Sunday morning and dockyard is calling!
I found it in the Rössler book: As the fins had no remarkable effect for the hydroplanes and to reduce the waterdrag (7%), the were removed at the bow.The aft ones remained in place to protect the control surface. So the holes were filled and sanded:



...and the "protectors" glued to the stern




Michael

I thought it was the other way around ... originally designed without bowplanes by an ambitious designer with visions of low drag, they later found them necessary. You just don't have enough fine depth control to maintain periscope depth accurately without bowplanes or sailplanes. The sternplanes make the boat porpoise too much. I know, we tried it on my first boat with the sailplanes static and using the sternplanes only ... just for laughs ... and just for a few minutes. Sucked.

Listen, periscope depth is a challange, especially with a heavy sea state. The ol' man gets really dissed when his scope keeps going under ... and he has to log every time the sail broaches, too! Now, add a snorkel headvalve that keeps slamming shut and popping everybody's ears ... and you really find that you need those forward planes, man. Seriously! A planesman at PD is one busy guy, watching the shallow depth gauge like a hawk, constantly pulling rise and pushing dive back-and-forth, trying to keep on top of what the boat's doing. He gets yelled at a lot. "Scope's under ... DIVE! Mark your depth, dammit!"

Once submerged at depth, it is possible to trim the boat and set the sternplanes static in one position and then maintain depth with the bowplanes or sailplanes ... and that's often done. But sternplanes only just makes the boat bob up and down too much.

I think the 23 started out with sternplanes only and then ended up with both.

I believe Michael is talking about those fin-like guards being removed from the bow, not the planes themselves. Al

Oh, I see ... didn't understand that. I think those were for keeping netting from snagging on the planes ... and also to protect the planes from banging against the tender while tied up. I hadn't realized they had removed the guards. Thanks for setting that straight, Al.

I actually DID read that the 23 started out originally as a prototype without bowplanes, though.

Yes, they started the design without bowplanes and decided 1944 to add them guarded with fins. And this fins were later removed to reduce drag (7%), the bowplanes were still in place.


Michael

The use of camels when tying up to another vessel or a pier protects the planes ... also retractable bow planes protect themselves. Modern boats don't have these fins protecting the planes ... although some of the Russian boats had fixed stern planes with what amounts to ailerons on the trailing edge, like an aircraft's horizontal stab.

I think those 'fins' on the XXIII were mostly intended to deflect cables away from, and possibly snagging on, the planes, particularly the mooring cables of underwater mines. Al

Michael,

Do you have any detailed photos of your most excellent fabrication of the inside dogs and linkages for your watertight hatch? I can't believe how realistic that thing looks and I've seen plenty of them. Can you digress just a little on what materials you used for those, please?

It looks like tubular plastruct, brass wire, and a few triangular pieces. Very impressive; the hatch looks "heavy" the way it should.

Also, have you fabricated the torpedo tube watertight doors' opening linkages yet?

I used styrene waste and evergreen to scratch the hatch; the spring is made of some lead wire and I found this pics in the www:



The opening linkages of the torpedo tube (I think you mean the connection between inner and outer doors?) are hidden behind the outer door, so I left them out!


Michael

Old pic with painted hatch:

Actually, I meant the through-bulkhead rod coupled to the bellcrank that actually opens the outer torpedo tube muzzle door. The inner torpedo tube door is inside the torpedo room and the outer torpedo tube muzzle door is at the other end. This round outer door ... not to be confused with the rectangular shutter ... has a bellcrank above its hinge and the through-bulkhead rod pushes on that bellcrank and pivots the door open.

One other question: are we sure that the shutter, when opened, is against the inner surface of the now-opened torpedo tube muzzle door? Some subs had the shutter cranked inward first and then the muzzle door was pivoted open outside of that afterward.

Apparently, opening the shutters was a noisy evolution due to their hinges and guides and these were opened well before commencing an attack run. The tubes were only flooded, equalized, and unmuzzled just prior to shooting. That way, aborting an attack left you with still-dry torpedoes.

If any of you have a photo of the shutters and muzzle doors opened, that will be appreciated.

Maybe this can help:

...and here's that mechanism on a type XXI boat:



Michael

Well, I did some searching and found a post in another forum which seems to confirm that you have it correctly depicted with regard to the shutter being outside of the muzzle door. From the "Fine Scale Modeler" web forum I found this post:

"WARNING!!!!!
Several days ago I put some info here, that I've found to be bad.
I have always believed that the torpedo tube outer doors and shutters operated in the same way as their US counter parts. I WAS WRONG !!!
The US doors and shutters open in one motion. the outboard edge of the muzzle door is attached to the aft end of the shutter, by a hinge. When the door opens it pushes the shutter foreward and inboard, clearing the torpedo's path. It's quick, simple and as close to "Sailor Proof", as anything can get.
However, the Germans did it differently.
First the door was cranked open, until it was parallel to the centerline and well inboard of the torpedo tube. Then the shutter was cranked open. It was hinged to the hull, at the foreward end. The aft end swung inboard, until the shutter was parallel to the centerline, against the door and out of the torpedo's path.
When the torpedo tube was fully open, and ready to fire, the muzzle door was hidden behind the shutter, except for the door hinges and a small portion of its inboard edge.
I hope no one acted on my earlier info. I did, and I'm now filling, rebuilding and reshaping the modified parts.
Mike "

It appears that the hinge for the muzzle door must be stood-off inboard from the torpedo tube a fair distance so that the muzzle door leaves enough room for the shutter to close in and still be out of the torpedo's line of travel.

It also now appears that the hinge and bellcrank will be visible because the rear edge of the shutter is considerably farther forward of the hinge when open. This is because of the angled cut of the end of the torpedo tube. The shutter would have to clear that longer, outer edge of the torpedo tube.

Bottom line: I'm going to have to kit-bash that hinge and bellcrank if I model the tube open and ready to shoot.

Normally it's time for painting... But first the tower has to be glued to the hull and than the periscope isn't in reach. And I wasn't satisfied with it. So time for scratching:

   

With some paint:



Why this effort? The periscope is visible through the opened hatch:



It wasn't easy tp bring this little thing into focus, but you can have a sense...


Michael

A better pic of the periscope:



And back to the FuMB 26 Tunis: there was a frame missing and the sloped ends glued to the pole:




Michael

Hi Michael,

Terrific work,

Al

Totally in awe, Michael.

The paint job started with lines of XF-1 Black as a try of preshading, followed with XF-9 Hull Red for weared off areas:

   

XF-54 Dark Sea Grey was the next to cover a layer of hair spray and the rest of the upper boat:

   

   

Cloudy gray and some black lines are still visible. A hard paint brush, a toothpick and warm water was uses to create some wearing.

   

   



The faults were filled with X-10 Gun Metal to show some steel:

   

...some pics with different angles of view to show the effect:

   

Before starting more weathering the underwater hull's waiting for a darker gray (XF-24).


Michael

That looks real good Michael. Al

Great weathering effects Michael, looking really good.

Si

How will you weather the propellor, Michael? It can't stay shiny brass ... the bronze props all turn into a dark brown.

...long ago posted






Michael

Ausgezeichnet!

FuMB-26 Tunis got some paint, cable connection and a clear cover in front of the FuMB-25 "Mücke" cone:






Michael

Hi Michael,

Looking good.

Al