metal
against the wall
Submitted by ron on Sun, 06/20/2010 - 15:31After dinner yesterday, as I returned to the baggage wall project, facing a critical decision, there was quite a debate, an epic battle actually, between competing internal voices, that went on for nearly an hour. One argued that just because I'm nearing the end, and eager to get on with the weighing, I shouldn't discard the long standing dream of having a little door in the upper section of the baggage wall, through which -- weight and balance permitting, of course -- I could poke lightweight but ungainly long items back into the tailcone, for example, fishing poles, collapsible antenna masts for some ham radio work or, most of all, XC skis. The other voice complained that such a feature would hardly ever be used and would take a ridiculous amount of extra time to build. The second voice was right on the facts, but guess which voice won. [Peeking at the photos below is cheating.]
The outcome of this battle was never in doubt. Gotta have that little ski port I've always dreamed about. (At least I eventually gave up on a hinged door and opted for just a simple cover plate.) The first photo shows rough cut and sanding of the first part of the job, the .032 doubler for the cutout. Fortunately, we have power tools (nibbler and mini-belt sander) for these tasks.
The next photo shows the doubler drilled and clecoed to the upper wall, with the center cutout marked onto the wall. [Note the Click Bond nutplates that will be used to mount this section to the bulkhead are still curing.]
The next photo shows the completed doubler (several hours into this project) all deburred, sanded, Scotch brite clean, and dimpled for countersunk rivets, ready for primer paint.
The next photo shows the ski port doubler fully installed... at 1 AM, after 6 hours of steady work. Unbelieveable, but true. The four open holes will have nutplates behind them to mount a simple cover plate over the port.
The last photo shows nearly all of the roughed in parts for the baggage wall, at mid-afternoon today. There's still quite a lot left to do, including a brace, floor and side mounting angles, alodining, paint, trunk carpet, but it's coming along. [Gotta like that spiffy XC ski port, eh?]
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surface operations
Submitted by ron on Wed, 04/14/2010 - 20:34Wahoo! As of a few minutes ago, the rudder and elevator cables are in, and at long last all flight control surfaces are now operational! It's an incredible sensation to sit (on the floor) in the cockpit and feel the rudder motion against the rudder return springs, the brake cylinders (still unfilled and a little loose) and the stick control of the elevator (still quite stiff Delrin bearings in the control column.) Many builders get this done earlier in the process, but I've postponed the cables in recognition of all the traffic banging around inside the fuselage while building other components. Didn't want to be climbing over cables all the time, perhaps damaging them. The delayed gratification at this stage is all the more sweet, I think, knowing that it's not just that the controls are working, but also that they are a sign the end of major construction is near. Truly a milestone moment!
The first photo is a closeup of the top elevator horn cable attachment, showing use of AN970-3 "fender" washers that have been drilled out to 1/4". They keep the cable thimble from sliding around too much, and protect it from the rather rough sides of the square tube steel elevator horn. When the stick is pulled back in the cockpit, this cable, which is attached to the bottom of the stick, is pulled forward, causing the top of the rotating rudder horn to go forward, raising the elevators. A couple of regular diameter washers are in there too. Note the piece of tape temporarily in place to prevent the regular washers from falling down inside the square tube. Don't ask.
The next photo shows use of a small piece of angle to lock the left and right rudder assemblies in sync. (I later found that good old ZIP ties worked much better than the clamps.)
The next photo looks forward, showing the right rudder cable hooked up to the rudder horn, and disappearing back into the fuselage through the rudder cable hole.
The next photo is a view from the control column looking aft at the run of the elevator cables. They actually take a slightly diagonal course from right (airplane left) to left (airplane right). The "fin" sticking up out of the floor just before the first pair of white cable guides is the center seat belt attach anchor point.
The following photo shows the aft run of the elevator cables. You can (almost) see the cable guides next to the ELT have some 1/8" Delrin pads underneath, to assure the cables will rise over the ELT mounting frame on the floor.
Finally, the whole assembly comes into view (Yay!) showing connections of the pedals, rudder return springs, rudder cables along the sides, and elevator cables and forward pulleys up the middle of the floor. The turnbuckles are just temporarily "pinned" here because the cables will have to come off for additional work on the control column and stick wiring, etc.
The next photo shows how the bottoms of the rudder return springs were attached to the engine mount bolts by a tang made from .040 chromolly steel. The tang lengths were cut so that when the pedal is at the most forward point of its travel, the spring will be fully compressed, but not kinked. The standard Murphy springs, shown here, have been frequently criticized for being too strong. Even just sitting low on the floor, the action felt pretty good to me. Of course, careful setup is essential and I think I've got the geometry where it should be.
The forward elevator cable pulleys are close to the control column, which helps keep the cables low, and also leaves room aft of the pulleys for the traditional mounting location of hydraulic pumps when the plane is equipped with amphibious floats.
Last but not least, another view of the whole assembly from the right door.
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seat stops
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fair tail
Submitted by ron on Sun, 03/21/2010 - 21:45The tail fairings are coming along. The top pieces require complex bends and rolls to get the correct shape. The roll where it meets the fuselage at the front edge fades to a plain, flat right angle bend at the rear. The edition shown below still needs various kinds of trim work, but the shape is correct, so it's a keeper. (Because the leading edge of the vertical stabilizer is offset 3/4" to the left of the centerline, the right side top fairing will be a similar shape, but bigger.) Due to weight concerns, I've decided not to install the aesthetically pleasing (and aerodynamically superfluous) "dorsal fin", but the geometry of holes around the leading edge of the vertical stabilizer won't preclude doing so later, if desired.
The third photo shows layout of the left lower tail fairing. The rivets at the four copper (1/8") clecos have been drilled out to replace dome head rivets with countersunk ones.
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top retainer
Submitted by ron on Thu, 01/28/2010 - 21:49The windshield's top retainer is ready. The photo shows drilling in progress. The holes go down through the center of the forward bulkhead flange, where the retainer will be secured by #8 machine screws into Click Bond nutplates.
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right light mount done
Submitted by ron on Tue, 01/05/2010 - 23:27The right landing light mount is done. It's similar in design to the left mount, just as strong but simpler and more elegant. The four standoffs used to clear the wing tip rib's lightening hole flanges are small rectangles of 3/16" bar stock, connected with short 6-32 stainless machine screws, washers, and fiber nuts. They make a very secure base -- more rigid than the direct rivet attachments used on the left wing. Tomorrow I'll hook up the wires for these and the NAV/strobes -- and have a light show. 
The first photo shows a front angle view. One of the 3/16" bar stock standoffs is clearly visibly at the lower rear attach point.
The second photo shows a side view. Note that the vertical piece at the rear of the mount is not parallel to the wing's leading edge, as it appears, but angled forward to align with the trapezoidal mounting shelf.
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right landing light mount #2
The right landing light mount. Note that the vertical piece at the rear is not parallel to the leading edge, rather it is angled forward as seen from view.
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