Idea of building a elevated landing pad

[Marclau]

O'K.........I have finally after 12 months convinced the misses that I want to get more serious about astronomy hence me beginning to look at a much larger DOB (12") then my current setups.

Living down the Peninsula, there is much less pollution and I'm fortunate I live on a 1/3 of an acre.

I have just finished building a large 6 square sunroom and have the opportunity to build a small area just purely for watching the sky.

My thoughts are as follows.......to build an elevated landing pad that sits pretty much along the roofline and next to the sunroom.
In other words, you need to climb a set of stairs where you come to a landing (possible enclosed and fully lockable where the scopes will be.
This area is away from my house but more importantly away from any other houses and is located in a dark part of the block with a fairly large tree to protect it from the elements from one side. Looking at building this from timber with possibly a retracting roof (manual on rollers).

Possible size would be around 2.4 X 3 meters.

Any thoughts.........especially on the elevated idea??

[Wavytone]

Yes, I built one a long time ago in Canberra.

The block we had was heavily treed and the only way to get a decent view of the sky was to go up, and like your idea I built a wooden platform 3m x 3m with a handrail at the level of the eaves. It was fixed to the house (double brick) on one side and had two 100mm sq. posts on the other side, with wooden decking to walk on. It was fixed to the wall at a corner of the house so there were two double brick walls meeting at right angles, running along two sides of the platform; this is necessary to ensure you don't stress the wall and cause it to fail. Alternatively if there is an interior wall at right angles this would do to stabilise it.

I had an 8" f/7 Newtonian, with a heavy equatorial mount, supporting this I had a 100mm dia. pipe stuck in the ground coming up through the platform, something like 3 metres tall. With all this length in the air there is no point burying it deeply, mine merely had a concrete paver underneath it. The pipe was filled with sand, which effectively damps vibrations. Where it stuck through the decking, the hole was oversize by maybe 20mm all round. I had two struts connecting from the pole bolted to the brick wall that stopped the top of the pole from swaying around, these were just under the platform but were arranged so that neither the pole, nor the struts touched the platform. This way you could walk around without shaking the scope. It was pretty stable.

If I was doing this again I would drop the height to leave a space under the eaves, 40-50 cm, and build a small locker tucked away in there to hold the scope and mount when not in use, that way you won't have to lug it up and down and it will be reasonably out of the weather.

Make sure you have a good handrail and maybe some wire lines as well at knee level - I nearly fell off a couple of times in the dark when I was cold and stiff.

My cat loved it too, and often kept me company at night.

[Marclau]

That sounds very similar to along the lines of what I want.......
I got a quote from a raised cubby house mob (if thats gives you an idea) but asked them to raise it higher by around 2 meters thus sitting nearly 3 meters high of the ground.

I'm killing 2 bird with one stone here and have the kids bikes underneath and then I have my area above.

I love the idea of the pipe filled with sand.........would cement be maybe a better option due purely to the height factor?
I visually see it extended from the sunroom (which is a new large pergola really but fully enclosed with framed windows etc etc.

I too would like then to leave the scopes inside when not in use complete with power, heater/cooler etc..........you have given me now much to reconsider.......thanks

[Wavytone]

Marcel,

No don't fill the pipe with concrete, for two reasons: the point of using coarse river sand is that it damps rapid vibrations very well, whereas solid concrete will resonate ("twang") like a tuning fork. Secondly when the time comes to dispose of this (possibly before you sell the house) its easy to empty the sand out and the pipe can be carried away. A 100mm x 3 metre pipe full of solid cement will be a bigger problem to dispose of.

I made mine with timber from a timber yard with little more than a circular saw and a drill. I just looked at how a typical deck is constructed and copied that, the result was quite cheap and even now would be a few hundred $, max.

Aah yes, just remembered one specific feature you will need - I had a very strong handrail on one side - made from 6" x 2" hardwood bolted with 2 12mm bolts to the vertical posts, with one end extended out a bit past the end of the platform. I had a block and tackle that clipped on this with snap shackles and a camlock clamp to use as a hoist for lifting heavy loads up/down like the mount, rather than attempting to drag it up the ladder. This is far safer than risking a mishap with expensive optics.

I used yachting pulleys and decent ropes discarded from my boat (I was a keen sailor), you can find these at any ship chandlers.

[Marclau]

Great........many thanks for sharing this...........more food for thought and agree about the sand as well............

[rmcpb]

Just when I had forgotten about my observing platform.

Thanks fellas.............................

[Quark]

Hi Marcel,

Many years ago, before my observatory went two storey, I was visiting Coonabarabran. The Sky Watch Observatory was in the throws of being built, the pier for the scope that was to be installed in the dome was in position.

It surprised me that the pier, which from memory was about 8 or 10 inches in diameter was filled with sand. When I tapped it with a rock it rang, not like a bell but clearly resonated.

When my observatory increased in size and went two storey I obviously required a pier. I have an engineering background and used 8" pipe for the pier. This pier is in in it's own separate plug of concrete that extends 4 feet into the bedrock, it is totally isolated from the concrete of the ground floor with strips of 1" thick polystyrene separating it from the main concrete floor.

I have 6 lengths of steel twisted reo, wired together that run the full length of the pier. The pier is filled with concrete. It is extremely rigid and even when hit with a hammer does not ring or resonate in any way.

I have a 16" F4.5 Newt on a very heavy German Eq mount bolted onto this pier. I regularly post my planetary images on IIS, these are captured with a DMK 21AU04 using an Orion filter wheel.

Obviously to get colour images I have to capture R, G & B channels and to do this I must physically rotate the filter wheel. I have my Laptop on a computer table beside the scope and as soon as I rotate the filter wheel and release it the image, at very high power on my screen, stabilizes instantly.

I can only speak from my personal experience based on the quality of the images I produce and the stability of the image when I do visually observe through my scope. I am very happy with my concrete filled steel reinforced pier.

For your interest I have attached an image of the pier, note the polystyrene strips separating the piers concrete plug form that of the floor. Also an image of what is mounted on the pier.

Regards
Trevor