And, if you don't always attack on 45° (C°°L use of DOS* graphics), it's sometimes hard to set your periscope even to the nearest degree ... hard to tell 349° from 348°.

How many zoom levels do you have? Is your periscope modded for more that two?

Took me a minute. :rotfl:

EDIT

Just read the above post. Two comments:

1. You didn't include your heading or your target's heading. Without those, it's not possible to tell if you've measured AOB properly.

2. The order you enter data into the TDC is important. I can never remember what goes first ... which is why I always visualize the setup in my head. If, after sending data to the TDC, the result doesn't look right, I go back and enter it again. RR knows the correct order but I find that, as long as you don't move your periscope from computed lead angle (or make any other changes to the setup), you can correct the display by reentering all data a second time.

* Correction: I meant ASCII code (brain fart).

Manchusen
 

Let's not get hung up on the AOB, my course or the target's course. The problem appears to revolve around the TDC creation of gyro angle. If we are supposed to enter the target's speed in the stadimeter, apparently it will be transmitted to the TDC. If so, and I believe I have shown it to be the case, I have a problem with successfully using the Cromwell attack technique. If there is a specified order to enter the data to avoid the problems my tests verified, then that could to be the solution.

On the other hand,

Assume, I am at a 45 degree angle to the target's course. Assume that its speed is 10 kts. Assume that I set the AOB properly and pull the range lever all the way to the right. Assume that information is sent to the TDC. Further assume that I plot the lead angle correctly and point the periscope at correct angle and fire when the target intersects it. Why should I bother entering the target's speed in the stadimeter? All it does is give me a gyro angle and screw up the shot? Theoretically, shouldn't the attack succeed even though I have not entered the speed in the stadimeter? After all, we are not relying on the TDC to calculate the firing solution.

I suggest you set up my attack scenarios and watch the gyro angle.

For test no. 1, surface your boat, set your speed to 0 kts, enter 10 kts. for target speed, set the AOB at 37 degrees starboard and pull the range triangle all the way to the right. Keep the PK off. Check the gyro angle. It will be 350 degrees.

For test no. 2, change the target's speed to 11 kts. The gyro angle will be 349 degrees.

For test no. 3, point your periscope at 350 degree at 10 kts. and resend the range. The gyro angle will not change. The same result follows if you point it at 349 degrees at 11 kts.

Now set the target's speed at zero. The gyro angle reverts to 0 degrees.

As Nisgeis emphasized: yes, that's all you need.

Unless you've already used the TDC and, consequently, it's no longer set to fire a torpedo straight out the tube. Every time you start the game, the TDC is set for zero gyro angle. But, if you enter data that changes the orginal setup, you either need to input the correct data or otherwise set the TDC so it reflects zero gyro.

What speed for the torps?

Edit: After trying to set up the described attack ...

LOL, that was fun. I assume you wanted the AOB of the target at the time you fire the torpedo. I tried backing into it but only ended up with a whole lot of triangles ... too confusing to sort out.

It was easy drawing the setup with your 37° AOB at the time the torpedo hits ... I could then determine the target's course and extend that course line backward for 1000 yards (equalling 10 knots). Completing the geometry, I got a lead angle of about 6°. But it also gave me an AOB at shoot time of 30°. So I tried what navigators call the "slip and slide" method ... adjusting the extended course line so it reflected a 37° AOB. But then the line wasn't 1000 yards long anymore. So I extended the line along the newly drawn course line ... resulting in a new AOB.

If you decide to do any more tests, please provide the following data:

• Target speed.
• Torpedo speed.
• Target's course.
• Sub's course.

It will save what's left of my sanity.

manchusen/torpedo speed
 

I am not at the computer where my game is set up, but I have always set torpedoes on high speed, so I believe they are set at 46 kts. I understand that if I were using slower speed torpedoes, the lead angle would be differerent under the Cromwell attack technique. It does not affect the 45 degree angle of Cromwell attack technique.

I assume you are asking because you want to confirm the gyro angle of 10 degrees and 11 degrees that my TDC calculated in my tests and to set the appropriate AOB. But the target's speed on the Cromwell attack technique and the torpedoes speed only play a role in calculation of the lead angle, and the TDC is not used for that purpose . That is why I believe that speed of the target should not be entered in the stadimeter, as it can only cause gyro angle errors when the TDC assimilates the information.

More for Manchusen
 

[quote=Munchausen]There was no target! The sub was heading at 0 degrees. I assumed that this was at a 45 degree angle to the hypothetical target' course. (i.e. with the sub heading at 0 dgrees, we can assume that it is at 45 degree angle to course of the nonexistant target). That takes care of the issue of the Target's course and the sub's course. Target speed was assumed to be 10 kts in test no. 1, 11 kts in test no. 2 and 0.0 kts in test no. 4. Torpedo speed is 46 kts. I do not think anything else is required.

I think this is all that is need to analyze this. I will be interested in Rockin Robbins and Nisgeis take on all of this.

By the way I saw you post re my radio question. All I want for now is to get one station working the right channel. That is my goal for the weekend.

