RR, you are correct that the ability to set long ranges on the TDC is not an issue for firing (I would rarely waste a fish at more than 1000 yards). However, that is not what I'm trying to do, so this limitation is a problem for me and I think it's unrealistic that we're unable to directly enter a target range into the TDC (like I can in SH1, SH2, and SH3).

I am wanting to use the position keeper to track the target from long range. Say for example, I could put in a range of 8000 yards plus the AOB and speed. I could enter that data into the TDC and turn on the PK. Then I could go deep and quiet until the escorts have passed, and know when the best time would be to return to periscope depth to finalize my solution before firing.

Anyway, thanks to all of you for your comments. You answered my question -

That's what I figured, but I was hoping I had overlooked something.

Another thing maybe the patch will fix
 

Another thing tht would be really good would be direct input from radar to TDC, just like you can from sonar.

For those who don't get what he's wanting to do, he's either read Dick O'Kane or channeling him (play the spooky music). When you're jetting from position to position with the scope down on an approach, when you slow down and raise the scope your first question is "did he zig?" If you can enter the parameters into the TDC and turn the PK on, the TDC predicts exactly where he is supposed to be (given no changes in course and speed) when you poke the scope up. You can set bearing even before the scope breaks the surface to minimize exposure. Then if he isn't where predicted, he's zigged! Since the stadimeter is lousy for distant measurements, the manual range input is really helpful here. Did I get it right?

Bingo! :yep: (except for the channeling part - :huh: )

I was being sarcastic, sorry I didn't make that clear, but the comments following were still interesting. Now I need to figure out (that is, really understand) why this is true. Because without pondering it, it seems counterintuitive.

Now, I've been using the O'Kane method. So in my best attacks I've pointed the ship at the target's track, and I've set the periscope at 0 degrees. I enter a range (with any requisite fiddling needed) to the target's projected track in front of me (along the 0-degree path). I enter the AOB at that point, too, which has been about 90-degrees (port or starboard). I enter the speed. It seems to have worked so far, so if I increase the range it seems that my gyro angle would end up being larger, to make up the extra distance?

In other words, it seems that I need to get the range right. At least for the way I'm doing it. I get a couple of checks on the target's path to ensure my range will be good. Am I doing the O'Kane method, or am I doing some Jazman method? I shoot fish as the juicy parts of the ship cross the periscope crosshairs.

A nice variation would seem to be to run parallel to the ship, and point the periscope at 90-degrees (or 270, depending on direction) so I can bring rear fish to bear, good for convoy attacking. Is this right?

Rockin Robbins has explained this to me quite satisfactorily. It has to be a right triangle in the targeting solution. When I work out the equation to figure out a gyro angle, I notice that it has nothing to do with range, but only the speed of the target, the speed of the torpedo, and the gyro angle, and the time to travel (which cancels out).

( X seconds ) x ( TorpSpeed yds/sec ) x ( sin(GyroAngle) ) = ( X seconds ) x ( ShipSpeed yds/sec)

Where X is the time to travel to hit. Range doesn't appear in the equation! (A diagram would help.)

sin(GyroAngle) = TorpSpeed / ShipSpeed

And with my calculator, it's easy to find GyroAngle.

So from my misses on my missions, I may not have been mis-estimating the range, but the angle on bow. (and / or the speed.) I was being a bit sloppy with the AOB, just eyeballing it.

For a non-right triangle, I can see the range is in there, and can't get cancelled out. (I'm looking at the laws of sines and cosines, is that right?) I see why I need a TDC to figure out the Gyro angle for me...