November - December 1999
Wing panels continued...
The left wing panel and both ailerons received the same finishing treatment as the right (see September - October). This required about 2 weeks of spare time effort. I recommend splitting up the finishing jobs and not doing the whole aircraft at once. Sanding and filling are so dull that at one point, my day job was starting to look good, and I think I may even have started talking to the dog.
Both ailerons were also prepped for paint.
I am trying a local auto body shop for the actual painting. The left wing was delivered ready to prime. They will prime, wet sand and paint on a time and materials basis. If the results are good and the price reasonable we will continue in this fashion.
Paint selection...
The Dupont 70s as recommended in the plans is no longer available. It was a fairly basic lacquer primer and contained 0.5 - 1.5 % (by weight) carbon black which RR considered desirable as an UV block. The replacement product was the Dupont 131 (Fill and Sand) which contained 0.1 - 1 % carbon black. This represents a roughly 50% reduction in carbon black content. This product has recently been discontinued as well and the new 2K Urethane Primer Dupont 1141/1144/1147 has taken its place. The carbon black content is similar to the 131 at 0.1 - 1%. I don't believe RR tested for UV penetration and I certainly don't have the equipment to do so either. I will instruct the painters to lay the primer on the upper surfaces heavier than normal in effort to make up for the reduced carbon black content of the newer product. Since the aircraft will be hangered UV exposure should be quite limited.
A Dupont Chroma Color (GM white #10) is being used per RR suggestion and a clear top coat (Chroma Clear) will also be applied to protect and enhance the finish.
I am using all Dupont products primarily on recommendation of the paint shop. I don't believe there is any reason not to consider other paint systems provided you ensure compatibility between the different components. The best way to do this is to use components from the same manufacturer. If the manufacturer has no information on the UV resistance value of its product check the primer MSDS for carbon black.
After priming, DO NOT leave any components in direct sunlight, as the heat generated could be sufficient to damage them.
Canopy...
A great deal has been written about this stage of the project and it can appear overwhelming. But if you've stuck to the plans so far you won't go wrong by continuing to do so here. Proceed with confidence.
A 2.5mm plywood cap was applied over the top longerons in the canopy area primarily for esthecics.
Canopy sills were cut to fit and the hinge was installed. I managed to fit a 15" section and still remain within the contours of the fuselage sides. Positioning the hinge more towards the front of the canopy allowed a longer section to be used. Having the hinge out of perpendicular alignment with the turtledeck changes the opening geometry slightly but is not a concern. Try to keep the ends of the hinge as close to the edge of the fuselage side as possible to avoid interference in the center area when open.
A single centering pin was installed near the center of the left sill and blocks for the canopy latches were installed fore and aft. The plans don't specify a location but I recommend the forward latch be placed as close to the instrument panel as practical. The aft latch should be located far enough forward that it can be reached easily in the event of an emergency egress. Too far aft and it will be under your shoulder.
The canopy frame was floxed into position (installed over temporary weatherstripping) and required little in the way of trimming to get a really good fit. My project was built as close to spec as possible with few modifications and all the prefab Rand Robinson components fit very well.
The insides of the sills were then glassed and the stiffener was foamed and glassed per the plans. I cut the height down and increased the width of the "gear stiffener" as recommended by Monte Miller in the KR newsletter #188. I'm not tall but am now beginning to realize how small this a/c really is. The sling seat looks mickey mouse as opposed to a built up unit but it can give you 2" extra headroom in addition to being suprisingly comfortable. I am glad I didn't try to get fancy here.
After everything had cured the canopy frame was removed to wrap the sills and glass the back of the stiffener. A cabinet lock was then installed. It is moderately effective but of course if someone really wants in...
The latches are Southco Draw latches with secondary catches available from Rand Robinson. They were installed with little fanfare and work quite well. The position of my throttle on the left side of the instrument panel means that it will be difficult to forget to engage the forward canopy latch before take-off (a bit of a 2-fer).
Now we separate the men from the boys...
To fit the canopy I decided to "sneak up on it" by making a number of small cuts. It may be the chicken-#$*& way but when dealing with a $500 + canopy just call me chicken-$%(*. First, I marked the centerline of the canopy and the canopy frame opening. Next I positioned the canopy and began cutting to fit in about 3/8" increments. Beginning at the front progressively lowering the front of the canopy until the sides were completely in position on the frame. I then removed about another 1/2" to give the canopy a flowing line into the turtledeck. The final cut to fit was made along the back of the canopy and after a little bit of trimming the fit was quite acceptable.
The gel coat was sanded back, the canopy was prepared pretty much according to plans then floxed into position.
Finally 2 layers of 9oz (6 oz is recommended but was unavailable) glass tape was applied to the joint.
The canopy assembly is now quite substantial. A big difference from the floppy frame I started with earlier this month. Overall the fabrication of this assembly was straightforward and very satisfying. It really completes the look of the project.
