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U-552 Type VIIc Submersible by yvesvidal - Trumpeter - 1/48 - Plastic

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I just received a parcel from Oto (RCSUBS). Shipping goes fast, less than a week.


This contains the rear bulkhead for the pressure hull, the torpedo doors set and some brass to finish the model and its stand (in some remote future): 


And the associated instructions to assemble the doors: 


More work in perspective....



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NIce added details. These after-market brass bits - sometimes in the many hundreds+ pieces tend to double the price of the original kit but add many times over that in the look of the completed build. Well worth the added cost IMO


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I worked on the torpedoes doors. Not an easy task. Keep in mind that a few parts have to be fabricated as nothing is provided in the kit by Trumpeter. Once again, the PEs from RCSUBS bring a nice addition to that delicate part of the Type VIIc submersible: 


Using brass rods, I fabricated 4 commands to link the door mechanisms to the front bulkhead:


Once painted: 





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A few little progress. Fine tuning of the torpedo doors and time consuming details. 


I found an old can of primer Plasti-Kote TR-253, in light gray. This stuff is fantastic and I remember using it years ago on brass. It covers very well, remains supple, is easy to feather and sand delightfully. Yes, the Vallejo is okay for plastic, but I had to peel it on all my brass PE parts before applying the TR-253. The primer is very matte, lacquer based and will likely accept acrylic Tamiya paints with eagerness. What a difference: 


The main hull is pretty much ready. The link between main hull and stern is almost invisible: 


Some primer was over-sprayed on the deck. It really sticks.


All the details of the stern, propeller shafts and PE parts have been sprayed. It looks harmonious and ready for painting: 


So, the next problem is finding another can of that product. The new packaging with the high-tech nozzle does NOT work. There are many people complaining on the internet about the new stuff, and I need to find the old style can. Why do they have to change a working recipe?







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After long hours spent thinking about the best way to present this model, I decided to go to my local hardware store to see what I could find. The Trumpeter stands are not bad but come short for a more elegant presentation.


They are perfect to hold the two halves of hull together and provide a nice stand to work on the model, during its construction. The keel locks in place and the support is very sturdy. However, I wanted something more unique and that would provide the onlooker, a chance to see the underneath of the machine. So, I decided to get two 6 inches long piece of brass tubing, which would allow me to pass the electrical wires into the base.


The brass nuts are fitting tightly, after carving some of the plastic away, and the anchoring is secured with two components epoxy glue. 


Only the main hull will be supported, the other half locking into place in the stern and the multiple magnets. The result seems to be strong and sturdy and will be perfect once I get the second anchors in place. I expect the model to weight close to 10 pounds once finished: 


I am glad that this decision and implementation is almost behind me. That was not too easy. The Trumpeter stands can be used during the construction. Now, I need to find a nice board to present the whole enchilada..... Suggestions are welcome. That stuff will have to be close to 5 feet long and house the wires and a couple of contacts.



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I'm confused (normal for me).  Your post mentions gluing the "nuts" but the bottom photo only shows one.   I hope that was just a test and you're doing a second mount point.  Most excellent idea though getting it up and off the display base and also to hide the wiring.


I think you'll have make a "box" so the wiring can run underneath it.  Hit one of the home supply places.  They often have some nice woods like cherry, etc.  

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Both "nipples" (that is the plumbing term) have been installed: 


I think this arrangement is providing for a safe and strong stand, for a heavy model: 


The menacing torpedo doors: 


As expected, the nipples will provide easy access to the underneath of the hull, to allow the display of all these beautiful PE parts: 




The heavy work on the hull mostly done, I can now move to the interesting part of populating the decks, with all the PE parts..... or perhaps the rear torpedo room and electrical motors.





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So, the next construction step will be addressing the rear compartment: Torpedo room and electric motors bay.


I managed to find on the Internet, a translation of the original German Type VIIc manual that was provided with each submersible. This manual has nothing to do with what was published by the group of military scientists that captured the U-505 (Chicago Museum of technology) and reverse engineered it. It is the real deal that was given to every German commander to operate their vessel in the Atlantic. It is a mine of information and I will try to publish some excerpts as we move along the construction. The manual was written in German (of course) and has been translated in English by Maciek Florek. It refers to Submarines built in 1939 and thus corresponds to our model of the U-552.


