Wing Rigging: Joining the wings to the fuselage. This is something that has to done right and, I admit, I feel the pressure. I'm trying to be meticulous in my preparations. Wish me luck!
21 May 2010: Securing the lift strut brackets. I temporarily attached the lift strut brackets to the wing spars with hose clamps. If you look closely you can see that I wrapped them with duct tape to avoid damaging the spars. The exact position of the brackets will be determined during the rigging process. At that time I will permanently attach the brackets with rivets and epoxy.
Next I attach "line guides" to the wing tips. In order to establish the proper sweep a line that stands 1 inch away from the forward spars must be stretched from wing tip to wing tip. (The word "in" indicates which side of the block I want to face inboard.)
Witness Mark. Exactly 120 inches from the root of each aft spar I place a mark. By measuring from a select point on the tail I can insure symmetry in the way the wings fit the fuselage. Because the marks are prone to rubbing off bare aluminum I used masking tape.
The last thing I do is gather all the hardware. Referring to my inventory records I retrieve all the hardware and place it all in a dedicated box.
28 May 2010: Leveling the Fuselage. I moved the Cessna to a safe place across the airport. This makes room for the wing rigging. the first step is to level the fuselage in the center of the hangar. Linda and I do this together.
Adjustable blocks: Carriage bolts, nuts, and washers. Along with blocks of wood. A simple way to make fine adjustments to the level of the fuselage. I've stabilized the fuselage with shot bag style scuba weights.
Some details: You can see the line stretched from wing tip to wing tip. It's weighted with a 2 once fishing weight to make it align with the spar center lines. This was to establish a zero degree sweep. You can also see the steel strap and hose clamps used to hold the forward spar in position. I stole this idea from Ken Birchard when I studied the photos in his TeamKitfox album.
I also complete the drilling. Because I have to mount the wings on the fuselage one more time to fit the jury struts and butt ribs I'm doing this work in the hangar. The disadvantage over working in my garage is that much of my time is occupied driving to the airport and back. Also there is no escape from the heat. One advantage, however, is that I can use my air tools in the hangar. At home in my garage I would not subject my neighbors to the sound of an air compressor.
Spar Reinforcements: Attaching the steel reinforcement plates that I prefabricated last February.
Then enlarged to 1/8"
14 June 2010: I'm ready for the second fitting of the wings. This will have to wait until I finish my commitment to work at the Stetson University Brass Camp. I expect to be back to work on the Kitfox on 11 July.
12 July 2010: I'm back to work. In a few days I will remount the wings to the fuselage in order to fit the butt ribs and jury struts. Among other tasks I glued aluminum strips to reinforce the area where the canopy will eventually be mounted.
14-15 July 2010: Second wing fitting. Linda and I remounted the wings to the fuselage in order to fit the butt ribs and the jury struts.
Butt Ribs: The instructions tell me that the flanges should face outboard but I couldn't make it work. With the flanges facing inboard they fit beautifully. Of course this deviation from the plans could haunt me later. I'll just have to take responsibility for it. The shims are made from 1/16th thick hobby basswood purchased at the Hardware Store.
Jury Struts: This photo shows the right strut clamped in place. I have to confess that riveting the brackets to the spars was difficult and awkward. Some of the rivets did not seat well. I decided to let the epoxy cure to assure proper alignment and then drill out the offensive rivets and redo them one at a time. Since the struts will not be in the way I should have an easier time of it.
Bending the butt rib tabs. I improvised a poor man's bending brake with a bar clamp and two pieces of wood. It worked quite well. Once they were aligned to the butt ribs I trimmed them with a Dremel tool.
Progressing from here, My Plan. At this point I plan to bring one wing at a time back to my garage for completion. "Completion" meaning that it is fully assembled, covered with fabric, and ready for paint. Once both wings are back at the hangar I'll bring the fuselage to the garage for assembly. Once the fuselage has been covered all parts will be taken to the hangar for painting. After painting the fuselage will be brought back to the garage for completion. When that is done everything will be gathered at the hangar for final assembly.
