lead angle, just as if you were duck hunting. That's a learned skill.
No, in that regard the American TDC worked just like the game. However that is not a handicap. I used that "feature" in my Dick O'Kane method.

First you set up the TDC for what the AoB will be at time of firing. You're going to be 90º from the track and I have a rule of thumb for anything under 10 knots fire at 10º before your relative zero bearing and for anything 10-15, fire 15º before, higher speed make it 20º. That is a rule of thumb and people say "RR you're not being precise."

Well, actually I am, because while I choose the shoot bearing imprecisely, the TDC figures the gyro angle very precisely. No that torpedo won't generally go right up the zero bearing. I will be a few, maybe as many as five degrees off. But according to my experience and the Submarine Torpedo Fire Control Manual, any gyro angle under 20º was considered straight shooting where range mattered very little to a valid solution. Since my error is only 25% of the allowed variance, I hit every shot.

So long as you are shooting with position keeper off you can select shoot bearings arbitrarily and still get hits. With position keeper on you can shoot whenever you want so long as your solution remains valid.

So I'd say the American TDC is only a disadvantage if you want to try to force it to work like the German TVR. Taken on its own terms it's excellent. And the same is true of the TVR. You can't say it's garbage based on the fact that there are differences from the TDC.

After all, none of that matters. The only thing that matters is whether or not a target goes boom. If your device makes the target go boom it is a successful device.

But as for your question, with the American TDC you are not selecting the lead angle. You are selecting the shoot bearing and the TDC calculates the correct lead angle, inputs the gyro angle automatically (with manual backup available) to the torpedo and it hits. In my first Dick O'Kane (http://www.youtube.com/watch?v=2k5yJI6Z5AU) video, I blew the attack and ran my mouth as the target ran past my shoot bearing. Rather than quit and begin again, I just aimed the crosshairs at the bow and stabbed the "send bearing and range to TDC" button, then fired four. All four hit when my AoB was 10º wrong for when I shot. The reason is that the TDC calculated a new gyro angle based on my erroneous input, firing 10º too late, and it was still plenty close enough. I published the video as an example of how error tolerant the Dick O'Kane attack is. That's because of how versatile the TDC is.

[Rockin Robbins]

OK, so here's a thing. Ive seen you say or at east imply a couple of times now that the US tdc could be set up to receive constant bearing updates from the periscope, which would automatically calculate aob once course was entered.

If you (or someone else) can show me good proof of that, I might have an idea of a way to make that work in game.

I don't even want to try without knowing for sure though as the temptation to use it anyways would be pretty strong...
I learned that from Nisgeis. However, what I've seen from the manuals for the Torpedo Data Computer, Mark 3 (http://archive.hnsa.org/doc/tdc/index.htm), Submarine Torpedo Fire Control Manual (http://archive.hnsa.org/doc/attack/index.htm), Target Bearing Transmitter, Mark 9 (http://archive.hnsa.org/doc/pdf/tbt.pdf) and Submarine Periscope Manual (http://archive.hnsa.org/doc/fleetsub/pscope/index.htm), I can find synchro motors transmitting gyrocompass data to the various instruments, but no input from periscope or TDC directly to the TDC.

It's possible that someone with a better working technical vocabulary than I could read the same material and say "You dummy! Right there it is." But my eyes are swimming around aimlessly right now and my brain is overloaded analyzing some pretty deep stuff.

So my provisional and falsifiable answer is that it doesn't look like the periscope operator had any controls to automatically send bearing and range to the TDC, whether with a momentary send data switch or with continuous data feed.

I'm headed over to the Submarine Fire Control Manual for Attack Procedure and find instructions for one of the two TDC operators:
http://i196.photobucket.com/albums/aa293/RockinRobbins13/Silent%20Hunter%204/screenshot.414_zpsayqqcydg.jpg (http://s196.photobucket.com/user/RockinRobbins13/media/Silent%20Hunter%204/screenshot.414_zpsayqqcydg.jpg.html)

So it looks like he CHECKS to see that the radar values input automatically match the announced data, but he ENTERS "observed values as announced.....for a stadimeter or telemeter observation."

I'm going to have to say that unless conflicting evidence is found our game has it right on this one.

[snakedocpl]

Hi Gentlemen,

OK, so here's a thing. Ive seen you say or at east imply a couple of times now that the US tdc could be set up to receive constant bearing updates from the periscope, which would automatically calculate aob once course was entered.

If you (or someone else) can show me good proof of that, I might have an idea of a way to make that work in game.

I don't even want to try without knowing for sure though as the temptation to use it anyways would be pretty strong...

Well, what you are looking for is "Target Designation System". More details you can find here:
http://archive.hnsa.org/doc/fleetsub/elect/chap14.htm#14C

--
Regards
Maciek

[Rockin Robbins]

Hi Gentlemen,



Well, what you are looking for is "Target Designation System". More details you can find here:
http://archive.hnsa.org/doc/fleetsub/elect/chap14.htm#14C

--
Regards
Maciek

So again, it looks list the TDC operator was looking at an output that told him what to dial into the TDC.

http://i196.photobucket.com/albums/aa293/RockinRobbins13/Silent%20Hunter%204/screenshot.415_zpsprp1mpek.jpg (http://s196.photobucket.com/user/RockinRobbins13/media/Silent%20Hunter%204/screenshot.415_zpsprp1mpek.jpg.html)
http://archive.hnsa.org/doc/fleetsub/pscope/index.htm

[CapnScurvy]

I thought I'd put in my 2 cents worth.

