TDC torpedo speed selector switches

[Rockin Robbins]

I've searched seafarer's link for the Mark III TDC Manual and can't find any reference to the "simple selectors for the speed settings" for Mark 14 torpedoes. The only apparent possibility is the four dials on the poorly documented electrical section. There is one illustration and I can read enough to see that the right one is the power selector switch and the next one to the left is legible. That leaves two unidentified electrical knobs that may be the adjustment.

However, a schematic I've found shows a hand crank for Sz which is the torpedo speed. Hey, YOU try wading through all the calculation derivations to figure out what to look for! It's enough to make you plenty cranky if high level algebra and trig is not your native language.

http://i196.photobucket.com/albums/aa293/RockinRobbins13/SzTDCinput-1.jpg

There's your input, Vern, right on this easy-breezy little diagram. Yer top crank there, labeled S sub Z (Sz phonetically rendered there), that's crank 5F-A, is adjustable torpedo speed between 25 and 60 knots.

So I'm STILL curious where this crank is on the actual unit. And now I'm really mystified as to the necessity to rebuild (presumably to the Mark IV unit) when a boat was in drydock being adapted for the electrical Mark 18 torpedoes.

I have an irrelevent aside, but I'll hold it as I don't want to hijack my own thread. Again, sorry CapnScurvy, for my irrelevent aside in your thread hijacking your masthead height and differing AoBs thread. Hope you can get it back on track.:huh:

[seafarer]

Perhaps my poor choice of words, as I don't know actually how simple it is to input the data. I was also going by the schematic near the bottom here (this is for a Mk.IV - http://www.usscod.org/tdc-restore.html ). Sz is torpedor running speed. Another source I have somewhere mentioned that the TDC operator had to "input torpedo type and speed", but obviously if torp. speed is a discrete input parameter, then type would surely be unnecessary?

[Rockin Robbins]

Perhaps my poor choice of words, as I don't know actually how simple it is to input the data. I was also going by the schematic near the bottom here (this is for a Mk.IV - http://www.usscod.org/tdc-restore.html ). Sz is torpedor running speed. Another source I have somewhere mentioned that the TDC operator had to "input torpedo type and speed", but obviously if torp. speed is a discrete input parameter, then type would surely be unnecessary?

The cranks were not difficult to use and you only had to overcome the friction of the slip clutches. But using torpedo type as the input instead of torpedo speed would prevent lots of human error, I would think.

I still want to find a photo of the correct crank and its location on the TDC Mark III.

[Gino]

Perhaps my poor choice of words, as I don't know actually how simple it is to input the data. I was also going by the schematic near the bottom here (this is for a Mk.IV - http://www.usscod.org/tdc-restore.html ). Sz is torpedor running speed. Another source I have somewhere mentioned that the TDC operator had to "input torpedo type and speed", but obviously if torp. speed is a discrete input parameter, then type would surely be unnecessary?

The cranks were not difficult to use and you only had to overcome the friction of the slip clutches. But using torpedo type as the input instead of torpedo speed would prevent lots of human error, I would think.

I still want to find a photo of the correct crank and its location on the TDC Mark III.

Indeed, setting the input values on either the Position Keeper, or the Angle Solver is a piece of cake. You just rotate the cranks untill the correct values appear. This can even be done while the TDC is running and therefore is calculating the angles.
The TDC rather quickly to any changes in the scenario, with some exceptions.
For example, if the submarine should pass beneath the target a number of the mechanical elements will have to travel clear to the other end of their range to get back onto the solutions. The follow-up heads will not match during the time it takes for the elements to drive all the way to the other extreme. The whole TDC makes some very interesting noises while that is happening. It's a great machine to work on (play with :D )

I'll have to look at some photographs I've got at home, to see where the Torpedo Speed crank is located. I think it's the one in the middle on the Angle Solver.:hmm:

The Cod has a Mark IV TDC which means it has a Receiver Unit in the middle between the PK and the AS. Therefore we have the advantage that values from periscope, radar and/or sonar can directly be fed into the PK.


By the way, each torpedo came with a piece of paper at what exact speeds it could run. Every torpedo was tested at it's possible speed settings. For a Mark 14 that would be two. For every torpedo fired, the TDC Officer had to dial in the correct speed setting, according to the papers sent with each torpedo. That's why, if you read a patrol report, you'll find for every torpedo fired, its serial number.

