Haven't updated these in a while. I've finally got the pictures uploaded and things have (slightly) settled down, so I'll try to do some updates of what's been going on, but for now I'm going to start with where I am.
Working on the canopy this week. It is not going like I hoped it would. I've been trying to find a good fit for a couple of weeks, and never did find a way of putting it in there that was even close to what I thought It should be.
I emailed Vans, talked to our local RV builders, looked at Kent's, etc. Maybe this will work out ok and I just think it's too tight. I finally took the best compromise fit I could, but it's not very good.
Did a bunch of practice cuts and holes. It isn't the hand grenade it is made out to be. I drilled more than a dozen holes with plain old drill bits, didn't push, and not a one cracked. I finally got it to crack by really leaning on it when I drilled with a #12 (which is how a lot of people drill all the time - try to pressure through rather than letting the bit cut). Anyway, after doing that I felt a lot better about the whole deal. Here's some of my testing with a piece of scrap I trimmed off the other day.
I drilled the hole for the handle yesterday, then stared at it a long time and finally decided I had to cut it eventually, so I might as well just do it. Made the "big cut" Wednesday night.
Here's the hole - borrowed Kent Stitt's plexi bits (I'll try to remember to take a picture - they did *not* look like I expected). Drilled about a #30 to start, then enlarged with my small and large unibits, which cut it very cleanly. No cracks. 5/8" hole to start. It is actually too small. Later I ended up going to 3/4" to get a good loose fit around the handle tube.
Once it was drilled I polished it with 220 & 400 sandpaper.
I don't have any pictures of the big cut - too busy and covered with plexi dust. Here are the results.
Forward canopy just after the big cut.
Sliding part of the canopy after I'd cut it and taken it off to set on the table.
This is later the next day when I'm starting to sneak up on the final trim by slowly working my way in. I was also hoping that trimming more would help close up that awful forward gap, but I don't think it helped much.
Everyone had told me it would be much floppier after the cut, and indeed it was, but not in the way I wanted (and to be honest, I was 99% sure it wouldn't be). I needed it to be floppier fore and aft. It's floppier side to side.
Here's the problem area without any clamping and with the aft bow snug but my no means tight. This is the "natural" fit. The problem is that either for center bow is bowed too much, or the canopy doesn't have enough curve (or - possibly - they all fit this way and people just clamp them down and go).
And this is with it lightly clamped after fiddling with it for 40 minutes or so trying to find the best fit after I'd done some trimming of the back and sides. The gap is nearly 1/4". No way a pulled rivet can span that gap even if it is shimmed.
I *can* by pulling on it tighten it down obviously. It is alarmingly stiff side to side at the center - almost rigid. It would be possible to clamp it tightly and work from the center down and probably get it to fit. Seems way way way too tight though.
There's nothing I can really do but proceed with the process and hope for the best. If the fit is really really horrible (it seems like it is to me) I will probably try to Sikaflex it simply because drilling it and pulling it down that far just seems way too likely to crack it.
I'm going to work on various clamping strategies and fitting over the next few days/week to see if I can find a fit that gets close enough to rivet. We'll see. The other possible hope is that by leaving it lightly clamped for an extended period in a warm/hot garage, it may conform to the shape of the frame more and start to fit better. One can only hope.
Saturday I got about as frustrated as I've been with anything on this whole build. I elongated the hole for the handle attempting to find a better fit, but no matter how hard I tried to keep it from drifting, as I tried to get everything more or less in a position where I could attach the plexi to the frame (by whatever method) due to the rocking action from the high spot on the center bar, it would drift out of alignment. I must have tried at least a dozen times without success.
Elongated hole (just wrapped sandpaper around a highlighter - it cuts pretty quickly). I was sitting next to an RV-6 guy at SNF and he mentioned his canopy cracked at 16,000 feet one day when it was really cold - he hadn't left enough room around the handle. I will make sure I don't repeat his mistake.
I also tried clamping it fairly tightly and letting it get hot in the sun hoping it would "relax" (it did) but as soon as it cooled it went back to being too rigid.
After several hours of this I finally decided to try to fix the root problem. For whatever reason, either my canopy does not have enough arch in it, or the center bow of my frame is too arched, or both. The forward gap when the canopy was clamped to the aft bow was nearly an inch.
I decided to reduce the height of the bow by clamping a long 2x4 which bridged the gap, then tightening it down until I'd cut it down some. I snuck up on it slowly, and took about 3/32 to 1/4 of an inch out. Made a *huge* difference. I think I'll take out about another 1/8" - should be about perfect.
Once that was done, I started working on the width - as the plans mention, the plexi does indeed pull the frame wider. I'm on about my 4th iteration of narrowing and nearly have it perfect. If I take out about another 1/8" it should fit really well without slopping around.
Here's the fit after about 6 hours of the previous - aft bow lines up pretty well with the aft skins.
And the sides line up pretty well with the fuselage sides on both sides.
Another couple of hours of tweaking and it should be pretty nice. Then I'll clamp it down and trim some more.
