« Archives in December, 2009

Canopy again.

6 hours.
Six arduous, terrifying, frustrating hours of clecoing, unclecoing, reclecoing, and of course filing. I did, however, get the hinges drilled and got started on the rest of the canopy frame. I did it like the plans said, I got the hinges placed. Thanks to VAF, I picked up a few tips and advice from those who have gone before. For instance, I was able to make 1/4″ angle drill out of my die grinder that has heretofore been useless except as a deburring tool. Works great as long as you only need 1/4″ holes drilled. All I needed it for was to mark the spot on the hinge where the drill goes through, not actually drill anything. But I have to agree with many others; The plans and instructions for this part of the kit blow chunks. The sequence is vague, the suggested methods are weird, and it’s really difficult to picture a group of brilliant, rational men arriving at the decision that this is the way to go. But enough bitching. This is one of those things where you just have to sack up and dive in, and hope you don’t drill or cut anything past the point of ordering new parts. It’s an iterative process, a tweak here, bend a little there. and just try to get the best fit possible. Eventually, I got a result I can live with, for the most part.

After one of the numerous times the skin comes off the frame, the frame is clamped down onto the drill press table, where I’m driving a 3/8″ bit through a pilot hole I made by using a block of MDF drilled #30 in that same drill press. With 3/8″ holes drilled in the frame, the hinge bushings are press-fit into them by means of a pneumatic rivet squeezer loaded with flat dies.

So back on the fuse goes the frame, where the pins had to go through the bearing blocks and the bushings just right. This is tricky until you get the hang of it, and by tricky, I mean swearing, tool-throwing, demon-calling frustrating. But in the end, it hinges up just like it’s supposed to. Or not. In the down position, the hinge gooseneck makes contact with the bearing block spacer, which blows, although is quite easily fixed. I just had to shave off a little of the bearing block spacer at the point of contact and everything became irie.

This is a shot of one of the hinge pins. I opted not to have a canopy jettison system. It’s complex, it adds weight, and the chances of me needing to jettison the canopy and bail out don’t merit all the extra work and weight. Not only that, if I have to make the canopy go away, I can hit it with a canopy cracker and the wind will take care of the rest. So this method has the hinge pin linkage folded back and fastened to the F-745 (or 740-something– I can’t remember part numbers off the top of my head) rib, where it’s secured by an Adel clamp. The other end of the pin will take an AN365 stop nut and washer.

Here’s the assemblage with the skin clecoed on and the deck skin partially clecoed on. This is where the freakout happened. At one point I did this without putting any clecoes along the middle of the forward deck skin because I wanted to see the whole clecoed assemblage open and close with the skin on it. So what happens? I go to open it and the canopy frame skin collides with the forward deck skin. WTF? I started shaving off edges, wiggling parts, and I even got so freaked out I drilled off the splice plate to see if I could push the canopy frame ribs upward enough to buy me the clearance I needed. I rolled the canopy deck skin up along the edge just a hair. AT the end of it all, I clecoed the forward skin on in the middle, and yeah, there was enough clearance for the canopy frame skin to get by. Just.

As you might guess, this process leaves a hell of a mess. I had a clean shop a couple of days ago. This is going to have to wait til morning.
After all that, I was still looking for more punishment, so I got started on the rest of the frame. I made the requisite spacers and placed them around the longerons as specified. Then I made the splice plate for the two F631 channels (which are copies of the channels used in the roll bar) that form the aft frame of the canopy.

Like so.
That’s it for now, I’m going to chill out with some sake and some spicy snacks, maybe watch a little TV, then have that dinner thing.

More canopy work.

5 hours.
Finally got the fuselage latch mechanism done. Managed to get the stupid yellow knob on there without mangling the screw much, and it opens and closes the aft latch arm just like it’s supposed to. The bolts are cotter-pinned, the brackets are riveted, the UHMW tape is applied. OK, maybe it’s not ALL done; the little spring-loaded rod pushing the latch ratchet closed isn’t on there. I still have to blind-rivet the center-section covers on, but I hate closing things I might need to get at later. So here’s that bit:

Latch in closed position. I know, this is filler, but it at least gives you an idea of how the canopy is held down, keeping it from becoming… drafty.

Open position. Silly knob pulls the latch backwards and releases the hooks aft.
So with that done, it was time to move on to the next fun bit: The canopy frame. I’ve only got one photo. This process is fairly uninteresting, and it all looks the same.

This is all about clecoing and unclecoing and re-clecoing. If you’re just joining us, a cleco is a temporary faster that pokes through a hole drilled through two pieces of metal and holds them together. That’s what the chrome bristles are in a lot of these photographs. This process is about incrementally tightening slop. Various arcane voodoo rituals are performed to insure that the skin of the canopy frame fits up to the forward fuse skin, the hinges are in the right position, and the frame is the width of the fuselage, etc. etc. Then you put in the splice plate, drill it to #40. Un-cleco, remove chips and burrs, check fit again, drill to #30. This is NOT easy. All kinds of things are waiting to shift, move, drift, and jump. But at the end of it, if you do it right, you have your canopy frame to the point where you can drill the holes for the hinges. This is where I’m at right now. I think. A couple more hours of this and I’ll be ready to drill the hinges, which is kind of scary. Screw this up and it’s two days down the rabbit hole.

Aft canopy latch

2 hours.
Before I left for Japan, I started working on the aft canopy latch.. This is a big steel bar with a claw on each end and the idea is that when you secure the latch on the side, these claws hold the canopy bubble down in flight. Honestly, aerodynamic forces hold the canopy bubble down in flight, but this keeps everything sealed and comfy. I only screwed up once: the 6061T6 tube that goes between the canopy latch handle and the idler arm connected to the latch bar got tapped to 1/4-20 instead of 1/4-28. After I got back from Japan (yesterday) my replacement bits had come in, and I was able to get the proper drill and tap from the hardware store, so I finished the canopy latch pushrod. No worries. I also had to order some bolts from ACS, since I misplaced (and have since found) the drawer with all the ones in it necessary to complete this op. So everything’s good to go, I just need to install the idler arm and we can move on to the canopy frame.

Canopy latch

3 hours.
More canopy latch work. I buggered up the 6061 T6 tubing by tapping it with 1/4-20 instead of 1/4-28, the threads needed to accept the rod-end bearing and the latch idler clevis. I did get the latch hardware drilled and fitted, and it all goes back into the box for now.
Note: I’m publishing this on Dec 22, but the actual events happened on Dec 5. I had to go to Japan for a week, and it’s only now that I’ve been able to get caught up.

This is the canopy latch hardware temp-installed. This is truly a situation of kneebone-connected-to-the-thighbone. From one or two reference points, you have to spider your way down the decision chain through a series of matchdrills, and if you do it right, you get a setup that looks a little like this. The yellow handle pulls back and releases the claws on the canopy bubble.

Outboard, there are two metal tabs. when you squeeze them together, they release a spring-loaded ratchet. Once that’s done, you push the aft tab in and it exposes a lever, which is the same piece of metal the yellow handle’s connected to. This lets you open the canopy from the outside.