View Full Version : Learning TDC - A test

03-18-2005, 10:44 PM
Hey fellas,

This is my first sub sim game, but I'll be ****ed if I'm going to play with automatic targeting. Unfortunately I'm having a tough time figuring out the art of TDC targeting. I would like to perform a test with you guys, and see what results you come up with. And if you prove yourself better than me (not hard), perhaps you could give a few pointers.

Here is my problem. I'm approaching a C2 Cargo ship at about 1000 meters and 35-40stb AOB. This is where I have a save in game. At this point I start entering data into the TDC. (**By turning off manual targeting in the realism settings, and then restarting the mission at this save point, I know EXACTLY what the cargo ships course is**) The exact range is 1000 meters... and within 10 seconds of starting the savegame, it's closer to 900. So within TDC, I take a height measurement that gives me roughly a ~950 meter range. No problem. That measurement should be accurate. Next I take an AOB guess. Since I know the EXACT AOB is 35-40, I just "cheat" and put that in right away.

Now comes the tricky part that screws me up. To collect speed I start the stopwatch and let it run for 10-15 seconds. Everytime it gives me a speed of 3kts or 4kts. Now, I KNOW the speed the cargo ship is traveling at is 6kts. So, even though my range measure is pretty **** accurate... and I know my AOB is dead on... it always underestimates my speed measurement. As such, my torpedos are always behind... sometimes by a full boat length.

Here is a picture of my data right before launching:

I'm going to post my savegame for anyone to download and compare results. Immediately after the game loads, hit F3 (attack periscope) and target the C2 Cargo ship right in front of you. Within 10 seconds you should have range and AOB entered. Add another 10-15 seconds for speed calculation, and then fire. That's what I've been doing... and it's not working for me. The savegame is called 'TDC Test'.

Here is the savegame file(s):

Here is where the files go on your computer:
C:\Documents and Settings\*****\My Documents\SH3\data\cfg\SingleMissions

I guess my main question is why the TDC computation is giving me such a low speed calculation... even though when I know my range and AOB are correct. Because of this, I'm always shooting behind the target.

Am I approaching this entirely wrong? Am I not suppose to wait until 1000 meters before collecting data? I notice the Gyroangle says the exact same reading as my periscope bearing. Is the gyroangle not supposed to be the calculated angle at which a torpedo shoots to intecept the moving target??? Is my TDC data not getting inputted?

Thanks for anyone that participates and shares their results with me.

03-18-2005, 10:51 PM
did you update your bearing before firing?....hit the "V" key again.....or double check the TDC screen and enter it yourself.

The only other thing I could think of having taken Naval Navigation basics...is that you are entering a relative speed and not actual speed...dont know exactly how the game compensates for this but AOB has something to do with it.....I would say you are not updating your bearing to target...

03-18-2005, 11:13 PM
I assume by "V" key you mean the checkbox on the data pad (right below Speed). I do that, and I see that it does indeed update the gyroangle. Now my gyroangle says about +4 degrees than my periscope bearing. This makes sense, as the torpedos would need to shoot ahead of the ship...

But the result is still the same:

AGGGH! Frustrating.

The root of the problem is my slow speed calculation. Those torpedos still think they're shooting at a 3kts ship. http://forums.ubi.com/images/smilies/16x16_smiley-sad.gif

03-18-2005, 11:43 PM
i may not be the right person to help you since i do not yet have this game and have never played a sub sim before, but i do know that the longer you time the ships movement with your stopwatch the more accurate the speed estimate. and i think i read somewhere else in this forum that a good amount of time to run the stopwatch is 30-40 seconds. if that seems too long to wait just remember that speed of the enemy vessel is not something that is going to change in the course of stalking it, so you don't have to wait till just before you fire the torps to estimate the speed. you can do that when the ship is still out of range. and then when you are ready to fire the torps all you will need to update is range and AOB.

03-19-2005, 01:27 AM
I think the speed measurement is computed based on RANGE and CHANGE IN BERING during the alloted TIME.

Thus if the target sweeps X degrees at Y distance, assuming a straight course, then it says that's about some distance D in time T. D/T = Speed.

Since your range is right and you time has to be accurate.. then it's the swept degrees that's innacurate. Make sure that you are facing the exact same part of the ship when beginning and ending the stop watch (you can spin it like mad in between probably). A nice way to do this is to use the lock view function.

Mon Pavion
03-19-2005, 02:37 AM
I have found I have the SAME problem with the speed determination. I know the range is right, and the AoB, but the speed is ALWAYS underestimated. Once i get a speed from the computer, as a rule of thumb I punch it up a bit knowing that it is to slow. The result is usually a direct hit. If I use the speed the comp gives me, my torps always pass behind.

03-19-2005, 07:26 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by TheGeneral_D:
I have found I have the SAME problem with the speed determination..... Once i get a speed from the computer, as a rule of thumb I punch it up a bit knowing that it is to slow. The result is usually a direct hit. <HR></BLOCKQUOTE>

Yeah.... I noticed the same thing. Using my 'normal' TDC inputs, right before firing I bump up the speed estimation to 7kts. Sure as sh*t, the torpedos score hits 90% of the time.

But I'd still like to be able to take accurate readings on my own for when I start up my campaign. The only reason I know the ships speed is 6-7 kts is because I used automatic targeting to check. During my campaign that won't be an option. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

There was some good information posted already. I think I'm going to try a totally different apporach and see if I get better results. Gathering all the data at 1000 meters and under 10 seconds doesn't seem to be working.

Thanks for the input thus far.

03-19-2005, 08:07 AM
I would set your torpedos for "medium" or "fast" speed. I bet thats all you need to do, cause the torpedos are travelling too slow in relation to the ship target, hence their always late on arrival.

03-19-2005, 08:21 AM
I can't help but wonder if the targets bearing has an impact on the measurement. If the target was moving directly perpendicular to your point of view, it would be a simple math problem to take the angle between two sightings and figure the third leg to get the distance covered in a measured time. But if the target isn't moving directly across, that means the range will change between the two sightings, and the angle covered will be different. Since you are dealing with a roughly 37 degree AOB, perhaps the game calculation isn't taking that angle difference into account when figuring the speed. It might be more accurate if you were taking the sightings from a 90 degree AOB.

03-19-2005, 02:45 PM
I would be concerned if the speed calculations were 20% out. What if your targets a ship doing 15 or 20 Kts, is it going to give you a reading of 12.5 Kts and 15 Kts. Why not try making a single player scenario with 3 ships doing a certain speed (10,15,20 Kts which you write down. And see what speed u come up with when you play.
I might be less accurate at slower speed! After all 1 knot out at 6 knots is a big error in my book. But if I were 1 or 2 knots out when the target is doing say 18 knots would be more acceptable in my book, but still not good.