This is a combo entry, a process that started saturday and finished up sunday.
I finally got the frame lined up as well as I could, with full knowledge that it’s going to change, no matter what. Mainly I wanted to get everything clamped and locked before moving on to what has been built up to be the scariest part of the whole build: Cutting the canopy. Let me reassure you, it’s still scary. You hold in your hands the ability to fark up a $1200 part in less time than it takes to say ‘Oh sh–‘ and while you’re forming that curse, the Grand Ganyon has opened up longitudinally in the canopy, splitting it asunder in a nuclear winter of white plastic dust.
Fortunately, this did not happen. Me mate David came over to lend his critical eye, reputed thoroughness, and practical experience with plexiglass from his boyhood days working on signage at his Dad’s shop. So we measured, and marked, and taped, and checked, and checked, and read the plans, then measured again, and checked, then checked one more time.
until finally, generations of grizzled old homebuilders barked in my head, “Just grow a pair and cut the damned thing already.”
So we did.
Now, I didn’t actually cut the plastic at the angle the grinder’s at right now, I was just getting lined up. It’s pretty good that they give you a lot of extra plastic to practice on. Eventually we make some scrap and wound up with something vaguely canopy-shaped…
…And leaving a bunch of sharp, dangerous scrap plexi all over the floor.
“Nope, haven’t buggered it up yet.”
Through the sliding glass door at the vast mess. Even the lizardbrain responsible for autonomic functions remembered to cover all the exposed holes in the engine on its stand, but my conscious self didn’t get around to throwing a sheet over it until the following day. No harm, no foul, right?
Front’s trimmed, sides are trimmed back a bit, and it’s nearly time. By this time, we had decided to knock off, I think, and hit it the next day.
At this point, there’s some more measuring, puzzling, and visualizing, because we want to make damn sure we don’t lop off something that’s needed to actually hold the thing on there. So on Sunday we actually got round to it.
There it is. That strip of blue tape is the where the cut is going to happen. The arrows clearly mark which side of the tape to cut. We found out that I can make nice, straight cuts if I have the tape as a guide. The sharpie line isn’t as good for that, and this worked fine. Also written there are things like “Cut this side” and “Don’t F— The Goose!” I’ll let Dave explain that one. This tape line goes right down the middle of the cabin frame/roll bar. It’s actually on the plans and in the instructions, and it’s one of the few absolutes called out, unlike everything else at this point which is ‘Just kinda make it fit.’
This is the last time the canopy will be in once piece, other than the cut-off babyslicers all over the floor. Here, Dave’s clamping down some rails on either side to relieve the bubble’s tendency to spread outward. Behind his head, you can see the space heater going full tilt, keeping the shop at a plexi-comfortable 80 degrees.
Woot! There it is! The canopy is severed into two halves. So there you have it.. Steady hand, clean cut, no cracks. Phew! We did remember to break the edges, but they still need some more work.
OK, but how does it fit? Let’s find out.
Not bad. Nothing a little trimming and fudging won’t fix. Came damn close to trimming off too much on that left rear side though.
That was huge. Next comes all the fiddling and trimming to get it locked in, then the ugliness of drilling it to the canopy frame.
David came over today and we managed to mark the centerline on the canopy bubble. We dropped it on the plane, and realized that we were in no position to begin cutting anything until some more research was done. So now I’m scouring the net for tips and tricks.
BTW, this entry will grow as I find more things.
1: I’ve fitted eight canopies, and have it down now where I can get the job done in about 2 hours. My advice is don’t trim anything off the back until you are satisfied with the fit at the front and sides. The rear edge will come forward as you trim the front. -rocketbob on VAF.
2: Looks like the whole damn flange goes, up front there. http://www.mykitlog.com/users/display_log.php?user=hydroguy2&project=294&category=2793&log=61594&row=37
3: Just a hint for all of you who are starting to cut your canopies on the side x sides. Don’t follow Van’s instructions on the order of the cuts. Make the “big cut” BEFORE you trim the sides up to the lower edge of the side canopy rail. If you make the big cut first, you will have a lot more material to work with when fitting the windscreen. If you follow Van’s instructions, you essentially be forced into a position where you will not be able to bring the side of the windscreen down over the sides of the forward skin. In some cases, being able to do so will allow for more fitting options and lead to a better fit for the windscreen. Hope this helps. -alpinelakespilot2000 on VAF
4: Heat up the shop. 75 degrees.
