Questions regarding historical/realistic torpedo settings

[Albrecht Von Hesse]

Hey there. Got two quick questions, both regarding torpedoes. I'm looking for actual historical/real answers.

With regards to impact and magnetic pistols, what was involved in changing from one to the other? How long did that take, and could that be performed once the torpedo was in it's tube (outer door closed and outer door open)?

With regards to setting running depth, what was involved to do that? Again, how long did that take to do, and could that be performed once the torpedo was in it's tube (outer door closed and outer door open)?

At the moment doing either is the work of a moment to click impact versus magnetic settings, and the same goes to changing running depth. For one, I'm honestly interested in learning how their torpedoes were fuzed and set, and for another I want to operate/play setting torpedoes realistically.

Any help or advice (or answers! :p ) will be greatly appreciated!

[KeptinCranky]

As far as I know running depth and speed/course could be set with the eel in the tube, through the TDC, but the pistol was either set to magnetic or impact back in port or with the eel outside the tube, it definitely couldn't be changed with the eel in the tube.

[von Zelda]

With regards to impact and magnetic pistols, what was involved in changing from one to the other? How long did that take, and could that be performed once the torpedo was in it's tube (outer door closed and outer door open)?

With regards to setting running depth, what was involved to do that? Again, how long did that take to do, and could that be performed once the torpedo was in it's tube (outer door closed and outer door open)?

At the moment doing either is the work of a moment to click impact versus magnetic settings, and the same goes to changing running depth. For one, I'm honestly interested in learning how their torpedoes were fuzed and set, and for another I want to operate/play setting torpedoes realistically.

I've read numerous books on u-boat history and I don't recall any reference to the procedure or method for changing magnetic to contact pistol. I do recall that the magnetic pistol would fire on either the magnet change or on direct contact. I assume if one wished to use a contact only pistol, that would require the torpedo to be pulled out of the tube and a contact only pistol put in place of the magnetic/contact pistol. In the early stage of the war (prior to and immediately after the Norway invasion) commanders were ordered to use contact only pistols.

As to running depth, I'd assume they had some type of mechanism or tool to set the running depth of the torpedo while it was in the tube.

Memoirs by Karl Doentiz gives a pretty good explanation of the torpedo and pistol problems during the war. Besides the defective magnet pistol there were other torpedo malfunctions which made diagnosis of the torpedo problem very difficult to solve: (1) The contact pistol would not always fire on a direct hit because the design of the contact pistol was extremely complex and just poorly designed. I believe this was overcome by recovering a British torpedo and using their rather simple design. (2) Initially the fins on the contact pistol were made in too small a diameter and/or too few fins which resulted in the torpedo bouncing off the side of a ship if the torpedo hit with less than 90-degree angle. (3) There was a major problem with running depth for quite a long period of time. Orders were sent out to set running depth 2 to 3 meters shallower than desired to try to over come this problem, but running depth remained very irratic. The problem was corrected only when the pressure sensing device used to control running depth was found not to be air tight. Air pressure built up in the u-boat as it submerged for longer periods of time, the pressure changed in the sensing device due to air leakage and this caused the torpedo to run deeper that set.

Therefore, in my humble opinion, to be realistic as much as the game will allow, I set the pistol on contact only and use a shallow running depth (1 to 3 meters). I hope this is helpful. And, read as many u-boat books as you can find, they'll give you a great deal of insight.

[Kpt. Lehmann]

Good post von Zelda.:up:

[von Zelda]

Good post von Zelda.:up:

Thanks Kpt. Lehmann, it means a lot to me coming from you!

[Sailor Steve]

Yep, that pretty much sums it up. I always use magnetic up until I get the historic message to stop using them, then contact only until they give the message to use the new, improved magnetics.

Someone once posted a picture of them being changed, and it was definitely a physical procedure done outside the tube.