The following describes the Machinery and Propulsion Plant. You can see the main Diesel engine, followed by the primary clutch, the electric motor/generator, followed by a second clutch, main thrust bearing, stuffing box, shaft and propeller.

Motorwelle Engine shaft
    Schwingungsdämpfer Flywheel
    Dieselmotor Diesel engine
Dieselmotorkupplung Diesel engine clutch
E-Machine welle E Motor shaft
    Schott 16-1/2 Bulkhead (frame 16-1/2)
    Maschine 2 Motor 2
    E Maschine E motor
    Maschine 1 Motor 1
Hauptkupplung Main clutch
Druckwelle Thrust shaft
    Hauptdrucklager Main thrust bearing
    Flanschenkupplung Flange coupling
Schraubenwelle Propeller shaft
    Wellenbremse Shaft brake
    Stopfbuchse Stuffing box
    Druckörper Pressure hull
    Vorderes Stevenrohrlager Forward - Stern tube bearing
    Hinteres Stevenrohrlager Aft - Stern tube bearing
    Wellenbocklager Shaft strut bearing
    Schraube Propeller




More details soon.



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Another excerpts of the "Manual", explaining what are the five modes of the propulsion plant. The Support and Buffer mode is particularly interesting and very advanced in its behavior:


Inter-operation of the engines and motors.
  a) General.
    The diesel engines provide a maximum surface speed of about 18 knots and both E-motors provide a submerged speed of 8 knots.  The different working modes are listed below:

        Diesel engine only drive,


        E motors only drive,


        Support and buffer mode,


        Diesel-electric drive,


        Charging mode.

    Exhaust gas from both diesel engines can be diverted and used for blowing out the main ballast tanks and main ballast and reserve fuel oil tanks.
  b) Diesel engine only drive.

In diesel engine only drive; both diesel engines drive the propellers via the diesel engine couplings, E motors, main couplings, thrust shafts and the propeller shafts.


In this arrangement the E motors are just a part of the drive train and the armatures are un-powered.  The fan blowers of the E motors rotate slowly powered by voltage generated due to the remanent magnetism of the un-powered rotating armature.

  c) E motors only.

With E motor drive only, the diesel engine coupling is un-clutched.  The E motors are powered by the battery and work as motors driving the propellers via the main couplings, thrust shafts and the propeller shafts.

  d) Support and buffer mode.

In support mode, the output power of the diesel engines is increased by switching on the E motors additionally.  Each diesel engine via the diesel engine coupling and in addition each E motor acting as a motor drives the propeller.  The buffer mode is used in rough seas.  The diesel engines drive the ship's propellers as in "Diesel engine only drive".  The E motor voltage is adjusted such that with normal conditions the loading and discharge current

    are equal to zero.  If the screw runs above the surface, thus causing unintentional reduction of load on the diesel engine, the E motor works as a generator preventing an inadmissible increase in diesel RPM.
  e) Diesel-electric drive.

Diesel-electric drive allows driving both propellers even if one diesel engine has failed.  The operational diesel engine works directly driving the propeller on its side.  The E motor whose armature would normally run idle, works as a generator delivering power to the other ship side.  The E motor on the other side drives the propeller; the diesel engine clutch is disengaged.  The current from the primary E motor can either be switched in such a way that it only drives the secondary E motor or an additional light charge of the batteries takes place.

  f) Charging operation.

Charging operations can be differentiated as follows:


        Charging with a disengaged propeller shaft,

            Charging while running on the surface with diesel engines.

When charging with a disengaged propeller shaft, the diesel engine drives the E motor via the diesel engine clutch.  The E motor runs as a generator and charges the storage batteries.


When charging while on the surface with the diesel engines; the diesel engine power drives the propeller.  At a constant number of revolutions from the diesel engine, the E motor charges the batteries.  In this case, the diesel engine must provide power for the propeller and for charging.



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I am afraid there won't be much updates for a while. I am debating how to build the rear electric motor compartment and wish to present both motors.