As far as I know, the input for the TDC was basically a manual one. Verbal "calls" for the various settings coming from the Fire Control Party. It's true the TBT could signal in which direction it was pointed. This signal was not directly linked to the TDC. I don't believe any other inputs were automatically made.

Talking about AoB and the authentic aspects of the game....the game's American Stadimeter missed the mark by a wide margin. For the most part the Periscope's Stadimeter Dial provided the bulk of the information needed for the TDC.

http://i175.photobucket.com/albums/w132/crawlee/PeriscopeStadimeter_zpsrd0urivo.jpg

The Stadimeter Housing Unit was fastened onto the bottom of the Periscope. The outside view was brought down through a set of prisms, passing through the Stadimeter len's before going to the eye piece. It had two half len's that slide next to each other, giving the double image. Depending on which axis the sliding edge was pointed to, Up/Down, Left/Right.....the Stadimeter would produce either an estimate of target course angle (AoB), or an estimate of range. Both shown on the Stadimeter Dial.

Target Aob and Range could be found within less than a minute by most Captains. Instructions were to have the "Stadimeter Operating Knob" turned in the farthest clockwise position when lowering the periscope. This created the ability to have the two Stadimeter len's first slide on the horizontal axis....giving the AoB of a target, when the Approach Officer first raises the periscope. Then with a further counter clockwise twist of the knob, the axis shifted to the vertical.....giving an estimated range (provided a height/length figure was found in the Recognition Manual, and the Stadimeter Dial was set to the appropriate measurement). This "shift" between the two axis was within a single complete turn of the Operating Knob.

http://i175.photobucket.com/albums/w132/crawlee/Stadimeter_lens_zpsl2n0nbwt.jpg

The Stadimeter had two dials, both identical, on either side of the Periscope. It was faster to have a second observer stationed at the opposite dial to make the reading of range or target course, rather than the Captain who kept his focus at the eye piece.

The Stadimeter Dial automatically moved the center Dial Ring (one of three Dial Rings of the Stadimeter Dial), when you positioned the double image on the correct reference point. The third outer ring of the Dial was manually set to the "Targets Length". The inner dial ring was stationary, representing the "Targets Height".

Although there was no direct link to the TDC, the observer usually called out the found range and target course to have the TDC operator input the information. Unlike the TBT (Target Bearing Transmitter), which did have direct input to the TDC operator for just target bearing. No such direct link was made from the Periscope.

In both devices, the game has taken some creative license in simulating their functions and capabilities. In the Stadimeter's case, the game left out an important function for determining AoB from the real life unit. The game only allows the Stadimeter to work vertically, not horizontally.

With the TBT, there was no Stadimeter to help in range finding attached to it. Neither were there Telemeter Divisions for judging range. The following image shows what a TBT view looks like, taken at the Submarine Force Library and Museum, Groton Conn.

http://i175.photobucket.com/albums/w132/crawlee/P1010374-1.jpg

In reality, the TBT's only usefull function was to provide Relative Bearing of a focused target

=========

Something else missing in-game. In the above diagram of the periscope, you will see the reference to the knob and clutch (just below the eye piece) for a "Stabilized Line". The Stabilized Azimuth Line provides a "line in space" within the field of view. It was used to determine speed of a target. The line was electrically governed by the subs gyro compass which kept the line at a singular position, irregardless of the subs possible changing position.

Once the line was "plugged in" (it was not good to leave it operating for too long because the synchronizing motor could fog up the interior of the scope) the passage of the target over the line was timed with a stop watch, then calculated using the estimated target length to determine target speed.

The "clutch" was used to engage the synchronous motor, that was governed by the compass. You had a cord that really was "plugged in" to make it work.

As you can see, the Periscope gave you Speed, Range, Target Course (AoB)....all in one easy process. The game missed the actual simulation of this by a large margin. Not only giving us wrong height measurements, wrong scaled viewing, no length measurements (accurate or not), and incomplete simulated features of the devises used in real life.

[Aktungbby]

Umm. To clarify about this. The Germans couldn't do this in real-life. The automatic periscope connection did not exist. AoB data had to be manually input by a crewmember; meaning this mechanism is purely a game device, like 'locking' on a target with the periscope.



http://www.uboataces.com/images/torpedo_maintenance.jpgPrecisely!:shucks:"The crew programmes the torpedo."

[BigWalleye]

http://www.uboataces.com/images/torpedo_maintenance.jpgPrecisely!:shucks:"The crew programmes the torpedo."


Erm, beggin' yer pardon, but yer a bit late to the party. You really should read all the posts on this thread. Then go check out tvre.org/en/ for an eyeopener as to what the Siemens T. Vh. Re. S3 actually was, and still is, capable of doing. That would include getting continuous input from the sub's gyrocompass and the periscope/UZO target bearing transmitter, continuously calculating a firing solution, and automatically (No human intervention!) setting the torpedo gyro angle while the eel is in the tube. The TVR S3 was in service in the KM from mid-1941 on.

Please note that tvre.org represents the results of reverse-engineering the existing Siemens S3 which was installed in U-995 when it was launched in 1943 and can still be seen on board that vessel at the Laboe museum today. Check it out. Better than a movie!

[Rockin Robbins]

Absolutely, that's one thing the American and German instruments had in common: they automatically set torpedo gyro angles. That doesn't mean that the crew couldn't set them themselves if they had to.

[TorpX]

Although there was no direct link to the TDC, the observer usually called out the found range and target course to have the TDC operator input the information. Unlike the TBT (Target Bearing Transmitter), which did have direct input to the TDC for just target bearing. No such direct link was made from the Periscope.



This matches my understanding of the USN's fire control and procedures.

This begs the question: since the Germans linked the p/s to the TVR, and we had a link from the TBT, why didn't they link the p/s to the TDC?





