Ali Dome

[gm7pbb]

Hi, just picked up a nice Ali Dome , its made from 1/4" Ali, the guy built the Dome then moved to Canada, this will replace my roll-off-roof. The same guy built this dome had the charles frank 6" scope from my last posting. I have to pick the runner and wheels up yet, the dome is 2.4m wide inside so big enough for my 12" skywatcher. there is even a geared hatch, which could be motorised at some point. just have to work out the wall hight next. any comment welcome as it has been a while since I last had a dome.

John

[ollypenrice]

Quite a scoop! Looks great.

Olly

[Peter Drew]

The wall height is usually determined by how low you wish to point the telescope. In the case of a Newtonian reflector this will be pretty low and you could step in through the aperture of the dome. Is the construction entirely of 1/4" aluminium? if so, it must weigh a "ton".

[gm7pbb]

99% of the ali is 1/4" and yes it is heavy but that also depends on how strong you are, lol , two of use moved it onto the trailer in les 10 minutes. Needs to heavy in my location, these fibreglass things would just blow away up here.

[Nermal]

wow - looks awesome

Good find!

[Mike Hawtin]

You jammy so & so, it really looks the biz. First thing I would do having previously had an ali finished dome is to paint it white as just that makes an enormous difference to heat build up inside during the day even if it's cloudy.

[FraserClarke]

You jammy so & so, it really looks the biz. First thing I would do having previously had an ali finished dome is to paint it white as just that makes an enormous difference to heat build up inside during the day even if it's cloudy.

Really?? I have just read a piece (from Horace Dall ~1950) comparing the Al and White painting, and he came down heavily in favour of Aluminium. His explanation, which makes sense, is that white paint isn't very white at the wavelengths of thermal radiation... maybe that is different with modern paints though...

[Marmite]

"Observatory Paint."

[skybadger]

Hi John

Would you mind telling me more about how the dome shutter works - I have a similar dome in fibre that I'd like to motorise and its been far from easy.

Cheers

Mike

[Mike Hawtin]

Really?? I have just read a piece (from Horace Dall ~1950) comparing the Al and White painting, and he came down heavily in favour of Aluminium. His explanation, which makes sense, is that white paint isn't very white at the wavelengths of thermal radiation... maybe that is different with modern paints though...

Yes really, that dome appears to have no provision for ventilation, the heat build up during the day will be much more than a white painted dome, the nicely warmed up scope inside will consequently take far longer to reach thermal equilibrium, I am speaking from personal experience with my old C11.

[gm7pbb]

Hi Skybadger (Mike) I will be removing the shutter to to check it over at some point soon, so will take a few pics for you to see how it runs on the gear setup, very simple.

Hi Mike Hawtin, there is a good bit of ventilation at the base of the dome and around the shutter, the shutter is boxed so it looks like there is no gap, even in this weather it is not that hot/warm inside the dome, which I was suprised at. When its dark up here its cold so dont think it will be to much of a problem, it will just make a change instead of having my head blown off all the time or the scope shaking in the wind, 20-30mph is about the norm up here in winter!

Cheers

John

[ncjunk]

Lovely dome and an interesting link to observatory paint!

[Mike Hawtin]

Hi John,

glad to hear you are well ventilated, it will make all the difference, I had all sorts of problems with condensation in cold weather until I sorted the ventilation. Enjoy your dome, it is amazing the difference it makes to have the scope set up ready to go straight away.

[gm7pbb]

Hi Mike. that was my main worry ,condensation, but will find out when I ge the walls set up and dome in place, yes looking forward the the lack of wind, my roll-off-roof is great but the wind is a big problem up here. Thanks for your comment and I'm sure I will be back to you about domes at some point, lol

John

[Marmite]

An oldie, but still a goodie:

'The Painting of Observatory Domes as a Protection against Solar Heat'

(360 KB PDF)

[Budgie]

Hi John,

You jammy little.......

Where'd you find that on the island?

I was wondering what would stand up to our climate up here and, as I already have large ratchet straps holding my shed down, I did think a roll-off-roof would be the ideal thing to go for on Lewis.

Still, you've got a couple of months to get the base built, before the nights return.

[teleskopjo]

great find.. how are you getting along with it ?