Full build report: Uboat XXI (1/72) – sunk and raised (years later)

[falo]

P R O L O G U E

Hi Gents,

this is the beginning of my Type XXI U-Boat build report. The kit was a chistmas present to me in 2016. I needed one and a half year to finish the XXI as I took my time. It is planned that the boat shall be later a part of a sculpture of which more later at the end of the build report. So this boat will be no stand alone model – this factor is to consider.

The kit is from rcsubs (Oto Gerza) and IMO only for modellers with advanced skills and still more patience. I don’t know if these above mentioned requirements are dead-on to me but I gave my all to stand the pace with all these fantastic build reports here on AMP. So please bear with me.

My aim was to replicate a XXI which is heavily weathered respectively to imitate the look of a boat which was sunk and raised (years later) as a wreck – like U 2540 the later „Wilhelm Bauer“ and today „serving“ as a museum boat in Bremerhaven (northern Germany) and reconfigured to (wartime) U 2540.

The kit is finished so this is a „fast forward“-build report limited by sorting all the pics and notices. Due to this circumstances I show first of all detail pictures of the finished work to arouse your interest. The next post will start in chronology beginning with an deep inbox review.

Please stay tuned!
Thanks and best regards.
falo

[SG]

WOW!i dig it. Excellent Excellent Excellent work Falo!

[GlennCauley]

This is a MODEL?!?
Wow... I thought these were pics of the real thing.


Incredible, my friend, just incredible.


Looking forward to seeing the work-in-progress report. 

[Islandern]

Looks fantastic, what a great build and weathering!

[falo]

@ SG, Glenn and Anders: Thanks for your warm Words.

Regards
falo

[falo]

B U I L D   R E P O R T

What’s in the box? Parts breakdown

So let’s start with an deep inbox review and as already mentioned in the first post of this thread I will report from now on chronology. The kit comes in a very sturdy cardboard box and after opening you’ll find the following parts:
– blueprint respectively more a schematic drawing in 1/72 scale (the photo etch parts are highlighted in grey and deep black),
– three photo etch frets,
– vacu formed hull divided in four parts and „Balkongeraet“ (hull parts are rough pre-cut),
– sheet leftovers from the vacu forming process,
– 3d printed parts, for example the conning tower is printed in one piece with open flood holes,
– and a compact disc with historical pictures of the XXI and pics from Oto’s own build.

The kit don’t supply you with the following items:
– periscopes,
– 2 cm gun barrels for the AA guns (four barrels needed),
– propellers and anchor,
– UZO with binoculars,
– radio direction finder antenna loop,
– hatch for the conning tower and (visible) inner structure of the ct.

Most of the above listed („missing“) items are available on the aftermarket for example the well known suppliers/companies like „Eduard“, „CMK Kits“, „l’Arsenal“ or „Shapeways“ (3D shop). So IMO it won’t be an issue to get hands on these parts. Hope I don’t forget an item, in that case I will give it later.

Conclusion:
This model is far away from being a shake and bake kit like those from Tamiya, but I didn’t expect this either and finally this kit is after my fancy.

If you have any questions please don’t hesitate to ask.

Best regards.
falo

[falo]

Horror vacu(i)?

The work began with the four parts hull (vacu formed).

I used the schematic drawing to cut the hull to length. I fixed stern and bow to the drawing and cut away the overhanging vacu material – in the middle where the two hull parts meet – to get the accurate length of the complete boat.

Previously I had compared the supplied drawing with those shown in „Vom Original zum Modell – XXI“ virtually as a measurement back-up. At the end I get two halves, but as I reached this task, I was aware that the hole vacu deck from stern to bow was to broad. One look at the drawings from the above mentioned book approved my appreciation. But you will see (later in this build report) that this was not an issue because the whole deck will be constructed by photo etch parts. It was just a matter of the support construction for the pe parts.