Let me see what I can find more on this topic.

groetjes,

[Rockin Robbins]

I feel like a kid in a candy store! In many ways, the production of a mechanical analog computer is more amazing than a digital one. Instead of invisible electrons moving from bin to bin, an invisible process, in the analog computer gears, shafts, clutches, readout dials where you might have to interpolate to find the answer, are all present. The machine has to be carefully adjusted to work properly, and as the manual says, haphazardly making adjustments may result in a web of anomolies so pervasive the machine cannot be set right again.

On one level, the thing is primitive. On another level, it is a work of art with inconceivably consumate craftsmanship. I can't wait to see those photos! Thanks Gino:up:

[seafarer]

As far as I can tell, the best photo's available are those at http://www.maritime.org/tdc.htm but I cannot read any of the labels on the machine :damn:

The answer, I'm sure, would be in:

The Fleet Submarine Torpedo Data Computer
by Harvey G. Cragon (134 pages)
Cragon Books; First edition (November 23, 2007)
ISBN-10: 0974304530

But Amazon is out of stock. Anybody care to check their local library?

[Gino]

You may want to check: http://www.hnsa.org/doc/tdc/index.htm

There you'll find everything you don't want to know about the Mark 3 TDC...:D

It doesn't show you the labels at the machine, but it does tell you how it works :up:

I think the book you mentioned is also derived from that manual.

THE authority IMHO is Terry Lindell who is attached to USS Pampanito. He's also the one that brought Cod's TDC back to life.

Like I said in my previous reply, I'll check for photos at home...

groetjes,

[Gino]

Ok, so it is not the best of pictures, but here goes.

A glimpse of the Angle Solver on USS Cod

http://img253.imageshack.us/img253/5555/img0034hp6.th.jpg (http://img253.imageshack.us/my.php?image=img0034hp6.jpg)

Above the cranks. Label left: SPREAD AFT
Label middle: TORPEDO SPEED
Label right: SPREAD FWD

The rest should be legible from the manual...

Position Keeper drawing I have been working on:

http://img216.imageshack.us/img216/198/positionkeeperwipib1.th.jpg (http://img216.imageshack.us/my.php?image=positionkeeperwipib1.jpg)

And the whole thing in one drawing. Mind that this is WIP, so some dials have not been put in there yet.

http://img216.imageshack.us/img216/462/tdc2drawxq5.th.jpg (http://img216.imageshack.us/my.php?image=tdc2drawxq5.jpg)

Questions?

I have more photos, but the quality ain't that phenomenal :cry:

groetjes,

[seafarer]

Awesome Gino, thanks. I could follow the schematics alright, but then trying to figure out just how that actually worked for input on the real thing was what I was missing. Just knowing which dial is which now makes it much easier to picture actually using the machine.

[M. Sarsfield]

I take it that the FWD and AFT "spread" dials are actually represented by the offset dial that we see in the game?

[Gino]

I take it that the FWD and AFT "spread" dials are actually represented by the offset dial that we see in the game?

Yep, you're right.

I found out that the Mark 3 has also a nice feature on their Torpedo speed crank. I don't know which revision level (or Mod) but it appears that later models had also the capability to set the Torpedo Depth with the same crank. On Cod the Torpedo depth is set at the torpedo tube. So, maybe this setting is related to later torpedo tubes.

groetjes,

[Rockin Robbins]

The bottom crank(?) is the radius of turn for the torpedo. This was one of the reasons given for the TDC overhaul in the book I read, that the electrical Mark 18s had a different speed and different turn radius. Now we know that the TDC could handle that anyway!

I have to locate the reference and determine who was so misinformed! Looks to me that they were just updating Mark III to Mark IV, most notably inserting the receiver module.

This just gets more and more interesting!:up:

[Gino]

The bottom crank(?) is the radius of turn for the torpedo. This was one of the reasons given for the TDC overhaul in the book I read, that the electrical Mark 18s had a different speed and different turn radius. Now we know that the TDC could handle that anyway!

I have to locate the reference and determine who was so misinformed! Looks to me that they were just updating Mark III to Mark IV, most notably inserting the receiver module.

This just gets more and more interesting!:up:

I don't know if they did do upgrades from Mark 3 to Mark 4. Pampanito (SS-383) which was built later than Cod (SS-224) still has a Mark 3. Icefish (SS-367) and Hawkbill (SS-366), which both went to the Netherlands after the war (after being Guppied) had Mark 3's. One of which is on display in the Dutch Navy museum in Den Helder.
Also, inserting the receiver was a major operation, which would include opening the pressure hull on the conning tower, making extra room for the receiver etc.
Would have been very expensive...

