Distance to track?

[Sniper297]

TDC shows bearing, range, angle on the bow, target speed, and gyro angle, but the most important thing it don't show is distance to the track. I haven't found any way to ask one of the officers to guesstimate the distance, so I was going to make a table, but before I did I thought I would check and see if somebody already has such a table.

[Krupp]

Try this:

(AOB/60) x range = distance to track

Remember the 300 meter minimum range for the torpedo. No tables needed necessarily, but would be handy tho..

[don1reed]

The left column is the AOB.

http://img494.imageshack.us/img494/6780/dxtotrack6pu.jpg (http://imageshack.us)

[drEaPer]

Im no native english speaker. Can someone explain "distance to track" please?
Thanx!

[Krupp]

Not mine either, but let's try. Track is the calculated or estimated range from (to) targets path to your current location. When you are directly on the track, ahead of the target, the AOB is 0 degrees. I reckon....

Edit: thanks for the table don1reed. Handier than using a calculator :lol:

[Sniper297]

WOW! Thanks, don1reed, exactly what I was looking for. I've had subsims since the original DOS GATO, and always estimated distance to the track, but these type II U-boats don't have much to spare for last minute manuevering.

drEaPer, I'm brand new to this forum, but let me see if I can figure out how to post a picture;

http://img253.imageshack.us/img253/6933/00nh.jpg (http://imageshack.us)

[/img]

Target is red, subs are green, the track is the projected course of the target if he doesn't manuever. In all three cases the range to the target is 3000 meters, but the actual range is not what you want - you want the torpedo run distance. In an ideal situation you fire when you are at a right angle to the target within 500-1000 meters, and the gyro angle is zero. (Actual angle will be slightly less than 90 degrees, since the torpedo run is what needs to be 90 degrees) Sub #1 is 2000 meters from the track, he has to run like hell to reach the ideal firing position. Sub #2 is at 1000 meters from the track, all he has to do is wait for the target to get to the firing point. Sub #3 is way too close to the track, he needs to turn around and move away from the track to give the torpedo enough arming distance.

Using don1reed's table it makes it easy to figure out ihow far you are from the ideal firing position, if the target range is 5000 meters when you first see it and the angle on the bow is 30, you're 2500 meters from the track and need to move 1500 meters closer. If the angle on the bow is 3 at the same range, you're too close to the track and need to move away from it. Especially when the ships are in convoy, it's important to do all the high speed running to get into position when the target is still as far away as possible, since high speed running near the target will give you away.

[Coolhand01]

don1reed, sniper297

wouldn't the speed of the torpedoe either hinder or help...both of your charts appear to have a fixed torpedoe speed...please correct me if i'm wrong...CH

[Sniper297]

Nothing to do with speed, it's all about firing position. The torpedo speed would affect when you fire, but not the ideal firing position. Looking at don1reed's chart, as an example you first sight a ship 6000 meters away, heading southwest. Range is 6000, angle on the bow 30. You look at the 30 in the left column, trace across to the column under 6000, and the distance to the track is 3000 meters. You want to be within 1000 meters, but if you turn directly toward the target and try to close directly you'll end up at a bad angle. You could also set up what the aviators call a pursuit curve, running fast and leading the target, but then you still have no way of knowing if you're leading too much or not enough, or running too fast or too slow. So you turn your sub northwest or southeast (depending on which side you're on) to get at right angles to the target's track, then close on the track. When the range closes to 4000 meters, you again check the angle on the bow. If it's increased to 50, you're falling behind and need to speed up, if it's still at 30 you're 2000 meters from the track with 1000 meters to go, if ithe angle on the bow is down to 20 you're 1368 meters from the track and should slow down.

The beauty of that chart is it considers only angles and distances, speed of the target is irrelevant since the angle to distance formula works at any speed.

[Sniper297]

http://img302.imageshack.us/img302/6273/116vs.jpg (http://imageshack.us)

Them despicable British don't normally accomodate me by coming directly at me, but sometimes it happens. AOB is 1 starboard at 6600 meters, using don1reed's chart I find that I'm only 113 meters off the track.


http://img302.imageshack.us/img302/9241/120zq.jpg (http://imageshack.us)

Normally you turn toward the track at right angles, in this case I'm already too close, so I turn to port. He's heading ESE, so I turn to SSW and increase to standard.

http://img302.imageshack.us/img302/6518/133af.jpg (http://imageshack.us)

At 5000 meters I'm 1040 meters from the track, so;

http://img302.imageshack.us/img302/2697/149jv.jpg (http://imageshack.us)

I turn WNW to parallel the track, submerge to periscope depth and slow down.

http://img302.imageshack.us/img302/7029/150hf.jpg (http://imageshack.us)

Check AOB again at 3000 meters, distance to track is increasing slightly, so I turn toward the track.

http://img302.imageshack.us/img302/662/161py.jpg (http://imageshack.us)

At 1500 meters range, 940 meters from the track, I start my turn starboard to 90 degrees angle to the target.

http://img302.imageshack.us/img302/8395/175ee.jpg (http://imageshack.us)

Almost in perfect position, not completed the turn yet when one of them newfangled aereoflyingmachine contraptions shows up. Well, the target is nearly broadside, gyro angle close to zero, so shoot & scoot, take her down to 20 meters (don't wanna order crash dive, North Sea is too shallow!)

http://img302.imageshack.us/img302/993/182eg.jpg (http://imageshack.us)

At that range I couldn't miss even without the perfect angle.

:up:

[Curval]

lol @ the "Party Pooper".