From BigWalleye:

Was it possible to get the TDC to calculate a deflection angle and include that in the gyro angle setting? The in-game TDC requires that you estimate your own lead angle, just as if you were duck hunting. That's a learned skill.


I don't see what you mean here.

How are you defining deflection and lead angles?

If you input the correct Target bearing, range, Aob (i.e. target course), and speed, it calculates the required gyro angle to hit the target, and this is updated in real-time. What else is do you need?

[CapnScurvy]

This begs the question: since the Germans linked the p/s to the TVR, and we had a link from the TBT, why didn't they link the p/s to the TDC?


Regarding my statement of the TBT having a "direct link".......I miss spoke. The TBT signaled in which direction it was focused, however the input was only to a device that the TDC operator could read as Relative Bearing. The direct input to the TDC was made manually by the operator.

[BigWalleye]

This matches my understanding of the USN's fire control and procedures.

This begs the question: since the Germans linked the p/s to the TVR, and we had a link from the TBT, why didn't they link the p/s to the TDC?





From BigWalleye:



I don't see what you mean here.

How are you defining deflection and lead angles?

If you input the correct Target bearing, range, Aob (i.e. target course), and speed, it calculates the required gyro angle to hit the target, and this is updated in real-time. What else is do you need?


Maybe I've been missing something here. I always understood that you had to establish your own lead, as Robbins describes above. I thought the fish would go where you pointed the 'scope, not ahead of the aim point. Maybe I always misused the TDC. Honestly, I haven't played SH4 in a couple of years. While my love for the Silent Service goes back to RAdm Dykers (and despite my distaste for Nazism!), I pretty much focus on SH3. In SH4, I always used a normal approach and Kentucky windage, often successfully, but I can't claim to have mastered the TDC.

[snakedocpl]

This begs the question: since the Germans linked the p/s to the TVR, and we had a link from the TBT, why didn't they link the p/s to the TDC?I think, that is by design. The Angle Solver of the US TDC is driven by Position Keeper. I mean, that Angle Solver calculates final solution based on the target parameters calculated by Position Keeper (which is modelling the relative position between the target and own ship). After inputting some initial values into Position Keeper, it constantly updates the position of the target relative to the own boat. There are some outputs (for instance GENERATED BEARING), which are used to verify, if assumed initial values were correct. So they read GENERATED BEARING, set the TBT or periscope at this bearing and then - if the target was there - that meant, that model is correct. If not - the initial target parameters were wrong.
Look here: http://archive.hnsa.org/doc/attack/index.htm
Paragraphs from 520.
It seems, that - based on the visual (and radar) observation, operators input the target speed and range. Then the Position Keeper calculates the target position relative to the target, and then GENERATED BEARING is compared with the real, observed bearing. And then corrections to the speed and/or range were applied.
And so on.

The German TVRe was only Angle Solver. So it calculated gyro angle, based on the actual target bearing, angle on the bow and parallax correction. It did not contain mathematical model of the target movement relative to the own ship (as in US TDC). So direct link from UZO/Periscope was necessary to have up to date gyro angle (which is the function of the target bearing).

So there are to different approaches.

--
Regards
Maciek

[snakedocpl]

http://www.uboataces.com/images/torpedo_maintenance.jpgPrecisely!:shucks:"The crew programmes the torpedo."

Erm, beggin' yer pardon, but yer a bit late to the party. You really should read all the posts on this thread. Then go check out tvre.org/en/ for an eyeopener as to what the Siemens T. Vh. Re. S3 actually was, and still is, capable of doing. That would include getting continuous input from the sub's gyrocompass and the periscope/UZO target bearing transmitter, continuously calculating a firing solution, and automatically (No human intervention!) setting the torpedo gyro angle while the eel is in the tube. The TVR S3 was in service in the KM from mid-1941 on.

Please note that tvre.org represents the results of reverse-engineering the existing Siemens S3 which was installed in U-995 when it was launched in 1943 and can still be seen on board that vessel at the Laboe museum today. Check it out. Better than a movie!

And to be precise - on the photo Aktungbby has attached, the crew does not "programmes" the torpedo, but is checking the depth-steering engine of the G7a or G7e torpedo.

--
Regards
Maciek

[BigWalleye]

I think, that is by design. The Angle Solver of the US TDC is driven by Position Keeper. I mean, that Angle Solver calculates final solution based on the target parameters calculated by Position Keeper (which is modelling the relative position between the target and own ship). After inputting some initial values into Position Keeper, it constantly updates the position of the target relative to the own boat. There are some outputs (for instance GENERATED BEARING), which are used to verify, if assumed initial values were correct. So they read GENERATED BEARING, set the TBT or periscope at this bearing and then - if the target was there - that meant, that model is correct. If not - the initial target parameters were wrong.
Look here: http://archive.hnsa.org/doc/attack/index.htm
Paragraphs from 520.
It seems, that - based on the visual (and radar) observation, operators input the target speed and range. Then the Position Keeper calculates the target position relative to the target, and then GENERATED BEARING is compared with the real, observed bearing. And then corrections to the speed and/or range were applied.
And so on.
J
The German TVRe was only Angle Solver. So it calculated gyro angle, based on the actual target:D bearing, angle on the bow and parallax correction. It did not contain mathematical model of the target movement relative to the own ship (as in US TDC). So direct link from UZO/Periscope was necessary to have up to date gyro angle (which is the function of the target bearing).I

So there are to different approaches.

--
Regards
Maciek

Best simple concise explanation I have ever read! Excellent. Thank you.

