« Archives in February, 2010

This canopy sucks.

7 hours.
Everybody told me the suckage truly begins at the canopy. This, boys and girls, is true. After some epic procrastination, I got back on the ball today with the canopy. First thing that needed to be done was a plan. Everybody says not to expect the final position of anything until the canopy frame is riveted and the struts are in. OK, fine. I primed the underside of the canopy skin along the rivet rows, with a light dusting everywhere else, as well as the canopy frame near all metal-to-metal contact points. Then I riveted the skin on. That one sentence sums up about fifteen types of hell, and some truly lip-smacking victories along the way. There are several rivets that do not lend themselves well to any of the bucking bars I have. They’re nested near intersections of welded parts, so getting at them was interesting. The fit of the skin to the frame around the lower sides isn’t great, and requires a lot of pushing and straining to get the dimples to seat in the countersinks properly. Honestly, at this point, I’d rather have the old Me-109 style canopy made of flat panes and angles. Screw the view.

This photo shows the canopy on the bench, which allowed me to do the bottom side rows withe squeezer. After that, It went back on and I redid all the rivets I’d screwed up earlier. Only about three or four, though, which isn’t bad considering the contortions I had to employ to get sight, gun and bar all in the same place at the same time.
But all the suckage gave back one good thing: The gap between the forward edge of the canopy skin and the trailing edge of the deck skin closed up to a livable 3/32″, which was nice. I thought I was going to have to plaster it over with ProSeal. It also reduced the classic ‘air scoops’ outboard of the hinges, but these are still there. with a combination of rubber seal and rolling the skin forward, I think I can make them go away completely.
Then it was time to do the nitrogen struts. These have a little spring-steel clip on each end that grab a ball inserted into the end mount. To get the strut installed, you have to disengage these clips. You have to be careful with these. If you take them all the way off, there’s a chance they’ll go pinging away into the shadows of the workshop, never to be found again, or worse, burying themselves in the skin of your forehead. Wear safety glasses any time you mess with spring-steel clips under tension. The hardpoints for the struts aren’t exactly easy, either, especially on the left side where getting big fingers in past the latch release mechanism damn near impossble. As it was, I misdrilled the left-side aft hardpoint, so it’s at a slight angle, but it’s within spec, and it does work. But the suck part is getting the washers and nuts on. Here’s how:
put something sticky on your fingertip. Stick the washer to it. Run the screws through the mount pieces, through the holes, and reach up in ther with your finger and slip the washer over the end of the screw. For the nut, put a piece of tape on one side of the box end of the wrench. Seat the nut in there so it sticks to the tape. Get that up in there and get it started, then tighten it down.

The other side was more cooperative. But after all that, I wanted to see it work. So I took out the top clecoes on the forward skin, clamped up the aft channels, and let it rip. Stupid, stupid man. Thanks to the struts and the riveted skin, the gap between the skins was no longer enough to clear during opening, so the canopy skin caught and bent itself. Struts work, though.
After that, I took the frame back off and cajoled the skin back into a rough semblance of its original shape along the front edge and filed off some more metal. It still catches, so I’ve got to keep working at it. But at this point, it’s good enough to finish the process of drilling holes in the plexiglass.

The canopy is back on, waiting for final trimming and edge processing, after which I’ll drill the holes in the WD-725 side rails and the aft channels. The end isn’t in sight, not by a long chalk.. There’s also the bondo-fest that’s necessary to blend the plexi into the skin, and of course, the filler I’ll need to deploy to further un-mangle the forward edge.