Retractable Access

Though still baby steps…

With no handrails, it’s an awkward crawl upwards.

Decided I needed to start working on the means to get up to that docking port since I’d moved it up so high.  I had contemplated just some mobile stair set stowed handily out of the way, that could simply be moved into position and locked into place when needed.  But space being a premium, I decided I would at least try to devise some retractable version that could vanish on cue underneath the hatch’s frame when a travel pod comes a-calling.  With the space allotted me, I managed to come up with this little doozy, currently with heavy emphasis on the step aspect as it still needs some sort of railing.

It’s basically a singular central framework, steeply inclined with five sturdy steps mounted to it.  I researched a host of retractable options from attic ladders ranging from simple fold-down and yet still more complex collapsible varieties to folding boat gangways with self-leveling stairs.  I was inspired by many, but wanting to keep it simple I managed to work out a viable folding method for the bottom half of the staircase.  Just behind and under the center stair, a hinge mechanism swings the lower half of the frame with the bottom two stairs 180 degrees backwards to line up perfectly with the upper half, which when compact barely makes clearance into the cubby-space.  I am having several clearance issues during the actual deployment though, especially with the lower decking.  The entire frame has to extend out well past its final position in order that the bottom two stairs make clearance of that raised portion of the deck serving as a frame for the bay’s main opening.  Unfortunately even that far out, the entire frame would have to swing upwards a few degrees in order for the bottom stairs to miss hitting the floor itself while unfolding.

If one presumes the staircase is present by default when the docking ring is not in use then it could be a non-issue, since once the main deck plate is lowered there is no conflict.  Although it would seem excessive to have to open the entire bay door just to operate the stairs,  it would be necessary to lower and put it out of the way for any docking vehicle or module to make use of the port (the primary reason for retracting stairs in the first place).  If the stairs are default and nothing is planned to dock, they can remain in place despite the door’s status and then the floor clearance markings make even more sense now.  Still a swing upwards of the entire set at the top could make clearance for both obstacles non-issues, but it’s one extra hinge that makes things a bit more complicated.  I’ll have to contemplate it.  Of course all of this assumes that the stairwell itself is some automatic mechanism.  If the thing were a manual pull-out/unfolding device that just tucked away, I could go for an even simpler approach, but I think I want it to be a little more sturdy and permanent than your average pull-down attic ladder.

Also, some of my problem solving involving telescoping methods, may have me following a different approach that renders the clearance issues moot. I’ll be examining that option too, though it will be more time consuming.

I’ll try to get some close ups of the stairs later, in both retracted and deployed modes.

P.S. Pre-post Update: Got some work done on a handrail though I’ll be trying another version shortly.

Temporary handrails.


~ by starstation on July 8, 2012.

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