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Old 08-12-20, 04:17 AM   #1
achitan
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Join Date: Feb 2017
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SHO TDC solution calculator - one observation

Hi guys,

while the WoS super-mod is a God send, it can be hard to use the Attack Disk especially when you have to be a sub-commander while away with work for 2 months from your gaming laptop/PC and have to be able to command the steel fish with the Intel HD graphics of an office laptop - luckily it comes with an i7 behind it. The worst thing is the resolution reduction that will clutter the attack periscope with tools and buttons. Thus, the less time I have to use one of the pop-up tools the more time I have to actually watch the environment.

So following the attack disk manual provided and the procedures described in there, I've made a small command line app for Windows (compiled in 10, I don't know about compatibility with older versions) that will take your observation and compute the parameters to be put in the TDC for a correct shot - tested it extensively and I'm 4 for 4 in the provided TDC torpedo single mission (in the right places, too, if one takes into account that after the second torpedo the target will slow down quite fast) and I do the observation at the start of the mission (~3100 m away from the target).

Tools to use:
RAOBF - get the length and height ticks
chronometer - get the fixed wire time span
stadimeter - to get the range to the target (the default provided one is precise enough)


Basically, after these observations you would pull out the attack disk and start computing the same things that this app computes. Instead of using visual cues (problematic at low resolution) this app uses the equations behind the attack disk.



The image above shows the app's help output (whenever you don't give it enough parameters, this will appear. You don't have to type -help, /? or any other things. As you can see, the parameters to be given are described in the help screen.

When all the parameters are given, an extended solution is given as in the picture bellow.




The first and most important assumption made is that you are on a perpendicular course with the target and not moving. Of course this does not happen in usual pursuits and requires some maneuvering. Thus the first output is the shooting turn. This is the amount of turn in degrees (left or right, you'll have to judge that) that you'll have to make to get from a pure pursuit of the target (bow on the target) to a course perpendicular to its'. If you've managed to position on the perpendicular, then you can ignore this.


target speed is the speed of the target in knots obtained with the fixed wire method. It is fairly precise and precision grows with AOB - the beam of the ship introduces errors, directly proportional with half the beam distance.



shooting distance is the distance from the target at the moment of the launch. It is not the distance the torpedo travels, but that is also covered.


shooting AOB is the AOB at the moment of the launch.


shoot at bearing may be the most important parameter of the shoot. When the target gets to that bearing, send out the fish!


distance to impact is the actual distance the torpedo is traveling to hit the target. This is important for timing the hit or miss or dud. And here I can talk about the second and final assumption of this app: gyro angle of the launch is 0. Everybody knows by now that the most precise solution is the 0-angle one as no torpedo turn can induce errors in the calculation. Actually, this is also the method implied by the Attack Disk manual.


time to impact is the time in seconds that the torpedo will travel to hit the target.


The parameters I gave the application in this example were the ones to compute a solution for the TDC torpedo attack single mission where you already start off stopped at a perpendicular heading on the target's, while it is a beautiful Liberty ship cargo. So I measured a distance of 3100 m, the target's length and height are known (140.9 m and 26.2 m), 8.1 and 3.5 ticks on the RAOBF, 57 seconds to pass the fixed wire and 44 knots the torpedo speed. You don't have to be super precise (newcomers always fall into this trap) as ships are long and speeds are low so there's always room for errors. A ship hit under the first crane is not very different from one hit bellow the tower in the sense that a torpedo does a LOT of damage anywhere it hits.


After obtaining the shooting parameters, un-lock the TDC, put in the range and the target's speed. Be careful to have the correct torpedo speed already prepared though you can redo the computation with any speed (44/40/30...23). Put the shoot at bearing on the bearing dial THEN put the shooting AOB in the AOB dial. This chain is important as modifying the bearing after the AOB will make the latter be recomputed. Last but not least, move your periscope to the shoot at bearing position and lock the TDC again. You could shoot without locking the TDC. However, after I insert all my parameters in, because of the precision of the dials in the TDC, I still get a degree or 3 off to the right or left in the gyro angle solution. So by locking the TDC again, by moving the periscope a little to the left or right I can make the TDC get to a perfect 0 on the gyro angle. I can still shoot at my calculated bearing (even though the periscope is looking a degree to the right or left) or I can take the new bearing that the periscope is showing me to launch my torpedoes (the error is very small). What counts more is that the torpedoes don't turn.


So an actual attack of a convoy would look like:
- position ahead of the convoy
- bow on your chosen target and slow down (reduces errors due to your movement)

- make first observation to get the turn for perpendicular course
- make the turn and stop
- second observation to get the firing solution
- put all in the TDC and wait for the right moment


I guess this is not the ONE OBSERVATION advertised, but if you're already perpendicular to the target's course by other means, than it's only one observation .


Hope you like this and enjoy it as much as I did making it and testing it,
Adrian


The app is here
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Old 09-10-20, 12:53 PM   #2
RedRamage
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how to run this app ?
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Old 09-10-20, 04:18 PM   #3
Ashikaga
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I do not understand your laptop problem since in TWoS there is a mod to tackle any resolution problems.

OLtzS Ashikaga.
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Old 09-12-20, 04:13 PM   #4
Macgregor the Hammer
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Looks like a cool tool to play with, but I don't know if I would want to use it as part of developing firing solutions. SH5 has all the tools you need. The RAOBF, attack disk and an excellent TDC along with the map tools will give you all the information you need to plot intercepts over distance, torpedo firing solutions rather quickly.

The RAOBF is easy to use once you get the hang of it. The Angriffsscheibe (attack disk) takes a bit more time. Once you understand the concepts behind the circles and pointers, it's a an easy to use, powerful tool. You can also find rough firing solutions with the sonar.

I used a number of 3rd party tools when I started using manual targeting. I realized that I was making things more complicated and frustrating. I think using a TMA tool like this in practice missions is a good way to learn how things work in a firing solution but using it in 'action' might be more of a hindrance than help.

IMHO.......
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Last edited by Macgregor the Hammer; 09-12-20 at 04:39 PM.
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