Author Topic: Tores mailbox VIIC and VIIC/41 operation and technical details  (Read 572754 times)

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Offline tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3915 on: 13 Oct , 2018, 01:16 »
Don.
Your suggestion as to the exhaust blowing sequence seems to be correct. You are not able to hear the exhaust escaping  through the Kingstons, quite often the people on the bridge reported when they observed the gas bubbles, but as everything else in the word, experience counts, an experienced engineer was able to tell when the tanks were fully blown by using his feelings. Normally you are not able to empty the ballasttanks 100%, you shall always have some residue ballast water left, however I never experienced any free surface effect from the ballast residue. I guess you guys making games for a conventional submarine with WW2 technique have your difficultes. The recorded WW2 parameters were scares and you had no computer to feed, old fashion experience, smell, temperatures and sound were important elements. I could be sleeping in my bunk when a change in the diesel sound woke me up and I was in the engine room before any messenger woke me up. Many things happened due to mishandling by unexperienced crew during the latter part of WW2 as the war had taken its toll and shortage of experience became a problem. If you look at the various intricate systems like the HP blowing system, engineers have developed same over the years and made modifications to be able to handle various situations. It took time and experience to handle all these options effectively which computers can do today, I guess it is possible to incorporate some of the elements by f.i transferring pressures into volumes in case of ballast blowing etc. to make the monitoring a bit more computer friendly but the real thing during WW2 was monitoring based on pressuregauges and time, the rest human senses and experience.
Tore
« Last Edit: 13 Oct , 2018, 01:19 by tore »

Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3916 on: 13 Oct , 2018, 13:53 »
Hello Mr. Tore,


Thank you for the quick response to my question... It is good to see that you are again on the AMP website with your expertise. Have you fully recovered from your stroke with the physical therapy? Has your wife recovered from her broken hand from the auto accident? It seems like you all have had some bad luck this past year. Let's hope that this coming year will be non-eventful and much better.


I have not heard back from Casemate Publishing about Skizzenbuch. I'll give then a few more weeks and if nothing results, then I will form my LLC, Copyright Skizzenbuch, encrypt the files and distribute it for free.


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 #3917 on: 13 Oct , 2018, 14:20 »
Don.
I am indeed recovering very well having an extremely beautiful female physical therapist holding a phd. on just my condition helping my recovery. Enjoying every minute of the treatment. May be a waste for an old fart like me going on 90. My wife has recovered pretty well thank you and we are planning our blue sapphire wedding, 65 years, end this month. I share your hope that next year shall be less eventful than this but hope your Skizzenbuch shall materialize.
Tore

Offline VIC20

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3918 on: 13 Oct , 2018, 14:49 »
Tore, I’m glad to hear your recovery is doing well (with eyecandy).


Don, why don’t you publish it on demand via amazon or other publish-on-demand services? It doesn’t cost you anything, the risk of piracy is gone because it will be printed and you will earn money for the years of hard work on Skizzenbuch. You deserve a compensation for the work. If there is any technical problem then I could try to help you.

Offline tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3919 on: 13 Oct , 2018, 15:30 »

Rigth now National Geographic is showing a movie WW2 : "A hell under water" about the first documented torpedo attack by a submerged submarine on another submerged submarine. The incident happen February 1945 outside the fishing village Fedje on the western coast of Norway and they use the museum U-995 for the interior scenes, not very successful as the people (crew) are twisting wheels and handles meaningless and would in real life probably have put the U-995 to the sea bottom. The German Milk Cow U- 864 having a cargo of mercury for Japan had some engine trouble and was schnorkelling when the bristish submarine of the V class HMS Venturer heard her and later discovered the schnorchel mast of U- 864. HMS Venturer had only 4 torpedoer and the CO of Venturer set the 4th torpdeo a bit deeper than the other 3 anticipated U-864 would make a classic escape by going deeper when they heard the torpedoes. U 864 was hit and sunk at 150meters depth all hands lost. U 864 still causes us trouble today as she has a substantial amount of mercury in her keel laying and polluting the seabottom outside Fedje. HMS Venturer became Norwegian and renamed KNM Utsira a few months later. Below is KNM Kaura ex U-995 in the same area during a dummy attack . Although we had a fruitmachine we used the old style of attack, me calculating the parameters for setting the torpedo.
Tore
« Last Edit: 13 Oct , 2018, 15:36 by tore »

Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3920 on: 13 Oct , 2018, 15:56 »
Hi VIC20,


I have not found an on demand publisher that will publish a book with the dimension of 12 inches x 9 inches with about 516 pages with a minimum of 3 fold-out sheets in the back of the book...  Let's talk about this off line and my email address is donprince5207@comcast.net and perhaps I'm not talking with the right people...


Regards,
Don_
A man's got to know his limitations...
Harry Callahan, SFPD

Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3921 on: 14 Oct , 2018, 19:47 »
Hello Mr. Tore,


When starting the diesel engine on compressed air... The starting distributor is directing air to push down on the cylinder head to cause crankshaft rotation. When the correct RPM are attained by running on air, the fuel lever is set to run and injecting fuel which causes ignition. At this point, there may be several RPM happening before the starting air distributor is shut off by the diesel engine operator. Normally, the diesel engine has both intake and exhaust valves shut during the power stroke, or the valves are shut when compressed air is injected into the cylinder to simulate the power stroke.


My question is with both valves shut and when fuel is injected into the cylinder and we have ignition; does the ignited gases feed back into the air distributer and eventually back to the starting air canisters, or Is there a check valve on the starting air distributer to prevent this feedback from happening? Or is the ignition gases feedback simply not a problem?


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 #3922 on: 15 Oct , 2018, 02:15 »
Don.
The starting system originally designed for a direct reversible engine is complicated as you have to start both in a ahead and astern configuration. If we begin with the starting valve in the cylinderhead,(I guess you called the piston for cylinder head in your question) it is a combination of mechanical and pneumatic operation. Below is an image of the valve which is operated by its own sartingcam on the camshaft. Normally the valve is shut by a spring lifting the pushrod free from the cam. First stage of starting is you open the starting air supply valve admitting starting air to the lower part of the valve. A branch off after the starting air supply valve supplies air to the starting manifold. First stage of starting is moving the starthandle one step, admitting air to the top of the starting valve, pushing the lever of the valve rod up thereby
engaging the valve rod roller with the starting cam at the camshaft, now the starting air is controlled by the camshaft. I guess you have to study the diagram below to understand it fully. Some parts of the diagram is for a direct reversible engine and a few details are not shown on the diagram.
Tore 
« Last Edit: 15 Oct , 2018, 05:29 by tore »

Offline karel

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3923 on: 15 Oct , 2018, 03:56 »
Gentlemen.

Just to let you know. The new Das Boot teasers were released an hour ago. You can find them here.
https://www.youtube.com/watch?v=mZrL-JAmhVw
https://www.youtube.com/watch?v=XY1X6Z708aA

Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3924 on: 15 Oct , 2018, 20:31 »
Hello Mr. Tore,


Does this writeup look OK? Note there is a time period where fuel is injected when the starting valves are operational. Again was there an issue with cylinder chamber back pressure gases into the compressed air canisters?


Regards,
Don_

Procedure For Starting The Diesel Engine With Compressed Air

1. Opening the starting air valve (RED Hand-wheel) and admitting starting air into the lower part of the starting air valve provides compressed air to the starting manifold and the starting valves. There are six (6) starting valves; one (1) per cylinder.

2. Moving the starting handle to the start position directs compressed air from the starting manifold to the top of all six (6) starting valves. This air pressure forces all six (6) guide links to pull upward and cause the cam arm rollers to engage the starting cams.

3. One of the six (6) cams will be at a low position and the guide link will move higher and force the starting valve to open and admit starting air into the cylinder chamber and force the piston in a downward direction. This piston movement starts the crankshaft rotation whereby other starting valves will continue this running on compressed air process.

