More pictures and first ideas

First two additional pictures which I love!

A picture that me gives a bit more clarity about the man hole at one dome.

And a second picture which I love, preparation for riveting at one of domes.
I love this picture because I worked as a steam loco worker in young years and there I have seen again and again the numberless rivets and bolts at boiler and inside of firebox.

How I have written in my opening post I have drawn first a sketch in order to find raw dimensions of vessel and car and so found that it should have a diameter of 15 feet. That are in HO-scale around 50 millimeters (~ 2 in) and that is a good value here in European countries. Search for fitting materials was a success on first way.

This tube was available on a sanitary market and the clear balls are half globes for own filling and decorating on Christmas trees - both with exact dimensions.

With next searches I found additional information and data in web and so I found also exact values of pressure tank.

• Length: 34.5 ft (10.5 meters) - HO-scale: 4 3/4" or 120 mm
• Diameter: 15 ft (4.6 meters) - HO-scale: 2" or 52.5 mm
• Thickness of walls: 2 1⁄8 in (54 mm) - HO-scale: 0.025" or 0.62 mm
• Mass / Material: 85 tons (77.3 Tonnen) / steel

I think that I was not too far away with my calculation only only on base of that one first picture of prototype.

Next step was to draw an exact sketch with rivet positions.

(All dimensions in millimeter.)

And after that sketch I must make a master jig for pressing of rivets. 100 rivets? No, many 100 or maybe 1,000 or more yet. I will know it at end.

And that is my embossing plate now, equipped already with guiding rails for the styrene sheets.
I pre-drilled with a #76 drill bit and after I corrected not exactly positioned holes by "a bit force to wished direction". Next I used a #73 drill bit and repeated this all - and at last I finished it with a 0.7 mm drill bit, this is between #70 and #71. And then - the holes must sit must be sit without large differences - or you have made scrap! Note, all holes are fine deburred!
I must say that this is a job with highest accuracy and concentration. Against it the embossing of rivets is nearly a child's play.

The short hole-areas are long enough also for pressing long rows of rivets. You must move the styrene sheet forward  for some holes after a first embossing and than emboss the next rivets again, again and again. This is a many more simple way than to drill holes over a very long area.

Next steps ...

Next steps were relatively simple to do.

Some time ago I purchased a small and cheap LED lamp for using as a lighted worktable in order to press the rivets. Here I laid a white paper sheet on table under my jig for reducing the very bright light in order to make this shot.

This are the first rivets which I pressed on the jig with this small pressing tool like a fine center punch. This is an old screw driver where I ground a fine peak on it and then I polished it to a well runded head, as small as inside of rivet heads. I used here .015" / 0.4 mm styrene sheets and worked with the normal room temperature without each additional heating. Also the lighted table has room temperature and the LED lamps do not warm the table or jig. However I think that you should avoid too cold temperature because the material could rip, maybe.

These are my first strips in full length, left hand how it comes from the press jig and on right side glued on an enhancement sheet. This is .010" thick sheet and both together give the wished thickness for rivet plates - I thought. Theoretical it's correct, unfortunately in practice not how I have seen with next steps.

Next step was to build the

Next step was to build the straps which exist in two shapes. The good thing was that both shapes are not very different in their rivet arrangement so that I could use same pattern for both. I used my old master jig and added the rivets between the rivet rows on left and right side exactly after the prototype rivet arrangement of prototype (and on my drawing).
I think that this was not a very complicated work, however the problem was like before to drill the holes exactly in position.

First an attempt on a flat sheet ...

... and after an attempt how it should be at realization later where two large rivet sheets are glued on the big tube and additional the straps.
I think that this looks not too bad also when there some small inaccuracies are on rivet rows. However this sample is made from the first sheet where I have pressed the first long rivet rows.