Now I really understand how I always misused the TDC. I was using less than half its capability, in a way that was never intended. Still, I sank ships! Don't let BuPers find out, or I'll wind up shuffling papers at Mare Island!

[Aktungbby]

http://www.uboataces.com/images/torpedo_maintenance.jpgPrecisely!:shucks:"The crew programmes the torpedo."


Erm, beggin' yer pardon, but yer a bit late to the party. You really should read all the posts on this thread. Then go check out tvre.org/en/ for an eyeopener as to what the Siemens T. Vh. Re. S3 actually was, and still is, capable of doing. That would include getting continuous input from the sub's gyrocompass and the periscope/UZO target bearing transmitter, continuously calculating a firing solution, and automatically (No human intervention!) setting the torpedo gyro angle while the eel is in the tube. The TVR S3 was in service in the KM from mid-1941 on.

Please note that tvre.org represents the results of reverse-engineering the existing Siemens S3 which was installed in U-995 when it was launched in 1943 and can still be seen on board that vessel at the Laboe museum today. Check it out. Better than a movie!Apologies! I did include a ":shucks:" after 'precisely' I couldn't believe the photo's verbatim caption myself. Another caption for the same photo reads "World War 2 torpedoes were quite fickle. They had to be pulled from their tubes and serviced every two or three days." As per snakedocpl: I assmed it would have to do with the 'eel's' notorious depth problems prior to Lt Ites pressure discvery/solution abord U-94. Yer Siemans-ship don't mean a thing if the eel won't run at depth!On January 30,('42)!! the crew of U-94 (http://uboat.net/boats/u94.htm) made a little extra effort and conducted an on-board examination of their torpedoes amidst the Atlantic. They thus discovered an excess pressure in the torpedoes' balance chambers, where the hydrostatic valve controlling the depth at which the 'fish' ran was located. When they radioed back their findings, the Inspector of the Torpedo Department ordered a check on board all submarines in port. Half of the torpedoes were found to have the same problem, and the mystery of the torpedoes' deeper-than-set-depth run was finally fathomed. The results of this and later investigations were summed up into a Memorandum by Grand Admiral Raeder on Feb 9, 1942. :O:Proof: Heads rolled at German torpedo technology development (arrests and jail) and Ites, a POW until 1946, retired in 1977 as Konteradmiral!America and Germany learned the hard way that torpedoes are finicky weapons that cannot tolerate shortcuts. The most complex naval weapons of World War II, they demanded meticulous design, rigorous testing and intensive maintenance—not to mention exacting targeting and launch procedures. Lack of rigor at any stage from initial design to the torpedo's use in combat could result in failure, and the many opportunities for mistakes made it hard to tell where the fault lay, even after the weapon's poor performance became obvious.

Seen in this light, German and American torpedo failures are quite understandable. Only in hindsight is it apparent that the more complicated torpedoes developed for World War II demanded an unprecedented level of technical and operational evaluation. And even Germany's veteran submarine leaders never thought to second-guess their Torpedo Directorate until the problems became obvious.

Germany fixed most of her torpedo problems in less than half the time it took the United States because her submarine leadership was more experienced and because submarines were the mainstay of her navy. Doenitz and his staff knew from the start how to establish a trusting relationship with U-boat skippers and how to evaluate their reports. Senior American submariners had to learn those skills on the job. U-boats took the lead in Germany's naval war, while American submarines played second fiddle to battleships before Pearl Harbor and to aircraft carriers afterwards. If U.S. carriers had lost the Battle of Midway because their bombs failed to explode, it's safe to say the problem would have gotten a lot more attention than torpedo failures did.
I've been following this thread with great interest, look'd up all the links and had actually written two previous posts but deigned to submit due to the superiority of the ongoing discussion upon which I could hardly improve.:up:
It's the best discussion of the two systems I've seen in the forum in over two years. Anything though to get a rise out of a 'ol Wisconsinite:D A Hamm's all 'round!

[Hitman]

With the TBT, there was no Stadimeter to help in range finding attached to it. Neither were there Telemeter Divisions for judging range.

IIRC the reason was that, by the time the TBTs started being installed, all subs had radar -which was used on a quick impulse to get range on the already trained bearing and then switched off again for stealth.

[BigWalleye]

A Hamm's all 'round!


And one for the bear!:Kaleun_Cheers:

[Sailor Steve]

While my love for the Silent Service goes back to RAdm Dykers...
I just finished watching the entire series just a couple of months ago. :rock:

[Rockin Robbins]

IIRC the reason was that, by the time the TBTs started being installed, all subs had radar -which was used on a quick impulse to get range on the already trained bearing and then switched off again for stealth.
Fluckey tells about hooking radar to a telegraph key. Train the bearing, hit the key, get the range and no chance of any meaningful info getting out. They were too paranoid about such things. But when your life's on the line I suppose you take no chances. If it accomplished nothing else, and there's no evidence that it did, it let his crew know that their lives wouldn't be needlessly risked.

[BigWalleye]

I just finished watching the entire series just a couple of months ago. :rock:

Way cool! Where? Cable TV, on the Web, or DVD? I'd love to see the old shows again. Prolly get me back playing SH4!

If it accomplished nothing else, and there's no evidence that it did, it let his crew know that their lives wouldn't be needlessly risked.

And that, so I have read, mattered a lot to Fluckey. And his crew would have volunteered for a cruise to Hell as long as he was skipper.

[ColonelSandersLite]

Since we as captains aren't actually operating the TDC directly, I honestly don't see the practical difference between the tbt sending bearing information directly to the tdc and the tbt sending bearing information to the tdc operator who then enters it into the tdc.


