ronbrewer
05-01-07, 03:50 PM
Hello everyone,
I've been playing SH3 on manual targeting ever since it came out in 2005 and have had my share of learning all kinds of manual targeting methods. Like a lot of you I started out with the 3:15 procedure and eventually started doing the collision course method using slide rules and whiz wheels that was posted about a year ago. However, in the last couple of months I've been doing manual navigation along with manual targeting and found out just how difficult it can be to get a good torpedo solution when you no longer have that GPS type of accuracy on the map that shows exactly where your sub is located. Reading through the different posts about the common behavior of Uboat approaches to a target I found the following themes:
1) The Uboat would do an end around using just the smoke on the horizon and then close in on a rough estimate of a collision course.
2) The Uboat goes to periscope depth as soon as the target's smoke stacks are seen since waiting any longer gives the enemy the opportunity to spot you from the bridge when it becomes visible on the horizon.
3) The sub was always in motion and never did the hummingbird affect that could make it pop up on the surface and spoil the stealth.
4) The hydrophone was used a lot more than the periscope to get into a good position to have the target's AOB 90 cross your bow.
It's at this point that different methods were used to determine the target's speed and true course (which is what I've read was entered into the German TDC instead of AOB). One procedure that I have found good success with is the right triangle method where the Uboat would use tables of numbers to determine speed based on a particular range covered.
Using the right triangle method means as you close in on the target you position your sub so that when the target reaches AOB 90 you have the target's bearing at 20 degrees (or 340 degrees if starboard of the target). You only have to take one range measurement at that moment in time and then start the stopwatch. The tables of numbers will have everything else for you once you get the time it takes for the target to reach a bearing of zero (cross in front of your bow). It also doesn't matter that your sub is moving during this time since you are basically traveling down the hypotenuse of the right triangle and it won't affect the time of the target to make it to a zero bearing. However, you do want to be going slow (around 2 to 4 knots) so that you remain hidden and so that you don't beat the target to the crossing point! Once you look up the speed on the tables you have everything you need for a firing solution. The target will be at AOB 110 when it crosses your bow and the range you took at AOB 90 is still good enough for an estimated torpedo impact time since your sub is moving down the hypotenuse. You can enter an AOB 110 on the TDC well before you start this procedure since you will position your sub to make it accurate. Below is a drawing of the sub and target's position and path of travel.
http://img164.imageshack.us/img164/407/rightangleattackep4.th.jpg (http://img164.imageshack.us/my.php?image=rightangleattackep4.jpg)
The steps for an attack are as follows:
1) Set up the TDC for AOB 110 (port or starboard depending on attack position).
2) As the target approaches AOB 90 get your sub in position to have it at bearing 20 degrees (340 degrees for starboard attack) when it actually reaches AOB 90.
3) Start the stopwatch and take a good range measurement. Lower the periscope since the 20 degree run may take a while.
4) Flip to the right table that is the closest match to your range measurement.
5) Enter the range into the TDC while waiting and use the hydrophone to see when the target is close to zero bearing.
6) Raise the periscope and stop the stopwatch when the target crosses your bow.
7) Find the closest match on the table for the seconds shown on the stopwatch and enter it onto the TDC. Open the tube doors.
8) Go back to periscope and swing it to the target that has passed your bow as you entered the speed.
9) Wait a second or two for the auto TDC to adjust to the new periscope bearing (not modeled in the game but was done in real life) and launch the torpedo!
For an example of the numbers used in one of my attacks:
1) Attack on the target's port side and had a range of 1172 meters at bearing 20 when target reached AOB 90.
2) Rotated the range dial to a little less than 1200 on the TDC.
3) Used the table for 1200 meters to calculate speed. The table shows the target will travel just under 436.76 meters since that equals tan20 * 1200.
4) Stopwatch displayed a little above 112 seconds so I chose a speed of 7.5 knots for the target (table had 7.51 knots for 114 seconds and 7.78 knots for 110 seconds).
5) Moved the periscope to about 354 degrees and fired the torpedo at the middle of the target (auto TDC adjusted to AOB 116).
I have the spreadsheet for ranges of 1000 meters up to 2900 meters. The formulas used are tan20 * AOB 90 range to get the distance the target will cover on short leg of the right triangle. And then distance covered / seconds * 1.96 to convert to knots. If anyone is able to host the file for downloads let me know and I'll pass it along. Below is a snapshot of the tables for 1000 meters to 1300 meters (may need to save it as a jpg to get the original size):
http://img509.imageshack.us/img509/6669/targetspeedyy9.th.jpg (http://img509.imageshack.us/my.php?image=targetspeedyy9.jpg)
Like I said in the beginning, there are a number of manual targeting methods available and I've found that this procedure works fine now that I do manual navigation as well. Below is a list of pros/cons for this method:
Pros: Sub can always be on the move to maintain depth, no calculators or slide rules needed, AOB and range entered at leisure, not tied to game map.
Cons: Need accurate AOB 90 identification (one of the easier AOB's to identify since the bridge is square), need accurate range calculation, for fast moving targets you may need to do an end around after determining speed if you delay looking through the tables and entering speed on the TDC after the target reaches a zero bearing.
By the way, if you have to do an end around then to get the target's true course just subtract 70 degrees from your sub's true course (or add 70 degrees if you are starboard of the target). Since you have the speed and true course you can just come straight in for an AOB 90 attack after the end around, provided the target hasn't changed course and/or speed.
Hope this procedure helps some of you out. At some point in the near future I want to offer another spreadsheet I have that provides lead angles for torpedoes in case any of you want to simulate a defective TDC after depth charges or just to see how the WWI sub captains had to use the law of sine's to point their sub ahead of the target since gyro angles hadn't been designed yet.
