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The plywood dome continues to leak just enough to cause ugly white mould on the laminated, birch ply ribs. I wish I had used aluminium for the whole thing but I was building an unusual dome with trapezoidal panels. The complexity of all the different angles and panel dimensions might have ended in horrendous costs even as a completely DIY project.
Moreover I wanted it to be painted green to avoid it being of high visibility. Though even here there is a neightbour's building partially concealing it from the road. So that only the very top of the dome is visible from a distance. There are also trees growing between the dome and the road. Further, tall hedges prevent the dome being seen except through a rather narrow gap along the drive beside the house.
Only one neighbour could see it from this angle but they are 175 yards away. Which is also at the nearest point of the rural road. The top of the dome would be visible from the road only from 300 yards away. Down to 200 yards away, but only if a driver actually looked sharply off to the right while travelling at 50mph.
Which gives me the confidence that a shiny aluminium dome would probably pass almost completely unnoticed. Except perhaps to the eagle eyed. A larger dome would be better for longer OTAs. Though nothing longer is anticipated than the straight 7" f/12. Which is proving to be slightly prone to catching the wind at low angles in winter.
One alternative would be a modified, calf rearing dome in heavy fiberglass. At 4.4m [instead of the present 3'] the size would be ideal. The normal finish is white gel coat. Though a vertically gored version in green GRP is also available from another manufacturer at greater cost.
The sheer size is a shock! I ran a tape measure from the east wall of the dome. The 4.4m would be more than 2' beyond the veranda fence to the west! It would also be taller than the green dome by 70cm at 2.2m.
The downside would be the need for complete demolition and rebuilding of the present, two storey, observatory building to match the much larger dome. The calf dome would need to be modified to provide a horizontally opening, observing slit. Fortunately the central panel, of three, is the only part needing such work. Some serious reinforcement would be required at the zenith.
The most serious downside is the overall weight at 200kg or 440lbs. Which can be reduced by three sections at 150lbs each. Though once it had been lifted into place I'm sure my friction roller dome drive could easily cope.
A long working life is guaranteed. Statistically, it should easily outlast me. I'm not sure I am ready to invest so much time, money and energy into a bigger dome now. The 3m/10' is fine if I would just accept the new 6" f/10 H-alpha as the main telescope. Then ensure the dome lasts for a few years before it disintegrates. The plywood and its painting has been a serious disappointment. I'm hoping the warmer weather will allow me to sand the panels back to the wood and repaint directly with the quality paint. No cheap undercoat!
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