That being said, there is something very important in the link provided by snakedocpl. It says directly on the very same page: 14C6. New installations. The latest design installations have, in addition to the units described above, additional transmitters operated by the sound gear and the periscopes for the transmission of both bearing and range to the stations equipped with indicators. In addition, an improved model of the target bearing transmitter is provided with an own course dial energized from the gyro repeater panel so that the true as well as the relative bearing may be read at the instrument. The ship's plans should be consulted for details.

The question is what is meant by new installations? 43? 44? Just after the war? That manual was published less than a year after japan surrendered. I wonder if anybody has more specific information?

[ColonelSandersLite]

So I found a periscope manual from 1940 and I'm pretty sure there was no bearing transmission then. I did find somthing really cool that I wish was in the game though.

http://www.maritime.org/doc/pdf/periscope-type2-1940.pdf

Read page 9 of 15 (of the pdf, the actual pages are not numbered), right hand page under the headings "description of stabilized azimuth line" and "operation of stabilized azimuth line". That is one cool tool. Also, pretty sure it's impossible to get it in the game.

[BigWalleye]

So I found a periscope manual from 1940 and I'm pretty sure there was no bearing transmission then. I did find somthing really cool that I wish was in the game though.

http://www.maritime.org/doc/pdf/periscope-type2-1940.pdf

Read page 9 of 15 (of the pdf, the actual pages are not numbered), right hand page under the headings "description of stabilized azimuth line" and "operation of stabilized azimuth line". That is one cool tool. Also, pretty sure it's impossible to get it in the game.

Cap'n Scurvy has a periscope photo of the stabilized azimuth line and a description of how it was used in Post #26 of this thread.

[BigWalleye]

Since we as captains aren't actually operating the TDC directly, I honestly don't see the practical difference between the tbt sending bearing information directly to the tdc and the tbt sending bearing information to the tdc operator who then enters it into the tdc.

You're right. There is no practical difference. Actually, as Approach Officers, we do send target bearing data directly to the TDC, when we click on the "Send" button. R/L Approach Officers didn't. They just said: "Bearing mark." and other members of the approach party did the rest. If you want to follow the R/L prototype, you have the install SH4Speech. Then you can order: "Bearing mark." and have your AI "crew" do the button-pushing.

[TorpX]

I think, that is by design. The Angle Solver of the US TDC is driven by Position Keeper. I mean, that Angle Solver calculates final solution based on the target parameters calculated by Position Keeper (which is modelling the relative position between the target and own ship). After inputting some initial values into Position Keeper, it constantly updates the position of the target relative to the own boat. There are some outputs (for instance GENERATED BEARING), which are used to verify, if assumed initial values were correct. So they read GENERATED BEARING, set the TBT or periscope at this bearing and then - if the target was there - that meant, that model is correct. If not - the initial target parameters were wrong.


Yes, I see your point. I kind of forgot about that aspect of the operation.

[CapnScurvy]

Cap'n Scurvy has a periscope photo of the stabilized azimuth line and a description of how it was used in Post #26 of this thread.

Hi BigWalleye, that photo you mentioned is not looking through a periscope. It's looking through one of the eye pieces of a TBT (that's the Nautilus conning tower in the background).

http://i175.photobucket.com/albums/w132/crawlee/P1010367.jpg

I forget which side it was, but the stationary lines within the one lens is what you're looking at.

http://i175.photobucket.com/albums/w132/crawlee/P1010374-1.jpg


I don't have a picture of what the Stabilize Azimuth Line would have looked like within the Kollmorgen Periscope. Guess it was just a vertical line, separate of the Telemeter Divisions within the lens.

[ColonelSandersLite]

From the instructions on the thing, I get the impression that it is a pretty fat line too. If it was as thin as the regular lines on the optics, using one side of the line as reference would probably be a non issue in practicality I think.

I'm also pretty sure it wasn't holographic from the description. It was probably literally a plain black metal bar that would move across the periscopes eyepiece at a rate determined by the gyrocompass, periscope bearing, and submarine speed.

[snakedocpl]

I think, that is by design. The Angle Solver of the US TDC is driven by Position Keeper. I mean, that Angle Solver calculates final solution based on the target parameters calculated by Position Keeper (which is modelling the relative position between the target and own ship). After inputting some initial values into Position Keeper, it constantly updates the position of the target relative to the own boat. There are some outputs (for instance GENERATED BEARING), which are used to verify, if assumed initial values were correct. So they read GENERATED BEARING, set the TBT or periscope at this bearing and then - if the target was there - that meant, that model is correct. If not - the initial target parameters were wrong.


Yes, I see your point. I kind of forgot about that aspect of the operation.
Please note, that US TDC made possible to launch torpedoes without using periscope. If the target course parameters for the Position Keeper were correct and target moved on steady course, the Commander did not have to look through the periscope to aim the torpedoes. In reality, just before launch, the Commander looked through the scope to make sure, that target is there, where it should be.
Cap'n Scurvy has a periscope photo of the stabilized azimuth line and a description of how it was used in Post #26 of this thread.
The stabilized line in space was also present in the German periscopes manufacted by Zeiss. They called it "Feste Linie im Raum". As far as I know, the WWII U-Boats were not fitted with periscopes with this feature.

From the instructions on the thing, I get the impression that it is a pretty fat line too. If it was as thin as the regular lines on the optics, using one side of the line as reference would probably be a non issue in practicality I think.

