Reproduced below is a full posting by Richard McColman at the University of North Carolina's Morehead Planetarium and Science Center in Chapel Hill, NC. This appeared on the Dome-L planetarium mailing list September 2, 2013 and was in response to a query about using portable planetaria in hospitals:
I think you could use a GoDome for an audience with a couple of wheelchairs, but I wonder whether the "birth canal" entrance/exit door could become frustrating with a whole group of wheelchair-bound audience members.
I will say that we have used a standard GoDome for several years, and have experienced some frustrations. While the entrance/exit is a nice idea in theory, we haven't found that it works quite so well in practice, partly because it's a bit of a squeeze for audience members to go through it, and partly because the weight of the entrance/exit causes the dome to sag down on the door side, at least in our experience. I know that there's supposed to be adjustment vents to modulate the flow of air to various parts of the dome in order to keep the extrance/exit fully pressurized, but in practice we could never get a satisfactory balance to keep the door from sagging during programs -- particularly when the fan was turned down to anything below full speed (but also when the fan was running at full tilt). This wasn't our only frustration, though...
We also experienced multiple instances in which the inner door zipper jammed, and more importantly, the fabric where the zipper was attached frayed and split. It appears that the weight of the entrance/exit creates stresses on the zipper and zipper area of the dome, forcing the zipper wide open when unzipped. The operator has to really work to close the zipper, and all the weight-induced stress and pulling the zipper closed leads to jammed zippers and frayed fabric. The dome is made in China, so we had to send our dome overseas to get the zipper and surrounding area repaired (though the last time, we opted to get a local awning company to do the job, for a quicker turn-around). We also had an issue with fabric patches not matching in color when the folks in China repaired light leaks. This led to quite visible squares showing up during projected programs. (I found out later that the patches to this sort of dome should be attached to the dome exterior rather than the interior, in order to minimize this sort of issue. Granted, the extra swath of fabric we received with our dome got misplaced, apparently, and that led to the patches needing to be pulled from a different fabric run, making them a different color. But even with a different color, had the patches been made on the exterior, they would have been much less obvious in the projected dome content.)
Some of this frustration would have been lessened had we not had the round-trip-to-China shipping turnaround issue. We use our portable planetarium a lot, and can't be without it for very long at a time, usually. Fortunately, Sky-Skan graciously sent us a loaner dome on at least one occasion -- we bought our GoDome through Sky-Skan along with our Sky-Skan PD-II digital portable system -- and this allowed us to avoid canceling programs during at least one dome repair.
I don't know whether the sagging entrance/exit and resulting zipper and surrounding fabric damage is an issue with the elevated tube models, but it sure seems to be an issue with the standard GoDomes, at least in our experience. The only other variable I'm aware of that might account for the entrance/exit sag could be that we were using a Sky-Skan-engineered fan, and I don't know how the air-flow spec on that fan compares with the fan that GoDome normally supplies. But I do know that Sky-Skan is pretty good in their engineering and design practices, so I'm not inclined to suspect this as an issue.
In the end, we decided to replace our GoDome with a Digitalis dome. So far, it looks like that design is going to work much better for us. It does have a regular zippered entrance/exit without the big airlock of the GoDome. Despite that, or maybe because of it, the Digitalis dome seems like it's working better for us overall, and having folks enter and exit is actually quicker and less problematic that squeezing through the "birth canal" of the GoDome. And as I understand it, the Digitalis dome is made in the US, so getting repairs done should prove to be a much quicker turn-around. It also weighs considerably less than our GoDome.
Do note that I'm not attempting to slam GoDome here. I'm merely relating the experience that we've had. Others may have different experiences, I imagine.
As far as wheelchairs in a dome -- not just portables -- I often worry about the discomfort level such audience members will experience due to a lack of head and neck support, given that so much of the visual content on the dome requires looking up for extended periods. I'm not sure what to do about that in a portable dome, but in our large fixed theater I will sometimes suggest that wheelchair-bound audience members transfer to a standard theater seat, if possible, to gain the head/neck support. I know that that's not going to be an option in the portable, though. What this does bring up, however, is the issue of the dome height. If a elevated tube model of inflatable dome is selected, it will tend to exacerbate, I think, the lack of head and neck support, since the wheelchair-bound audience members will have to look up even higher than in a standard inflatable dome.
I wonder if someone could design a special headrest support attachment for wheelchairs in planetariums. It seems like a lot of us would want to purchase a handful of those to address the head-neck support issue for our wheelchair-bound audience members.