[REL] 3D TDC and Radar Range Unit

[razark]

Originally Posted by Nisgeis

Feedback = updates, you quiet lot .

Sorry, I don't have a lot of feedback yet. I've really only started getting into this. A few minutes here and there.

Now, if you'll take the wife and kids, and square it with the boss, I'll give you a nice solid week of testing...


So far, I'm trying to get the procedure down. Not sure I've got it, though. The radar bearings I get are about seven degrees off of a visual bearing through the scope. The range I seem to be getting down alright, though.

[Nisgeis]

Originally Posted by razark

The radar bearings I get are about seven degrees off of a visual bearing through the scope. The range I seem to be getting down alright, though.

If you can, use optical bearing and radar range.

Repeat the chant:

Optical bearing and radar range
The best combination will never change
Optical bearing and radar range
Then your plot shall never be strange.

If you must use radar bearing, you MUST use the trailing edge of the radar lobe, e.g. when you have swept over the target clockwise, when you go counter clockwise to pick the target back up after you have swept over it, as soon as you have picked up the target then that's the bearing. Due to faults in the sensors in SH4, the radar will pick up a target at relative bearing of 000 (due north) from 353 to 000.

If you can see the target though, use optical bearings over radar bearings because they are much, much better!

[razark]

Originally Posted by Nisgeis

Optical bearing and radar range
The best combination will never change
Optical bearing and radar range
Then your plot shall never be strange.

Taping that to the side of the computer.

I was using the radar bearing to try and get a handle on it for plotting long range contacts. I started beyond visual range, and once I moved closer, I took a peek through the scope to verify. I've turned map contacts back on.

Originally Posted by Nisgeis

If you must use radar bearing, you MUST use the trailing edge of the radar lobe, e.g. when you have swept over the target clockwise, when you go counter clockwise to pick the target back up after you have swept over it, as soon as you have picked up the target then that's the bearing.

That's what I was trying to do. Perhaps I was doing it wrong. I'm going to check my procedures and try again.

Originally Posted by Nisgeis

Due to faults in the sensors in SH4, the radar will pick up a target at relative bearing of 000 (due north) from 353 to 000.

000 - 353 = 7
Like I said, my bearings have been 7 degrees off. To port. Rather consistently. If had a target at 000, I'd get a bearing of 353.
(I'm thinking operator error. I'll go yell at the guy operating my radar. It seems he needs a bit more training.)

Originally Posted by Nisgeis

If you can see the target though, use optical bearings over radar bearings because they are much, much better!

That makes a lot of sense.

[I'm goin' down]

First some observations.

I keep forgetting that after using the Speed Dial to calculate target course and speed one is required to reset the stadimeter to the Range Dial before taking a new range and bearing reading. Thus, when I go to the PPI radar screen and pursue the process of taking another range and bearing, it is a waste roughly 50 percent of the time.

I gave up on manually computing speed and course. They do not correlate to the TDC solution closely enough right now, and the variance causes confusion. Also, sometimes I forget to plot for a minute or two. There are too many steps to keep straight.

I haven't tracked a ship with map contacts on, but I will have to start doing it. The ship I have been chasing in game replays is in the middle of a rain storm, so I do not know if I could see the map contacts anyway.

Because of the time lag between determining range and bearing and plotting that data, I take an approximate distance my boat has travelled and mark the area behind my boat with an "X". At ten kts., I assume my boat has traveled 400 yds. (I used the nomograph on the Nav Map to make an "educated" guess. I mark the spot with the "X" and plot from that point per the tutorial by John Channing.

Here are my recent readings. Note, I could not see the target because of a rain storm.

Bearing Range TDC solution
343 degrees | 7240 yds. | ---
294 degrees | 8430 yds. | 14 kts @ 163 degrees
18 degrees | 9856 yds. | 15 kts @ 151
12 degrees | 9570 yds. | 14 kts @ 154
15 degrees | 9780 yds. | 11 kts @ 186

[I'm goin' down]

Can your mod be mdified so that our overworked captains are not required to the Range Dial before taking range and bearing readings intended for transmission to TDC? For example, if a captain like IGD, one of our better officers on the line, takes readings, why can't they be stored until he opens the Range Dial on the stadimeter. That way, if the stadimeter has been set to its default position, i.e. the Aob Dial, IGD could open the Range Dial, send the readings to the TDC and not lose the readings he had taken before he realized his second in command had tinkered with the stadimeter and returned it to its default position.

James Forrestal
Secretary of the Navy
7 July 1944

[I'm goin' down]

I tracked a merchant with map contacts on using the mod. I think most plots followed it course pretty closely. However, speed was another matter.