So, yes it is getting more interesting...

groetjes,

[M. Sarsfield]

I can't think of any museum boats sporting a Mk. IV TDC, but I do like the idea of being able to select where the input comes from. This is sort of modeled in the game with the "send bearing" switch on the sound stack.

[Gino]

I can't think of any museum boats sporting a Mk. IV TDC, but I do like the idea of being able to select where the input comes from. This is sort of modeled in the game with the "send bearing" switch on the sound stack.

The USS Cod (SS-224) that is in Cleveland, Ohio has a working Mark 4 Torpedo Data Computer...
I know, because I have operated it myself, and I hope to do that again this summer.

Also the drawings I put in an earlier reply, are from that TDC.

So Mark 4's were used during ww2, no doubt about that.

groetjes,

[M. Sarsfield]

The Cod might be a rarity. A lot of boats probably got the upgrade after the war, if they were kept around for GUPPY conversions and such.

Btw, Gino, have you been to the new www.submarinemuseums.org (http://www.submarinemuseums.org) website? We don't have a representative from the Cod, yet. Maybe you would like to be the mouth piece for that boat? It will create more visibility of what the Cod is doing/dealing with and it's a great place to swap ideas and stories about boat maintenace and restoration.

[LukeFF]

I don't know if they did do upgrades from Mark 3 to Mark 4.

Norman Friedman mentions in his book that Mark 3s were upgraded to Mark 4 but doesn't note whether this was during the war or not.

[M. Sarsfield]

I emailed the guru that keeps the Mk. IV TDC running on the COD and asked him when it was originally installed and if it can be broken down into small enough subcomponents to fit through a hatch. I'll let you know what he says.

[Gino]

I emailed the guru that keeps the Mk. IV TDC running on the COD and asked him when it was originally installed and if it can be broken down into small enough subcomponents to fit through a hatch. I'll let you know what he says.

Could have asked me that... I would have called him :D

One answer I already know: Even disassembled the TDC does not fit through the conning tower hatch. The PK and the AS are simply too wide for that.
As far as I know, the TDC we have has been in the Cod since commisioning.
That also confirms something I noted on the web yesterday: The Mk4 was introduced in 1943. Cod may have been one of the first to receive a Mk4.
That later boats still received a Mk3 may have something to do with which shipyard built the boat, and what did they have in stock?
Cod was EB built, so I presume that EB, since they are not a governement shipyard, ordered their alotment of TDCs at the last moment. Thus they would have no stock of Mk3's, and thus a Mk4 was built into Cod. Now Pampanito was Portsmouth built. Launched July 1943, Cod was launched May 1943. So, it could be that Portsmouth had a supply of Mk3' that they would have to 'get rid of' first.
That would also go for Batfish, launched May 1943 by Portsmouth shipyard.

However, it doesn't fit when we look at Hawkbill and Icefish who were built by Manitowoc from August/September 1943 and launched in January/February 1944. They had a Mk3 TDC. Also these two were Guppied, and the TDC was not updated to Mk4. It may have been updated to another Mod, but the receiver was never built in. :hmm:

I think we need the support of the US TDC Guru, Terry Lindell. Let me see if I can 'find' him...

groetjes,

[M. Sarsfield]

Yeah. I'm really curious as to the limited use of that model. Maybe it was a trial program and they wanted to see if there was any added benefit to adding the third input panel. Also, by mid-'43 we were really sticking it to the Japs - sub attacks, specifically. The Navy may have decided that there wasn't a huge advantage, boats were already getting lots of successes with the fixed torpedoes, and they stayed with the cheaper/simpler Mk. III.

[Gino]

Just got of the phone with our TDC-guru (as you call him...)

Well, I couldn't have been more wrong... :oops:
The Cod did receive a Mk3, that was upgraded to a Mk4 after the war.

They would 'only' have to separate the PK and AS from each other and fit in the Receiver unit.
Essentially the TDC remained the same, you'd still have to crank in the basic parameters. The receiver 'units' could be used by selecting the appropriate switch on the Receiver.

Now, what utterly puzzles me is that Cod who never was in the Guppy program did receive the upgrade, but e.g. Hawkbill and Icefish never did.
Must have been a government thing...

So it seems that most, if not all boats, received a Mk3 during ww2. And that some of those boats received the upgrade and others didn't.

Let me get out an e-mail to someone who might know the precise data...

