The
basic idea was to have an extending step in approximately the same place as the
plans version, with a simple actuator. I wanted a rod that extended from a
tube, just 
the lower longeron (to help with strength and support).I didn't like the plans step, hanging out in the breeze, and I didn't like the AeroCad version of the retractable step that was available, so I decided to invent my own.
The
basic idea was to have an extending step in approximately the same place as the
plans version, with a simple actuator. I wanted a rod that extended from a
tube, just above below the lower longeron (to help with strength and support).
In this picture, you can see the bottom curve of the fuselage, the nose gear to the left, and the retracted step toward the right.
Here
you can see a close-up view of the step, retracted into the tube. The end
of the tube and rod are filed to the same shape as the surrounding fuselage
curve (although the paint isn't sticking very well to the aluminum tube or end
of the rod. The rod is a close fit into the tube.
This
picture shows the tube as it extends into the fuselage, on top of the inner
floor and just forward of the rearmost section of the front thigh supports on
the pilot's side. You can see that I floxed the tube to the floor and
covered it with 2 BID near the fuselage side AND the far end. The black
box at the top right is the altitude encoder, and the orange box is the ELT.
You can see the end of the control cable, and the black delrin "flange" that's
screwed to the side of the rod. It attaches to the rod through a slot
that's just barely visible on the top of the tube. Moving this "flange"
back and forth (right and left in this picture) makes the rod slide in and out of
the tube, extending the step.
The thin black plastic piecebetween the tube and the ELT/Encoder is a delrin slider for the "flange" to slide on, and it has a "stop" at the left end, so that the rod/step can only be extended so far. It's screwed to the fuselage floor. The actuator cable COULD pull the rod out further, but two things would happen - first, the rod wouldn't be well supported in the tube, and second, the ball bearing detent/lock in the cable actuator would fall out and disappear into hyperspace, never to be seen again. Ask me how I know.
There's duct tape wrapped around the "stop" end of the "flange, as a fine-tuning of the positioning of the step. I'm sure that there's a more elegant way of achieving this end, but since this all lives under my butt and no-one ever sees it, I'm not sure I care. Actually, I'm pretty sure I don't care.
Here
you can see the step/rod in the extended position, with the cable pulling the
"flange" down to the stop.
And
last, this is the business end of the actuator push-pull cable (the black one -
the red one is the parking brake, as labeled). It's a button lock version,
meaning that you have to push the silver center button in to get the cable to
move either in or out. Probably overkill, but I didn't want the cable
either extending or retracting on it's own, for obvious reasons.
When the cable is pulled out, the step extends, and when the cable is pushed to
the Instrument Panel, the step retracts flush with the external surface of the
fuselage.
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Copyright © 2005, 2012 All Rights Reserved, Marc J. Zeitlin