Author Topic: Tores mailbox VIIC and VIIC/41 operation and technical details  (Read 321515 times)

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Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3870 on: 13 Jul , 2018, 21:36 »
Hello Mr. Tore,


I uploaded Skizzenbuch with corrected pages 125, 126, 127, 128, 426, and 427 into Dropbox... Again let me know if it is OK?


Regards,
Don
A man’s got to know his limitations…
Harry Callahan, SFPD

Offline tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3871 on: 14 Jul , 2018, 00:22 »
Don
I`ll look into it soonest, but for the week end I take my wife to the coast to relax after a hectic week for an old man. Hopefully back on monday.

Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3872 on: 14 Jul , 2018, 00:44 »
Hello Mr. Tore,


Of course, you and your wife enjoy the beach and the weekend... How is her broken hand? Is it in a hard cast or a bandaged wrapping?


Regards,
Don_
A man’s got to know his limitations…
Harry Callahan, SFPD

Offline tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3873 on: 14 Jul , 2018, 01:17 »

Unfortunately they had to remove the hard cast as the parts were not matching correctly, redid the whole thing without cast and she got a lot of painkilling medicines and as usual a lot of side effects. But we are doing fine and shall be back next week.
Tore

Offline tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3874 on: 16 Jul , 2018, 01:40 »
Don Skizzenbuch Page 125.

I guess you should use my latest sketch, showing the diesel air duct coloured ligth blue all the way from the schnorchel air connection up to the engineroom main diesel air valve. From the latter valve the diesel air duct splits in two, ending in two large rectangular outlet between both engines and the pressure hull. When schnorchelling and in rough wheather surfaced, the seawater gushed down to the bilge far away from the air intake of the engines.  When the main group exhaust hull valve has a massive leakage which often occurred (in spite of the pneumatic grinding) there is a leakage chamber in the housing which can be drained to the bilge to prevent filling the exhaust manifold alongside the engine. Eventually the exhaust manifold alongside the engine has a possibility for a drain fore and aft to the bilge. These are not shown on plate 13 and can be easily be confused with the many coolingwater drain in the system.


Tore

Offline tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3875 on: 16 Jul , 2018, 04:30 »
Don Skizzenbuch page 127- 128.

I guess there is a misprint in the firing sequence of a 6 cylinder diesel which is cyl no 1-5-3-6-2-4.
The indicatorcocks are shown on the lower right image (not left).

Exhaust temperatures. You mention the coolingwater regulator is adjusted manually to keep the exhaust temperatures below a set level. I don`t think the exhaust temperatures are controlled in this way, but the materials of the components. Exhaust temperatures are controlled by the timing, combustion (load)and used for monitoring the  condition of the fuelinjection system, exhaustvalve seating etc.
« Last Edit: 16 Jul , 2018, 08:46 by tore »

Offline tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3876 on: 16 Jul , 2018, 05:19 »
Don Skizzenbuch page 427
I guess in the general description of the Michells thrustpads you should mention the shaft thrustdisc pushes on the forward thrustpads when the shaft rotates in ahead direction.

I  think the main reason for a submarines tailclutch is to disengage the propeller while charging the batteries along side, you don`t disengage the propeller for starting the dieselengines, unless you are alongside, think about all the old reversible diesels.
Tore
« Last Edit: 16 Jul , 2018, 07:38 by tore »

Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3877 on: 16 Jul , 2018, 16:17 »
Hello Mr. Tore,


If the main clutch is engaged and you are starting the Diesel engine, then you are adding the additional resistance of the prop/seawater which would be driving the U-Boat during startup. Is this not an extreme amount of load during startup? I don't doubt your answer, but I just want to verify the startup procedure...


Regards,
Don_
A man’s got to know his limitations…
Harry Callahan, SFPD

Offline tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3878 on: 17 Jul , 2018, 00:52 »
Don.
Most of the marine diesels in world are starting with a fixed blade propeller directly attached to the engine. Having a tailclutch is an exception rather than a rule. A direct reversible diesel as installed on the older VIICs had a manoeuvre sequence as follows: Starting with propeller engaged driving vessel ahead, manoeuvre astern, stopping the dieselengine, reversing the engine by axially shifting camshaft, starting the engine running astern, all manoeuvres carried out with the propeller engaged. This is standard manoeuvre for most of the marine diesels with fixed blade propellers, nothing special.
 Starting the diesel engine with the propeller engaged and submarine moored alongside might have a consequence, like one of my first battery charging alongside. We were alongside in a remote harbour way up north of Norway, we were moored at a wooden quay right in front of a shrimp peeling factory, built on wooden poles. I was on the bridge asking the engineer in charge if everything was ready for charging, got confirmation OK and ordered start the engine. Good old Kaura ex U995 made a jump ahead broke the moorings and ended up underneath the shrimpfactory while all the ladies working there ran screaming out of the shaken factory. The engineer in charge had forgotten the tailclutch.
« Last Edit: 17 Jul , 2018, 01:03 by tore »

Offline tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3879 on: 17 Jul , 2018, 01:14 »
Don
In addition to the above it was very convenient for the engineroom crew to have a tailclutch f.i. when having an engine repair and we wanted to have a testrun. With a propeller engaged you had to ask the officer on watch to double up the moorings prior to the test, with a tailclutch we were our "own masters" and could just disengage the propeller.

Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3880 on: 17 Jul , 2018, 03:27 »
Hello Mr. Tore,


Thank you for the information on the startup sequence, and I was very amused about the shrimp factory story.  Things like that do happen in real life!


Regards,
Don_
A man’s got to know his limitations…
Harry Callahan, SFPD

Offline VIC20

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3881 on: 17 Jul , 2018, 05:06 »
Hi Tore, do you know when they gave up the direct reversible diesel engines? (which boats were the last ones?)

Offline tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3882 on: 17 Jul , 2018, 09:18 »
Hi!

It`s a good question of which I have no concise reply. On the VIIC 41 like  U-995 they did away with quite a lot of weigths as the greater diving depth caused a lot of weight increase hence they removed some equipment including the reversing mechanism, but ordinary VIICs in our fleet had non reversible engines as well as KNM Kaura ex U 995. So we can`t assume this is the reason when looking for the boats with reversible diesels. If somebody should feel for making a research a very visible sign that the engine is a direct reversible type is the reversing cylinder up front of the engine as can be seen on my image below may we could trace the boats based on engine photos.
Tore

Offline tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3883 on: 17 Jul , 2018, 09:43 »
Further to my answer above I realize my image was not very clear so here is a photo of the real thing.

Offline VIC20

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3884 on: 17 Jul , 2018, 13:16 »
I guess pictures of the diesel engines of the different boats are rare and hard to find.