Chapter 19, The big flying surface . . .

This is a big one, literally and figuratively, building the wings! Note: My second (last, left) wing build was substantially the same as the right wing. My comments about the left wing at the bottom.

Feb. 18, 2007. Sliced up a sheet of 1/2" Baltic Birch for the wing jig blanks. I'll quarter them and add the 'stickers' later... much later.

Jan. 2, 2010. I traced the wing jigs onto Clearprint, then glued to the plywood with Scotch77 and cut them out on the bandsaw.No real secrets here, other than make sure you glue the tracings on the plywood according to the waterline, NOT the TE. Add your stickers before cutting, then cut the jig into quarters, paying particular attention to slicing the fore-aft split exactly on the waterline mark(s). This may help when jigging to the table.... string line the waterline (top/bottom) in addition to the plans method of level and plumb.

Jan. 8, 2010. Working alone, I precut each foam block to length with the proper 78.64° angle. My blocks are 8" x 16" x 108" in length, you'll need to do the math to see if 108" blocks will work for you. The long blocks are a bit cheaper, though $hipping them to your shop may kill you. But you will have extra foam to fix screw ups. 8" blocks also eliminate the need to scab a small piece on the inboard core.

Jan. 29, 2010. I laid my companion of 16 some odd years to rest today (there's a canard that flies to RR that now has a certain meaning...), and finalized plans (like food and grog) for the "Usual Suspects" to come up tomorrow (Saturday) and help with hot wiring the cores.

Jan. 30, 2010.We used the "Popcicle stick" method for the spar troughs, but without the sticks. After passing the spar trough, we paused for a few seconds, made a Loop-D-Loop with the hot wire saw, cut the troughs, and continued with the airfoil profile. Worked OK, mostly. As you approach spar trough, you have to 'float' the saw across the trough, else you get a small screwy dip as the wire drops into the trough while the middle of the wire is still 'lagging'.

You can see the Loop-D-Loop we did (in black magic marker) to the right. Pause generously in the loop, let the wire catch up.

Feb. 1, 2010
I spent hours measuring, sighting, re-measuring when setting up the wing core jigs. Like some others have said, the jigs may be considered just a suggestion. The cores do not fit tight. I settled on plumbing jigs #1 and #4, then string lining the rest according to the WL mark.

I made a small hot wire saw(?) to auger out the wing attach recesses. It's only a few inches of nichrome wire, and glows dull red with only a 6v battery. You may safely assume the cuts went real quick. Tip: Make the wire length such that you enter/exit the foam with the wire at a 45 degree angle to the foam. That way all corners will have a radius. The pockets lined with 2 ply BID, LWA's were tacked in with 5 minute. LWA6 will be exposed later, pointless to goober it up with micro/flox/sputum at this step.

Taking a leap of faith, I glued up the aft cores and prepped for the shear web layup. Now is when I cut off the 1" x 6" 'wedge', then cut the .6" wall. The shell wall cut was done with a hot wire saw clamped plumb just at the edge of the table. Mark the .6" thickness and cut slightly wide of the line.

Shear web done. Nothing to see here, move along please.

Leading edge cores welded back on after another round of measuring, head scratching, sighting... The cool part was the electrical channel hole sighted dead straight now, I was happy :)

Bottom spar cap mostly according to plan, the partial length roving strips ended up slightly longer than plans called for. As mentioned in an earlier chapter, make sure you have extra on hand just in case.

Before flipping the wing over, I hot-wire cut and tossed the sliver of foam at BL 55 that would normally be done before the spar cap step.

Top spar cap real close to plans. I needed a few short fibers to fill in at the bend. I played "barber" when cutting the ends of the tap eat an angle. Just like they do, I grabbed a few fibers and hacked at them with the scissors. Move toward the end a few inches, repeat hacking. After the peel-ply was removed, I could NOT tell where the fibers were stair stepped.

Top and bottom skins went on without incident. Tom Krell came up to help me with the bottom skin, first big layup for him I think. We rotated tasks during the layup, that's Tom slinging the squeegee in the pix.

I also added a second rudder conduit for a potential hidden bellhorn install. If you decide to do the the same, keep the channel at least 1" from the aileron hot wire slot else your conduit ends up inside the aileron cutout.

Feb. 20, 2010
Cure, sand a bit, jig up the trim router to make the .7" recess for the BL55 rib, ooger out the rib where the aileron bell crank goes, sight a bit, measure...

