Finished Canopy Fairing – 9 hrs

Sunday June 23, 2013

Continuing work on the canopy windscreen fairing I masked off the entire area and sprayed a light coat of gray primer on the surface to get a better look at the smoothness and overall shape. The blotchiness of the raw surface is just too hard to judge so I have been going by the feel of  my hands more than by sight. The primer showed a few minor defects including scratches, pin holes where the fiberglass fabric was exposed, and a few small divots – but not bad for this stage. However, the pipe tape is still in place and it is thicker than I want the final windscreen edge to be.

So I sanded the primer off completely and removed the pipe tape masking the windscreen. This gives a preview of the final edge although it is thicker than the final edge.

I put down a single layer of 3M electrical tape as a new mask line for the final edge thickness. I filled the defects I found with the primer and smoothed it out with another round of sanding. I carefully sanded the windscreen edge until it was just about flush with the new tape surface. It seems thin but that is the recommended final edge thickness, blending almost to nothing. Now here is my biggest mistake on this fiberglass work. At this stage the instructions said to brush on a heavy coat of epoxy so I did. That turned out to be a bad idea because it just does not go on uniformly at all. The surface was very irregular when it cured and I had to sand virtually all of it off to get back to a smooth surface. What a waste if time and effort. To make things worse, a bit of the epoxy got under the front lip and stuck it to the fuselage frame so when I raised the canopy it bent the lip, ruining my nice finished surface. So I had to straighten it and apply another layer of epoxy and filler to fix it. Not a disaster but I big pain to be sure. In this photo you can see the new filler along the front edge.

So after final sanding with 220 grit I decided I would try the primer again. If there are new defects this will expose them. I used a high build primer I picked up at Aircraft Spruce in a rattle can. Here is how it looked after spraying. To my relief there were no new defects other than a few tiny pin holes which the primer mostly filled.

After a few hours of drying time I sanded the surface lightly with 400 grit paper to remove the roughness and pulled off the masking for the final time. I am not great with fiberglass work but I am definitely happy with this result. It looks very nice. Even my wife, the unofficial quality inspector, said it looks good.

Here is an attempt at a close up that shows the final edge.

I was lucky to get this done this weekend because I continued to spend hours digging for a water leak in the front yard. I found one and fixed it, but there is apparently another because the hole is not drying up. What a pain. More digging to follow.

But I also succeeded in putting a coat of primer on the inside of the upper cowl.

And I tied off two of the four lower baffle flaps on the engine with the little wire retainers I copied from VAF. I tried three time to thread the rods provided in the kit for this but finally gave up and went with the safety wire method. Two more to go.

Started Laying Up Canopy Fairing – 8 hrs

Sunday June 16, 2013

This is the first of a series of posts on the layup of the fiberglass fairing on the front of the canopy. I have put this job off for too long because fiberglass work is messy and tedious. I really need to get it done however so I decided to make a go of it starting this weekend. I picked up tips on Bruce Swayze’s web site. Bruce did a nice job of documenting the process step by step. I started by preping the surface of the canopy and frame. I used 70 grit sand paper to rough up the surfaces and I cleaned the aluminum with acetone. I am using 7781 glass cloth from ACS for this job. I need long strips so I laid out a couple of strips of plastic sheet about 3 feet long and marked 0.5 and 0.75 inch wide strips.

I mixed up some epoxy with black pigment from ACS, poured it on the cloth between the sheets and rolled it out to impregnate the cloth. I used a rotary fabric cutter to cut the cloth and plastic sheets into the aforementioned strips.

I used .020 pipe tape to mask off the upper edge of of the fairing line on the canopy. Because the pipe tape is black I also put down a layer of blue masking tape on top so I would be able to see the edge better when laying down the cloth since the epoxy is also black.

I peeled the plastic off and laid the strips down on the canopy/frame joint starting with the 0.5 inch strips first. It took two 30 inch long strips to cover the seam from end to end with a slight overlap. I used a craft brush to stipple the glass cloth down on the surface and get it aligned where I wanted it. This view shows the layup after two layers. I’m glad I only mixed up epoxy for two layers at first because the epoxy was starting to get stiff by the time I got two layers down.

Several hours later I had eight layers down made of progressively wider cloth up to 2 inches. For the top layer I laid up the edge of the cloth flush to the edge of the blue masking tape line. Then I put down strips of peel ply to minimize sanding later. That also allowed me to roll out the layup with my rolling wheel to help push out bubbles. Getting to this point took about four hours. I spent the rest of the day working on a leaking water pipe in the front yard.

By Sunday morning the epoxy was well set and pretty hard so I took off the peel ply. I was happy to see that the layup looks pretty good for a first step. At least to my eye it does. But a lot of sanding is still required.

It took about 2 hours to sand it out and it revealed some high a low spots but nothing excessive for the initial layup. It makes a lot of dust fast so I ran my vaccuum with a HEPA filter a lot.

Here is a closeup view of the fairing blend from the canopy to the forward skin after I removed the blue tape. I did that because I need to get this sanded down to no more than the thickness of the pipe tape because I don’t want the fiberglass edge to be too thick. There are some voids along the seam but that is unavoidable. The best you can do is minimize it. I will fill these voids with another mix of blackened epoxy.

So I mixed up a squirt of epoxy with black pigment and applied some along the seam with a squeegee to fill those voids. Then I took the remaining black epoxy and added some micro to thicken it up and applied it in the low spots of the layup and along the surface of the aluminum. This will fill all rivet heads and let me sand the entire forward frame to a smooth contour (I hope). I now will let this set and begin sanding again tomorrow.

I also received my PC680 battery from Battery Mart this week so I installed that in the battery box on the firewall.