To be continued...

groetjes,

[M. Sarsfield]

Gino,

Thanks for contacting Paul about this. Our email server at work has been having problems with outside email contacts.

So, Mk. IV was just a mod to Mk. III by adding in the Receiver unit.

I'm guessing that there wasn't widespread upgrades, because by the end of the war and early Cold War days, more emphasis put on active and passive homing torpedoes that could also attack submarines at fairly deep depths (by late '40's standards). Doctrine was starting to move away from visual attack methods and move toward computer and sound assisted attacks.

That is just my 2 cents based on torpedo development history...

[Gino]

Gino,

Thanks for contacting Paul about this. Our email server at work has been having problems with outside email contacts.

I sure hope you don't think that Paul is the TDC-guru... :rotfl:

For this one I went directly to Dr. John. He is the one that taught me how to operate the TDC, that's the guru for me.

Although we now know something about Mk3 and Mk4, I can try to contact the Chief-guru to figure out what happened when, and how... :hmm:

Any specifics we want to know from him too?

groetjes,

[M. Sarsfield]

So, Paul isn't the guru. Fred Tannenbaum directed my questions to him on the Sub Museums website forum.

For radar input, ask him if the new receiver unit took data from SJ-1, FM periscope radar, or both.

[M. Sarsfield]

Gino,

Here's what Paul wrote to me:


Mark:

No absolute record, but my guess would be in 1951 when she was recommissioned. COD was brought up to late 1945 fleet sub standards in some regards, the short wire radio antennas and VHF whip and a radio shack refit below, and the Mark IV TDC (which can easily pass through the hatch). We did NOT get the SV or SS radars, but rather kept our Mod. 5 SJ and SD radars. The Navy didn't want to blow too much money on these Gatos when they were scrambling for GUPPY money and funds for Nautilus.

Why do you ask? How are things on BATFISH. We were just at the National Archives and saw tons of beautiful BATFISH photos (most published in the TIME/LIFE book "War Beneath the Pacific."

Paul


Since upgrading to a Mk. IV meant inserting the Receiver module between the PK and AS modules, it looks like the Receiver module is narrow enough (based on pictures) to fit through the bridge hatch. So, I think John and Paul are both right, depending on which modules you're talking about.

[Gino]

The Receiver can fit through the hatch. But the PK and AS units won't.
Paul also means the Receiver unit, and not the whole TDC. It would be costly to remove the whole TDC. The upgrade thus would consist of adding the Receiver and modifying the PK.

Yesterday I fired off an e-mail to the TDC-Chief-guru. I put the questions you had also in there.

To be continued...

groetjes,

[M. Sarsfield]

So, we're all on the same page, now. :D

[Gino]

So, we're all on the same page, now. :D

Yep, took a while to get there, but running straight and normal now :up:

Do you have your TDC running yet?

With the manual on the HNSA website it should be no big thing... :)

Maybe you should invite the TDC-chief guru over to have a look at it. He fixed Cods TDC and got it running in no time.

Fun thing is that two years ago we ran some tests (as described in the manual) and this TDC was still running within specification, even after over 40 years!!!

groetjes,

[M. Sarsfield]

Our real TDC is in an officer's club somewhere in Pennsylvania (probably Philly). What we have is a plywood mock-up with all of the cables cut and one of the torpedo firing controls removed. :down:

We still have the post-war surface radar and I'd like to get the scopes working, again. First, we need to run 120 and 240 power into the control room. The museum's main concern is repairing the exterior right now.

What type of shore power do you guys have running into the Cod? Where did you run the wiring to bring it on board?

[Gino]

What type of shore power do you guys have running into the Cod? Where did you run the wiring to bring it on board?

You'd have to ask Paul about that one. I know it's barely enough to run the lights... Even if we would be able to run the airconditioning again, there would not be enough power.

BTW Bummer about that TDC.

As for a working radar, we were thinking to restore our SD to working condition. But some other project needed more attention. Mind that the FDC (?) has to know about this, and you basically need a HAM (or better) radio license to operate the unit.
Cod being close to an airfield might hinder the process, although we are far lower in frequency than the airport radar.

groetjes,

[M. Sarsfield]

Yes, the FCC would want to know about the radar unit being operational. We have a ham club aboard, but I'll ask the FCC what license they want us to have for it to be running. It may be a basic broadcasting license or a specialized license for non-voice transmitters.

Okay on the power. Our curator is an electrical engineer and we're starting to look into all of the power requirements to hook everything up in the control room, again. We only have lights and modern HVAC working.