Got the side rails riveted to the forward frame. Quit before clecoing the skin back on. The Big Cut is coming up, and I’m realizing that I don’t have the proper space for that operation. I don’t have a surface large enough to set the canopy on while I actually do the cutting, other than the floor in the guest house bedroom. I’m not stoked about that, but I can make it work. No pics, because today’s work wasn’t that interesting.
After I cleaned up the shop, I had a look at the engine. The airplane that engine spent its previous life in, the Cessna 172 Cutlass RG, is a 28v airplane. So I have a useless 28v alternator and a useless 28v starter. Maybe not useless, but certainly of no use to me; I’m going to run a 14v system. Maybe. What I don’t get is what’s going to be 12v and what’s going to be 14v and whether or not it matters. So another thing to puzzle out. The good news is, i’ll be able to keep my firewall penetrations to a minimum, because the MGL RDAC (the box all the sensor probes connect to) is mounted on the engine side, with one comm wire going back through the firewall to the EFIS. I’ll need to poke holes for the panel bus power and the control cables, but that should be it. I hope.
Most of the time was spent cleaning the shop, after I drilled the WD-725’s to the forward frame and the aft channels, but what I really want to show off is this:
Still clecoed, of course, but I took the opportunity to thoroughly clean the shop. I policed up all the clecoes that had rolled under the furniture, vacuumed behind everything, emptied the trash, and sorted out a couple of the messier tool drawers in the toolbox. I vacuumed out the plane and went over the shop with the vacuum again. The goal was to hav the workbench completely clear, because the next fun thing that happens is the Big Cut!
Today I fiddled, tweaked, clamped, nudged, pushed, and wiggled the canopy frame for what seemed like forever, until I was finally ready to drill the forward splice plates. Basically, what needs to be done is the canopy frame has to be put in place using spacers and clamps for alignment, then it gets match-drilled at a few connecting points. The side rails have to be made to be flush with the fuselage side skin, less the thickness of the canopy sides. Now, you can tweak and wiggle all you want, the alignment still going to change when everything rivets up. If you cast the right bones and sacrifice the proper breed of chicken, everything just works when it comes time for final riveting. I’m beginning to see the method to the madness now, but the instructions still suck. For instance, here’s a shot of the whole biz, fit up and clamped down:
All the alignments are good, all the clearances are tested, all the bits line up like they’re supposed to. Now, here’s the part that burns my ass: After you’ve painstakingly fit all this up, they have you take it all apart so you can drill the aft hole pattern on the attachment points of the side rails. WTF?
Here are the instructions. Those scraggly black arrows I’ve drawn denote where these two steps, drilling the splice plates and the WD-725 side rails, SHOULD go. Maybe this is a test. Read, understand, prioritize. I guess I failed this one. I’d have preferred to drill these parts with their arbitrary hole pattern before I did all the fitting and tweaking. The canopy frame process is full of crap like this.
Splice plates, drilled and ready to go.
And after a bunch more checking, fitting, tweaking, and locking down, here’s the left splice plate, drilled to the canopy frame sections. It’s worth noting that you have to peel the skin back so you don’t drill through it Fortunately, I had a drill stop and good access.
Slightly wider shot. This is all going to come off in a bit.
Right side done the same way.
I’m not drilling the aft of the rails to the C-631 channels yet. Those are the c-channels that follow the line of the roll bar. Here, I’m guessing the drilling isn’t done until there’s a lot more fitment, probably involving the canopy itself. Next step is to deburr, countersink, and rivet the side rails to the forward frame. After that, look out, because it’s time to measure and cut the canopy itself. Yeah, that’s freakin’ scary right there. One wrong move and I turn on the tap to the tune of $1200.