Oh no, not another manual targeting procedure!!!

[Heibges]

Originally Posted by jmr

Heibges, would you mind sharing your MILS chart?

I had a complete chart but lost it. I was in the process of making a new one when I got really busy at work and stopped. Let me see if I can find it at home.

Basically what I did what make a single mission with a non-moving enemy ship. I got lined up at 90° angle, so I perfectly bisected the ship with my bow. TDC was automatic so I could see the exact range. I started at about 3000m away.

Using the scale on the UZO, I measured the length of the ship at a number of distances between 2400m and 400m.

After this I changed the enemy ship in the mission, and started over.

I'm not sure what the scale is on the UZO, but I called it MILS because I was familiar with that term. Each unit on the UZO is probably 5 or 10 mils.

Anyway, the chart looked something like this.

Ship..................1200m.........600m
C2 Merchant........6mils...........12mils
C3 Merchant........7mils............14mils

So if I measure the length of a C2 merchant, and it takes up 12 units in the UZO, I know the ship is 600m away.

[ronbrewer]

Originally Posted by Puster Bill
I might be a little confused (wouldn't be the first time), but what difference does it make to your torpedo solution if you don't know exactly where you are? After all, for all intents and purposes when you are attacking the assumption is that your boat is the 'center of the Universe'. All target data is in relation to your boat, ie., range, bearing, AOB. Only target speed is independent of your position, but that is a scalar, not a vector.

So I'm not following why manual navigation would make targeting harder. It seems it would certainly make interception harder, but your procedure assumes the target has been spotted.

Sorry about that. What I meant by manual navigation is that you use a transparent .tga file for your sub so it is invisible on the map. Some of the manual targeting procedures have you draw a couple of lines from the center of your sub to a specific range/bearing for a target ship. You can no longer do this under the manual navigation mod so I spent some time looking into a procedure that doesn't require the map and only needs one range snapshot. After reading about some of the geometry tables that were used by Uboat weapon officers (both WWI and WWII) I came across the right triangle procedure that has the sub slide down the hypotenuse during the speed calculation and doesn't require whiz wheels or slide rules for the last few seconds of the torpedo solution. Plus it allows you to manually turn the dials on the TDC in the conning tower (has always been one of my favorite parts of the sub simulation) without pausing the game and avoiding the notepad entries on the periscope screen that kind of take away part of the immersion for me.

Thanks,
Ron

[Canovaro]

Thank you for sharing, have to think about this a little.

[Maraz]

That's brilliant!

When do you exactly switch to auto TDC? After entering target speed?

It would be great having all the tables you made (have you tried filefront to upload the files?).

It would be interesting if you could share other methods and tables used historically.

Cheers
Maraz

[ronbrewer]

Originally Posted by Maraz
When do you exactly switch to auto TDC? After entering target speed?

That's right. Once I adjust the speed dial on the TDC I click the button to turn the light red so that it will start updating the gyro angles based on periscope movement. I also open the tube doors right after this since all torp settings are done.

I didn't mention it in the original posting but I also configure the torpedo pistol setting, running speed, and depth during the target's 20 degree run while the hydrophone guy whispers the updated target bearings. Makes the atmosphere in the conning tower a little tense.

One thing I haven't found good info on, historically speaking, is when the weapon officer would open the tube doors. I've been going on the assumption that they should not open until all TDC input data is complete. I also found out the game doesn't let you shut them if you go below 20 meters when evading DD's so I keep them shut until right before firing. Though it's not modeled in the game open tube doors should reduce the sub's depth ability.

Also, thanks for the heads up on the Filefront website. The following link is has the spreadsheet for right triangle attacks:

http://files.filefront.com//;7409015;;/

And this link has the spreadsheet that computes lead angles based on AOB and torpedo impact times (for defective TDC simulation or WWI style solutions):

http://files.filefront.com//;7409021;;/

Both are in Excel format and on the second one just enter in different AOB numbers to get updated lead angles. You'll find the same angles for AOB 80/100, 70/110, etc. I just printed out each table and stapled them together in a booklet format. Basically what you do in the game is set the TDC button to a green light so the periscope swings freely and the gyro angles stay at zero. You then have to position your sub to provide the lead angles for the torp based on the target's AOB. For example, if you get on a perpendicular course to the target you know that it will be at AOB 90 when it crosses your bow. Let's say the target is going 9 knots and you have the torp speed set to 40 knots. The spreadsheet shows a lead angle of 13 degrees needed for these speeds so you would turn the sub 13 degrees to the left (or right for a starboard attack) and then turn the periscope back to a 13 degree setting (or 347 degrees if starboard) and fire the torpedo when target's center reaches a bearing of 13 degrees (AOB 90). The torp will run staight ahead due to zero gyro angle and range really won't come into play. However, if you do a range check you can use the second tab of the spreadsheet to get an estimate of the torpedo impact time.

After doing this on a few patrols I really learned to appreciate that TDC!!

Thanks,
Ron

[ronbrewer]

Originally Posted by Puster Bill

By the way, Hitman is working on a whiz wheel/circular slide rule based on one that was actually used for targeting in U-boats during WWII. He's already made some good progress:
http://www.subsim.com/radioroom/showthread.php?t=113591

Yes, I saw that thread on Monday and I'm really looking forward to his work. He did a great job on the American version. When there is bad weather or poor visibility I think the slide rule method using a collision course is still the best way to intercept since it's tough to do a range snapshot and you have to get really close to verify AOB.

[MudMarine]

I understand that the S-Class Boats in the campaign does not have a TDC. Is this correct?

If this is correct those tables will be very useful.

[Puster Bill]

Originally Posted by ronbrewer

Sorry about that. What I meant by manual navigation is that you use a transparent .tga file for your sub so it is invisible on the map. Some of the manual targeting procedures have you draw a couple of lines from the center of your sub to a specific range/bearing for a target ship. You can no longer do this under the manual navigation mod so I spent some time looking into a procedure that doesn't require the map and only needs one range snapshot. After reading about some of the geometry tables that were used by Uboat weapon officers (both WWI and WWII) I came across the right triangle procedure that has the sub slide down the hypotenuse during the speed calculation and doesn't require whiz wheels or slide rules for the last few seconds of the torpedo solution. Plus it allows you to manually turn the dials on the TDC in the conning tower (has always been one of my favorite parts of the sub simulation) without pausing the game and avoiding the notepad entries on the periscope screen that kind of take away part of the immersion for me.

Thanks,
Ron

Ahhh, OK, that makes *MUCH* more sense now. I don't bother with the map view when in action, just for those long periods between contacts. Still, you could do a manual polar plot (like using a maneuvering board). I'm thinking about checking the bookstore where I work (a college) to see if they have some polar plot paper. That way I don't have to use an American maneuvering board to manually plot contacts.

By the way, Hitman is working on a whiz wheel/circular slide rule based on one that was actually used for targeting in U-boats during WWII. He's already made some good progress:
http://www.subsim.com/radioroom/showthread.php?t=113591