Thursday, May 10, 2018

Section: 46B
Hours: 6

Day 2 working on landing gear leg fairings. Today I riveted piano hinges into the leg fairings. It took all day. Lots and lots of holes, counter sinks, rivets.

Step 1: Mark location of holes on the piano hinge. I scribed the hole locations into the hinge and then used a black marker to put a dot on the end holes so they would be visible through the fiberglass. I really only needed to mark the starting holes at each end, because I used a rivet fan to drill all the rest of the holes.

Step 2: Insert piano hinge such that end holes are evenly spaced from ends of the fairing which coincidentally left a full hinge loop at one end. Then I used cleco clamps to hold the hinge in place and drilled holes at the starting holes for each end being careful not to drill into the opposite side. Then I used the rivet fan to drill and the remaining holes, starting from one end working to the opposite end. I inserted clecos as I went and used light pressure on the drill so the piano hinge would not push away from the fairing. Then I counter sank all the holes for the rivet head.

Step 3:  I inserted a spacer board to hold the back of the fairing open and then riveted the hinge on using the pneumatic squeezer.

The piano hinge is rather soft and the fiberglass has little rigidity so it was hard to ensure that the rivet would pull the hinge flush to the fiberglass. I found I had to use the rubber washer trick to squeeze the hinge firmly to the fiberglass. I also discovered it was really important to use a board spacer along the entire length of the fairing to hold the fairing open and keep the piano hinge flat with no sagging or bends.

After I finished the first fairing I noticed that the ends of the fairing were not being pulled together very well. I slightly adjusted the hinge position in the 2nd fairing a little further away from the trailing edge so that it would pull the fairing edges together with a little more force. That worked, but it also made it more difficult to insert the hinge pin. I used Boelube and eventually worked the pins into both fairings, but this is going to be a difficult task. Hopefully I will not have to remove/install the gear leg fairings very often...

My E-Mag Electronic Ignition P model 114 magneto package arrived today. My IO-390 came from Lycoming with 2 Slick magnetos, but I have decided to go all electronic ignition. I ordered direct from E-Mag and they put together a kit for my IO-390 that included 2 model 114 magnetos, 2 wiring harnesses, 2 sets of spark plug adapters for auto spark plugs and 2 accessory kits (manifold tubing, serial port plug, wire). They also included 2 shorter studs and a timing gear to replace the studs and timing gear that come with the Slick that was set up with a recoil starting spring. I was going to order from Spruce Aircraft Supply, but the timing gear is really expensive and if you order from E-Mag direct it is a little cheaper because they get a deal from Lycoming.

Also included in the box was a package of gourmet popcorn. I'm not sure how to apply that to the mags- I guess I'll have to read the installation manual ;-)

Wednesday, May 9, 2018

Section: 46B
Hours: 6

Today I worked on the landing gear leg fairings. The parts are beautifully molded but you have to be careful to assemble them without any twist. A small mis-alignment can induce a measurable twist with very little pressure. The manual suggests jigging the fairing on a table and measure with a square from the leading edge apex to the trailing edge with a square at both ends. The problem with this method is that it is difficult to find the leading edge apex. It is not marked or scribed and the position can vary depending on how you hold the fairing. I wasn't happy about the results using Van's suggested measuring method so I built some alignment jigs.

First I had to draft the templates. I guessed that the fairings use a NACA symmetric airfoil. I went to my favorite airfoil web site: airfoil tools plotter and input a guess at the dimensions to use for the maximum thickness. Unfortunately, the maximum thickness allowed for 4 digit NACA airfoils is 30% and the section used by Van's is more like 40% (to accommodate the gear leg tube diameter). I plotted a NACA 0030 and then scaled the height to get to 40%. The result doesn't exactly match the section used by the fairings but it is close enough for jigging. I added a box, axis lines and a cut out at the trailing edge to complete the jig design.

Then I printed the jigs full size on an 8.5 x 11 piece of paper and used 3M 77 spray adhesive to attach the paper to 1/8 inch plywood. I cut the plywood on the bandsaw and ended up with easy to use, accurate alignment jigs. Too bad Van's didn't include these in the manual...
 The jigs slip over the fairing at either end. I taped the tops of the jigs to ensure a tight fit. Then I aligned and squared the center lines of the jigs on a line on the table and made sure they were both sitting flat on the table. This forced the fairing into alignment with no twist. Then I taped the trailing edges to preserve the alignment.
Then I was able to drill 5 #40 holes and put in clecos.
 To finish up today, I cut the holes for the axel on both of the wheel pants. I marked out the holes following the dimensions given on the plans. Then I used a 2 1/4" hole saw to cut a slightly undersized hole and used a sanding drum to sand to final dimensions.