Here are the major problems, which I consider practical ones. They may be its undoing insofar as I am concerned, but I am keeping an open mind.

1. The Stopwatch-Every time you change screens, which is often, it has to be brought up if you want to see it. It is a pain in the ass if you want to manually calculate speed when you have taken multiple readings. If the default for the Stopwatch were set so it is on the screen by default unless you clicked to hide it, there would be far fewer procedural steps. (The only reasonable alternative I could come up with is to purchase a stop watch, which I will not do.) As it is now, there are already a ton of steps. Frankly, the way it is set up, if you write down the range and bearing for ten plots, you would have to bring up the stopwatch to the screen and stop it ten times to check the time for each plot beginning with the second one, and restart it another nine times to measuring the time for the next plot. That is a total of 19, count em - 19, procedural steps. If you you use the TDC to compute speed, and do it every other range reading, bringing up the Speed dial is an additional 5 steps.(I am absorbing the arduous task of plotting on the Nav Map as and in addition to the math involved to determine speed, which, while extremely time consuming, is central to working with map contacts off). Also, I used ten range and bearing readings because I gave up calculating speed manually. Even if the average number of plots is five, not ten, and the solution using the speed dial is also used, that is 9 additional steps. I decided to have the TDC perform that task in my situation. I had intended to verify the plotted course by comparing it to the TDC course solution, but quit when the TDC speed readings indicated 64 kts. and 84 kts. on two of the plots for the merchant I was chasing. Then, after my last measurement of range to target (4545 yds.), the merchant must have seen me, as it appeared to change course. At that point I had had enough.

2. I keep forgetting to switch from the Speed dial to the Range dial on the stadimeter after I tap the watch on the stadimeter. Thus, when I am ready to go to the PPI scope to begin the process of getting the next bearing and range, the process breaks down as I cannot send the readings to the TDC because the stadimeter has been opened to the Speed dial. So, I have to switch to the Range Dial and begin again. This is a major pain, and if it can be eliminated, it should be.

3. Finally, between the time you take each range and bearing, and send it to the TDC, the target is moving. How far it moves depends on whether you dawdle between taking the bearing and range and send it to the TDC. To minimize ship movement so the plot will be precise, I take a range and bearing reading, pause the game, put a mark a couple of hundred yards behind the boat, resume the game, and send the range and bearing to the TDC. Sadly, I am making an educated guess at the distance the boat has travelled in the interim, as it could be going more than a couple a couple of hundred yards, or less, depending on how fast my boat is going. Also, if wait to mark the Nav Map until after returning to the periscope screen and swiveling the periscope or TBT to the correct bearing, the target travels further still. So, where do you put the mark on the Nav Map to measure range? And when do you do it?

The mod is a technical masterpiece. How practical it is may be another matter entirely. It may be that a written procedural check list is required. If it turns out that becomes a procedural hell, I for one, will leave it to others to master.

[John Channing]

For 1) and 3): Once you start the watch it keeps running regardless of what screen you are in. Just hit the "X" key to make it appear. But I think you might be over using the watch for some reason.

To get a speed estimate just get a range/bearing at the radar station and head quickly to the plot. Put an "X" when your boat is. Then, on a piece of paper, write down the range an bearing. Afer 3:00 mins get another range and bearing and put an "X on the map where your sub is and write down the range and bearing. Then you can take your time to plot the two measurements on the map, measure the distance between the two results, subtract the last digit and voila... speed estimate.

For 2) It's a game limitation. You just have to get diciplined about switching back to the Range setting every time you leave the Periscope/TBT.

JCC

[Nisgeis]

IGD, I can't tell anything for certain from your plot data as you were obviously manouvering at the time, so I can't see definitely what was wrong. From the last three plots looks like your bearing might have been off.

Don't stop and start the stopwatch, keep it running as it's much more accurate that way. Assuming the target is on a straight course, after 30 minutes you can measure the distance travelled from the start plot and divide that by 100, which will give you a much more accurate speed.

Also, you're probably trying to do too much at once. You don't have to do everything at each step. You don't have to get a course and speed estimate each time (note that this is independant of starting and stopping the stopwatch and gets its time from the when you actually sent the data, nothing else). If you aren't getting an estimate every time, then you don't have to worry about sending it to the TDC. So, you just have to plot it.

As JCC says, take your range measurement and bearing then put an x on the back of the sub, if that's how you want to plot. From that point on, you don't have to plot it quickly and you can even pause the game. It also makes it much easier to plot if you stop completely, as you don't have to move all the tool around for each plot, but you may miss fast targets if you do that.

