dle's Oz Build

[David47]

This weekend consisted of finishing off some loose ends and doing a control system friction “audit”.

First off, both the rudder fibre glass LE and the fin TE were bonded in place. There was quite a bit of work that went into finishing these parts to the point of bonding, so it was nice to finally see them attached. I made a much better job of the rudder LE hinge and stop arm cutouts than I did with the fin TE fairing. Just need to not get so excited when using the Dremel, which is a must for this kind of work.

Bonded all the rudder cable ferrules in place after cleaning up the holes with a fine file. This is a messy job as I tended to get adhesive inside some of them so had to use a 3” nail poked through in order to get rid of it.

From last week, I was concerned about the amount of friction I had in the aileron and elevator control circuits, particularly the latter. So I disconnected all actuation rods and checked both elevator idler arms and the aileron bell crank for free rotation. I also checked the control stick cross tube mounting and found a minor amount in the nylon bearing. I loosened off the bolts attaching the nylon block a bit (thanks Jim, Josh and Carl) and that helped. However, the elevator idler arms, in particular had excessive friction so I disassembled both idler arms, re-sanded the bolts, re-reamed the bushes, applied more grease to the bolts and assembled all together. Both idlers now swing freely without any bolt rotation. I did the same for the aileron bell crank and reassembled. Same result. At the same time as friction reduction, I also swapped out all nyloc nuts and bolts at each rotating joint and replaced with shank drilled bolts, castellated nuts and cotter pins.

Without the elevator attached, the amount of friction in the elevator system was considerably reduced, to the point where you could move the control stick with insignificant force. Same result for the aileron. With the elevator attached however, there was a marked increase in friction, although not quite as bad as I had before sorting the idlers. I know this is, in part, due to fitup whereby either the elevator or stabilizer has a slight bow in the spar as I had to lever the two together a tad to get them to align last week. I haven't tried it yet but I suspect some of that will disappear when I grease the hinge point bearings and bolts. Fingers crossed.

Finally, I temporarily attached the main landing gear leg as I’ll need the main and tail wheel gears on to move the fuselage to another shed for painting. What impressed me was the alignment of the gear blocks and the fuselage mounting tubes. I checked the fit of the bolts in both block sets and then in the fuselage mounting tubes independently after reaming the tubes per the manual. To my pleasant surprise the bolts aligned beautifully in all components ( i.e. both blocks and the tubes). Given that the fit of the bolt in each component was a running fit, and only needed a minor amount of tapping with a soft mallet to get everything pulled up, that’s good effort to get such accurate positional tolerancing. Looks to me as though the fuselage weldment jig and the mounting block drill jigs could have been match drilled, which would be a sensible thing to do for such a critical joint. Regardless of how this was achieved, I “dips me hat” to Kitfox for a top effort.