I'm also pretty sure it wasn't holographic from the description. It was probably literally a plain black metal bar that would move across the periscopes eyepiece at a rate determined by the gyrocompass, periscope bearing, and submarine speed.
Well, looking at the drawing at the end of the manual (http://www.maritime.org/doc/pdf/periscope-type2-1940.pdf), it seems, that it is quite fat line. I have attached the drawing with essential elements marked:
http://s15.postimg.org/9k9vdpsqh/lines_1.png

I think, that in the view field, this line looked as on images below:
http://s17.postimg.org/8ljg4dkb3/lines_2.png

http://s12.postimg.org/a5f82t6gt/lines_3.png

On the first image, the line was positioned at the bow of the (stationary) ship. On the second image, the periscope was moved to the left.

Hi BigWalleye, that photo you mentioned is not looking through a periscope. It's looking through one of the eye pieces of a TBT (that's the Nautilus conning tower in the background).

I forget which side it was, but the stationary lines within the one lens is what you're looking at.

Looking at this manual (http://www.maritime.org/doc/pdf/tbt.pdf), it seems, that TBT was not fitted in "stabilized line in space".

I'm also pretty sure it wasn't holographic from the description. It was probably literally a plain black metal bar that would move across the periscopes eyepiece at a rate determined by the gyrocompass, periscope bearing, and submarine speed.

The stabilized line compensated only change of periscope bearing and change of submarine course. It could do nothing with the speed. To make the target speed most accurate, the speed of own submarine should be relatively small.

--
Regards
Maciek

http://postimg.org/image/j4ti0li2f/ (http://postimg.org/image/j4ti0li2f/)

[CapnScurvy]

Snakedocpl, I believe your images of the Stabilized Azimuth Line are a bit misleading. The line could be placed anywhere within the periscopes Field of View. It was independent from the Telemeter Divisions........ so it was not "centered" to the FoV. You focused the line (bringing it in sharper), placing it just ahead of the targets bow, then turned the clutch "in" to engage the synchronous motor (which would have already been plugged in) just as the targets bow touched the line. Using a stop watch, you time the passage of the target. Unlike the images, there are no graduated marks, or scale for the Stabilized Line......just a line.

I'm not nit picking your help, just don't want to mislead anyone. :)

The stabilized line compensated only change of periscope bearing and change of submarine course. It could do nothing with the speed. To make the target speed most accurate, the speed of own submarine should be relatively small.


The estimated target Speed is calculated by knowing the estimated length of the target, and how long the target takes to pass the Stabilized Azimuth Line. That's why the stop watch is used. Estamated Speed was found.

Looking at this manual (http://www.maritime.org/doc/pdf/tbt.pdf), it seems, that TBT was not fitted in "stabilized line in space".


That's correct. The TBT has only the permanent "cross hairs" as shown. Which by the way were "illuminated" for night use.....when plugged in.

[ColonelSandersLite]

The stabilized line compensated only change of periscope bearing and change of submarine course. It could do nothing with the speed. To make the target speed most accurate, the speed of own submarine should be relatively small.http://postimg.org/image/j4ti0li2f/ (http://postimg.org/image/j4ti0li2f/)

I'll go over the rest in more detail later, but I would like to know where you're getting that particular piece of information. It's possible that the stabilization mechanism assumed a standard tactical speed (like maybe 2 knots submerged or something). However, it does not say anywhere that I'm seeing that sub speed is not known to the unit. It does specifically say that it is getting data from the ships gyrocompass, which knows ships speed.


@scurvy
You're misreading him on that first quote. He's talking about sub speed, not target speed.

[CapnScurvy]

ColonelSandersLite........:up:

[snakedocpl]

I'll go over the rest in more detail later, but I would like to know where you're getting that particular piece of information. It's possible that the stabilization mechanism assumed a standard tactical speed (like maybe 2 knots submerged or something). However, it does not say anywhere that I'm seeing that sub speed is not known to the unit. It does specifically say that it is getting data from the ships gyrocompass, which knows ships speed.


How gyrocompass knows the ship speed? I have always thought, that it knows only its course. The speed is measured by log.
The periscope manual says:
The azimuth line is actuated by a self synchronous motor, which in turn is governed by the gyro compass of the submarine. The position of the line is thus independent of changes in the course of the submarine, but if the periscope is rotated in its bearings the azimuth line will of course move against the field.--
Regards
Maciek

[snakedocpl]

Snakedocpl, I believe your images of the Stabilized Azimuth Line are a bit misleading. The line could be placed anywhere within the periscopes Field of View. It was independent from the Telemeter Divisions........ so it was not "centered" to the FoV. You focused the line (bringing it in sharper), placing it just ahead of the targets bow, then turned the clutch "in" to engage the synchronous motor (which would have already been plugged in) just as the targets bow touched the line. Using a stop watch, you time the passage of the target. Unlike the images, there are no graduated marks, or scale for the Stabilized Line......just a line.



These images are my impression, because I have never look through the periscope with stabilized line. The impression based on the construction drawing of the ocular box. I marked stabilized line with red color. Of course it can be moved through the view (after decoupling from motor). The first drawing presents it after placing it at the bow of the target. On the second drawing the scope was rotated, but line stays at the same place as before (rotated by synchro-motor). That's why I wrote, that target is stationary. In reality, the target would move, and the line would be slightly shifted relative to the bow.

--
Regards
Maciek

[ColonelSandersLite]

The gyrocompass needs to know ship speed in order to compensate for latitude & speed error. For the basic theory, see page 10 of the gyrocompass manual here: http://www.maritime.org/doc/gyromk7/index.htm

So yeah, the periscope is connected to the ships gyrocompass, which gets speed from the underwater log.

[snakedocpl]

The gyrocompass needs to know ship speed in order to compensate for latitude & speed error. For the basic theory, see page 10 of the gyrocompass manual here: http://www.maritime.org/doc/gyromk7/index.htm

So yeah, the periscope is connected to the ships gyrocompass, which gets speed from the underwater log.

