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| Cardassian designed airlocks, Deep Space Nine |
I always thought the airlock doors on Star Trek: Deep Space Nine were pretty cool, kind of steam punkish with their great big gear teeth in the age of warp drives and teleportation. Yesterday, since I was feeling under the weather, I amused myself by thinking about how they might work. Since you have these great big gear teeth, and since the doors rotate as they are opening or closing, you might think those gear teeth have something to do with how they operate. You could control the motion of the door with a two racks, one on the top and one on the bottom, like so:
rack and pinion mechanism
mekanizmalar
However, the racks will need to be quite long. They would need to be twice as long as the door is wide. In addition, the top rack would need to travel twice the width of the door so it would need a space four times as long as the door width. That might be okay on a giant space station, but it would be problematic on something smaller like a space ship.
One way to make it more compact would be to have three motors with pinion gears spaced equidistantly around the circumference. The motors would be mounted on slides. We wouldn't need to actually spin the door until it was in position to close, but it wouldn't hurt.
You don't need a top rack, just the bottom rack to roll on, and that's just to make use of the big teeth in the illustration. The big problem is sealing.
ReplyDeleteYou need the top rack to roll the door. As for sealing, that's why I postulate the existence of a big screw thread around the circumference.
ReplyDeleteUsing a rack to drive the door wastes too much space and you've got those big old teeth around the circumference.
ReplyDeleteI'm obviously not understanding your design, but that's OK because my life isn't going to depend on it.
I'm pretty sure whoever came up with design just thought the big gear teeth were either appropriate or maybe just cool. The Cardassian's were a highly militaristic society, and military hardware tends to be way overbuilt. I can imagine that once the door was rolled into position, it continued to rotate, and a screw thread protruding from the rear surface (that we are never shown), screws into the door opening to seal the door. If you need to open that door when you have air on one side and vacuum on the other, the force needed to turn that door would be considerable, hence the giant gear teeth. Operating the door with giant racks operated in turn by hydraulic rams would mean you could have remote control of the door without having to have dangling cables or hoses. It also keeps everything within close proximity to the plane of the door.
ReplyDeleteOK, but with a rack engaged by those big teeth top and bottom are used to move the door. I don't see how it could keep turning to engage a screw thread without moving it more. The top rack rolls it in, then a normal right hand thread would require the top rack to change direction but the bottom rack would have to move also for the door to screw in.
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