Quote:
Originally Posted by 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.
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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). 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.