Well, you are right, the speed is used to get the corrected course. But all the gyro repeaters (driven by gyro compass) receives only course. At the end of the periscope manual you have wiring of the plug and socket. You can see there two power lines (R1 and R2)and three phase lines (S1, S2, S3).
Here you have got wiring of the repeaters:
http://www.maritime.org/doc/gyromk7/part2.htm#pg72
There is no way to transmit speed, only the course.

--
Regards
Maciek

[ColonelSandersLite]

Good catch, you're certainly right on that. The stabilization must have used an assumed submarine speed. Whether it was 0 knots or some other number, I see no indication of. I sort of doubt it was 0 as if this is the case, the entire system is sorta pointless as you could just use the centerline of the periscope instead.


It seems that the 89KA40/1.414 was replaced by the 91KA40T/1.414HA sometime during the war. Looking at the maintenance manual for the new model, I notice that the stabilized azimuth line function is completely omitted. No mention as to why, but I would think it was either regarded as mechanically unreliable or just not useful. That might (or just as easily might not) tie into the above uselessness of a stabilized line that does not in any way account for submarine speed.


I'm not sure when exactly these replacements where made but looking at a few periscopes in surviving boats (no, I didn't check them all, just a few) the ones I saw where all the 91. I had been thinking that maybe the groups in charge of one of the surviving boats would be willing to provide a picture but I suspect that there are probably no surviving model 89s left.


As an aside, it seems the "observation scope" at the start of the war was 88KA40/1.99 (a type III). Replaced by the 92KA40T/1.99 (also type III) and then the 93KN36 (type IV). Again, dates are something I don't have.

Type I - Obsolete (S Boat scopes maybe? No information)
Type II - Attack Scope
Type III - General Purpose
Type IV - Night Scope

[CapnScurvy]

I've come to the same conclusion Colonel.

The earlier Kollmorgen periscope model had the Stabilized Azimuth Line, the 91KA40T did not. It stands to reason why there's no reference to using the Stabilized Line in the 1952 Submarine Torpedo Fire Control Manual (http://archive.hnsa.org/doc/attack/index.htm). Also, I could find no periscope images of the Line in use.

I did find an image that I couldn't resist to show :D:


http://i175.photobucket.com/albums/w132/crawlee/Jap%20in%20Periscope%20copy_zpsdjhwszkh.jpg

[snakedocpl]

Good catch, you're certainly right on that. The stabilization must have used an assumed submarine speed. Whether it was 0 knots or some other number, I see no indication of. I sort of doubt it was 0 as if this is the case, the entire system is sorta pointless as you could just use the centerline of the periscope instead.


It seems that the 89KA40/1.414 was replaced by the 91KA40T/1.414HA sometime during the war. Looking at the maintenance manual for the new model, I notice that the stabilized azimuth line function is completely omitted. No mention as to why, but I would think it was either regarded as mechanically unreliable or just not useful. That might (or just as easily might not) tie into the above uselessness of a stabilized line that does not in any way account for submarine speed.


I'm not sure when exactly these replacements where made but looking at a few periscopes in surviving boats (no, I didn't check them all, just a few) the ones I saw where all the 91. I had been thinking that maybe the groups in charge of one of the surviving boats would be willing to provide a picture but I suspect that there are probably no surviving model 89s left.




Well, I think the same. Taking into account correction for own speed would require the knowledge of the target AoB and target bearing (you don't need correction if the target is just ahead, but you need if it is abeam). All this would require small calculating device. I think, that such device was not developed because it would be complicated, its input depended on estimated value of AoB, so it would not give any advantage over plotting or even estimating. I suppose, stabilized line was abandoned because it just impractical. The absence of such device in U-Boats periscopes (despite the fact that Zeiss manufactured periscopes with "Feste Linie im Raum") would confirm such assumption.

--
Regards
Maciek

[TorpX]

Well, I think the same. Taking into account correction for own speed would require the knowledge of the target AoB and target bearing (you don't need correction if the target is just ahead, but you need if it is abeam).

Actually, you don't necessarily need the target Aob.



Below, is a geometric solution for timing by wire that doesn't make use of any "stabilized line", or special equipment. In this solution, you do need to know the Aob, and of course, target bearing, and sub speed.

The 'line' moves with the sub, but the angle doesn't change.

The underlined term in the formula accounts for the movement of the line and the space along the target track marked by 'n'.

http://i1130.photobucket.com/albums/m526/TorpX/Misc/TimeWire2_zpsvs7dq8yc.png



However, if you had a mechanism to move or "stabilize" the line, there are other possibilities. Below is a diagram illustrating what a solution might look like with the line being moved. This simplifies the calculation of target speed in that the underlined term in the first formula is eliminated.


http://i1130.photobucket.com/albums/m526/TorpX/Misc/TimeWire3_zpsz0cyez6d.png

Note that for the mechanism to know how fast the line is to be moved, the range has to be known.

The initial rate of change of angle a =

(Vu*k sin a) / (2*pi*Range) * (360*60)

I computed an example for a sub moving at 3 kn., timing a target at 2,000 yds., at 45°.

(3*0.563*sin 45) / (2*pi*2000) * (360 * 60) = 2.05° per minute

The problem with the above is that the rate of change of the angle is not constant, so it would have to be dynamically calculated by the TDC, or some mechanism. Of course, the calculation is no more complicated than the other quantities the TDC calculates, so it is certainly possible.

Without some kind of mechanism to calculate the above, I don't really see any point in the technology.

