tdc questions

[andqui]

It's July 1945, and there aren't many targets at sea, so I crept up along the chinese coast at night. When I turned into one fjord/sound/inlet, I saw a row of five parked merchants, sitting ducks. I opened all forward tubes, set the target speed to 0 on the TDC.

I then proceeded to place the TBT exactly where I wanted it to hit, and then hit the red flag at the top of the range entry, sending new bearing info to the tdc, and fired each torpedo. For some reason, the gyro angle generated did not match the bearing of the target I selected. I mean, if the speed is set to 0, doesn't that essentially turn the TDC into a point-and-shoot operation? Why would the gyro angle have any difference from the bearing of the target.

Anyway, all the torpedoes tracked 3 degrees left of what they were supposed to, and only one hit. I did get to see geysers of sand being blown up from the beach, and then torrents of starshells and AA fire. That was pretty cool.

but why on earth did the torpedoes go left? Speed was set to 0, AOB was left at the default, and I just used the range entry to update the TDC bearings. Does it have something to do with currents?

thanks

[Rockin Robbins]

Nope. What kind of range was in the TDC? If there is no range in there its behavior is going to take you by surprise. I always make sure I have at least a 1300 to 1700 yard range in there. This will ensure that you hit most anything with a gyro angle of less than 30º that is less than 3000 yards away.

Gyro angles are always different from any non-zero bearing because of the distance between the periscope and the end of the torpedo's reach causes a parallax angle. This parallax angle is determined by the range value in the TDC. If zero is there then crazy things happen that you won't like.

[Munchausen]

Attacking sitting ducks at anchor is the best place to use your stadimeter. But there are a couple tricks ... one, being you should always double click (or double-insert) data being sent to the TDC ... then check the arrows on the TDC dials to make certain they're pointing where you expect them to be pointed.

First, make sure you have the proper torpedo tube selected.

Then, set speed to zero ... double click to send (and re-send) data. Set AOB (it never hurts to do this ... even if it really makes no difference for a stationary target) ... double click to send. ID the target, set mast height, take a stadimeter fix ... and send the data (range and bearing) to the TDC.

Check the geometry, as depicted on the TDC dials. If all looks good, then open the torpedo tube (manually) and shoot. Else ... don't shoot. Instead, take another fix.