Tuesday, May 8, 2018

Section: 46B
Hours: 6

I continued fitting the wheel cover parts today. I initially sanded the flanges to achieve as thin a join line between the two halves as possible. I went slowly and cycled multiple times between sanding and checking the fit. I was able to close up the gap, but I wasn't able to improve the match at the bottom where the wheel opening is. The nose section nests over the tail section and was obviously coming up short where the wheel opening is. Where the flanges overlap, there was close to 1/4 inch difference on both sides of the wheel opening.
 I determined that parts of the nose section had been laid up a little thicker than optimal. The manual specifies that you thin down the section where the joint layup occurs, but I also found that the bottom corners were too thick (see below).
I went all the way around the nose section and thinned the inside edge of the layup to a consistent thickness using a sanding drum on the dremel tool. I also went around the outside of the tail section flange with the sanding drum to smooth it out.
By evening out the thickness of the flange area of the nose section and smoothing the outside of the tail section flange I was able to get the wheel opening to almost match up. Much better than what I started (see above).
I also put a slight bevel on the inside of the nose flange area to account for the slight radius in the joggle of the tail section flange. This really tightened up the fit. By evening out the thickness of the nose flange I also ended up with a much better exterior fit. I now have a much smaller mismatch in thickness between the two halves at the join.

After all the sanding described above, I then did a careful measurement with the mounting bracket (as described in the manual) and discovered both the wheel pants were still slightly too long. I did another set of sand, fit, measure cycles to cut down the nose flange to get the overall length to spec.
I'm really glad this part of the build is done!!!!

Monday, May 7, 2018

Section: 46B
Hours: 6

While I'm waiting for the wheel bearing grease and tire talc to arrive I decided to start work on the fiberglass wheel and gear leg fairings, Chapter 46B. I spent day the trimming the wheel fairing parts. The scribe lines are a little hard to see so I ran a tape line on them. I cut within a 1/16 inch of the tape line using the dremel tool with a cut off wheel. I run the shop vac at the same time as I cut with the dremel tool to capture the dust. Then I sand to the scribe line using a long sanding board. I taped a strip of sanding paper to the cardboard core from a tape roll for sanding the inner radius of the curved sections.

Saturday, May 5, 2018

Section: 29
Hours: 5

I had skipped installing the air vents so I decided that would be a good project for today. I trimmed the edges per instructions in the manual. There were scribe lines on the back of the plastic that were in the correct location for the top and I used that line as a reference for squaring off the tail. I trimmed for 1 left and 1 right vent setup. I cut using my bandsaw and sanded the edges and flattened the back using my belt sander. You have to use light pressure when sanding otherwise the surface will heat up and the plastic melts. I used a single edge razor to scrape the edges for a nice smooth finish.
The manual suggests mating and adjusting the flange on the airplane, but I found it was helpful to first clamp using a flat surface and then check for fit on the fuselage sidewall. I had to adjust the bend in the flange a little to get an optimal fit.
I ordered the aluminum ($$$) version of the vents because they close better than the plastic ones provided with the kit. I very carefully trimmed one corner of each vent to match the support flange. Here are the assemblies screwed together. I won't install these until I prime and paint to match the rest of the cockpit.

Friday, May 4, 2018

Section: 40B
Hours: 6

I assembled the tail wheel this morning. The washers specified for the wheel bolt up did not allow enough treads for the castle nut, so I substituted some thinner washers.

Here is the standard Van's tail wheel assembly trial fitted to the spring.
I spent the rest of the day honing the tail wheel spring to fit into the socket tube in the fuselage tail. The two mating zones on the spring come unpainted and ground to a semi-smooth finish. I spent some time sanding powder coat overspray and rust out of the socket tube and then trial fitted the spring. I couldn't get it inserted past the first mating zone, even with grease applied. I then started honing the mating zones using 400 grit sand paper on a flat board. First I sanded the zones to a shiny finish but they still did not fit. I eventually had to reduce the diameter of the mating zones by about 0.001 inch before they would just barely slide into place with a lot of grease and force.
Success at last- tail wheel spring inserted into the fuselage tail.
I used a taper pin to get the spring to final location in the socket tube and then final drilled the bolt hole and inserted and torqued the bolt. Here is the final assembly with tail wheel attached! There is absolutely no play between the spring and the socket tube. Hopefully it will be good for many years of service.

Thursday, April 26, 2018

Section: 38
Hours: 3

I pulled the canopy off the fuselage and counter sank the screw holes.