A U-Boat In Ireland

[The Boattrainman]

After many coats of primer and sanding of blemishes the tower is now 'in the grey'.




I can't work on the attack scope raising mechanism till I start the hull, which is up next.




The Boattrainman

[The Boattrainman]

The six body shells are cleaned up and glued together, starting with the middle two which holds the 104mm WTC.




3mm holes are drilled in the bullheads to take a linkage using a flexible snake from aft to fore for the front dive planes.




The bulkheads are not glued in place yet, as they must be joggled under the deck and lined up so they are hidden beneath cross members.

In the first photo below, the top of the bulkhead is visible, and is hidden in the second photo where the pencil points.




The entire hull (fore, middle and aft sections) is taped together for strength and checked for alignment, forgot how big this think is at 1705mm/5 feet 7 inches!




The shells are made from 1mm - 1.5mm styrene and very delicate, so it's much easier to 'Dremel' out the slots for the scale flood and drain holes when they are stabilised by taping them all together.




The Boattrainman

[The Boattrainman]

The front dive planes are one of the kits strengths and are built as per the instructions.

A square is used to ensure they are level, at 90 degrees to the bow.




There are lots of kit supplied bits and pieces for linkages, but I'm going with a simple snake and plastic arm on the centre of the dive plane connecting rod.




However the rear dive planes and the prop shafts are a problem, as one of the major (one of many!) faults is the shafts exit the hull at an angle instead of straight in line with the keel.

The angle is so the shafts will connect with the two motors which are just below centre in the WTC, why the designers did this is a mystery as there is room to set the motors a bit lower and in line with the keel as per the prototype. As I'm building a new tech rack in the WTC, I'll re-set the motors position later.




To start to rectify this, the shaft shrouds are cut away for repositioning, I estimate moving them down 7/8mm will fix the outer appearance (they are the wrong shape, but I'll use them as the basis for better ones later).




This was a very difficult job, as the plastic is thick here and I wanted the shrouds intact, so a Dremel drill was not used just a sharp knife and lots of patience.

The Boattrainman

[The Boattrainman]

The next step is to sort the rudders.

The kit supplied rudder support is junk but useful as a template, the outline is drawn onto a scrap piece of wood.




4mm X 1mm brass bar is pinned to the board and soldered in place, then bent by hand in a vice to the shape of the original




The new support is used to align the rudders and their shafts, an extra piece of brass tube is put on top of the rudders as they don't butt up directly to the hull.




A square section piece of brass is used as a pillar and long 2mm machine bolts willbe used to secure the rudder support to the hull.




Now the rudder tubes can be epoxied inside the hull.

The Boattrainman

[The Boattrainman]

To set the square pillar, two pieces of styrene are inserted inside either side........




........and two small brass tubes one inside the other, so the 2mm machine screw will pass through the pillar straight into the hull.




The final arrangement with small plastic supports to hide the machine screws




The machine screws go into rivet nuts inside the hull, a brass bar is soldered to them to ensure they don't rotate and then they are flooded with epoxy.




Now the rudder tubes are given plastic surrounds and filled with epoxy, and the tubes are attached to the collets and ball end screws........




............... and the twin pushrods go to a rotating fitting, with a single pushrod to the WTC and rudder servo.




A neat system for a tight space with twin rudders.





The Boattrainman

[Scott T]

Love the square shafts in the round rudder tubes. Thought that might work.

[The Boattrainman]

Scott,

I had my doubts about the square shafts, the Robbe kit supplies square brass moulded into the rudders and square brass rod to join the two sets of dive planes

It works for perfect alignment, but the fit for the dive planes is a bit rough because you need to file the holes a bit in the hull and dive plane supports and the edges of the square tube tend to catch.

So I'm swopping the square tube for round tube for the dive planes, but the rudders are fine as is.

Rob

[The Boattrainman]

The square shaft is seen here at the end of the front dive planes.




It is swopped out for a 4mm round brass bar.




Next up is to set the rear dive plane supports, which in the instructions is described badly and to sort would require superhuman levels of 'eye hand' coordination.