To stabilize the hull halves I supported the seam with „Revell plasto“ on the outside and inside I used plastic card stripes strengthened by two component filler for cars. In addition the vacu parts are stable and round about 1,5 mm thick so no frames were needed to steady the hull at this stage of the build. I suppose this thickness was opted because the kit was priority designed for radio control (rc) models and that means you need space for the pump and propulsion system, propeller shaft and so forth.

For control purposes I fixed the two halves with Tamiya tape and let the „complete“ hull rest on my favorite chair. Later on I realized that the hull was to long for my motor skills because nearly every doorframe was „kissed“ by the hull during changing my workplace from working bench to my balcony where I did filling, drilling, sanding and painting. Now it crosses my mind but too late to change the thread title in „sunk, raised and dinted years later“.

Best regards.
falo

[falo]

Missing cheeks

As said before I compared the supplied drawing from time to time with those from Koehl/Roessler („Vom Original zum Modell – XXI“) and soon I saw that the vacu hulls missed the – what I call – the „cheeks“. If you look at "Frame_32.jpg" (red encircled) for example you know what I mean. A friend of mine has an unassembled XXI from Revell (1/144) and so I got an impression how the cheeks looked like.

Before I formed the cheeks I added the vertical lines of the bow for orientation matters with a felt pen. The original XXI boats were built in sections by different yards. Finally the sections were shipped and put together from one specialized yard. Every XXI had eight hull sections ("Sections.jpg"). Without thinking too much I took DiBond sheets from my spare box to form the cheeks for both sides of the hull. The DiBond material is ideal for bending but later I learned it the hard way that the DiBond choice was an (time-consuming) mistake. I suppose due to the relativ thick vacu material (circa 1,5 mm) the cheeks are not reproducible through the vacu form proceeded. But IMO it is no great task to add the cheeks for the smart modeller who would choose plastic card for that task of course 

Best regards.
falo

[falo]

Panel line transfer

The next task was to mark all the panel lines on the two hull halves with a view to the scribing. Again I had an eye on the drawings of Koehl and Roessler as mentioned before. Though I omitted the three torp doors because I want to show them in a open position and for that purpose I opted a laser cut solution so a vector drawing was required based on Koehl and Roesslers drawings. Jobwise I use Adobe Illustrator for vector drawings so this was not a big deal, learn more about that in the next post.

I marked the hull cutouts for the photo etch parts with a felt pen. Some cutouts had to be positioned directly on the in a further mentioned cheeks. To saw out these cutouts from the DiBond cheeks was very time consuming because the material has three layers: Aluminium a kind of black rubber (high-density) and again aluminum. The aluminum was difficult to saw out and sand. The rubber core frayed during sanding and slowed down the saw blade nearly to halt. As I said a post before the DiBond material was ideal for bending the cheeks in a rounded form but rework would be needless if I had chosen plastic sheet for that task. Learning never stops.

Best regards.
falo

[falo]

Photo etched and laser cut parts

At a first step It’s important to seek and glue the pe parts before starting scribing because some recessed lines from the photo etch has to match the marked lines respectively the felt pen lines has to align the recessed lines. And remember that the XXI was built in eight sections (plus conning tower of course) so the lines has also to align the deck to simulate correctly the sections.

With an eye on the weathering process I altered the depth of my scribed lines to simulate a more or less overgrown edges. You will see later that this was helpful to figure wear and tear on these areas. Unnecessary to mention that my „beloved“ DiBond material was very stubborn during the scribing process, I have to order a lot of spare scribing blades.

Besides: That’s IMO the annoying thing during building a ship hull: You have to do it for both halves. Next time I will build a asynchrony ship like the „B-Wing“ from the Star Wars movies!

As mentioned in the Post before the laser cuts based again on the Koehl/Roesslers schematic drawings the chosen material was „Lexan“ because its thin, tough, flexible and reacted very good with superglue or two-component adhesive. Picture „DSC_0019.jpg“ shows the attributes of „Lexan“: For the above row of the flood holes the material has to be flexible, for the more straight row of the flood holes below the material has to be stiff.

