Pulsar 2.7m and a very large shoe-horn?

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Having discovered the sheer weight of the 4.4m calf dome I had to have a serious rethink.

The 2.7m Pulsar is likely to be somewhere around 2.5m between opposing ribs. The reflector is 2m long. That leaves 18" maximum clearance to be shared at both ends. Not that it is ever likely to be used horizontally. The 7" f/12 refactor will not fit horizontally with any sort of dewshield in place.

I daren't trust my optimism so I needed a full scale simulation. Half an hour later I had three stepladders and bike stand supporting some drain rods in a 2.5m diameter circle at about shoulder height. I carefully arranged these around the folded refractor on the big mounting on its 1m tall test stand.

A 2m length of alloy, simply tied onto the refractor framing, simulated the piggy-backed reflector for length. I even added a bit of hose to make a full scale dome profile. Somehow, I doubt this is going to offer much shelter from the wind!

I built the shed, working alone, years ago and it is still standing. The dome would be placed half way back, along this side of the shed, with a suitable access gap between the two. The 2.6m dome is about the same width as the shed. It is intended to have the observatory floor at eaves level to allow a clear view over the ridge to the east. You would not believe how many times I have climbed a ladder, leaning against the shed, to imagine the view from an even more imaginary observatory.

We must now assume that I am not daft enough to make a tight, cylinder wall of the exactly the same diameter as the dome. If this assumption holds true then I think we have a workable size of dome in the Pulsar 2.7 flat roof [or dome kit] fitted on a larger, square "box" observatory.

If I follow this path I get a ready-made, off the shelf, well-proven and working dome. Throwing a simple box observatory together is fairly quick work. A raised box with 8' legs is slightly more work. The upside is that it won't completely dominate the back garden. I had superimposed a 4.4m observatory on a photograph of the selected site and it was absolutely vast seen from the house!

The Pulsar 2.7 is relatively tiny at the correct scale.  Though the space it takes up is largely irrelevant anyway. It is an unimportant area containing a few leggy shrubs and tree saplings where once two huge birches were standing. The downside is having exposed steps unless there is room for a trapdoor in the necessarily much smaller footprint of the observatory floor.

My wife suggested placing the Pulsar dome on top of the shed. An interesting idea at the risk of leaks while under construction. Lifting the dome into place would need a crane. Or very great care. But what a view! The internal supporting structure would make working in the shed far more difficult though.

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