Gwen's all metal scratch built 1/32 Type VIIc

[gwen]

Hello everyone,

I'm new to the subcommittee and its forums but I have just started a new project and wanted to share it and collaborate with people with a lot more RC sub experience than I have. I think I came to the right place.

I have been building and flying RC airplane models for many years. I'm also a private pilot and built and test flew my own replica WWI Fokker DVIII about 9 years ago. I have always wanted to build a large scale RC Type VIIC u-boat. And being a scratch-building kind of woman I decided to build mine out of metal. The superstructure will be all aluminum and I plan to make the sea hull from thin sheet brass. Three days ago I started cutting out bulkheads from aluminum scrap and today I have the superstructure of the aft end of the boat mostly finished.

I have based my plans on the combination of a paper model and the drawings in Westwood's Type VII U-boat book.

Here are a few photos of what I've done so far:

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I plan to build my own dive system and working torpedo system later on and will be looking for constructive input into those.

More updates as the work progresses.

Gwen

[Guest]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Nice work.

Do bear in mind weight but also that brass and aluminium will react very corrosively in water. It would be better to use aluminium throughout, and as it's almost a third of the weight of brass you can afford to make the hull plating a bit stouter.

[gwen]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Nice work.

Do bear in mind weight but also that brass and aluminium will react very corrosively in water. It would be better to use aluminium throughout, and as it's almost a third of the weight of brass you can afford to make the hull plating a bit stouter.

The primary reason I'm thinking of using brass rather than aluminum is that I can solder the hull plates together. Do you think I would still have the corrosion problem if all the aluminum parts were sealed with epoxy paint prior to the application of the brass hull? I agree on the weight issue. As for stoutness I was planning on reinforcing the hull interior with epoxy.

[Guest]

Re: Gwen's all metal scratch built 1/32 Type VIIc

If it's well coated, it should be alright.

you can solder aluminium, but it's tricky stuff. A modeller over here in the UK scratchbuilt a sub with all aluminium frames and plating. He use Lumiweld to stitch the plates together.

Modern adhesives are another possibility.

[jefftytoo]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Hi Gwen!

As a long-time SubCommittee member, let me take a moment here from your metallurgy discussion with Sub Culture to put on my good will ambassador hat: I offer you a HEARTY WELCOME to the SC! It's a thrill to see another woman join our tribe (we have and have had a few amongst us, but this has been sadly rare within our group), and it's especially gratifying to see one taking on such a large and challenging project—and with such obvious skill and panache! We'll all follow your progress with interest. Again, Welcome Aboard!

"Alaaaaaaaaaarm!"
JeffP

[gwen]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Thanks for the help subculture, I appreciate the advice.

JeffP, thanks for the warm welcome and the kind words! I look forward to getting to know folks around here and sharing all the great projects everyone is working on.

Gwen

[gwen]

Re: Gwen's all metal scratch built 1/32 Type VIIc

By the way SubCulture, I meant to say that I estimate the entire hull will take approximately 12 square feet ( give or take a bit) of sheet brass to cover. At .7 lbs. per square foot of 26 ga that would weigh in at 8.4 lbs for the whole hull. I don't that's too bad for a seven foot model.

[bob_eissler]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Hi Gwen,
I don't think you can count a paint coating to truly seal when the object is submerged in water. I think corrosion is much worse when you have dissimilar metals.

[gwen]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Thanks Bob. I'll do some testing with the materials and see what happens before committing to the method.

[thor]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Gwen,

I am a mechanical engineer and deal with metal alloys as a profession. I can tell you that Andy is quite correct. Brass and Aluminum do not play well with each other. A paint coating cannot be counted on to provide protection to separate the two metals sufficiently to isolate the galvanic action that will occur between the two.

I admire your ambition and skill that you display in this project. I would like to welcome you aboard the SubCommittee! I am very excited to have you here. You are among friends who are all willing to help you in any way possible.

Matt

[salmon]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Welcome Gwen!
I love what you are building and how. Cannot wait to learning new things from you too! It is thrilling to see such an ambitious project and normally I would give a speech about how tough it is to buiid a sub. It would go something like start simple and work your way up (crawl, walk, run). Heck you started way up there, but since you built a Fokker and flew it, I can only say, you go girl! We stand by for any assistance you may need. Great group of folks here with a lot of knowledge that want to see you succeed!

Going back to metal interactions, Anodized aluminum (or aluminium for our neighbors to the north and across the pond) is that immune to the corrosive effects of dissimilar metals?

Peace,
Tom

[thor]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Tom,

The anodization process deposits a corrosion coating on the surface that is electro-conductive. The problem with most dissimilar metals stems from the differences in ionic charge which effectively turns the two alloy interface into a battery with one side being the anode and the other the cathode.

Matt

[salmon]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Thanks Matt for clearing that up! You rock!
Sorry Gwen, in my limited knowledge I thought I had a thought, but sadly it was the pizza.
Wait, you could use the two metals and a potato to generate electricity to run the sub....no, no, another pizza moment. I do not know why I feel so silly today.
Peace,
Tom

[vasily]

Re: Gwen's all metal scratch built 1/32 Type VIIc

In reality, will galvanic corrosion be a problem for a model? Model subs spend only a few hours in the water, and many hours on the work bench. Or, in Gwen's models case, displayed in an art gallery. I look at Engel's models and see lots of brass and aluminum. Of course, the aluminum appears to be mostly or all anodized.

[southern or]

Re: Gwen's all metal scratch built 1/32 Type VIIc

Having a Engel kit, I can say that most of the metals that are in contact with the water seem to be stainless steel and brass. The rest stays inside the water tight 'deck,' surrounded by the fiberglass/epoxy hull and deck. Even the w/t deck cover is stainless, though every one I've seen on the web has had theirs replaced with a sheet of clear Acrylic.

Gwen, have you done the math yet to determine what will be needed for positive and negative buoyancy? I'm also interested in what water you'll be sailing in (fresh, salt, chlorine). I didn't see anyone bring this up, but salt (some pools are salt now) and chlorine water are fantastic conductors which speed up the anodization process. Fresh water isn't as good, but is a better oxidizer. I've never heard of it being used in scale, but in real life sacrificial metals like zinc are used to slow anodization and oxidation. Most ships and some subs have zinc bars along the hull that gets oxidized and anodized away to preserve the hull. If you want to go down another path there is always Anti-fouling paint, but thats a bit extreme and expensive.