Trumpeter really simplified this compartment with just one motor and very few other parts. I suspect that this was their last module and they probably had too much rice alcohol in their system, when designing it. They could have included both motors, both clutches and both shafts but decided to go cheap and not provide them. 


I am trying to obtain spare parts from Trumpeter and that is a major challenge. Some people have made it, most could not get anything. I have also contacted one person who built that same kit, without the interior and offered to purchase the internal parts. There, again, no response.


I may have to fabricate the parts myself, but it will never reach the level of precision of the molded injected parts. So, I am revamping the compartment, to place in the front what would have been relegated to the back of the module (a la Trumpeter). 


If anyone has a lead to purchase sprues X, Y and V, please let me know. Ideally, and if I could afford it, it would be worth buying two kits, keeping some sprues and re-selling the rest for someone who wishes to build the external hull only.


Decisions, decisions......



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7 hours ago, popeye the sailor said:

have you checked E-bay or various flea markets in your area........shoot,  even utilize the builtin board at your local grocer and hobby shop!

Yes, I have checked a lot of things on the Internet. It is not a common kit (due to its size and price) and thus the odds are not in my favor. 
I also have sent three E-mails to Joanna@trumpeter-parts.com with no answer so far. She must be vacationing in Paris or too busy to answer.


So, I have decided to move along and fabricate the parts myself. It will not be as nice as the molded parts (far from that), but since they will be behind, it may be acceptable for the time being. If I ever find some spare sprues, I can always rework the rear module.



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Yes, I checked Shapeways and they are way overpriced for custom jobs. Even their parts for submarine kits at 1/48 scale are rather expensive, although beautifully made. I also looked into molding plastic parts. That is a whole new world for me and I am not sure I can do that with success. For the time being I am going to go with my own fabrication and try to disguise it in the best possible way. Maybe Joanna in China will respond one day....


Some progress on the rear compartment. This is how the kit is built: 


All the good stuff is hidden from view. Very poor design from Trumpeter. Then only one electric motor/generator is provided. That is the parts that are the most difficult to recreate. My implementation will be very approximate for a good reason.


I have replicated the three ribs provided in the kit and placed the original parts in the front. The rear part are absolutely non visible, once the compartment is completed.


The roof section was presenting a large opening, perfectly visible. It was necessary to remedy to it.


Finally, the bulkhead with the electric motor stands and torpedo storage platform: 


We will see how to go from there.





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Some small progress with the installation of electric motors. Just to give you a sense of what is being prepared: 



Joanna (from Trumpeter) has not responded yet. Let's face it, she probably will never do.


The platform is painted with Vallejo Stainless Steel and re-enforced underneath with two strips of 0.080 x 0.080 from Evergreen. That makes it a lot more realistic.



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1 hour ago, yvesvidal said:

Joanna (from Trumpeter) has not responded yet. Let's face it, she probably will never do.


Have you tried contact Stevens International for the parts trees? Stevens is the USA distributor for Trumpeter. it's unlikely the Chinese will deal directly with you as Stevens likely has a contract with them as the sole USA distributor. I would definitely contact Stevens for the parts you want. it may take a while, but they may have them.


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A few words about the electric motors. Yes, as you may have guessed, I am trying to give some movements to that otherwise static model.


The original submarine had two propellers running in a contra-rotating way, as always. I am using small Chinese motors with a high reduction gear, giving me a rotation speed of 40 RPM to 60 RPM, depending of the voltage applied to them (around 6 VDC).


Since, the whole model will be powered in 12 Volts, I placed these two motors in series, making sure that they spin in the right direction as the prototype was. The propeller shafts are made of Brass tubes and rods as we saw previously. Because of the extremely slow speed of rotation, there will be no need for bearings of any kinds (or even lubrication). I just may have to hide the rubber tubes that will be used to couple the shafts to the motors.