19 July 2010: Back to the Garage! The right wing, its stand, and both flaperons have been transferred to the house. You may notice a pink ribbon on the top stringer. It's surveyors tape and its marking a place where the glue has let go. Since it will take a very small amount of epoxy I'll wait to fix it until I have to mix glue for a larger project.
22-23 July 2010: Varnish! With the exception of some places on ribs 1 and 10 all the wood now has a second coat of varnish.
Fittings! Sealed with thread seal and tightened just beyond hand tight. The threads in the tank will not tolerate an aggressive amount of torque. I'm letting the thread seal cure overnight before I flush the tank and permanently install it. You can see places where the end rib needs additional varnish and epoxy
Fabricating the Sight Gauge Plate. A picture story.
Complete: I temporarily fitted the sight gauge tube in place for the final fitting. (I regret that I did not take a photo.) The priority was to make sure that the tube was not in contact with the metal to prevent chafing. To accomplish this I had to settle for a little misalignment of the two pieces. I'm sure that when the airplane is complete it would be barely noticeable. But I know it's there. In this photo you can see one of four blocks that extend from the tank to the #1 rib. This is specified in the builder's manual and is necessary to stiffen the rib against the pull of the fabric. Since there was nothing provided in the kit to make these with I elected to make them with 3/4" dowels. I intend to varnish them.
31 July 2010: Installation of rib #2. Since the 2nd rib is just the bit that is aft of the rear spar with a capstrip that extends under the tank I came to the conclusion that the best way to install the it was to combine it with the installation of the last section of the trailing edge. This would insure proper alignment. When the epoxy is set I'll complete the installation by blocking in the capstrip. Along with this I filled the gaps between the tank and ribs with epoxy.
1 August 2010: Blocking in the capstrip. By extending a straight edge from rib 1 to rib 3 I was able to spot the location of the capstrip for rib 2 at each point along its length and block it in place. I used old drafting weights to hold everything in position while the epoxy cures.
7 August 2010: Time Out! For about two weeks I'll be occupied with the Cessna's annual inspection.
14 August 2010: I'm Back! The Cessna is ready for inspection and I'm back working on the kitfox.
False ribs along the bottom of the tank. The ribs have to be trimmed to accommodate the tank. I placed a rib along the side of the tank and spotted its position with a level serving as a straight edge. I drew a cut line and made a rib that would serve as a template for the rest of the ribs.
A Temporary "Hinge." I use strips of duct tape to make a hinge that allows me to swing the extrusion to a position that allows me to apply epoxy to the gluing surfaces. A lot of epoxy had to be spread and I had to work quickly due to the Florida summer heat.
27 - 28 August 2010: A shelf for a magnetic sensor. I've yet to select what I intend to install on the instrument panel but I've reached some conclusions:
The Dynon SkyView system is an example of a system with an all-in-one attitude and heading sensor. Aside from the sensor I'm very taken with the "gee-whiz" features such as synthetic vision. But that leads to another consideration. Is there a real advantage to having synthetic vision in a Kitfox? (At least in the manner Linda and I intend to use our Kitfox.) For us the answer is no. I don't know what system I will eventually install but if I were to purchase it today it would be a Dynon D100 EFIS and D120 EMS.
Once again I resort to Google SketchUp. I can experiment making it with virtual wood rather than real wood. The idea is to have a permanently attached shelf with a removable shelf where the sensor will be mounted. If I'm successful the design will allow me to attach the sensor on the removable part and then thread it through the end rib and attach it to the permanent part. I've researched the sizes of several units and dimensioned the shelf to accommodate any one of them.
Tomorrow is Cheer or Cry day. I'll attempt to attach the removable shelf by reaching through the end rib. If I can do this then I will be able to do the same with the wing covered.
29 August 2010: I'm cheering. I was successful in attaching the removable shelf through the end rib. You will notice that I use zip-ties. They're as non-magnetic as I can get. The guides hold the shelf in alignment. Anyone is welcome to copy my design but, remember, until I fly the airplane this design is unproven.
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