But here you see that the rivet sheets are a bit too thick. And this finding was an important result of this step by step attempt. As I wrote before already the result should be correctly if you calculate with the original thickness of styrene sheets. However the gluing of two sheets in combination with glue and pressed rivets made each of plates a bit thicker than wished. And a last problem was to glue the pressed sheets on the tube. I was lucky that I had found a tube of exactly that diameter that I wished to receive but its made from polypropylene - and that is one of plastic with worst gluing characteristics. Not one of solvents does react with this! However I found a two-component glue, first component "activated" the surface and the second glues both materials - unfortunately with a relatively thick intermediate glue. And so the rivet plates are too mighty and I must reduce the thickness of styrene sheets, one or both.

However now I know what I should do for receiving a good looking model of this pressure tank - or called with NASA terms the "Variable Density (wind) Tunnel".

The thick tank goes into realization

After all these attempts I would like to start the model now - with a bit thinner styrene sheets as new tank courses.

I fixed two rivet sheets with rubber rings on the basic tube where I "activated" the gluing areas before, positioned them exactly and then I filled CA-glue drop by drop into angles of tube and styrene sheets. I was surprised how good and simple this was to do and how strong the fixing is after the glue has bond.

The second course in process ...

... and here a view on one end of tube and how I plan to fix the domes at ends of tube. The basic tube is a bit shorter and so received small lips by the courses where I can insert the domes.

A preview in future however a lot of work is to do before.

Next preparations for domes - I made a sketch of the general construction of domes with its strengthening ring and seams and the rivet arrangement. A lot of rivets!

However I would like to receive a proof that my construction was correctly drawn before I will start with drilling of 200 and more holes into a new rivet embossing plate.
And again I made an attempt. The sketch were printed in the right scale and I "glued" the parts with a plenty of water onto one of domes. And it's looking good, I think! Next steps can be started.

Wow!

I was thinking that Archer Rivet decals were gonna cost you some serious $$$, but it's neat to see it done "old school" as some would say.

Looking forward to the rest of the built.

Hmmm

Now all you need is a little mustard and some beer to wash it down....

John

That's really cool, btw. I love the way you're doing the rivets. How do you punch them so they don't go all the way through the plastic?

Thanks for replies!

Thanks 'Art in Iowa' and John!

I must admit that I never thought to use Archer rivet decals. I would like to receive a model of that tank which should be as close to prototype as I can do. And the rivet structure is very specific here, look especially on dome ring. And I would not use two different rivet types on this model. That were my intentions.

John, drinking a beer - not a bad idea! However if we speak about beer then we should drink a good German beer! Some times ago I have read that 1350 breweries exist in Germany - a good number so that we should never to die of thirst! However this model should be indigestible also with best mustard. I think that it would be better if I should to build a good model!

Because the dome ring was yet a bit to large so I corrected the sketch of my last post and I shot a picture again with new rivet strips made from paper - and so I will continue the project in next days. (Pictures are exchanged already.)

Rivets and a lot of small parts

Next step was to build and complete the domes, first the rivet rings. This time I printed the sketch with rivet ring before in the right scale, glued that on a brass sheet and transferred all the rivet positions through the paper onto the brass sheet. I think that this was the many more simple way to receive the embossing plate than I would make a compass and straight-edge construction for marking all these rivet positions on the right place.

And so it was done simple, fast and very exactly! 168 holes - drilled with a #73 drill bit (0.6mm).

The first rivet ring was also very fast punched, however I needed three attempts in order to receive this first good looking and usable dome.

Look on this picture of dome with manhole and door and you know what I had to build! The outer circle must get a diameter of 2/3 inch or 16 millimeters. (The hole in dome is 1.5 mm larger.)

This is the result of cutting, drilling, grinding and combining of a large styrene ring on outer edge, short capillary tubes from injection cannulas, stiffening cones, small brass flat bars and NBWs - positioned and glued together so that I received "my" manhole. Without ring wrench!

Last step was to glue the manhole including door from behind into the large hole in dome. For fixing this part before gluing I built a small and fast made fixture so that I could set the manhole part exactly in center of dome. In center of fixture is a small screw which holds all parts together until glue was set. Ready! Ok, I needed nine or ten days for this part of pressure tank. Unfortunately, I must admit that the door of the manhole is not to be opened, sorry! Nevertheless, I promise that I will give next time a bit more trouble!