4. After the required RPM is reached, move the left fuel handle from stop to a point beyond 0 the minimum (the maximum is 55) and then ignition occurs. Now, move the right starting handle to operate which results in the roller cam arms being lifted off the cams and the compressed air being vented at the starting manifold into the diesel room. Turn off the starting air via the RED hand-wheel on the starting air valve. At this point, the diesel engine will be run-up until the operating temperature is achieves and then put on-line at the commanded speed.

Shutdown – move the left fuel handle up from the amount of fuel to Stop.

In the photo of U-995’s right starting handle, it only has two (2) positions; run [at the top (Betrieb)] and start [at the bottom (Anlassen)], and the reason for this difference is because U-995 diesel engines do not have reversing. If it did have reversing, then there would be a reversing handle to the right of the starting handle as I have indicated in the modified photo. However, on U-995 if there was a need for reversing, then the e-motors will be used for that function. If there is a lack of compressed air to start the diesel engines, then they could use the e-motor to crank the diesel up to speed and then inject the fuel for ignition.
« Last Edit: 16 Oct , 2018, 01:11 by Don Prince »
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 #3925 on: 16 Oct , 2018, 03:06 »
Don.
Below is a revised scheme of the starting system may be it clarifies the system a bit better.  As to your concern of the combustion gases entering the starting air vessel I dont think it is a problem as the starting air cams are timed to open the starting valve at an optimal piston position past the TDC during the compression expansion stroke when the cylinder pressure is lower than the starting air pressure (30kg/cm2). There is no fuel supply at this stage. However when you are moving the fuelhandle towards fuelsupply you are at the same time venting the upper part of the starting valve and the startingvalve pushrod  is removed from the camshaft and the valve is shut by the spring.  Some times you obtain a supercharging effect by the starting air. Furthermore as far as I remember the startingair supply valve is a NR valve. This starting system is very conventional and is even today operated in thousands of dieselengines.

On some simple semidiesels you actually fill the starting air vessel by the combustion gases allowing same to enter by the starting air pipe.
I once had an incident where due to a mechanical failure  the starting valve stuck open. The result was overheating of the pipe, not very dramatic, only some brown coloured paintings.
Tore
« Last Edit: 16 Oct , 2018, 10:55 by tore »

Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3926 on: 16 Oct , 2018, 13:35 »
Hello Mr. Tore,


This video shows a German Diesel engine and other components clutch and generator at the end of the video...

https://www.youtube.com/watch?v=zLfa43_1WH8

It looks like at the beginning the one person is pumping lube oil through-out the engine before starting with compressed air. I believe they started the Diesel engine with the clutch engaged and connected with the generator.

Regards,
Don_
« Last Edit: 16 Oct , 2018, 13:49 by Don Prince »
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 #3927 on: 16 Oct , 2018, 23:18 »
Don.
The starting procedure of a smaller MWM diesel seems to be a bit cumbersome, but in principle correct. On a VIIC GW engine you use the electric stand by lubeoil pump to put up the lubeoil pressure before turning, then you turn the engine by air with open indicator cocks, blow trough as we called it, before the starting procedure.

Tore

Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3928 on: 27 Oct , 2018, 14:32 »
Hello Mr. Tore and all,


We have a real author among us... Dougie Martindale's book "Gunther Prien and U-47: The Bull of Scapa Flow; From the Sinking of the HMS Royal Oak to the Battle of the Atlantic" will be available on Amazon on November 1, 2018. The publisher is the Naval Institute Press and Amazon's listed price is $28.03, and you can pre-order the book. I have just ordered my copy...


Regards,
Don_
A man's got to know his limitations...
Harry Callahan, SFPD

Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3929 on: 29 Oct , 2018, 03:31 »
Hello Mr. Tore,


Question about exhaust blowing MBT 1 and MBT 5... Assuming the U-Boat is in a fuel oil configuration with FBT 2 and FBT 4, then we blow MBT 1 and MBT 5 with exhaust gases. Are they both blown at the same time, or do we blow one of them at a time (Which)? I think we would blow MBT 1 first because of an emergency dive situation...  Just checking....


Regards,
Don_
« Last Edit: 29 Oct , 2018, 03:37 by Don Prince »
A man's got to know his limitations...
Harry Callahan, SFPD