Work has started on Al's Observatory

[lacad01 (Adam)]

Great stuff, good to see it in action Looks like you've got a twin brother in the obs

[h0ughy (David)]

nice shot Al

[sheeny (Al)]

Thanks Dave.

Originally Posted by lacad01

Great stuff, good to see it in action Looks like you've got a twin brother in the obs

That's my best Zaphod Beeblebrox impersonation.

Al.

[allan gould]

Al
Just had a good read through your observatory site. Great read and setup. The Pod has one advantage over the Sirius obs and that you certainly get "more sky" for your money. The slit in the Sirius certainly needs your eye on it so that you don't start photographing the dome, but thats something Ill have to get used to. I see David has a mozzie zapper in his dome and it looks like Ill have to do something about it as thre little devils love it in there.

[sheeny (Al)]

Yeah, that's one of the things I like about the POD. It's a good compromise between a dome and a roll off roof.

ATM I'm investigating the PZT (POD Zenith table) which will allow me to push the dome off the POD by 30" or so to get a clear view of zenith. It wasn't an issue with the C8 and the CG5 mount, but the EQ6 is taller and the dove tail offset from the centre of the RA axis is greater meaning more of the sky around zenith is obscured by the dome. Combine that with the C11 OTA and its a bit limiting without the PZT mod.

The other mods that I'm waiting for a clear weekend (and someone to give me a hand with) is fitting a solar fan into the dome to keep the temps down.

Mozzies aren't an issue in Oberon. It is not often warm enough for them. I think I've had one night with mozzies.

Al.

[kinetic (Steve)]

You can't get full zenith with these pods Al?

Steve

[sheeny (Al)]

Originally Posted by kinetic

You can't get full zenith with these pods Al?

Steve

In the standard configuration and the pier mounted centrally, no. A lot of the POD users OS reckon to offset the pier from centre so you can get zenith, but after playing about in CAD I decided it made little difference - some part of the sky will still be obscured near the meridian. If there's part of the sky which doesn't have much of interest to you, then that's the bit to ignore.

For me it made little difference and as I said, the problem was trivial with the C8 SGT. However, the PZT mods costs about $700, and allows the you to push the dome up to 30" north or south on those occasions when the zenith obscuration is going to be an issue.

It makes it a hybrid between a dome and a roll off roof.

Al.

[allan gould]

The PZT would be a great idea and I saw them advertised a while back. Makes sense if what you want to image is at the zenith or thereabouts.

[sheeny (Al)]

I just ordered my PZT kit. Should be good.

Al.

[allan gould]

Originally Posted by sheeny

I just ordered my PZT kit. Should be good.

Al.

Well done - hope it doesn't take too long to get to you

[sheeny (Al)]

Well today was the first opportunity in a long time that I've had anyone around to help me lift the dome off the POD for a bit of maintenance and to fit a solar fan.

We lifted the dome off and I was going to give it any extra coat of black Fusion paint on the inside to try to keep more IR out during the day, but unfortunately the masking tape I was using decides to peel off in sunshine. So I flagged away that idea.

I had some Dow Corning 791 to re-caulk the dome, so that was next. I haven't had any problems with leaks from the old caulk (roof and gutter silastic) but it was badly cracked and was very much a compromise when I built the dome. I cleaned up the surface of the dome with a scotch-brite pad to try to get some active molecular ends on the HDPE for the new caulk to bond to. The old sealant peeled out very easily BTW... it was just sitting there basically.

I also fitted the solar fan I bought a couple of months ago. I cut the 150mm diameter hole in the outside dome shell first with a jig saw, then drilled 54 1/2" holes in the inner dome to provide equivalent open area to the fan grill for ventilation. A full width bed of Dow Corning 791 beneath the fan gasket and held in place with 3 screws.



Al.

[duncan]

Hi Al,

Certainly looks the goods mate. Glad everything went well.
Any thoughts on condensing all of this and putting it in the "Projects and Articles" section?
I would imagine that more people in the future will give the SkyShed Pod pretty serious consideration.
Congratulations on the new observatory and on the presentation of the assembly from start to finish.
Very well done.
Cheers,
Duncan

[mozzie (Peter)]

Originally Posted by sheeny

Well today was the first opportunity in a long time that I've had anyone around to help me lift the dome off the POD for a bit of maintenance and to fit a solar fan.

We lifted the dome off and I was going to give it any extra coat of black Fusion paint on the inside to try to keep more IR out during the day, but unfortunately the masking tape I was using decides to peel off in sunshine. So I flagged away that idea.