Depth and gyro settings were changed with a mechanical (later electric) device that fitted into a slot on the outside of the tube, but went right through to the torpedo inside. This is actually shown in the 'Uncut' version of Das Boot. Lining the fittings up was part of the reason it took so long to load the eels.

[deepboat]

I usually mix and match between contact and mag torps depending on the situation. When do you get the historical data to change settings? Thank God for acoustic torps, saved my @#$ more than once but when do they become ineffective when allies introduce counter measures?

[Sailor Steve]

When do you get the historical data to change settings?
The Radiolog mods have most of the historical messages sent. People are always posting about their boat being ordered to patrol a certain area or head for home, and we always have to point out that those are for immersion only...but they also include the historic orders to dial back the magnetic settings, or stop using them altogether, so it's a great help.

[Albrecht Von Hesse]

Thank you von Zelda and Sailor Steve.

With regards to playing 'realistic' I've been doing what Sailor Steve does: use magnetic until BdU says to stop, then go back to magnetic when I get the 'go-ahead' message. (By the way, does anyone have the exact dates for those official notifications?)

With regards to the actual, real methodology, from the research I've been able to do and with my own, real-life experience with fixed and semi-fixed ammuntion, I think the following is probably accurate:

http://members.home.nl/paajtor/SHIII/whisker_det.jpg (credit to Paajtor; got it from his siggy)

The nose is probably fastened/removed with a wrench or spanner, permitting the pistol body to be inserted and removed. It's probably the same pistol for both contact and magnetic detonation; you just disable or enable magnetic detonating. The fuze is part of the pistol (and possibly, but it doesn't look so, the booster charge). So in order to activate or deactivate the magnetic portion you'd have to physically unscrew the nose and remove the pistol; definitely not do-able once the torpedo is in its tube, and not something that looks quick and easy to do when it's not in its tube.

I knew the gyro angles had to be able to be updated with the torpedo in its tube, and I was reasonably sure so did running depth. Thanks, Sailor Steve, both for confirming that as well as mentioning just how that was done.

As an aside, I discovered two interesting torpedo tidbits (both from wiki):

1) The [G7a] torpedo was of a straight running unguided design, stabilized by a gyroscope. The G7a was of variable speed, running a distance of 6km at 44kts, 8km at 40kts, and 14km at 30kts. The 44kts setting was used only by torpedo boats like the Schnellboote.

2) The T2 model of the G7e was in service with German U-boat fleets from the first day of WWII. In stark contrast with the G7a steam driven torpedo, the T2 left no visible stream of bubbles to alert ships they were under attack, and was virtually silent; however, these were the T2's only advantages over the G7a torpedo. The T2 in all other respects performed abysmally when compared to the G7a. Its range was much shorter than the G7a's at only 3000 m, and it ran much slower at 30 kt (55 km/h).

I remember when the T2 used to have a range of 3000 meters before GWX changed it to 5000 meters. I wonder why, when historically 3000 meters seems to be accurate? Now, the G7 e/T3 has a range of 5000 meters, but the T2 didn't.

[von Zelda]

I remember when the T2 used to have a range of 3000 meters before GWX changed it to 5000 meters. I wonder why, when historically 3000 meters seems to be accurate? Now, the G7 e/T3 has a range of 5000 meters, but the T2 didn't.

IIRC, to obtain the 5000 meter range with the T2, the batteries needed to be preheated. Otherwise the range was only 3000 meters.

[Albrecht Von Hesse]

Some more input ::grins::

http://members.home.nl/paajtor/SHIII/whisker_det.jpg

Again, if what I've been researching and reading I'm understanding and intepreting correctly, in the above image, to the left, is the contact and arming mechanism. The central, 2-bladed prop is the arming mechanism; it had to spin so many revolutions (equivalent to the 300 meter arming distance) before the pistol/torpedo is armed. The four outer blade arms are for off-90 degrees contact detonation. Striking square on would transfer the contact impact through the central 2-bladed piece, while an off-square impact would push back one of the outer bladed arms and set off the fuze.