Here is a picture of the electric motor compartment of the U-995: 



Talking about the "real" electric motors on a Type VIIc, here is an excerpts of the "Manual" : 


  a) Design and performance data.
Manufacturer B.B.C. Mannheim
  A.E.G. Berlin
Weight of a machine with fan blower B.B.C. 8100 kg.
  A.E.G. 8170 kg.
U-505TableMargin.gif U-505TableMargin.gif  
Motor rated power: 276/238 kW (60 min/continuous)
  Rated current: 1470/1240 A (60 min/continuous)
  Voltage: 210 V
  Number of revolutions: 295/280 RPM (60 min/continuous)
  Excitation voltage and current: 110 V  28 A
Generator rated power: 465kW(continuous)
  Rated current: 1550 A
  Voltage: 300 V
  Number of revolutions: 450 RPM
  Excitation voltage and current: 110 V  28 A
  b) Machine construction and connections.

The E motors serve as motors to drive the propellers and as generators to charge the batteries.  Each E motor is built as a fan cooled, totally enclosed, direct current, double-armature, with compound winding and commutating poles, has 2 x 8 main poles and just as many commutating poles.  The motors are designed for forward and backward drive.  Both armatures of the E motor can be connected in series or in parallel for drive.  If one armature is damaged, the motor can still be driven in parallel connection.


Cooling is provided by a blower directly attached to each motor.  It draws fresh air from E motor room and blows it into the center of the E motor.  The exhausted air is cooled in 2 water-cooled air coolers lying between the E motors.

    E motor armature connections:
Drive setting
Setting of the armature
Dead slow
half speed
2 x half speed
Drive setting
Setting of the armature
3/4 speed
2 x 3/4 speed
Emergency speed



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Working on the roof of the rear compartment: 



The Trumpeter kit is more or less accurate here and there is room for additional details. The holes will host the four white LEDs, the last hole to the left is the rudder control axle. Some of the pipes are original and prototypical, others have been left to the imagination of the artist.


The mechanism on the ceiling of the rear compartment is the manual control of the rudders, in case of the failure of the electric systems. A large wheel will take place, once I have painted the ceiling.


From the "Manual": 


1)  Steering System.
    The rudder installation includes the following:
            Two identical main rudder planes parallel to each other,
            Forward dive planes,
            After dive planes,
            Plane drive,
            Steering stations,
            Steering lines.
    Steering plane construction:
    To keep the driving force low, all steering planes are built as displacement, balanced rudders.  They are made from watertight plating on both sides, with stiffeners provided between the plates.  The spaces between plates are filled with tarred wood.
    Steering plane protection:
    A skeg is provided to protect the main rudder, especially from hitting the bottom, from which two arms lead to both rudders and are attached to the rudder pins.  To prevent entanglement with naval mine wires and antisubmarine nets all linkages are made smooth and all faces are rounded.
    The outer edges of dive planes are protected against naval mine wires.
    To avoid corrosion (galvanic current between bronze and steel in sea water) all steering planes are provided with zinc protection plates.
Main rudder installation.
    The main rudder is twin type and can be either electrically or manually driven.
U-505TableMargin.gif U-505TableMargin.gif U-505TableMargin.gif
    The main rudder is driven by means of vertical intermediate shaft, which passes through the pressure hull between frames 1 and 2 and which is driven by worm gear.  The shaft bearing is installed at the pressure hull and is re-tightened from inside by a stuffing box.
    The top of the intermediate shaft (in the upper-deck) is attached to a double arm, which is connected by means of two long connecting rods with two, center-facing, main rudder arms.  Each main rudder has an area of 2.75 m².  The rudder maximum deflection is 33° when electrically driven and 35° when manually driven.
U-505TableMargin.gif U-505TableMargin.gif U-505TableMargin.gif
Ruderblätter Rudder planes
Fester winkel Fixed angle
Drehpunkt des Ruderblattes Pivot point of rudder planes
Hauptruderhebel Main rudder arm
Schubstange Connecting rod
Senkrechte Zwischenwelle Vertical intermediate shaft
Doppelhebel Double arm


    The maximum deflection of the main rudder and forward and aft dive planes is limited electrically by means of a limit switch and mechanically by means of mechanical limit stop.



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The ceiling of the rear torpedoes / electric motors room, is pretty much done: 


Decals have been added on the dials and indicators. When dry, I place a few drops of clear-coat to simulate the glass lenses.


The wheel is used in case of emergency and failure of the main steering system.


It looks relatively realistic. I am avoiding the dirty / patina presentation as most of these vessels were well maintained during their short lives, at least in the inside.




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