Best regards.
falo

[falo]

Torp Doors

Again I have used Lexan as material for building the inner structures of the three torp doors. This time without a laser cut solution but supported by a leather punch and sanding sticks. Honestly I have to confess that I forgot to draw them with Adobe Illustrator during my work on the laser cuts so I practised my scratch building skills.

Maybe you have still in mind that the XXI shall be the center of a planned sculpture. This is the reason wherefore I wanted to show two of the three starboard torp doors in open position. Because later the track of the water bubbles – caused by a launched torpedo – shall be used as a retainer. Due to steadiness the core of this retainer is a hollow steel rod encased with the water simulation making from translucent two part epoxy, cotton wool and micro balls. Afterwards more about that task. Currently I’am occupied job wise and with a move so I have not begun yet with the second part of the sculpture but the XXI is finished together with the rod as mentioned in the first post of this thread.

Because of considering the rod I had to build in advance the inner torp doors to find the right inner hull position for the rod and the rod brackets. For that task i built two rough dummies from cardboard plastic stripes and straws. Later I build torpedo tube doors partial from scratch by using pe parts and again straws and styrene sheet. Unfortunately I have no pictures of this work stage only a blurred one („DSC_0050.jpg“). Sorry.

Best regards
falo

[cgbillb]

Falo
Nice job on your build, I have the same kit after about a hour I put it up on the top shelf for a some day build.
Bill

[falo]

Hi Bill,

thanks for your bland words.

From my today experience with that kit I have to say that the two hull halves were the most time consuming parts. And now I'am asking myself if it would have been better (and faster) to scratch build the complete hull. As a basis there is a good XXI paper model (1/100 so you have to scale it up to 1/72) from "Halinski Model Kartonowy". Certainly by using the kits excellent pe parts for the flood holes etc.

Regards
falo

[falo]

Scribing

After scribing both hull halves I used a dark wash as a panel liner to check, if I did not forget some panels.

To simulate the inner structures I test fitted some ribs temporary with blue tac. The ribs should later hold curved plastic card to simulate the recessed inner pressure hull and the frames. As opposed to a VII/C or a IXC you won’t see much of the inner pressure hull later.

During the construction it became clear that it could be an advantage to build such „sunken and raised“ U boat model because here and there occuring bungled work would or could be covered by the heavy weathering. However this also means that the time consuming scratch built parts (for example the inner structures of the torp doors) could be covered later by algae and seaweed too. A pity but easy come, easy go. With the hull length in front of me on my desk and the required pigments for it, I began parallel to made my own pigments for the weathering task by collecting small dry branches and autumn foliage and reduced them to very small pieces to bulk up my Lifecolor Set „Algae“ due to cost saving.

https://www.dersockelshop.de/farben-/lifecolor-combo-set-7-algae_lifecolor_spg07.html

Regards
falo

[falo]

Painting starts

At long last the fun began – the painting!

I used the hue „steel“ as a primer and as a revealer to show my filler and sanding errors (red circle: „DSC_0043.jpg“). Because of the sheer size of the two hull halves I forgot some parts of the hull to level out. So I had to reworked theses hull areas and prime them again. Due to cost saving I used a very fine filler from a car component store.

The second reason to use steel as a primer was to simulate the real shade of steel as a first layer of the weathering (of which more later). As well the steel color was purchased by the above mentioned car component store and decanted directly from the rattle can for using it with an airbrush system. Because I haven’t an airbrush system I asked a friend for help and he lent me his for while.

During priming more and more little flaws showed up. Today I suppose that the pauses between the plenty filler and sanding sessions were the reason why I forgot to fill some parts. Sometimes I had a delay for weeks until the next filler session starts. Maybe it would have been better to mark the intermediate results with a Post-it Sticker or Tamiya tape.


Regards
falo