Mar. 3, 2010
Mark up the skins in prep for cutting the ailerons. You'll be wise to read the instructions several times here, there's several places that'll bite you if you're not paying attention. 1) Your perpendicular cut at the trailing edge is the same on the top/bottom skin at the outboard end, but is not on the inboard. 2) The width (chord) of the aileron at the outboard end is not measured at the end, rather 12" inboard from the end. That said, I don't know if my aileron is wider or narrower than everyone else (a major concern?), but I need to make sure I cut the aileron out of the left wing the exact same way. How/where the ailerons are cut will also affect jigging the winglets.

I used a cabinetmakers veneer saw for the cuts, the cutting edge is curved like a Kentucky's finest cask, and leaves a very thin kerf. It's as dull as a politician at 'open mike night' now, but it got the job done. I have an aileron (singular) now :)   I removed 3/8" of foam (leaving the flag of bottom skin intact) from the aileron leading edge, then screwed the 7/16" balance rod on with dry micro.

Mar. 7, 2010
Since I have to heat up the basement for layup's, I try to schedule as many as I can for one session. This session I did the aileron 1 ply BID over the balance weight, the aileron spar cutout in the wing, and the inboard wing rib.

Started with the aileron 1 ply BID. It's thin (duh), and goes around compound curves. Slap the cloth on the balance rod, let it droop for a bit, work it in, have some coffee, work it in a bit, take a pee, grab some peel-ply, check the forum, work it in some more... Peel-ply, 4mil poly, and clothes pins may be your friend here. So will working/stippling this layup until it starts to firm up. It's a simple layup (one ply), but I hated it.

I recall Wayne Hicks spoketh "dats real tight in there", referring to the aileron spar area in the wing... it is. I left glassing the inboard rib till last, but did the aileron spar trough and outboard rib 'as a unit'. I had to make 1" laps, none on top of a future hinge. The inboard rib was done last, as you need to cut/poke/trim into the torque tube hole one inch. Oh joy. One extra bid ply at the hinge locations, then close-pin everything to aluminum angle to make sure it cures straight.

I'm using JD Newman's spherical bearings, I potted the click bonds onto a two ply bid piece, then micro'd this onto the foam prior to glassing the rib. Slip some heat-shrink (3/16") over the threads before glassing

Inboard wing rib was done in pieces too. The 'arrow' shaped upper/lower/outboard faces, then lap the three plies on the shear web and 1"onto the first.

I deviated from the plans, somewhat, with regard to installing the hinges to the aileron. The plans have you bondo the hinge on, remove the aileron, drill the holes, pop off the hinge, clean the bondo, add flox, then pop rivet (or something like that). I used flox in place of bondo and dispensed with the above steps. Pix here, and here. Note the finish nails are to help hold the aileron from falling into the gap, as well as maintain location until the flox cures. The sheet metal slivers in the pix are just that. I found that was all that was necessary to hold the hinge leaf against the aileron until the flox cured.

Notes, tips, comments:

  • Consider adding a strip of peel-ply at the wing rib glass-glass edges before skinning the bottom and top of the wing. Also consider going a bit light with the slurry on the top skin where the winglet will attach, or don't slurry at all. There was a recent incident where a winglet de-bonded due in part to not sanding all the micro off prior to doing the interior wing-to-winglet layup.
  • On my second wing, I recessed the foam slightly for the click-bond 'unit' (mentioned above) for the spherical wing root aileron bearing, and held the wing root rib glass 1/8" - 3/6" short (cut/trim when glassing) around the studs. I applied a plywood 'compress', the same basic shape as the bearing housing, to make a flat bearing surface for the aluminum bearing housing. If I'm not clear here, it will be once you see the click bonds, and glass your wing root. Here's a pix that shows a bunch.
  • The aileron in the second wing was cut from the wing with a utility knife, linoleum cutter, and the veneer saw mentioned above. After gluing the balance rod on (hold it .125-.250" short, span wise), the ends of the aileron were then trimmed square on the table saw.
  • Ooger out some more foam for universal joint clearance before you glass the aileron rib/spar in the wing.
  • The plans are somewhat vague as to the shaping of the foam in the inboard rib (wing root). I removed the foam from the bottom spar cap, and the entire shear web. It appears I should have left a thin sliver of foam (the same thickness as LWA-7) between LWA-7 and the rib. The plans view M-M does not show a phantom line indicating a bend in the three ply UNI reinforcement. Oh well.
  • Your Nylaflo tubing will arrive all coiled up. Bake it in the oven at 180 degrees for two minutes, and it'll straighten right out.