random pattern radome

[Fransien]

Hello,

My name is Fransien and I am new to this group, so I hope there is someone who can help me with this problem.

 
I am a Dutch artist who fell in love with the type of geodesic dome of the radomes in Teufelsberg, Menwith Hill, UK, or Misawa Security Operations Center, Japan (see attached pictures).

I would really like to build a model of the misawa radome. I realize that the pattern of the triangles is random, but how on earth where they designed and constructed? And how would I go about designing a similar pattern.

If anyone could shed any light on this 'problem' it would be very much appreciated!

Regards,
Fransien
Amsterdam

[Dick Fischbeck]

Hi Fransien

The pattern is not random. It is quasi-random you might say. The 20 triangle of the icosahedron are divided into identical patterns. The idea is to reduce resonance of the radar waves.

Someone here will be able to give the details.

Welcome!

Dick

[Ken G. Brown]

I note that some of the patterns are seven sided and in one case at least at lower left in the front dome in misawa.jpg, two pentagons are next to each other.

   Ken

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[TaffGoch]

There are several rotation & mirror symmetries, and planar intersections (slices,) that define the edges. It takes some photo study, from different angles, to recognize them.

In 2008, I modeled an example of one of the smaller radomes. (Even the smaller ones are pretty big):

It's posted in the 3D Warehouse, should you want to study:

 http://sketchup.google.com/3dwarehouse/details?mid=5d7384f9e11698fec383d5a884c3d93e

-Taff

[TaffGoch]

I don't recall where I got this "blueprint," but it was likely the AFC, Inc website: http://www.radome.net/

[TaffGoch]

...Yep, this page has plenty of diagrams, from which to choose: http://www.radome.net/radomesize.html

[TaffGoch]

Wow, the 110' radome spec-sheet even has the parts pattern labeled for you:

[Ken G. Brown]

Do you have any idea of the rationale for this chosen geometry and how it was derived?

Ken,

from my iPhone

On 2013-08-21, at 14:32, TaffGoch <taff...@gmail.com> wrote:

Wow, the 110' radome spec-sheet even has the parts pattern labeled for you:

<AFC 110 radome.png>

[TaffGoch]

Ken,

Criteria: (1) seemingly-random, and 2) limited panel count (increased repetition)

The radomes that I've studied maintain icosa/dodeca primary vertices, while rotating/twisting geometry bounded by these primary vertices. You can see it in this study GIF I made, while investigating the geometry, myself:

This is the simplest example that I could find, at the time. 

Finding the icosa/dodeca vertices, in larger tessellations, would be my first step in reverse-engineering a layout.

-Taff

[TaffGoch]

Here's my study of Teufelsberg radome symmetry:

So, you can see that it's not random, but quasi-random, as Dick Fischbeck wrote, in his initial reply.

-Taff

[TaffGoch]

Those with sharp eyes will recognize that my last two posts depict the exact same geometry.

Did you catch it?

-Taff

[TaffGoch]

Note that the Misawa radome (the 3rd one, in the background) uses this geometry, as well:

-Taff

[TaffGoch]

Menwith Hill, too:

-Taff

[TaffGoch]

MIT's Haystack "observatory" pattern is a bit easier to spot:

[Dick Fischbeck]

Good work!

[TaffGoch]

BTW, the MIT Haystack radio observatory, in Massachusetts, is on our Google Maps (Domes of the World):

https://maps.google.com/maps/ms?msid=212647990607384677670.0004ad181506bbe39b599&msa=0&ll=42.622899,-71.488327&z=19

Interesting Google Maps aerial photo; taken when the tattered dome was being renovated with new fabric:

-Taff

[Dick Fischbeck]

Cool. Good resource. 

-- 

[Fransien Kroon | ITV Hogeschool voor tolken en vertalen]

Wow guys,

I am really impressed with this. With your tips, I think my high school level geometry will suffice for working out the exact dimensions of the tiles, now. It seems like I've got my work cut out for me, though!

But not to worry, I like a bit of brain exercise every now and then.

Thank you very much, Taff! I will share the results with the group in due time. But don't hold your breaths: I also have a day job.

Cheers,

Fransien

2013/8/22 Dick Fischbeck <dick.fi...@gmail.com>

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[TaffGoch]

Fransien,

I 3D-modeled the radome of interest, in SketchUp:

If you don't have/use SketchUp, I can export the 3D model, to DXF, DWG, OBJ or 3DS, if one of those would be useful to you.

