Author Topic: Tores mailbox VIIC and VIIC/41 operation and technical details  (Read 288492 times)

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Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3885 on: 17 Jul , 2018, 16:57 »
Hello Mr. Tore,


I was wondering (I know that could be dangerous) about conserving fuel... Running on 1 diesel engine and free tailing the opposite propeller looks to be the most economic way, but the rudder would be needed to maintain the course. Then again, they could be driving with 1 Diesel engine and using its e-motor as a generator to power the opposite e-motor to drive its propeller drive shaft; possible the rudder may be in use as well... Since the driving Diesel engine is getting resistance from its e-motor acting as a generator; does this mode cause more fuel use?


I believe both options are viable... Do you remember using one or both options, and which is the most economic?


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 #3886 on: 17 Jul , 2018, 17:03 »
Hello Mr. Tore,


I updated pages 426, 427, 428, and added the index back to Skizzenbuch. The latest version of Skizzenbuch is in the Dropbox folder...


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

Online tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3887 on: 18 Jul , 2018, 00:41 »
Don fuelconserving.

You are entering into a very complex area in the operation of the submarine diesels, introducing many  unknown elements as the submarines variation in water resistance related to the speed, propeller efficency in relation to revs., dieselengine variation of specific fuelconsumption related to the bmep ( brake mean effective pressures) etc. We did not have access to all these figures so we did not have any instructions as to the variation in the operation modes.
The specific fuelconsumption is usually measured at the testbed using a waterbrake, following the theoretical propellerlaw, the result is not always matching the real thing onboard, certainly not on a submarine having so many variables. In your proposal you introduce a load which increases the BMEP outside the propellerlaw graph (waterbrake).  I have no figures, but should imagine your theoretical suggestion could be viable, but you have to watch your engine (exhaust temperatures) carefully not to overload the engine (excessive BMEP). I don`t think you should include this topics in the Skizzenbuch, its a topic for the real theoretical experts.
Tore
« Last Edit: 18 Jul , 2018, 00:43 by tore »

Online tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3888 on: 18 Jul , 2018, 01:33 »
Don Skizzenbuch page 426, 427, 428.

Checked OK. May be you should use ahead pads and astern pads for the Michelle thrustbearing instead of forward pads and aft pads.
Tore

Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3889 on: 18 Jul , 2018, 09:58 »
Hello Mr. Tore,


I took your advise and changed the thrust pads to ahead and astern...  I was not going to add the info discussed about fuel economy running. I was just curious...


Also, I updated Skizzenbuch to reflect the changes in Dropbox...


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

Online tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3890 on: 18 Jul , 2018, 10:21 »
Don, very good. As to the very complex picture of fuel economy and the many way of operating dieselengines-generator/E-motor I guess it would have been an interesting thing for an IT man to make an optimal programme for the various running modes with the numerous variables.
Tore

Offline bianco64squalo

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3891 on: 18 Jul , 2018, 23:45 »
Hi Don and Tore,
I was wondering when you expect to finish the work on Skizzenbuch.
You know that there are several U-Boat enthusiast waiting for the availabilty of your work, obviously paying for it...
The problem has already been addressed, and one possible solution is to make a file available and printable on demand, upon payment.
What do you think about ?
An answer would be welcome.
Respect.
Fillippo from Padova

Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3892 on: 19 Jul , 2018, 00:44 »
Hello Fillippo,


As far as I'm concerned, "Skizzenbuch: U-Boat Type VII C Project" is complete. I do not plan on adding anything to the 516 page document. Possibly some grammar corrections and having the two (2) pages allocated as a foreword done by a friend.


A book publisher Casemate Publishers UK is looking at Skizzenbuch as a possible e-book in a PDF Format. They have downloaded my full PDF file "Skizzenbuch 11 x 17 - M + I.pdf and will let me know their decision in about 2 - 3 weeks. 


However, if they decide not to publish the PDF, then I will absorb the expense by getting a US copyright ($55.00 for multiple authors) and create a US State of Georgia Publishing Company LLC ($150.00) sometime in November or December of this year. Then in January, I will purchase CopySafe Software ($295.00) to protect the distributed free PDF file.


Free distribution may be done through several websites to be determined...


Regards,
Don_
« Last Edit: 19 Jul , 2018, 17:42 by Don Prince »
A man’s got to know his limitations…
Harry Callahan, SFPD

Offline Raymic1

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3893 on: 19 Jul , 2018, 19:59 »
Fantastic Don.
I hope this all goes well.
Look forward to getting it in some way soon.


Ps I hope Casement don't put it out with a massive premium. As a unique specialist tech doco I'm assuming in hard book form it would be quite expensive. I wonder if the PDF from them will be the same.?
Cheers

Offline Don Prince

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3894 on: 29 Jul , 2018, 23:58 »
Hello Mr. Tore,


U-96 had an early bridge/tower design that had air stacks on the inside of the bridge, and intake stack windows/panels on the outside of the bridge. These stacks are for the diesel air supply. However, there is the diesel air stack under the winter garden in back of the tower with a mushroom type top valve. I don't believe there was a connection between the two? Was this just a means to get air below the winter garden? It looks like later bridge/tower designs eliminated the two bridge stacks...


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

Online tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3895 on: 30 Jul , 2018, 06:36 »
Don.
I don`t think there is a connection, the dieselair main input is the main disk valve on top of the diesel air duct inside the tower casing and the towercasing inlet ducts are merely to ensure sufficient air access to the void space inside the casing. Likewise the external ventilation ducts have the main inlet (and, in the older version, outlet) inside the towercasing. There are some variations in the arrangement particularly after the introduction of the schnorchel system. In spite of the well protected inlet of the dieselairduct a substatial amount of water entered the engine room bilge in rough  weather, this is one of the reason the external ventilation duct is separately from the large dieselair duct as you want to avoid water intrusion to the electric fans. The ventilation inletvalve casing had a special drainage system to the controlroom bilge as well. 
Tore

Online tore

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Re: Tores mailbox VIIC and VIIC/41 operation and technical details
« Reply #3896 on: 30 Jul , 2018, 06:47 »
Don
The reason for the complicated arrangement of having separate ducts for the various air inlets is if you would have the inlet for the diesels via f.i. the bridgehatch the large diesels would created an excessive "draught" through the bridge hatch making difficult to use as an access hatch.
Tore