New project - USS Nautilus

The first sail is out of the mould. Not that bad and the resin-cast cover fits quite perfectly:





The moulds for the aft control planes are ready as well:

The bow:

Got the stern section out of the mould....

Design is finished. With a bit of luck I'll have some photos of the real mdel (raw assembly) by Saturday.

Getting there:

Looking very good, Andreas!

David

First set of milled structure parts arrived and it looks quite good:




And as I had the pleasure to spend last week sick at home I tried what my CAD offers in terms of making sketches for build instructions…...looks good:

Even if it doesn't look like it.....this is going to be the mould for the rear bulkhead:

This will be the motor feed through of the Nautilus. Basically it's an advanced version of the ones I have in my U-1. Took a while to find a workshop that is now doing the parts. I guess I'll make some more.... The parts will be made of bronze and brass, it will have a ball bearing and an ID 4 mm rotary shaft seal. It will be attached to the rear bulkhead via a simple M16 fine thread and sealed via an o-ring. Advantage: only one hole in the bulkhead, no additional holes that have to be sealed. And it saves so much space in your boat....

And the first half of the mould for the rear bulkhead...

decks have arrived.....eastern present ;-)

The moulds for the rear bulkhead are done...


And the first part has turned out quite nicely. Notice the round flat surfaces that will help to seal the motor fedthoughts.

I've decided to make the watertight main section out of glass fiber, too. Attaching the deck to a plexiglas tube works, I've tried it successfully. But one has to fill the transition with filler and that is a) an annoying work and b) the result is, compared to the exact and sharp lines of the bow and stern, sub standard. So I have prepared the respective CAD files and ordered the milling of the preforms......

Dr.Schmidt wrote:I've decided to make the watertight main section out of glass fiber, too. ...

...so you think about a GRP tube instead of the plexiglass tube, I suppose. I know that there are glassfiber reinforced plastic tubes available for industrial purpose (e.g. for chemical applications), maybe a "Standard" gauge might fit for your dimensions. A submarine modeller colleague from Bremerhaven had got such a tube (but of much bigger size) for his model of class 212A in scale 1:30.
Otherwise laminating a GRP pressure hull tube by your own is also an annoyoing work....

No, no gpr tube. The whole middle section is going to be one piece made out of glass fiber. Pretty much like that...

...but you know that your deviation from the ideal circular shape of the cross section of your presure hull will result in a more or less reduced pressure resistivity. Compared to a cylinder a hull with a cross section shape like this will buckle more easily (also resulting in loss of buoyancy), the hull structure will be less stiff. Well, if you increase the wall thickness and don't plan to dive a little deeper than a few meters this might be still ok (I assume you might calculate pressure resistivity by FEM).
In addition you must also consider that the space just beneath the deck (that should be above the water surface when the model is surfaced) is no free flooding area any more and so it develops more buoyancy when submerging. This must be compensated by more ballast.

All valid Points.

Stability - no, I didn't do FEM simulations. But I'm pretty sure that this is not going to be a major problem. The deck only represents a minor deviation from the cylindrical shape. It's Elevation above the cylinder is not high, just about 1 cm. So laminating a 2 mm thick hull with a 3 mm deck and about 4 mm GPR at the seams (were you have twice the 2 mm) will most probably be sufficient. I'll have a Engel pressure switch, so the diving depth should not exceed 2 m = 200m mbar. Should be feasible.

Buoyancy - true, but actually I do not know if the extra  buoyancy  will help or cause problems. That's to be tested. I plan with a 750 ml Engel tank in a 61 cm long 10 cm diameter hull. That's less volume than e.g. in Engels 212a. It will definitly add roll stability when the boat is submerged. And: I'll have both Options if the full hull does not work.

Hi Hermann,

thanks for challenging me with this discussion. You made me think and I actually had a great idea how to alter the design of the gpr main hull so that the buoyancy Problem becomes minimized and also the stability problem will be reduced. I'll post a picture later today......

Cheers Andreas

This is how it's going to be. I can minimize the additional volume of the deck by making a trench in the structure that will be free flooding. The trench will also enable the flooding of the sail and it will connect the free flooding stern and bow sections. The photo-etched brass deck will get cuts that help venting the trench. The bridge structures help to ensure that the deck does not bend. The remaining left and right bump of the deck superstructure will be filled e.g. with resin and microballoons. This makes it possible to lay down the glass fiber in an almost perfect circular shape, restoring the full strength of a tube structure.

While waiting for the milled parts for the middle section I started gluing the prop shafts, the bayonet catch, the rudder bearings into the stern section. Here some pics. I'm currently reworking the photo etched deck but version one already fits quite perfectly.....

O.K., new deck design is done.....

Still waiting for the new milled parts. So on with small stuff:

PU cast parts - masts and anchor:


Sail: milled to the right size and filled inside:


Bridge assembly:


Bridge in the sail:


And that's how it's going to be:

Design......



...milled:

First steps of the moulds are done.....