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  • #31
    Completed the wing-side wiring this week. Not going into details since it is pretty straightforward stuff, other than to say all servos are wired separately (no shared power hookups - one wire, one Multiplex connector pin). Using PowerBox premium wire and servo connectors exclusively. I really like their stuff.

    The Jeti solder boards for Multiplex green connectors are the shizzle. I no longer dread soldering up these connectors. One piece of advice...when soldering the boards to the connector, make sure you have the opposite side plugged in. The pins "float" a bit in the shell, and having the connector mated holds them in proper alignment.
    Last edited by tewatson; 01-07-2021, 07:45 PM. Reason: Updated text.
    Tom

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    • #32
      Tom,
      Thank you for taking the time to detail the build. Although the replies to the post are few, the analytics are pretty impressive. There's a good following on this build thread.

      Len
      Len Buffinton
      Team Horizon Hobby

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      • #33
        Working on fuse-side wing wiring. Used Emcotec 90 degree solder boards for the Multiplex connectors, to keep the harnesses tight against the fuse right from the connector. These are just a bit trickier than the other boards to arrange and solder, plus the heat shrink procedure required a bit of thought. Came out nice.
        Last edited by tewatson; 01-16-2021, 12:33 AM. Reason: Updated text.
        Tom

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        • #34
          With the harnesses done, time to finish out the pre-molded fuse connector sockets. Standard stuff, though somewhat more time-intensive as there was full-thickness (~2mm) fuse layup material at the bottom of each socket. Drilled and cut to rough size, then finished by hand with small files for a snug fit. Connectors will be held in place with a dab of Goop inside top and bottom, so they can be removed if ever necessary.
          Last edited by tewatson; 01-16-2021, 12:12 AM.
          Tom

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          • #35
            Last night's project was the TEK probe receptacle. With a removable fin/rudder, did not want to monkey with a tail probe, so went with a fuse-mounted setup as used on v-tail ships. The idea is to get it more or less perpendicular to the flight axis, so I fashioned a remedial fuse leveling setup. Taped a straightedge along the airfoil centerline, and used a small carpenter's level on the upper edge to adjust the fuse supports. Shaped a small lite ply block to provide internal support, and with the fuse set level it was easy to see the drilling angle required.

            With the 3mm hole drilled in the block and fuse, used the actual probe/receptacle assembly as an alignment guide, and glued the support block inside with thickened five-minute epoxy. Secured the receptacle tube with a small fillet of Goop where it exits the block. Done.
            Tom

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            • #36
              On to the FES. This part makes me nervous, being my first one and all. There will be three sub-projects - pilot bearing install, motor install, and motor battery placement. Since my plan is to maiden and fly a couple outings just as straight aerotow, don't need to have a functional FES right off the bat. However, the motor does need to be in place since it's obviously a huge factor for balance and will influence where other components need to go (e.g., tow release and flight packs). The motor packs will be at the CG, so the retention system can be figured out later.

              Using a Torcman NT530-28 14p/14w motor and Torcman quick-release prop adapter. This will be a 10s setup and the removable prop means quick changeover from powered to straight sailplane. My plan is to set it up with the thrust line centered (zeroed) in pitch and yaw. I interpret this as parallel to the airfoil (pitch) and to the fuse centerline (yaw). Right or wrong, it's what I'm doing.

              First step is the motor pilot bearing. Since the motor shaft adapter is a precise fit in the bearing, motor alignment thus follows the bearing. The trick is figuring out not only how to align it, but also to hold alignment while epoxy cures. The motor shaft is 8mm, as is the pilot bearing alignment bushing. Drilled a small hole centered on the nose, and enlarged one drill size at a time, finishing with an 8mm prop reamer. The finished hole size will be 12mm, but left it at 8mm for the bearing install (this is important, as it eliminates the need for an external forward pilot tube support).

              Next, set the fuse level. Did this the same way as for the TEK probe install - taped a straightedge along the airfoil centerline, and used a small carpenter's level on the upper edge to adjust the fuse supports.

              To actually align the bearing, used a thin-wall 8mm diameter x 1 meter long carbon tube from CST Sales in Tehachapi, CA. It's extremely light (no sagging) and laser-straight. It was a simple matter to pass the tube through the nose hole, slip the bearing and bushing on, then attach a bubble level to the tube. Fashioned a small styrofoam block to sit at the landing gear bulkhead as a rear support, and adjusted the height until the tube showed level (remember, the 8mm nose hole precisely holds the tube up front). The tube is long enough to leave a good portion protruding from the nose, enabling visual yaw alignment. With the tube aligned, applied MGS epoxy mixed with chopped glass and silica to the lower half of the bearing retainer, and slid it forward into place. Re-checked fuse level and tube alignment, then left it to cure.

              Because of the fuse profile, a gap remained on the top side of the bearing...enough so even thickened epoxy would sag through. Fashioned a small crescent-shaped filler out of 3mm ply to physically close the gap, using a small diameter brass tube as a holding device to shape and fit it. Once in place, glued the top half of the bearing using the same thickened epoxy mixture. Finally, used the prop reamer to open the nose hole to 12mm.

              Explaining all this took longer than actually doing it (excluding cure time, of course). MIL-spec precise? No. Good enough for this application? Yes (I think so, anyway). At least I'm satisfied the thrust line alignment is not off by orders of magnitude. Next up is the motor install.
              Last edited by tewatson; Today, 07:09 PM.
              Tom

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