Quote:
Originally Posted by Urge
You can lay out a 45° attack plot on the map but when you zoom in all the way it may be off by a degree or even 2 that is not obvious at lower zoom levels.


Munchausen wrote...
I am referring to zooming in on the nav map. Sorry if that wasn't clear, it made perfect sense in my head but I guess it didn't translate well.

Urge

I have cleared the deck
 

I have cleared the deck and I am going to hunt ships and use the Cromwell attack technique, with the lead angle determined per Old Tex's chart re Cromwell Method of Torpedo Attack, and I WILL NOT INPUT THE TARGET'S SPEED IN THE STADIMETER. I will report back after the mission. Take her down.

My next assignment is the Radio Mod.

I think this is where you are going wrong. The AoB that you enter is the AoB of the ship currently. The 45 degree intersection means that at the point of impact the target's Aob will be 45 degrees to port or starboard. What I think you are doing is telling the TDC that the target already has a 45 degree AoB at the shooting bearing. This will make the TDC think that the target has a different course, which takes the target further away from you, so it tries to compensate by making the torpedo head a bit to the left or right to compensate.

To properly get the AoB, you need to calculate the angle between your line of sight to the ship. If you want to use the TDC to verify your shooting calculation, this means that you will need to enter the information as it will be when the target crosses the wire. That mean you need to measure the angle between your line of sight and the target's course on your drawing. That is the target's AoB at the time to shoot. You then put this info in, at the shooting bearing, with teh target's speed and it should give you a zero gyro angle shot.

If you are going to use the TDC in such a way though, it's no longer a simple drawing method and you are starting to use the TDC the way it is meant to be used, except with the PK on and then you are fully manual targetting. And then you can use spreads, which are a much better way to shoot torpedoes, spreading from aft to bow you'll get a whole lot more bang for your buck. You're only a step away :D. Keep going. I admire your perseverance!

That's a good tip, gives you a bit more accuracy.

Nisgeis has hit on half of it. The AoB is VERY important here. Use the rule: 45º minus the lead angle.

And the rule of thumb for a 10 knot target (or anything close to that). Out of the air, produce a 10º lead angle. For a target moving from right to left, your shoot bearing should be 10º then, not zero as you shot. I don't get excited about anything less than a 10º gyro angle, even at extreme range.

With this example, you would set the TDC for speed: 10 knots or whatever the target is going. Set AoB at 45-10=35º port. Now the torpedo will go up the approx zero degree bearing to hit the ship. You're shooting at 10º. When he gets to zero, there will be a surprise waiting for him. I hope he's happy with his Christmas present.:yep:

As Tim Tebow, you are throwing the ball not to where the receiver is, but where he will be when the ball arrives. Did I just lose three-quarters of the world or what?http://i196.photobucket.com/albums/a..._greenguys.gif

Hmm?
 

No news yet. I tried two attacks on task forces. I did not input the target's speed on the first attack, but I did input it on the second one. I will stick with the second alternative for now, as not entering the target's speed may have been a bad idea.

The first attack. I set up too late, so I decided to try a reverse Cromwell attack, firing at a carrier at a 45 degree angle as the task force was pulling away rather than closing. A destroyer got in the way and absorbed two of the four torpedoes, and the other two missed.

The second attack. Again I set up too late. Again, I set up for a reverse Cromwell attack as the task force pulled away. My sub was detected, rammed, and depth charged. I fired four torpedoes at a carrier at the requisite lead angle. I had previously set the speed and range, but I did reset the AOB. All four shots missed. I checked the Attack Map. While reseting the AOB to deal with the fact that that target was pulling away, the task force, including the target, had turned 60 - 70 degrees to port (away from my sub), and were almost parallel to my boat, presenting minimal target aspects. The shots missed, but not by much, which was a pleasant surprise. The course shift by the target likely accounted for the misses.

I have saved the second attack a point where I was closing for the shots, so I can replay the attack and see if I can avoid detection and get properly set up for the Cromwell attack or if necessary, for what I call the reverse Cromwell attack.

:hmm: Perpendicular? Wouldn't that present the maximum target aspect?

Perpendicular was a mistake which I corrected.
 

Darn, your mama taught you how to read.

I saw parallel in my head but I typed perpendicular. I just corrected the post. And next time I will try to sneak something past you....

First things first: Thanks for the method Nisgeis and thanks for the tutorial Rockin Robbins (hope I got the credentials right)

The most helpful to me in the tutorial was the part about the vector solution on the NavMap. It was helpful to the point of me forgetting about approaching at certain angles and just measuring the given situation as well as forgetting about any TDC Input. At best I identify the target for getting torpedoes running depths.
If this is just my method to avoid "driving like a drunken sailor" or if I'm just to drunk to drive at all, that's a different topic.;)

I'm thinking that it could be helpful to reference the explanation behind the vector solution and its demonstration in the stickied tutorial thread, since Dick O'Kane and John P. Cromwell are the two extreme cases of the same solution.
Having it covered here under 4 pages of questions and ty's might not be ideal.

Yes you did. Initially RR didn't want to include the vector analysis as part of the tutorial, but thankfully I managed to talk him round. If you're drawing the vector analysis, you're only a short step away from using the TDC for any situation that might come up.