-Taff

[Fransien Kroon | ITV Hogeschool voor tolken en vertalen]

Hi Taff,

Thanks!

I use sketchup so this is an excellent help. Thanks to your explanation I can now instantly spot that it is not the Misawa radome, though ...

The symmetry on the haystack radome is also interesting. But I like the Misawa dome the best because it still has that random 'feel' to me, even now I know where to look for the symmetry. I guess it is because the symmetry is a bit more complicated than the other ones. And because the lower tiles are distorted to form the base? Or am I again missing something that is obvious for you all...?

Fransien


Op 22-08-13 20:56, schreef TaffGoch <taff...@gmail.com>:

Fransien,

I 3D-modeled the radome of interest, in SketchUp:

[TaffGoch]

...at 7:20 AM, Fransien wrote: "...I can now instantly spot that it is not the Misawa radome, though ..."

There are 3 different domes in the Misawa photo.

I modeled the largest, most difficult one, in the background. 

The one in the foreground should be easier for you to model. (The middle one is, obviously, the simplest to attempt.)

-Taff

[Fransien Kroon | ITV Hogeschool voor tolken en vertalen]

Hi Taff,

You are so right. On both counts.

Thanks again,
Fransien

Op vrijdag 23 augustus 2013 schreef TaffGoch (taff...@gmail.com):

> ...at 7:20 AM, Fransien wrote: "...I can now instantly spot that it is not the Misawa radome, though ..."
> There are 3 different domes in the Misawa photo.

> </mail/u/0/s/?view=att&th=140ac46325f98689&attid=0.1&disp=emb&realattid=ii_140ac3db548fdda8&zw&atsh=1>

> I modeled the largest, most difficult one, in the background. 
> The one in the foreground should be easier for you to model. (The middle one is, obviously, the simplest to attempt.)
>
> -Taff
>

[TaffGoch]

SketchUp has a "perspective" view mode, which I don't use often, but, it can come in handy, when needed.

With perspective, and the field-of-view (FOV) setting, you can match photograph geometry, to replicate a scene. This permits fine-tuning of the radome 3D-objects:

With SketchUp's "background" (watermark,) and perspective features, I was able to "adjust" my radome models, to very-closely approximate the vertices of each radome. The perspective is not perfect, but it served its purpose, in the above depiction (model attached, below.)

I didn't customize the bottom rows of triangles, to match the ground-plane truncations of the real radomes, but that could be easily done, using the same perspective-view of the 3D models, "overlaid" on the underlying background photo.

I don't go through this process often, because it takes a lot of trial-and-error (for me, anyway.)

-Taff

[TaffGoch]

I looked up the Misawa radomes on Google Maps, and measured the approximate sizes and separation of these 3 radomes, revising the model to incorporate the "real world" sizes. (I was surprised to find that the foreground and middle radomes, regardless of the different tessellations, are approximately the same size!) I also took this opportunity to customize/truncate the base triangles, to match the photo:

I uploaded the revised 3D model to the Google/Trimble 3D Warehouse:

http://sketchup.google.com/3dwarehouse/details?mid=312b66fefc2a2cd286509ade26108092

For those interested in the original online photo, it can be found at Panoramio:

http://sketchup.google.com/3dwarehouse/details?mid=312b66fefc2a2cd286509ade26108092

I've also added the Misawa radome complex to our "Domes of the World" Google Map:

https://maps.google.com/maps/ms?msid=212647990607384677670.0004ad181506bbe39b599&msa=0&ll=40.720201,141.321849&z=17

-Taff

[TaffGoch]

My mistake, the original online Panoramio photo URL is:

http://www.panoramio.com/photo/37470019

-Taff

[TaffGoch]

I stumbled upon a different radome tessellation (different from the above,) at Balado Bridge, Scotland, west of Kinross. It's an RAF radome, adjacent to an old, disused RAF airfield:

I geo-located it, on Google Maps:

https://maps.google.com/maps?q=56.209494,-3.461686&ll=56.209453,-3.461756&spn=0.001398,0.004104&num=1&t=h&z=19

(I haven't yet added to our "Domes of the World" Google Map, but will do so.)

The radome appears to be ~80 feet in diameter. (Note that Google Maps has, just recently, added a measurement feature, activated by clicking an icon in the lower left corner, next to the scale bar.)

The SketchUp model is posted at the Google/Trimble 3D Warehouse:

http://sketchup.google.com/3dwarehouse/details?mid=474c6ba50a879d9d24377aac91b864b1

-Taff