Thanks,
Ron
I've been playing SH3 on manual targeting ever since it came out in 2005 and have had my share of learning all kinds of manual targeting methods. Like a lot of you I started out with the 3:15 procedure and eventually started doing the collision course method using slide rules and whiz wheels that was posted about a year ago. However, in the last couple of months I've been doing manual navigation along with manual targeting and found out just how difficult it can be to get a good torpedo solution when you no longer have that GPS type of accuracy on the map that shows exactly where your sub is located. Reading through the different posts about the common behavior of Uboat approaches to a target I found the following themes:
1) The Uboat would do an end around using just the smoke on the horizon and then close in on a rough estimate of a collision course.
2) The Uboat goes to periscope depth as soon as the target's smoke stacks are seen since waiting any longer gives the enemy the opportunity to spot you from the bridge when it becomes visible on the horizon.
3) The sub was always in motion and never did the hummingbird affect that could make it pop up on the surface and spoil the stealth.
4) The hydrophone was used a lot more than the periscope to get into a good position to have the target's AOB 90 cross your bow.
It's at this point that different methods were used to determine the target's speed and true course (which is what I've read was entered into the German TDC instead of AOB). One procedure that I have found good success with is the right triangle method where the Uboat would use tables of numbers to determine speed based on a particular range covered.
Using the right triangle method means as you close in on the target you position your sub so that when the target reaches AOB 90 you have the target's bearing at 20 degrees (or 340 degrees if starboard of the target). You only have to take one range measurement at that moment in time and then start the stopwatch. The tables of numbers will have everything else for you once you get the time it takes for the target to reach a bearing of zero (cross in front of your bow). It also doesn't matter that your sub is moving during this time since you are basically traveling down the hypotenuse of the right triangle and it won't affect the time of the target to make it to a zero bearing. However, you do want to be going slow (around 2 to 4 knots) so that you remain hidden and so that you don't beat the target to the crossing point! Once you look up the speed on the tables you have everything you need for a firing solution. The target will be at AOB 110 when it crosses your bow and the range you took at AOB 90 is still good enough for an estimated torpedo impact time since your sub is moving down the hypotenuse. You can enter an AOB 110 on the TDC well before you start this procedure since you will position your sub to make it accurate. Below is a drawing of the sub and target's position and path of travel.
http://img164.imageshack.us/img164/407/rightangleattackep4.th.jpg (http://img164.imageshack.us/my.php?image=rightangleattackep4.jpg)
The steps for an attack are as follows:
1) Set up the TDC for AOB 110 (port or starboard depending on attack position).
2) As the target approaches AOB 90 get your sub in position to have it at bearing 20 degrees (340 degrees for starboard attack) when it actually reaches AOB 90.
3) Start the stopwatch and take a good range measurement. Lower the periscope since the 20 degree run may take a while.
4) Flip to the right table that is the closest match to your range measurement.
5) Enter the range into the TDC while waiting and use the hydrophone to see when the target is close to zero bearing.
6) Raise the periscope and stop the stopwatch when the target crosses your bow.
7) Find the closest match on the table for the seconds shown on the stopwatch and enter it onto the TDC. Open the tube doors.
8) Go back to periscope and swing it to the target that has passed your bow as you entered the speed.
9) Wait a second or two for the auto TDC to adjust to the new periscope bearing (not modeled in the game but was done in real life) and launch the torpedo!
For an example of the numbers used in one of my attacks:
1) Attack on the target's port side and had a range of 1172 meters at bearing 20 when target reached AOB 90.
2) Rotated the range dial to a little less than 1200 on the TDC.
3) Used the table for 1200 meters to calculate speed. The table shows the target will travel just under 436.76 meters since that equals tan20 * 1200.
4) Stopwatch displayed a little above 112 seconds so I chose a speed of 7.5 knots for the target (table had 7.51 knots for 114 seconds and 7.78 knots for 110 seconds).
5) Moved the periscope to about 354 degrees and fired the torpedo at the middle of the target (auto TDC adjusted to AOB 116).
I have the spreadsheet for ranges of 1000 meters up to 2900 meters. The formulas used are tan20 * AOB 90 range to get the distance the target will cover on short leg of the right triangle. And then distance covered / seconds * 1.96 to convert to knots. If anyone is able to host the file for downloads let me know and I'll pass it along. Below is a snapshot of the tables for 1000 meters to 1300 meters (may need to save it as a jpg to get the original size):
http://img509.imageshack.us/img509/6669/targetspeedyy9.th.jpg (http://img509.imageshack.us/my.php?image=targetspeedyy9.jpg)
Like I said in the beginning, there are a number of manual targeting methods available and I've found that this procedure works fine now that I do manual navigation as well. Below is a list of pros/cons for this method:
Pros: Sub can always be on the move to maintain depth, no calculators or slide rules needed, AOB and range entered at leisure, not tied to game map.
Cons: Need accurate AOB 90 identification (one of the easier AOB's to identify since the bridge is square), need accurate range calculation, for fast moving targets you may need to do an end around after determining speed if you delay looking through the tables and entering speed on the TDC after the target reaches a zero bearing.
By the way, if you have to do an end around then to get the target's true course just subtract 70 degrees from your sub's true course (or add 70 degrees if you are starboard of the target). Since you have the speed and true course you can just come straight in for an AOB 90 attack after the end around, provided the target hasn't changed course and/or speed.
Hope this procedure helps some of you out. At some point in the near future I want to offer another spreadsheet I have that provides lead angles for torpedoes in case any of you want to simulate a defective TDC after depth charges or just to see how the WWI sub captains had to use the law of sine's to point their sub ahead of the target since gyro angles hadn't been designed yet.
Thanks,
Ron