:up:

[don1reed]

@ Coolhand01

If you use the chart above, it can help you determine how far away the target is from you.

i.e.,

Lets say your WO spots a ship Br.090R, range: 50hm, and you peer through the Zeiss 7x50's and further determine that her AOB is Red 045.

Using the above chart you match up 45° in the left column with the figure to the right beneath 5000m = 3536m. This is a snapshot of how far away you are from the target's course (aka Track) at that instant. 3536m.

You only need to get within 1000m of the target to have a chance for a desent shot...so you now have to change course and maneuver to get into a perpendicular attack posture on the target, and hustle up to it's track line to be within 1000m or so. (aka Closest Point of Approach, CPA)

[Joe S]

Why not use the ruler to draw a line on the Nav map indicating the target's track and then use the ruler to measure the distance to any point on the track that you want. Thas how the fire control team would have done it Joe S

[Sniper297]

Not sure how you'd do that, I don't actually get a target course. They give you a general compass point (ESE, NNW for example), but that's not really accurate enough to plot out a track. I know in the real world the target is likely to zig-zag which would throw the whole thing off, but knowing where he's gonna be if he don't manuever is the first step to getting into a good firing position.

Off topic, but anyone with any knowledge of actual WWII TDCs? My understanding was that the skipper would sight the target and push a button, which entered the range and bearing into the TDC. A couple minutes later he would do it again, and the TDC gears would start cranking, comparing the first observation to the second, and plotting speed and course from that. In the absence of further input, the TDC would continue to plot the position of the target based on the last input it had, until it was either updated or shut off. Sub simulators don't work that way, when you drop the scope the TDC stops running. AFAIK in the real world the skipper raised the scope, got range & bearing and hit the button, then dropped the scope (30 seconds or less) and waited 3 to 5 minutes before looking again. TDC would continue running showing where it thought the target was, but these games don't do that - lower the scope and you lose the target. Consequently you have to leave the scope up for a running plot, which is unrealistic.

[Coolhand01]

You can concievably do it by raising and lowering the scope in the game.At the first sighting you can mark the ships position by figuring the AoB and distance by using the ruler and marking the chart. After say five position plots at 5 minute intervals you have a course. If the target is zig-zagging you can connect the lines and dertermine a base course and thus be able to figure out your best possible firing position. I have done this before and it works for single and convoy contacts. With the convoy's you have to only track 1 ship as the turns are "coordinated" so in theory the whole convoy is just 1 ship. Please correct me if I'm doing this wrong.

p.s.
I will also be using don1reed's chart. (With his permission of course). Every little bit of info helps.

CH

[todd293]

I dont understand how raising the scope and pushing a button then lowering it and raising it in a few minutes and doing it again would give you the range to target. I could see how that would give you the speed. I figured that real uboat captains had to first identify ship then use the slash marks on the scope to measure the ship mast to get the range. I dont pretend to know alot about this but would like to know :yep:

[Coolhand01]

Taking the first mark will give you the range, and Aob. The second gives you the speed.You also redo the Range and AOB.Retake all readings on subsequent marks updates the TDC and establishes a base course.This requires using a real pencil and paper as well as the scratch pad at the scope or Uzo. It also tells you if there are any speed changes between readings,how long each leg of the zigzag is Etc...It's not as complicated as it sounds.

[Sniper297]

Not sure when the technology came about, but i suspect the Germans had it first. Instead of using known mast height some advanced periscopes and TBTs (US equivelant of UZO) had a split image - when you rotated the focus so the two images were lined up, that gave you the range. It's actually pretty old technology, I remember reading about a "come up glass" around the time of the War of 1812. My Dad had a 35mm camera from the 1920s that had a similar rangefinder lens.

[Joe S]

There are a number of ways to find the range. US recognition manuals not only stated the mast height but had a grid by which you could estimate the range by the relation of the horizon to the target. Another method would be the range finding reticle in the scope, or the dual image rangefinder in the scope, or sonar or radar. The captain would center the target in the crosshairs and the fire control party would recort the relative bearing. The captain would estimate the range by one of the above methods,. and the estimated angle on the bow. That data would be entered into the TDc and the fire control party would enter the location of the target on the map. This would be done several times. Once you enter the position of the target twice, the line between the two locations is the targets course. In SHIII, the ship icons on the map represent the work of the fire control party, except that in order to mark their location you must enter a map mark. Unfortunatly, in SHIII you cant drop map notes like you could in SHII, a big step backward in my opinion,but the little map marks that we are allowed to make do work. I make as many of these obervations as circumstances allow, keeping the scope up only as long as absolutely necessary, 5-6 seconds at the most at close range.

The range is the least important piece of information needed for a fire control solution. I manually set the range at 1,500M and manuver for a shot at about 1,200 M. So far I have had very good results. I recently had a target that was zig-zagging, and by marking its locations at the start of the turns I was able to predict its Zig-Zags pretty accurately.

If you can find the little book that came with the old dos sub sim called Up Periscope, it has a very good description of the work of the captain and the fire control party and the making and keeping of the manual plot. There is also a complete WWII TDC fire control manual online, and a link to it on one of the threads here. I hope you find this usefull. If you have any questions, fire away. Joe S

[todd293]

why in the world did they put this tool in the periscope that we have to use when they could just as easy of used what captains really used as you all know its hell trying to keep the bottom line on the waterline of the ship and try to measure the mast while in a storm and the scopes bouncing all over the place with three destroyers breathing down your neck :damn: I feal like i could adjust these lenses till they matchup versus that thing we have to use :damn: :damn: :damn: could this be modded in somehow