Geodesic dome kickstarter project

[spaceman_spiff]

Could these domes be adapted for astronomy  ? see the link:

https://www.kickstarter.com/projects/942255452/hubs-geodesic-domes-made-simple

You could place it on a rotating platform and your done!

Any thoughts?

[xtreemchaos]

thats very interesting,food for thought,it could be adapted for a obsy with some kinda hatch made and rotating platform.thanks for sharing ..charl..

[michael.h.f.wilkinson]

Not sure this would be easy, as the slit for the scope to look through breaks the geodesic structure. Having said that, Barnes Wallis would certainly know how to adapt it

[chrisjordan]

Hi,

I'm the maker of the hubs of which you speak, somebody on Kickstarter has ask me a related question. I replied as below:

"You could however cut sections from the sticks and have thin rigid metal rods across the viewing line. You'd only occasionally lose a small fraction of light (and gain an extra diffraction spike)

And as the hubs can be popped in and out, you could just pop out a stick on the odd occasion that one causes a real problem. This would be by far the easiest solution."

I'd be interested to know what you guy think a the effect a 6mm rod would have in the view of, say a 150mm reflector.

I guess even the worse case of  900mm2 removed from 17500+ is not going to be too bad in terms of light lost... 5% ish (I realise that this assumes, no secondary mirror in way) 

But what kind of refraction, or other issues would be a problem?

I'd be nice to work this out properly, then I can give a better answer; and this is a nice use for the domes.

thanks

Chris

[spaceman_spiff]

Hi Chris,

It is great that you are part of the conversation  .  Some my thoughts/questions are:

- With metal or hard wood rods is the structure adequately strong enough to withstand the elements? I assume yes, since the your site shows it being used outside.

- Could you put panels between the struts? This could be advantageous because... 1) keeps out the weather when observing, 2) help support the structure so that a rod could be removed without destroying the dome.

- I was thinking that with panels installed, the dome could be covered by a tarpaulin when not in use. 

- The only other issue I am unsure of is security. 

[spaceman_spiff]

Regarding your questions Chris, there are far more experienced astrophotographers on this forum than myself who can give better answers. I suspect that a reasonably narrow obstruction will lead to a new diffraction spike (as you mentioned) and will slightly reduce image contrast (the effect should be very small).

I guess the main point of an observatory is to allow unobstructed viewing from a sheltered, securable location allowing a telescope to remain set up while not in use. If the geodesic dome design can achieve these criteria then that would be very encouraging. 

[chrisjordan]

Hi Spaceman (Mr Spiff?),

The hubs were designed to provide an open frame or be covered by netting or canvas, though saying this panels could be attached if you used more regular wood. and caps/covers placed over the hubs to provide weather proofing. I think material (a good acrylic canvas, like used on boats, would last well) with a flap would be easiest (security though may be an issue, like you say)

Adding panels doesn't really add any more strength - triangles are inflexible of course.

and yep hardwood will last a long time, and the hubs will be made of automotive type plastics to last outside too.

hope this helps, and thanks for the thoughts.

Chris

[callump]

There are a couple of articles about building an observatory with geodesic dome in back-issues of Sky & Telescope magazine, and if you google. you'll probably find a few. 

Something I had considered seriously for a while.

There is the problem of the slit - really you don't want cross pieces, so you'd need some reinforcement around the slit. And then there is the problem of the slit cover, and keeping it all weather-proof. But probably not insoluble.

I expect the main difficulty will be sheathing the dome - but there are probably some innovative ideas (like using plastic film) or more traditional materials like canvas or hardboard.

Will be interesting to see if anyone gives this a try...

Callum

[spaceman_spiff]

I am considering it but time and space are against me at the moment! Although I am thinking of knocking the shed down in the next few months (rats burrowed underneath it!).  That may be an opportunity to try it out.

BTW i'm a fan of Calvin and Hobbes, hence spaceman_spiff.

[Demon Barber]

What a great idea/product,with a little lateral thinking i`m sure it could be adapted for astronomy.

I will watch this fledgling idea with great interest.

Regards

Mike

[chrisjordan]

Hi,

Thanks for your kind words; we've had a few questions about this now and what with this thread and one backer thinking of doing exactly this we've just posted an update showing an idea on how we could solve this:

http://bit.ly/bwhubs-ks-sgl

The idea is to mount the scope just ahead of the top hub, so you can go vertical, or you could move the top hub back if you wish.

Be great to know what you think.

thanks again for your interest and have a good weekend.

Chris