Wiring and fiberglass.

12 hours.

This is for yesterday and today. I finished up the elevator and HS fiberglass tips. You’ve heard me piss and moan about fiberglass before, so I’ll spare you that this time, but yesterday’s experience was not great. I got the HS off the futon in the other room and set it up on the bench so I could mount and balance the elevators. When I last left the HS, I’d done the fiberglass tips, but I hadn’t done much else with them, and they needed a good amount of shaping before the elevators could swing freely. One side was fine after some filing and sandpaper, the other had the foam too close to the edge so I sanded all the way through the filler and started taking out foam.. This isn’t good. Raw foam isn’t helpful, so I had to mix up some flox, both to fill in the elevator tips after balancing and reinforce the left HS tip. I had this cool thing set up where a thin piece of sheet was curved round the elevator tip, making a form for the flox that would guarantee the free motion of the elevator through its travel.

Would have worked too if the tape hadn’t popped loose, leaving me with a distorted lump of flox on the front of one elevator. I had to file/sand that back into shape, then glop in a load of micro filler to get the final shape.

So there it is curing away.

I busied myself with antenna mounts while the epoxy was setting up. First was the transponder antenna. I’ve decided to put this on the floor behind the baggage bulkhead. All antennae need doublers, even the stubby transponder antenna. The skin of the aircraft isn’t thick enough to provide structure on its own, so I had to take a piece of .063 and make a plate that the antenna can grip onto.

Today I did the final shaping and priming of the HS and elevator tips. While I was waiting for paint to dry, I worked on the doubler for the Garmin GPS antenna.

Installing these doublers aft of the baggage bulkhead is interesting. First thing you do is drill the holes in the plate at four corners, then one in che center. Then you go inside the ship, down the Jeffries Tube, and position the plate where you want it for proper antenna location. Don’t forget to bring your drill. Use the plate as a guide, and drill the skin using the center hole in the plate as a guide. Then measure to square the plate up with surrounding stuff, then drill the corners of the plate. Now it gets fun. You have to dimple all four holes in the skin that match the corners of the plate. You need to use your 3/32″ pop-rivet dimpler for this, but you do it by crawling into the ship, placing the dimpler, getting back out, making the dimple, then repeating 3 more times. In the case of the GPS antenna, there are also screw holes to deal with, which means platenuts. Oh, don’t forget to countersink the skin side of the plate.

Since I was in the tailcone a lot today, I figured I’d do some nagging things I was going to have to do anyway, like the restraint cable clevises and removing the ELT antenna cable. Yeah, can’t run the ELT cable through bulkheads. If you crash, the airframe might fold and sever the ELT antenna cable where it passes through a piece of sharp metal. I decided to run the trim servo wire down that run in its place. Then I ran the transponder antenna wire alongside the two GPS wires on the left side and did the BNC connector.

I don’t want to spend a lot more time down there. It’s cramped, hot, and dusty in there. If I can get enough servo wire slack so I can work on the connector outside the ship, that will make me extremely happy.

Comments (2)

  1. 1:54 pm, January 18, 2011Uncle Bill  / Reply

    These old bones hurt just thinking about crawling in and out of that tail cone. I have to get help replacing the sump pump on the boat.
    Do you sleep? It’s 6:30am here in Fl and the date on your above comment is today. Having run a machine shop for the last 20+ years I am astounded at your knowledge and skill with regard to metal working – where did that come from?

    Uncle Bill

    • 11:03 pm, January 18, 2011stjohn  / Reply

      Most of my metalworking skill comes from this project and internet osmosis. Practical stuff like edge distances, rivet lengths, number of threads exposed on a locknut, etc. mostly come from the Aircraft Mechanic’s handbook, which came out in the 40’s or 50’s. It’s much revised, but you can tell from the drawings of people at work that it’s been around for a long time. Also the Van’s Air Force site has been invaluable. The knowledge on that forum is unbelievable. There are U2 pilots, turbine mechanics, manufacturers, air traffic controllers, software engineers and at least one shuttle pilot who frequent the site regularly.

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