Building the canard.
Feb 18, 2007, "K" jigs. I read on a other builder sites how time consuming it was to make all ten of the canard "K" jigs. The jigs that the canard foam pieces rest in for assembly after the shear web is done, and before you start on the canard spar caps. I ain' t the sharpest tack in the box, but I can make up for that with tools. . . Some of those are sharp!
I traced the single "K" jig on the stock ""M" drawings onto a sheet of drafting velum (Clearprint™), sprayed the back of that with "77", and pasted that to a scrap of 12mm Baltic Birch left over from cutting the wing jig cradles for chapter 19. Band sawed this to a rough outline, then finished to the line with a sanding drum in the drill press.
I then glued a strip of 12mm to the jig above, just touching the baseline of the tracing. Rummaging around in the junk drawer, I found a couple of new toggle clamps which I then screwed to the top of this. Trim up the sides on the table saw to make parallel, we're just about ready to rock.
Still using the scraps from the wing jigs, I ripped up a pile of 12mm birch to end up being 3" x 9.5". I put each blank into the jig made above, and penciled the outline onto the bottom. Head over to the band saw to rough them out, then back to the jig to make them real purdy.
Put a Hugh Jass top bearing pattern router bit in the router, attach that to the router table, and make some dust. Ba-da-bing, 10 minutes later I have 26 identical "K" jigs. I only need ten, I donated a few of the extras to be given as a door prize when I was at RR this year.
Sep. 10, 2008, Templates
Sep. 12, 2008 Lift tabs, etc.
While I was in '.125" metal mode', I also cut out the elevator hinges, aileron bellcrank brackets, and both trim lever/handles.
Dec. 16, 2008
Jan. 6, 2009
Jan. 7, 2009
I screwed two 10' 2x4's to the table from the bottom. The canard cores stick out past the 2x4's a few inches, shouldn't be a problem.
The plans say "use 3" nails..." to jig the cores to the 2x4's, I used 2 1/2" finish nails spaced every 6-8 inches. DO NOT forget to angle them zigzag like. The plans also say to string line the trailing edge... I would have liked to, but the trailing edge is pretty well hidden between the jigs. I strung along the spar cap joggle (picture), and made a leap of faith that the trailing edge was also straight due to how well the cores were cut, and how they fit together. There was a slight bow in each foam piece, so the nails at the ends of each block were Bondo'd first, then I shimmed to the string line before Bondoing the centers of each block. I estimate 1/16" of bow.
Jan. 8, 2009
The shear web layup was pretty straightforward, though I took 10 pieces of UNI to complete. Counting error on my part? I pre cut the lift tab crush plate BID pieces with a paper cutter. Picture of the peel-plied shear web. Notice I weighted the lift tab crush plate area, don't forget to shim one side up (the nails in the picture) so the cured surface will end up being something plumb.
Bottom spar cap went pretty well to plans, I filled the trough with nine strips of spar tape. After cure, I spline sanded smooth. Tip: be conscientious in filling the trough. Once cured, it does NOT sand as easy as urethane...
Jan. 16, 2009
Jan. 17, 2009
Jan. 19, 2009
As before, I bondod the outside support legs on first, then ran two string lines to add the middle three. Saw the fishtail off, no need to get real close (else you hit the staples). Score/knife the foam at the 1/2" mark, then grab a loose end of the peel ply and pull. I micro'd in a small radius at the junction of the shear web and canard tip foam joint, and allowed to cure slightly. Enough cure so that foam dust didn't stick. Much anyway.
Sand the top to approximate profile, enough that you can check for check for straight and level everywhere with the templates. Switch to 100 grit and finish up the profile. Don't forget to taper the leading edge from the bottom skin layup.
Sand the shear web surface again. The top spar cap was like the bottom, though I placed 12 strips. Peel-ply, cure overnight, then set in the tent for a semi-elevated post cure. Check the leading edge bottom skin taper job, and sand a joggle in the ends for later tip layup's
I opted to put my second NAV, and the GS antenna on the canard. Sand the high points off the spar cap first though, and use your templates (all of them) to check contour while your at it. The coax routing to the interior of the fuse is a close cut. You'll need to clear the elevator hinge hardpoints, yet stay 'inside' enough so you don't cut into the fish-tail (AKA: trailing edge of the canard). I stopped my cable channel cut just inside of the lift tabs, then final drilled at an angle with a long 3/16" drill bit through the bottom skin. I left about 20" of coax in excess, so that it will go direct to any radios. This may avoid a weight penalty of having to make a 10" extension... with two BNC connectors... and a BNC coupler. Light planes fly fast I hear.
Sand the trailing edge 1/2" lap joint again, and rip into the top skin layup. I found that when I was done wetting out a ply, I 'flipped' the hanging leading edge end up onto the top then brushed a bit of epoxy on it. This made for a relatively painless way of getting epoxy onto the lap with the bottom skin.
I have a small 'gull wing' depression at the trailing edge lap, near where the foam stops. I'll fill this with dry micro at contour stage. I'm leery of putting more epoxy (micro) on top of a bubble-gum stage lower layer.
Fork it, weez done :)