SUBSIM Radio Room Forums - View Single Post - TDC Explanation PDF

Chromatix · 06-09-16, 10:05 AM

I'm finding Marulken's TDC much easer to use than SH4's in manual mode, probably because it more closely matches how the real ones worked.

I'm never quite sure what SH4 is doing with the data I feed it, and if there's a way to check what SH4 is generating against reality (without map contact updates, that is), I haven't yet found it. That's why I play SH4 with automatic targeting.

Marulken gives me all the relevant data up front and lets me decide how to use it - much more realistic and intuitive.

I disagree however with your recommendations of what order to set the inputs in. Here's what I recommend:

1) Set the target speed to zero if it isn't already.

2) Enter a provisional target bearing, either from periscope or hydrophones. Optional: enter rough estimate of target range too.

3) Stop engines and begin timing the waterline passage. While waiting, make estimate of target AoB and enter that into TDC.

4) Enter target speed into TDC. There will now be no lag between subsequent range/bearing data entry and tracking. Lag causes misses astern.

5) Take new, precise measurements of target bearing & range; enter these into TDC. For this an assistant is helpful, otherwise point periscope slightly ahead of target to compensate for data entry lag.

At this point TDC is faithfully tracking your estimated data. The most likely source of error is now in the AoB, which is notoriously difficult to estimate visually. Begin manoeuvring for favourable attack position.

6) After a short time (say 30 seconds), take new, precise range and bearing measurements. Check these against the TDC's generated range and bearing, remembering to correct for lag if playing solo. If they don't match, correct them and then also adjust the AoB. Repeat at regular intervals until attack is made or abandoned.

7) When in attack position (ideally, target crossing your bow beam-on at 1000m range) and TDC generation checks properly, fire a torpedo. One is enough to sink a destroyer, and there is no provision for firing a divergent spread to compensate for aiming errors.

06-09-16, 10:05 AM	#2
Chromatix Watch Join Date: May 2011 Posts: 26 Downloads: 11 Uploads: 0	I'm finding Marulken's TDC much easer to use than SH4's in manual mode, probably because it more closely matches how the real ones worked. I'm never quite sure what SH4 is doing with the data I feed it, and if there's a way to check what SH4 is generating against reality (without map contact updates, that is), I haven't yet found it. That's why I play SH4 with automatic targeting. Marulken gives me all the relevant data up front and lets me decide how to use it - much more realistic and intuitive. I disagree however with your recommendations of what order to set the inputs in. Here's what I recommend: 1) Set the target speed to zero if it isn't already. 2) Enter a provisional target bearing, either from periscope or hydrophones. Optional: enter rough estimate of target range too. 3) Stop engines and begin timing the waterline passage. While waiting, make estimate of target AoB and enter that into TDC. 4) Enter target speed into TDC. There will now be no lag between subsequent range/bearing data entry and tracking. Lag causes misses astern. 5) Take new, precise measurements of target bearing & range; enter these into TDC. For this an assistant is helpful, otherwise point periscope slightly ahead of target to compensate for data entry lag. At this point TDC is faithfully tracking your estimated data. The most likely source of error is now in the AoB, which is notoriously difficult to estimate visually. Begin manoeuvring for favourable attack position. 6) After a short time (say 30 seconds), take new, precise range and bearing measurements. Check these against the TDC's generated range and bearing, remembering to correct for lag if playing solo. If they don't match, correct them and then also adjust the AoB. Repeat at regular intervals until attack is made or abandoned. 7) When in attack position (ideally, target crossing your bow beam-on at 1000m range) and TDC generation checks properly, fire a torpedo. One is enough to sink a destroyer, and there is no provision for firing a divergent spread to compensate for aiming errors.