S.M. U-1 (a new RC project)

[DrSchmidt]

Progress on the U1 molds. I laminated the second quarter and put in the filling material. After the curing of the epoxy I sanded everything flush, removed the wooden box, unscrewed the master from the base plate and loosened the parting plane supports. Then I could turn everything around, remove the screws of the threaded inserts and then remove the horizontal parting plane. Everything worked super easy....enough good quality parting wax!!! Then I cleaned then master from putty and wax residues and applied another layer of parting wax. Looks good so far.

[DrSchmidt]

Top coat and coupling layer for the second quarter (the upper half ) of the mold are in....

[DrSchmidt]

More progress on the S.M. U1 mold. Cleaned up the horizontal parting plane, removed the remaining boards of the first box and started setting up the second box. Every step is usually interrupted by putting down another layer of parting wax. Shoul be ready to laminate the second quarter soon....

[DrSchmidt]

So far so good...the epoxy resin has cured and the filling material can be sanded. So the next step was to grind it and the edges of the GRP flush with the box. This way one creates a plane surface for the the GRP bottom, that will be applied when the mold is separated. The I could remove the vertical parting plane. Worked quite easy and the master and the seam to the first quarter mold look O.K. A bit of touch up work here and there and then the second quarter can be set up.

[DrSchmidt]

I laminated the first quarter mold. If you want straight tools that don't warp when temperatures change it is important to make the GRP layers symmetric. Different glass fabrics have different thermal expansion and asymmetric layering will cause the GRP to bend when the temperature changes. This can be avoided when the layering is symmetric. In my case I started with a layer of 280 g/m^2 then two layers of 600 g/m^2 and then a final layer 280 g/m^2. First thing is to wet the mold surface with resin, the I apply a coupling layer of resin mixed with cotton flakes. This way I can make small radii bigger and smooth the surface, which will make laying down the fabric easier. Then comes the tedious job of laminating....









When that is done, I fill the box with resin drenched filing material, that will enhance the stiffnes and pressure stability of the mold significantly.





All in all about 1 m^2 of glas fabric, 1,5 kg of epoxy resin and about 5 liters of filling material.

Important thing: don't forget to clean your siccors when done!!!

[DrSchmidt]

I'll agree as soon as all four parts are done and the master does not stick to one of them when I try to open them....

[He Who Shall Not Be Named]

Put in the M5 thread inserts and the indexing pins. Like David showed lately, the threads will be used to attach a plastic plane that will create a defined edge to laminate against, so that you the hull does not have to be trimmed later on. The M5 screws were covered with release wax and PVA.

Solid, well thought out arrangement, expertly executed, near perfect materials selection... you GERMAN'S!

[DrSchmidt]

Now the interesting part starts.....I applied the top coat for the first quarter mold, an aluminum-filled epoxy resin. Went down quite nice. I use a new resin, as I cannot buy the one I used for 30 years. EU regulations about the trade for dangerous chemicals. So it this one, which worked quite similarly. After the application I sprinkle the surface with cotton flakes using a kitchen sieve. After curing of the resin, the excess of the cotton flakes will be removed, leaving behind a thin nap that will later act as adhesion layer for the GRP. That way I don't have to work wet in wet.

[DrSchmidt]

Put in the M5 thread inserts and the indexing pins. Like David showed lately, the threads will be used to attach a plastic plane that will create a defined edge to laminate against, so that you the hull does not have to be trimmed later on. The M5 screws were covered with release wax and PVA.

[DrSchmidt]

We'll find a way without someone dying....

[He Who Shall Not Be Named]

Who do I gotta kill to get one of these kits, Doctor?

David
(like I don't have enough to do already!?)

[DrSchmidt]

The seams to the parting planes are filled. The vertical plane was complicated but I got it. Also drilled the holes for the indexing pins and the thread inserts. Now I'm preparing the additional wooden planes to complete the mild box...

[JHapprich]

As busy as you are, U-2 and U-3 would be good company to complete the 1st training group? If i remember correctly, from U-5 on they serial produced combat units, while U-4 was a copy of U-3.

Those early boats are still exciting, always loved visiting U 1 at the museum in Munich!

Great work, Dr.Schmidt!

Jörg

[DrSchmidt]

Well, the U1 never was a combat boat. It was originally designed to demonstrate that certain design specifications for a submarine could be met, so that the Kaiser would adopt submarines into his Navy. At that time (1906) Germany was building up its navy to counter the superior British Navy, and huge armored battle ships were thought to be the way to go. So U1 made the case pro submarines. But due to its little size, the petroleum motors and only one torpedo tube, it ended up as a training boat.

[redboat219]

"torpedo los".