Torpedo Experiment
 

In order to test torpedoes, solutions, theories, etc., I have embarked on a new campaign just to test some torpedo ideas. Two ships in tight formation were spotted, and their speed and trajectory were determined.

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Saved before diving. Estimated range at firing: 2000 meters. Proceeding to firing position.

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Lead angle: 14 degrees. Solution drawn.

http://i42.photobucket.com/albums/e3...ps0ae92935.png

A quick peek through the scope shows the ships are closer than anticipated. Range adjusted to 1800 meters. Lead angle unaffected. Alles in ordnung.

http://i42.photobucket.com/albums/e3...ps4e8617f8.png

One eel at each ship. Impact, 4 meters. Both impact. First ship impact at stern. Second ship impact amidships.

http://i42.photobucket.com/albums/e3...psa9ed4579.png

A warship wanders in. Taking no chances, I dive and keep my stern on the ship. Ahead slow.

http://i42.photobucket.com/albums/e3...psd9d038a5.png

A ship has sunk. Which? I don't know.

http://i42.photobucket.com/albums/e3...ps605cace6.png

It was a medium cargo ship. About 5000 tons.

As usual, I maneuver to the opposite side of the beleaguered ship to see whether it needs any help.

http://i42.photobucket.com/albums/e3...psf26d42da.png

As this is a torpedo test, a third eel is launched.

http://i42.photobucket.com/albums/e3...ps63b291fd.png

4 meters depth. Impact.

http://i42.photobucket.com/albums/e3...ps058d4bd2.png

Looks amidships to me.

http://i42.photobucket.com/albums/e3...ps84e6864f.png

Target sunk. Ship identified: Modern tanker.

http://i42.photobucket.com/albums/e3...psf957a71f.png

Take 2. Forward ship now targeted with a magnetic torpedo at 11 meters depth.

http://i42.photobucket.com/albums/e3...ps8ee4a88c.png

Second ship now targeted with a magnetic torpedo at 10 meters depth.

http://i42.photobucket.com/albums/e3...psdaba9dc6.png

Alles in ordnung.

http://i42.photobucket.com/albums/e3...psde9a06c8.png

First torpedo bounces off?! :nope: How can that happen if the depth is set below the keel? Shouldn't the magnetic trigger cause it to explode anyway? Second torpedo explodes near midships. A warship wanders through.

http://i42.photobucket.com/albums/e3...ps38deeb92.png

Warship evaded. Further follow-up on the targets would be required.

Comments?

You are playing the campaign?

A reload does not necessarily spawn the identical vessels iirc (depends on distance).
Your second take may have changed the medium cargo into something different sporting an 11 or 12 meter keel.

Use a single mission for your testing and define your targets directly.

A magnetic fuse has to pass under the keel in ~ 1m distance.
If your eel hits the hull the magnetic fuse will fail.

Your impact fuse may trigger, if the device hits the hull's surface within an angle of 90° +/- 30° of any direction - including downwards.

The impact fuse is allways active - the magnetic fuse is only added after your selection.

Discrepancy report.

http://i42.photobucket.com/albums/e3...ps891c4443.png

Take 3. Ships on gyrophone. 7 knots, 90º AOB at moment of impact. Bearing 0º. Depth: 4 meters, impact.

http://i42.photobucket.com/albums/e3...ps5d428f28.png

Proceeding to firing point. Ships on approach. Range from intersection 2000 meters. As we already know from previous experience, the targets will be slightly closer. Range in targeting computer: 1800

http://i42.photobucket.com/albums/e3...ps2902067f.png

Gyroangle at 000º is 014. Solution drawn on map. Switched to F6 screen. Flooded both torpedo tubes.

http://i42.photobucket.com/albums/e3...ps8420b9ed.png

Returned to observation scope. Gyroangle has changed?! :hmmm: The only thing I did was flood the tubes. Will compare before and after pictures once posted to ensure that nothing else changed. Alles ist nicht in ordnung.

http://i42.photobucket.com/albums/e3...ps453bc79e.png

Even with the new gyroangle, both torpedoes appear to be heading too far astern for my taste.

http://i42.photobucket.com/albums/e3...pse776ec21.png

Well, we can't argue with success, can we? It sure is strange, though.

http://i42.photobucket.com/albums/e3...ps8875caf5.png

Modern tanker, just as before.

http://i42.photobucket.com/albums/e3...psb44b9a6a.png

Warship comes through, right on schedule. The other ship seems to have stopped. It wouldn't be neighborly if we didn't check up on him, would it?

http://i42.photobucket.com/albums/e3...psa0691563.png

He goes down too. Same type and tonnage as before.

Did you at any time use the lock key command to get the periscope on a target? Or moved either of the periscopes sideways?

It turns out that tube 1 and 4 often have a different lead angle from 2 and 3. I believe it's because they are on different sides of the boat. I did about 20 minutes of testing. I originally thought that opening the tube door changed the lead angle, but that theory didn't pan out.

Ah, definety intresting! :hmmm:
I never noted it, and your explanation sound logical to me.

Well yeah. If you use different torpedo types. But unlikely due to the tube having a position difference. That angle would be almost imperceptible.

It is likely is that you encountered the T1/T2 torpedo speed and lead update bug during your tests. (check the GWX manual known bugs section) I see you have different torpedo types in your tube. If the torpedoes have been set to different speeds, selecting between different tubes does not update to the apropriate lead angle. At some screenshots you clearly have type 2 in tube 1 and 4, and type 1 in tube 2 and 3.

Make sure all tubes carry the same torpedo type, and are set to the same speed. So this bug cannot have any effect.

Ah well, that was the culprit.
Anyway, at the start of a patrol I usually load two tubes with G7a and two with G7e... just to be prepared in case of a daylight attack (in which case I tend to prefer the G7e).

I remember this bug, but cannot remember the specifics.

Is there a way to negate the bug for the currently-selected tube? I vaguely remember that if you manually select the speed prior to firing it fixes the bug? Because I often start patrols with all T2s inside but T1s outside, and when I pull some in I end up with a mix in the tubes.

Steve

Here is what the GWX manual says about the TDC bug:

There is a bug with the Vorhaltrechner (―deflection calculator,‖ also referred to as the Torpedo Data Computer, or TDC) in stock Silent Hunter III
: the TDC does not always recognize when you have adjusted the speed of a steam-powered T I, T I FAT, or T I LUT I torpedo from ―fast‖ or ―medium to ―slow. The workaround is to always left-mouse-click on the torpedo speed selector before leaving the TDC view if you have changed the speed of a torpedo, as this appears to ensure the TDCrecognizes the correct torpedo speed settings. You don‘t have to change the speed setting when usingthis procedure–just click on the ―speed‖ button to ensure the TDC ―accept the new speed setting.