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I'd like to start by thanking all the wonderful folks who responded to my earlier questions with suggestions and pictures of their work. Last weekend I closed the canopy skin and have some fresh questions (see near bottom).
Since I don't have a website displaying my progress or comments and suggestions I figured I'd post my experience here. I followed the new procedures for stiffening the forward area of the canopy as outlined by several of you. I first cut and installed the stiffeners (two crosswise, and one longitudinal on each side), which I made from 1/4" honeycomb sandwich panel (what some call prepreg). I then filled the areas between these with foam and micro. The canopy skin took quite a bit of trimming and adjusting. I had followed what I understood to be the directions given by the manual, but had cut too much by trimming the skin to 1/16" inside of the scribe line on the inside, and about 1/4" on the
front and back and 3/8" on the side of the outboard edge. The sides and front came out very close, but I hadn't left enough along the back (rollover area), both inboard (canopy glass side) and outboard. Luckily, I had kept the cut off material, which was still usable, since the Dremel cutoff wheel that I'd used only took out about a 1mm kerf. I reinstalled these pieces with very light (4oz?) hobby fiberglass BID cloth laid up on the inside. A word to the wise, leave extra, extra material on the edges.
I ended up making two cuts in the canopy skin, though I probably could have made just one at the center at the rear. I wanted to bridge the center cut that had been made in the stiffener, so I made one cut about a foot from the centerline on each side at the rear. Except for some heating and bending at the front at the canopy interface, the stiffener went on reasonably well. It still took a long time.
The skin was interfering with the canopy glass at the 10 and 2 o'clock positions, so I called Lancair and spoke with Pat who recommended I grind the canopy as required to fit the skin. This did the trick. I installed clecos around the outside perimeter of the skin and then clamped with three blocks on each side (using screwes through the stiffener and skin and wing nuts on the outside) some 1/2x1/2" angle aluminum stock, which held the skin tight against the edge of the canopy along the sides. The front and rear took a few sand bags.
Yesterday I installed the canopy struts (somewhat) per the manual. I created an aluminum fixture with holes 11 1/2" apart (per the build manual revision online) and used it to place the brackets onto the rear of the firewall. However, I was unable to install the bolt that connects the struts as it would interfere with the lock nuts, so I reversed the direction of the two bolts that hold
each bracket to the firewall. In other words, I've got the bolts installed from the back, with high temp lock nuts intalled on the firewall front side. BTW, I did install an additional pair of alignment plates to the canopy, and whether due to them or more likely, due to the stiffening done to the forward area, I do not see any bowing or other deformation due to the struts pushing up.
Now for the questions:
Is there a problem installing the canopy bracket bolts from back to front, with high temp lock nuts on the hot side of the firewall? The primary concern would be interference of the higher profile lock nuts (higher than the bolt heads) with the heat blanket. Standards also generally call for bolts and screws installed from front to back and top to bottom, but I don't consider that a hard and fast rule under the circumstances.
I understand the proper installation is with the strut cylinders up, and the
pistons pointing downward, to keep the pistons from being undamped when not in fluid when the canopy fully opens. Is this correct?
Finally, the struts have about one inch left until full compression when in the canopy down position. They're fully extended when the canopy hinges are nearly in contact with the fuselage, ie. canopy fully up. I have to push the canopy about 30-40degrees up until its held by the struts. Is this normal? It seems high. Is my canopy too heavy? Struts too weak? Or should I install the brackets so that the struts are just about fully compressed when the canopy is down? In other words, is the strut force a strong function of displacement (it would seem they ought to be, but I can't test this) or are they nearly constant in force with compression?
One recommendation, if you can do it. I'd suggest doing all the canopy work before the center wing section is
installed. I have my fuselage on a rotisserie (borrowed from Jim Vosters--thanks Jim) and have not yet installed the wing. I can't count how many times I've simply ducked under and into the cockpit area. For those of you wanting to use the factory wing/fuselage alignment fixture, I guess you're out of luck, unless you're going to stay there a while anyway...
I do want to also thank Pat and the others at Lancair who have answered some relatively simple--but important to me--questions. Last time I posted here I had called a few times without much luck getting technical assistant over the phone. Since then I've called numerous times, and have each time been put on the phone with a guy from the shop without having to wait for a call back. It's been great.
Cheers,
- Kyrilian
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