[I'm goin' down]

If I plot an "x" and continue playing, when I return to draw the range and bearing with the protractor tool, my boat has sailed off into the future. According to Mr. Channing's delightful tutorial, you draw two angles with the protractor. The first is from the "x" through the boat at 0 degrees. The second is from the "x" through the bearing reading. You are instructing me to draw the first angle (0 degrees) but the boat is not there to plot it correctly. What is the solution to this problem?

Divide by 100? Using the 3 minute rule, you would divide the distance travelled by 30 minuties to get kts. per minute. If the target travels 10,000 yds. in 30 minutes, its speed is 333.33 kts per minute. Under the three minute rule the speed is 10 kts. per minute. Why are you dividing by 100?

[razark]

Originally Posted by I'm goin' down

Divide by 100? Using the 3 minute rule, you would divide the distance travelled by 30 minuties to get kts. per minute. If the target travels 10,000 yds. in 30 minutes, its speed is 333.33 kts per minute. Under the three minute rule the speed is 10 kts. per minute. Why are you dividing by 100?

10,000 yards in 30 minutes is 9.87 knots. 10,000 divided by 100 equals 100. It should be "divide by 1,000".
10,000/1,000 = 10 (knots)

[Nisgeis]

Ah, yes, you spotted my deliberate mistake - you know, just to test you were all awake. Well done for spotting it! Ahem!

[I'm goin' down]

Originally Posted by Nisgeis

Ah, yes, you spotted my deliberate mistake - you know, just to test you were all awake. Well done for spotting it! Ahem!

lmao. (We knew you had a weakness, as it obvious from the mod. I am surprised you have sunk anything, and you might want to rely on the TDC or razark for speed calcs.!)

high 5 to razark. (Nisgeis thinks no one reads his posts.)

As for a reading goes, how about anwering the question posed above, which is,
" If I plot an "x" and continue playing, when I return to draw the range and bearing with the protractor tool, my boat has sailed off into the future. According to Mr. Channing's delightful tutorial, you draw two angles with the protractor. The first is from the "x" through the boat at 0 degrees. The second is from the "x" through the bearing reading. You are instructing me to draw the first angle (0 degrees) but the boat is not there to plot it correctly. What is the solution to this problem?"

[I'm goin' down]

Originally Posted by razark

10,000 yards in 30 minutes is 9.87 knots. 10,000 divided by 100 equals 100. It should be "divide by 1,000".
10,000/1,000 = 10 (knots)

I do not want to go off thread for too long, but: 10,000 yds travelled in 30 minutes means you are traveling at the brisk pace of 16.66666 yds. per second (10,000 [yds] \ 600 [10 (minutes) x 60 (seconds per minute)]). If the target travels for one minute (i.e. 60 seconds), it is galavanting along at the rate of 999.96 yds. per minute (16.66666 [yds. per second] x 60 [seconds].)

[razark]

Originally Posted by I'm goin' down

As for a reading goes, how about anwering the question posed above, which is,
" If I plot an "x" and continue playing, when I return to draw the range and bearing with the protractor tool, my boat has sailed off into the future. According to Mr. Channing's delightful tutorial, you draw two angles with the protractor. The first is from the "x" through the boat at 0 degrees. The second is from the "x" through the bearing reading. You are instructing me to draw the first angle (0 degrees) but the boat is not there to plot it correctly. What is the solution to this problem?"

If your boat is traveling in a straight line, use the protractor to draw from your boat, to the "X", and then to whatever the bearing you measured was. Since the boat was at the "X", and is now somewhere else, the line from the "X" to your boat would be the heading it took to get there, so that leg of the angle lies along your 0 bearing.. This wouldn't hold true if you were turning, but turning during a radar reading would make it hard to get good data.

[razark]

Originally Posted by I'm goin' down

I do not want to go off thread for too long, but: 10,000 yds travelled in 30 minutes means you are traveling at the brisk pace of 16.66666 yds. per second (10,000 [yds] \ 600 [10 (minutes) x 60 (seconds per minute)]). If the target travels for one minute (i.e. 60 seconds), it is galavanting along at the rate of 999.96 yds. per minute (16.66666 [yds. per second] x 60 [seconds].)

10,000/(1800 [30 minutes * 60 seconds per minute]) = 5.5555... yards per second = 9.87 knots

But skip the yards per second stuff, and use a lot less math. Keep it easy to figure in the head. Go straight with the three minute rule. That's why it's there in the first place.

Three minute rule: In three minutes, distance traveled in yards = speed in knots * 100.

So, In 30 (three * ten) minutes, distance traveled in yards = speed in knots * 1,000 (100 * 10).