Wing Plumbing (Nov. 14th 2004)

Time now to think about the pitot- static lines and the wiring for wingtip strobes (If I ever will mount wingtip strobes is currently unclear, alternative would be a transparent vertical tailtip for the ACL, however I'll do the plumbing anyway, you never know...).

Sure, this looks different as shown on the plans. The leftmost tube is reserved for wingtip wiring, the other two for pitot-static. The tubes are housing plastic water tubes, 12mm outside diameter. The tubes are quite stiff. The chaff protection is quite slippery, so thermal expansion of the tube is assured. I made 10 of these, so the pitot tube will be mounted further outboard (the original placement I don't like so much, I suspect it will receive some of the prop blast there, further outboard seens a better location). Also undecided is if the pitot tube will go on the right or on the left wing.

These are the brackets where only the electrical wiring will go thru. I made 20 of these (remember my Sonex got 14 ribs on each side plus the two root-ribs).

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Bushings (Nov. 12th 2004)

Oiled-bronce bushings are used a lot on the Sonex. Actually I would prefer roller bearings on the control system - but here I'll stay with the original plans. The problem with the bushings is that they will be pressed into the bore. So the hole must be very exact. I made mine 0.05mm undersized. This is just enough for pressing the bushings on the vise with moderate force (if the bushings will rotate in their bores - then goodnight - won't think about that).

...and the next problem just follows: I can't buy such a precise drillbit over here in Metric-Land. This is the way I took off 0.08mm from the bushing's outside diameter. I used a small file and ran the drill at max speed (2400 rpm). My digital caliper is exact to 1/100mm so it went like: file a bit, measure a bit, file a bit... finally I got it right to 2/100mm.

My fist victim was the elevator idler. The bores should be line-drilled before the bushings will be installed. This proceeded better as expected (sometimes Murphy is absent). It always pays out for such things that you take a little more time.

View 90 degrees rotated. I clamped the angle-construction on my solid steel riveting block.

SURPRISE! the bushings are in-line at the first try! (usually I fabricate at least three parts until I get it right).

This is a totally different story. Instead of the steel tube which is specified on the plans I make the shafts from small stainless steel rolls. This rolls however have to be opened up for AN-3 bolts. This went wrong for the forst two tries. Seems this cannot be done on the drillpress. I have to visit the mechanic shop next week...