Cloudynights doesn't have a planetarium forum, so I'm not quite sure where to post this. Bu this is where the builders gather, so it seems like the best fit.
I put up a post over at the Observatory Central website, which has several different forums related to planetariums. But it does not get the traffic and views that CN does, and I haven't gotten any responses. It's been up for less than 24 hours, so I may well get some replies, but I figured it wouldn't hurt to post here, too. Rather than r-write everything I wrote there, I'll just paste in what I posted there. If anyone has any ideas, leads, critiques, or whatever, I'd be grateful for them.
"I was given a Spitz A4 projector by someone who has posted here. He had tried to get it up in a public dome but couldn't find a way, so offered it anyone who thought they might be able to. I convinced him that I would give it my best, so he gave it to me, with the understanding that I would give it back if things didn't work out for me, either. In my local school district, we recently got a referendum approved to build a new performing arts center (PAC), and our superintendent loves the idea of making a planetarium a part of it, especially since I'll provide the projector.
"Here's the issue: we will (almost certainly) not have a dedicated, permanent space for the dome. The hope is to find a way to make a foldable, 24-foot dome that can be raised up into the 'flies' above the stage. I see it as a fabric hemisphere with a steel skeleton made with -- possibly -- electrical conduit. The fabric material does not need to be completely opaque, since the stage can be made completely dark be simply turning off the theater lights. So the weight of the dome can be kept to a minimum, meaning the steel framing does not need to be super heavy-duty. I see the frame being on the outside, made up of about 18 to 24 ribs, and these ribs will slide through sleeves (just once, when we first assemble the thing) on the outside of the dome. When not in use, the dome should open (with a zipper? Velcro?) and the ribs can then be rolled together to flatten the 'tent' of the dome. It would not need to fold up to the smallest size possible; just enough to be flat enough to raise up on a couple of cables attached somehow to one or more of the ribs. We will have motors that will be able to lift several hundred pounds, so I think this would be easily doable.
"When the folded dome is lowered from the flies, I see us opening it up and locking the tightness of the dome by lowering braces that fit between the bottoms of the ribs, and then supporting it on its bottom edge with several (4? 6? 8?) posts about four feet tall, which we will install into some kind of holders in the stage floor. Folks will ether sit on the floor, or we will have chairs that can be set up (we have plenty of those on wheels). We'll also need a way to move the projector on some kind of wheeled base from a storage closet on an edge of the stage. I want to find a way to make this as simple and quick to do as possible, so the planetarium can be set up in a reasonable time, for use by students and the public. I live one block from the school, so they'll have someone ready to help.
"I've talked this over with some others who think it can be made to work, and I think I have the skills to do much of it, along with help from the shop teachers at the high school. But the one thing I have no skill set for is the making of the dome. What size and shape to make each of the sections of the dome; how best to sew them together; how to make the ribs come together at the top (I'm imagining a small wheel with all the ribs having rings on the ends; like a giant, round shower curtain.) I'm hoping folks here might be able to point me toward sources/ideas, or even to someone who has, or who could, do it. I've been told (but not gotten a guarantee) that the school district could find some funding for the making of it. I'm on the school board, so I might have some influence on that (but again, cannot guarantee it yet). If I had some solid leads, I could present the idea for consideration.
"Again, the projector was originally housed in, and is set up to be used in, a 24-foot dome.
"I could write a bunch more right now, such as how I own and use a Starlab 16-foot planetarium. And about talking with John Hare from Ash Enterprises about this project, since he services the A3p projectors at two schools (one high school and one university) nearby. But I'll wait to say much more while I wait to see if anyone here can help. The ground-breaking for the new PAC is going to be some time around Thanksgiving this year, with the construction lasting about twelve months. The planetarium project does not to be done as part of the initial building of the PAC, but I think it would help to keep the idea moving forward if it was at least well under way during that time.
I only post here every few years, and always have gotten great advice. Thanks in advance for any ideas!"