I had some Dow Corning 791 to re-caulk the dome, so that was next. I haven't had any problems with leaks from the old caulk (roof and gutter silastic) but it was badly cracked and was very much a compromise when I built the dome. I cleaned up the surface of the dome with a scotch-brite pad to try to get some active molecular ends on the HDPE for the new caulk to bond to. The old sealant peeled out very easily BTW... it was just sitting there basically.

I also fitted the solar fan I bought a couple of months ago. I cut the 150mm diameter hole in the outside dome shell first with a jig saw, then drilled 54 1/2" holes in the inner dome to provide equivalent open area to the fan grill for ventilation. A full width bed of Dow Corning 791 beneath the fan gasket and held in place with 3 screws.



Al.

hi al the pods going well here, ordered a poly cap for mine keep a bit more of the heat out.ive a solar fan and they do well no leaks with it or the pod.did you order the pzt with the next shippment coming over

[sheeny (Al)]

Originally Posted by mozzie

hi al the pods going well here, ordered a poly cap for mine keep a bit more of the heat out.ive a solar fan and they do well no leaks with it or the pod.did you order the pzt with the next shippment coming over

Yep. I've ordered the PZT.

I did record some afternoon inside/outside temps before fitting the fan, so I'll have to continue that now it's in to see how much difference it makes.

Al.

[allan gould]

Originally Posted by sheeny

I also fitted the solar fan I bought a couple of months ago. I cut the 150mm diameter hole in the outside dome shell first with a jig saw, then drilled 54 1/2" holes in the inner dome to provide equivalent open area to the fan grill for ventilation. A full width bed of Dow Corning 791 beneath the fan gasket and held in place with 3 screws.



Al.

Al
Where did you purchase the solar fan from? I've been thinking that I should install something like this in the Tempest Observatory.
Hope that the PZT works out as it looks like an innovative solution to the zenith situation.
Thanks Allan

[sheeny (Al)]

Originally Posted by allan gould

Al
Where did you purchase the solar fan from? I've been thinking that I should install something like this in the Tempest Observatory.
Hope that the PZT works out as it looks like an innovative solution to the zenith situation.
Thanks Allan

http://www.whitworths.com.au/main_it...AbsolutePage=2

Al.

[Screwdriverone (Chris)]

Hi Al,

You have probably thought of this already, but it wouldnt hurt to have a lower vent open in the floor or down as low as you can when the solar fan is running to be able to provide a cool source of air and circulate the cool air up through the top vent.

I know when I put my whirlybirds on the house, they did pretty much nothing until I put some eaves vents on the shady side of the house and then the temperature differential went from 5 deg lower than ambient to 15 degrees.

Of course, this may not be needed if there is already good airflow from under or through floorboards etc, but I thought I might mention it anyway.

By the way, how do you keep warm if there is no slit and half the pod is open to the sky? Are you able to heat inside (bar heater etc) without causing too many thermal currents?

Cheers

Chris

[sheeny (Al)]

Originally Posted by Screwdriverone

Hi Al,

You have probably thought of this already, but it wouldnt hurt to have a lower vent open in the floor or down as low as you can when the solar fan is running to be able to provide a cool source of air and circulate the cool air up through the top vent.

I know when I put my whirlybirds on the house, they did pretty much nothing until I put some eaves vents on the shady side of the house and then the temperature differential went from 5 deg lower than ambient to 15 degrees.

Of course, this may not be needed if there is already good airflow from under or through floorboards etc, but I thought I might mention it anyway.

By the way, how do you keep warm if there is no slit and half the pod is open to the sky? Are you able to heat inside (bar heater etc) without causing too many thermal currents?

Cheers

Chris

There's good ventilation between the dome and the walls in the POD.

Warmth is acquaired the same way as out in the field... layers of clothing, freezer suits, etc. Because there is no separate warm room, heating is not on. Too many thermal currents. Having said that, it is naturally far warmer in the POD than without. Radiation loss is less than 50%, there is exscellent shielding from the wind etc. I haven't used a dew shield or a dew heater on full power since I've been in the POD.

Al.

[allan gould]

Al
just a quick question. I went and bought the same solar fan as yourself and I see that of course the gasket etc is made for a flat surface. How did you accomodate the curve of the Pod?
Or did you just fill it with silicon?
Allan

[sheeny (Al)]

Originally Posted by allan gould

Al
just a quick question. I went and bought the same solar fan as yourself and I see that of course the gasket etc is made for a flat surface. How did you accomodate the curve of the Pod?
Or did you just fill it with silicon?
Allan

That's pretty much it, Al. There used to be a video tutorial on the Skyshed POD site about how to fit it. It's basically lay down a big pad of sealant before mounting the fan. If you slip the fan i the hole and trace around it you can get a good guide to how big to make the sealant pad.

Al.