Small Jobs (June 25, 2002)
The last few days I worked on the elevator trim-tab and other small jobs. I made about five different models of trim-tabs. The original Sonex design I didn't like so much because it is quite 'flimsy' and not usable with the trim servo. I experimented with small airfoils and other more exotic designs. This is the final result:
The supporting structure is made of 0.06" (1.6mm) material. The skin is of 0.025" (0.6mm). The lever arm is different from the Sonex design and located at the first third from the left. This will allow for a straight connection of the pushrod to the trim servo. The whole tab is much more rugged than the original design. The weight has only slightly increased. The skin is flush-solid riveted to the countersunk supporting structure. The trim assembly took about 5 hours to make (excluding priming).
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This is another small job, the mounting cradle for my new (used, from
ebay) Delcom radio. Even thus the Delcom is not at all the latest in technology,
it's the ONLY design which meets this four essential requirements:
The cradle is made from 0.025" (0.6mm) sheet and 0.125" (3.2mm) 2" x 2" 'L' extrusion. The cabinet is solid flush riveted FROM THE INSIDE. The battery pack is removed, the radio will be permanently wired to the on-board buss. The Delcom provides two threaded holes accommodating the two M3! screws on the top of the cradle.
Cradle viewed from the side (lots of AD-3 rivets used ;)))
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Preparations for Electric Elevator Trim (June 25, 2002)
Electric trim was a must from the beginning (see my ergonomics considerations). Today I finished the handhole cover plate on which the trim servo will be mounted. This way the whole trim asembly can easily be removed for inspection/service.
I have ordered the servo from http://www.rayallencorporation.com . It's $119 plus extra pushrod and forkends. The size is 70 x 70 mm. So it will fit nicely the 105 mm diameter cover plate.
First job was to make a large hole into this shining left elevator skin
(this are always such moments you think twice...)
This shows how the mounting ring fits from the inside. The mounting
ring is of 0.032" sheet and flush riveted using 8 1/8" rivets.
The ring will also contribute to reinforcing the cutout.The 8 triple holes
will hold 8 'anchor type speed nuts'. Screws used are of NAS548P 100 deg.
phillips flat head sheet metal screws.
All holes are dimpled or countersunk, so no sharp edges will obstruct
the clean airstream.
The result after five hours of hard work.
Fasteners used:
Next is priming, polishing, riveting, mounting servo. The trim tab will be constructed differently from the plans (too fragile for my taste).
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Elevator Fuss (June 16, 2002)
This weekend I primed the inside of elevator and rudder control surfaces - worked out better than expected. On Sunday I test-fitted both elevator parts to the center drive section (C06-02). This part is the fussiest I worked with so far (-O.K. I haven't yet drilled the wing attach blocks...).
The locations with clecos installed can be drilled using the regular
air-drill. For the remaining ones I'll try the angle-drill. For the red
encircled two locations there's NO WAY to match-drill them. What I will
do for these is measure as exactly as possible and then drill from the rear
of the rib - and pray to heaven the holes might align. If someone out there
has a better idea, pls let me know.
But this was not the only trap of this assembly. I build both sides of the
elevator with great dedication. However when I tried to assemble them the
center section didn't fit. The root rib was not perfectly vertical, so the
attach plate of the center drive was flush at the bottom but a gap of 1.5mm
showed up at the forward top position. What I did to save dozens of working
hours is a wedge-shaped shim plate of 0.063" sheet which goes between
the attach plate and the root rib - I hope this works.
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Riveting and Bolting the Pieces Together (June 10, 2002)
Finished riveting the forward fuselage sidewalls (so far). Did >not< rivet any of the wing attach angles, also did not rivet the firewall attach channel (would hate to drill these rivets out sometime later). Also the rudder and flap drive mounts are only clecoed - just in case...
Also riveted and bolted the vertical tail rear spar together (using solid AD rivets).
Here a problem showed up (which seems like a general problem of this design). The two bolts close to the radius of the T12-05 angle do not allow a clean installation of the shims / shims interfer with angle radius.
What I probably will do is radiusing one side of each of the two shims.
This will remove the protective cad-plating, so I also have to prime the
washers
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Forward Fuselage Sidewalls ready for Riveting (June 05, 2002)
Most of the forward fuselage parts had been made long ago and were already collecting dust. My handicap lately was our bad German springtime weather. Only at end of May outside temperatures rose sufficiently for priming.
This view in on the inside of the sidewalls of 'green monster'. Outside is already polished. I hesitate to hit the rivets right now. Reason for that is that some of the components (red circles) are only pilot-drilled (per the plans) and will finally be installed at a later time. There's nothing bad with this - except that when drilling out the pilot holes to 1/8" chips will collect between the (already assembled) longerons and sidewall skins. There will be ~no way~ to remove these hidden burr and chips. Anyway my clecos are running short and I'll have to bite the bullet soon.
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