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Hey, Jeff..... - TYPE VIIc question

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Postby Crazy Ivan » Thu Apr 27, 2006 9:23 pm

Jeff (or anyone else who knows),

What do these two little bumps on either side of the Revell hull represent? They look like reverse scoops, so maybe the aft ends should be opened up. But I'm not so sure....



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Postby JWLaRue » Thu Apr 27, 2006 10:06 pm

Hi George,

Reverse scoops is a good description of what they should look like...and yes, the aft ends should be opened. I can find/scan a photo and get it to you this weekend.

If memory serves, those are the vents for the torpedo tubes. Let me check to be sure since I believe I have only seen them described once in all the books I've gone through.

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Postby Crazy Ivan » Thu Apr 27, 2006 10:18 pm

OK, thanks!
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Postby JWLaRue » Mon May 01, 2006 8:18 pm

George,

Here are two photos that I've scanned and uploaded that show those protruding vents.....

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Postby Crazy Ivan » Mon May 01, 2006 11:49 pm

Thanks Jeff, I knew I could count on you! :D
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Postby KOEZE » Tue May 02, 2006 8:49 am

But unfortunately the exhausts are too low on the hull compared to these photo's
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Postby JWLaRue » Tue May 02, 2006 9:53 am

...either that or the height of the tube doors is wrong. Also notice that the relationship between the doors and the visible part of the pressure hull is not quite right as well.....

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Postby Crazy Ivan » Tue May 02, 2006 4:52 pm

And I'm guessing that the vent location likely did not vary on different boats. BTW, do you know which boats are in the photos?
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Postby gantu » Tue May 02, 2006 6:17 pm

This vent´s have something to do with the torpedopipes an exhaust valve for comprest air!
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Postby JWLaRue » Tue May 02, 2006 9:57 pm

George,

That's my observation as well....those vents were in the same place due to their function.

The top photo is the U-1060, which is a Type VIIF. The bottom photo did not have a U-number associated with it.

Gantu,

Yup, what I mentioned earlier. Thanks for the confirmation.

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Postby Don Prince » Fri May 05, 2006 10:04 pm

Hi Jeff,


The ports seem to be too high and too far to the stern... Aren't those the came as the simple holes in the earlier Type VIIc U-Boats?

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Postby JWLaRue » Fri May 05, 2006 10:41 pm

Hi Don,

I have seen some photos of earlier boats where the hull had a 'simple' opening that looked much like the casing slots.

....I'm not sure if I understand what you mean by to high and too far to the stern?

-tnx!

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Postby rokket » Sat May 06, 2006 4:30 am

Jeff - checked out your rc stuff, wow, very cool.

I agree that the vents are just not in the right place, and the p-hull seems a little off, but I'm not sure I'm going to alter/move either.

I didn't know the bumps were vents, wasn't the torp-launch air kept in the boat?
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Postby Don Prince » Sat May 06, 2006 10:49 pm

Hi Jeff,

I don't understand what the two ports were for... I don't believe they have anything to do with launching eels. Awhile back Ken Dunn wrote an excellent article for U-boat.net on the functionality of the German U-Boat torpedo tube...

Regards,
Don_

There was a plate that was inserted behind the torpedo before the inner torpedo door was closed. If you look closely at the lower left torpedo tube in the photo at: http://www.uboat.net/gallery/index.html? you will see the plate in place. There is a bar across the plate. I am not sure what metal the plate was made of but it weighted about 77 pounds. It had two "ears" that protruded from it that fit into corresponding groves in the torpedo tube walls - one grove at about 2 o'clock and the other grove at about 8 o'clock for the two tubes on the right and at about 10 o’clock & 4 o’clock on the left hand tubes. The bar in the photo shows their location. These groves were tapered near the outer end of the tube such that the plate slowed down before it stopped (perhaps to keep the noise down when it reached the end of travel but this is just a guess). When the compressed air entered the torpedo tube it did so between the plate and the inner torpedo tube door. As it expanded it pushed the torpedo out of the tube at a rate of about 10 meters a second. The plate stopped when it got to the end of the groves thus expelling the torpedo and sealing the tube so that none of the compressed air escaped into the sea and therefore no bubbles which would identify the U-boat's location were released. Water pressure after the torpedo was expelled forced the plate back down the tube venting the compressed air into the boat in the process until the plate stopped at the inner torpedo tube door. It did raise the pressure in the boat. There were also other things inside a U-boat (compressors etc.) that raised the pressure inside the boat but I suspect that firing torpedoes was one of the worst. Sometimes when the conning tower hatch was opened after the boat had been submerged for a while the hatch almost flew up as the pressure outside the boat was so much less than the pressure inside the boat. I don’t know if the pressure differential in the boat ever actually caused any problems more serious than ear problems but under the right circumstances it could have. Opening the conning tower hatch is the only way I know that they equalized the pressure inside the boat.

The plate (I don’t know it’s proper name however it is sometimes referred to as a “piston”) had to be removed before the tube could be reloaded and replaced again before the new torpedo could be fired.

I don’t know how soon the outer torpedo tube door had to be closed but at a minimum it had to be closed so the water that forced the plate back could be drained and the tube reloaded. An open outer tube door would have added some drag to the boat too so I assume they closed it as soon as possible.

I am not sure when the torpedo propellers started running normally however I have read of “hot runs” in the torpedo tubes of a U-boat before. In one case a “mine ejector” was used to eject the already running torpedo however I have no idea what a mine ejector looked like or how it worked.

Hope this helps.

Regards,

Ken Dunn




Edited By Don Prince on 1146970249
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Postby JWLaRue » Sun May 07, 2006 4:06 pm

Hi Don,

...sounds like Kevin Dunn is not too sure himself!

This looks to be something that we need to try to get some better information on.

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