Instead,I start by thickening the horizontal support with extra styrene as it's just too flimsy, and thinning the dive plan bar support piece as it's too big and inserting two 1mm pins in the end.




Two corresponding holes are drilled in the red prop shaft holder and then one more pin added to the end of the support going into the hull along a straight line drawn from the rear dive plane connecting rod (now also round).




This sets the supports parallel to the line of the keel, with the shaft added it should be straight.




I've read other build logs where this is a struggle, but I think it's from following the tortuous instructions in the manual, this way is easier, plus the pins mean you can remove and refit the pieces many time to get it all aligned.

A final picture with both supports on each side, all just pinned in place for the moment.




The Boattrainman

[bianco64squalo]

Hi Boattrainman,
altough I don't care about the working model ( I prefer the static ones ), I'm really delighted of your work and your cleverness.....
Five stars model, indeed....

[The Boattrainman]

Thank you my friend.

I've made this kit before, back in 2006, back then I went with a basic build as per the kit and then tried to retrofit the sub to U203 with very limited results. So this time I'm doing the modifications from the beginning, in fact the 28 page kit instructions are now no use, as from here on everything has to be modified or scratch built as per the conning tower.

And the jury is in, I'm going for U557, as this suits the tower modifications (mostly) from 1941, and most of the hull details are fully documented by other modellers and on the web which will make life easier.

Up next is something I've never worked with before, the the custom bayonet locking system for the WTC, which Norbert Bruggen kindly supplied, a lovely bit of equipment.

Rob

[The Boattrainman]

U557 gets my basic boat stand, just project timber and some oak varnish with computer mouse mat strips for the sub to rest on.




The name is my usual brass plate and black vinyl lettering.




The Boattrainman

[The Boattrainman]

The suggestion for securing the inner bayonet locking ring is that it is 'butted' up to the WTC, and sealed around the outside with resin and resin bandage.

Here is the outer ring which is an easy push fit to the end cap, and then the inner ring attached.




Now the phrase 'butted' up is scary, with no ridge or lip to set the piece in place it's easy to get this wrong, here is the inner ring just resting against the WTC.




So to set this, I've made an additional ring of 1mm styrene................




The ring fits in a groove and overlaps by 10mm, so now it sits tight onto the WTC, and should make gluing with epoxy easier.




The two rings are marked at the optimum seal point by tape and a centre mark to line up with the centre line on top of the WTC. The rings pull apart when the inner and outer tape marks are aligned either left or right.




The Boattrainman

[The Boattrainman]

Both kit ends caps are the same, they have shapes moulded into them for shafts etc. for the stern end cap the shapes are removed, and the bow cap is just epoxied in place with the centre hole filled.




The available holes are used for an air valve, the main On/Off switch linkage bellows and the opening for the water inlet into the piston tank. Holes for servo connections and prop shafts will come later.




The bayonet lock fittings are epoxied to the stern cap and one end of the WTC and the 2mm O ring is inserted into the groove.




The parts are joined and the WTC is inflated slightly with air to see if it's air/water tight.




Here is how the WTC and bayonet lock fits inside the hull.




It's recommended to shorten the WTC by as the bayonet lock adds length, but there's no need as there's plenty of room in the forward hull.




The Boattrainman

[The Boattrainman]

And finally, a pressure test of both ends including the bayonet lock.

So the WTC has a volume of 5.4L (5400ml), I'm going with a 900ml piston tank (lets say 1L), and my bicycle pump does 100ml per stroke.

To simulate a full piston tank and the pressure the air that was in it would create in the WTC, here is the bayonet lock end in the sink with 25 strokes (25 X 100ml) of air, more that a good safety margin and no bubbles from the lock, in fact I kept pumping till the bellows eventually failed at 32 strokes!



A great bit of kit, from a legend in the bizz (although I found his book hard work!).




The Boattrainman

[trout]

That book makes my brain hurt, but every time I crack it open, I gain better knowledge. I just wish some of the electronic schematics were updated and clearer.