Ok, there is a second dome that I need. However, look how simply this dome was to be built, beside of the rivet ring. A small tube, a plastic ring and eight rivets and ready was the passageway and bearing for the shaft where the propeller of tunnel will be fixed inside.

Beside of this pressure tank or more correctly the "Variable Density Tunnel" I purchased two flatcar kits which now are on their way over the great pond and so the project can be continued also after finishing of this extraordinary load.

Bernhard you are doing the

Bernhard you are doing the impossible again, you kind of make that a habit don't you? Just beautiful work, building things like that shows the rest of us things that can be built instead of bought. Thanks for sharing.

As they used to say that one gets 2 thumbs up

Awesome!

 Bernhard, I do not know anybody who scratch build on the same level like you. You are in your own league!

Rob und Jürg, vielen Dank!

Thank you very much, Rob and Juerg!

However Juerg, I'm sure that I do not model in an own league. There are a lot of model builders with a very high level in their work. In three or four weeks we will have here an model train exhibition, unfortunately almost with less US layouts, however I will see if I can find a few of such models and their builders. How I know, one of these model builders will exhibit and I will show a few pictures you here. Be surprised! Incidentally, a modeler from Switzerland! Maybe that you know him even?

Nice!

Cool Load! ...and fantastic craftsmaship!

Bill, also thanks to you. I

Bill, also thanks to you. I hope for complete finishing of tank in next days.

Rivets, rivets, rivets ...

Before the tank will be closed by the cupolas I glued a bit lead into the basic part of tank because the flatcar has not a large own weight. With it I have reached 80% of the NMRA weight for 36' cars.

The last embossing pattern, this time for the traps of cupolas. (This times - 102 new holes only.)

I'm on a good way to finishing! Each step goes fast and faster now. (I should build a second tank and I'm sure that some details would look better yet.)

I'll take it

If you build a better second version I'll take the poor first one off your hands!!

Fantastic work,

Brilliant work and fun to

Brilliant work and fun to follow along. Looking forward to more updates!

Mike

Extrraordinary

Extraordinary is the right word for it   WOW!

Ready!

And this is also the first picture of this giant.

And a comparison.

I'm sure that a certain resemblance is recognizable.

An addition: Thank you very much for all your friendly comments!

Steam Generator

It reminds mne of a steam generator for a power plant

Looks great and portrays a

Looks great and portrays a really interesting time of experimentation and innovation.

Thank you very much, ...

Nick and Rob!

A picture here with a schematic view of inner construction of the tank or more exactly of the tunnel. Maybe that this will show you a bit more of that technology in the 20ties of last century.

A picture that you can see also on my gallery since today. Do you see the small plane model in the large steel jacket? Such a large and heavy object for testing such small models! But the VDT must have been very successfully!

A second picture yet with not such a serious background.

Do you know the builder of that tank? Please compare the picture of prototype - I have made only a small playing with pictures! And I'm sure that you can not find an entry of this company on one webpages, worldwide, nowhere!

A small joke with my "own company", shortly established here in my home city - "Bernhard's Model Train Manufacturing Ltd. in Dresden, Saxony". And watch the weight - exactly measured on a kitchen scales.

Enjoy!

WIND TUNNEL TANK

Wow, that is so neat !!!  BTW, excellent model !!!!

Nick, ...

... thanks again.

It's nice to see interest of members to my projects and also to technical background.

Flatcar(s)

Some days after last post here I received my two Red Caboose flatcars, both with outside fish-belly frame and 42 ft. long.

One of the kits should be built like the original model, the second one must to be shortened on 36 ft. equal to the original car for transporting the tank.

First I replaced the original steel weight plate by lead on original model and so I received a little bit more weight for this very light flatcar.

The second model were sawed and sanded on length very close to 36 ft. ...

...  and likewise I made multiple cuts on frame and glued it anew to right length.

Picture shows both models with completely mounted brakes. Above the 42' model with an AB-brake because the model is lettered with a "new date" in 1929 and below the 36' car with a split K-brake. So received two very different equipped models however nobody will see these differences if models are standing on tracks.