I suspect the reason the feature was not carried over, was that it was rendered unnecessary by RADAR. With a RADAR plot, the target speed could be accurately determined without identification, or knowing the ship's length.

[snakedocpl]

Interesting approach.

Actually, you don't necessarily need the target Aob.
Below, is a geometric solution for timing by wire that doesn't make use of any "stabilized line", or special equipment. In this solution, you do need to know the Aob, and of course, target bearing, and sub speed.
The 'line' moves with the sub, but the angle doesn't change.
The underlined term in the formula accounts for the movement of the line and the space along the target track marked by 'n'.
This one is similar to the German Ausdampfverfahren method. However, if you had a mechanism to move or "stabilize" the line, there are other possibilities. Below is a diagram illustrating what a solution might look like with the line being moved. This simplifies the calculation of target speed in that the underlined term in the first formula is eliminated.Note that for the mechanism to know how fast the line is to be moved, the range has to be known.
The initial rate of change of angle a =
(Vu*k sin a) / (2*pi*Range) * (360*60)
I computed an example for a sub moving at 3 kn., timing a target at 2,000 yds., at 45°.
(3*0.563*sin 45) / (2*pi*2000) * (360 * 60) = 2.05° per minute
The problem with the above is that the rate of change of the angle is not constant, so it would have to be dynamically calculated by the TDC, or some mechanism. Of course, the calculation is no more complicated than the other quantities the TDC calculates, so it is certainly possible.
Without some kind of mechanism to calculate the above, I don't really see any point in the technology.
I suspect the reason the feature was not carried over, was that it was rendered unnecessary by RADAR. With a RADAR plot, the target speed could be accurately determined without identification, or knowing the ship's length.

This in turn is similar to the German Auswanderungsverfahren method.

--
Regards
Maciek

[ColonelSandersLite]

All this would require small calculating device. I think, that such device was not developed because it would be complicated, its input depended on estimated value of AoB, so it would not give any advantage over plotting or even estimating. I suppose, stabilized line was abandoned because it just impractical.

I suspect the reason the feature was not carried over, was that it was rendered unnecessary by RADAR. With a RADAR plot, the target speed could be accurately determined without identification, or knowing the ship's length.

The more I think about it, the more sure I am that the device was simply ineffective.

AOB isn't actually required as the point of stabilization isn't moving (try shooting at a stationary ship to see what I mean, aob is not a required part of the solution). True stabilization not only requires knowing your own speed but also a specified distance to stabilize to. Sure, you can use assumed values for both, but that would render the device inaccurate. There is also a fundamental problem given the era. Unless you're stabilizing to infinity, the ability to solve the triangle in real time would take an analog computer that surely could never fit in the periscope. US submarines actually did have that computer, in the form of the TDC with position keeper, and it takes up a *lot* of room. Even stripping it down to the bare essentials for this particular job, I very much doubt it could fit.


Given that there is no way to input submarine speed or stabilization distance, and the computer that could do it probably couldn't fit into the periscope, I think it's safe to assume that the line was stabilized to infinity. This means that there is just no practical difference between just using a regular vertical line on the periscope and using the stabilized line so long as the submarine is not turning. In the real world, a 5 knot target will take around (depends on ship length) 50 seconds to cross the periscope line and this scales linearly with speed so a 10 knot target around 25 seconds and 15 knot target around 17 seconds.


I can't speak for everybody, but in my experience, the tactical limitation of not being able to turn while determining target speed is not actually a real issue, regardless of the method used to gather the data.


I think that torpX is right that radar rendered the device a moot point as well, but that doesn't actually mean the device was ever all that useful in the first place. Still, it's a cool idea that was ahead of its time, even if the level of technology at the time rendered it impractical.

[TorpX]

Given that there is no way to input submarine speed or stabilization distance, and the computer that could do it probably couldn't fit into the periscope...



This had to be done by the TDC. As you say, the machinery couldn't fit in the scope. But why would it need to? The outputs from the TDC could be fed into the mechanism to move the line. The position keeper already calculates and updates the target position, so not much else is required.


I think it's safe to assume that the line was stabilized to infinity. This means that there is just no practical difference between just using a regular vertical line on the periscope and using the stabilized line so long as the submarine is not turning.

I think this is a further indication that the TDC did indeed calculate the info for the line to move. Otherwise, the whole point is lost.

[ColonelSandersLite]

This had to be done by the TDC. As you say, the machinery couldn't fit in the scope. But why would it need to? The outputs from the TDC could be fed into the mechanism to move the line.

Sure, except that it wasn't. As far as I can make out, looking at the diagrams, the 89KA40/1.414 doesn't actually have any connection to the tdc and the stabilization motor surely isn't receiving any data from there. The sole exception would be possible ad-hock retrofits of the TBT system prior to getting the 91KA40T/1.414HA.

[TorpX]

So, you're saying the navy installed a totally unnecessary piece of machinery that didn't do anything?

Or, if it did something else, besides moving the line in such a way as to help the crew estimate the target's speed, what would that be?

[ColonelSandersLite]

That does seem to be the case. Trying ideas that are hypothetically better than they turn out to be in practice isn't exactly unprecedented. It might have helped a bit with compensating for ship pitching and rolling when surfaced, but given the doctrine when it was designed and installed, I sort of doubt that was the reasoning.

It's explicitly stated as being designed to help in speed estimation, but as far as I can make out, it was only installed in one periscope model so it would seem to me that the navy realized it was a mistake and scrapped it fairly quickly.

[Rockin Robbins]

There's also the fact that they might use the same piece of equipment for a submarine and a destroyer. It would have all the functionality of the DD but not all that would be available on a submarine, so that part wouldn't be plugged in.