||Order 3.5m & 3.6m lengths of 25mm square steel tubing from Roger Huttlestone for spreading weights during wing skin bonding. Move upper wing skin forward and clamp to spar with a wood spacer to prevent distortion. Mark outlines of 18 off 3" squares and their centre-lines onto BID. Slot 16 of them for fitting onto outboard ribs and make holes in all for conduit. Cut off corners to make them octagonal (ie an approximation to a circle). Abrade all rib faces with a small piece of fine Perma-Grit sheet. Mix 2 strokes of standard epoxy and wet out a batch of single BID patches on polyethylene sheet, plus the un-slit patches in a 2-layer layup with plies at 45 degrees. Plug the root end of the conduit and apply the 2-ply layup, followed by peel-ply. Apply the slit patches to the inboard ribs, one layer at a time, with the slits and plies rotated 45 degrees. The results are not too bad on the first one and improve with practice. Apply peel-ply on each one. Need another 2-stroke batch and a final 1-stroke batch to finish all patches.
||Remove peel-ply from BID donuts round conduit. Position top skin and mark tip for trimming. Cut off excess with coarse hacksaw blade in pad handle. Mark new outboard edge position of outboard horn box recess and start to cut away brown foam.
Break Redux test piece.
Both pieces of BID remain intact, so I decide not to use that Redux for anything important again.
||Finish cutting away upper skin brown foam at horn box recess. Scuff sand surrounding area and cut BID for 1 layer extending about 30mm all round beyond removed area. Wet out with 1 stroke resin & apply peel-ply in sections to ensure good conformity to tapers. Dig out foam from tip of skin about 5mm deep and abrade inner faces well (almost too well!). Mix 1 stroke resin and paint inside of recess, then add 2 doses of flox and butter it in to fill the recess. Turn on fan heaters to bring the humidity down and temperature up for the cure. By bedtime resin feels hard and climate is 28C, 46% RH so turn off heaters.
||Remove peel-ply from starboard upper wing skin horn box recess patch. File off excess flox from flox corner at skin tip. More care needed next time to avoid flox spreading onto outer surfaces, and to ensure skins are not abraded too much when cleaning out brown foam at tip in preparation. Check skin fit at tip and file LE of skin slightly for about 250mm from tip to get better seating against LE skin.
||Order 2kg Redux (Araldite 420) from Europa.
||Redux arrives. Phone Roger Huttlestone; steel tube now available.
||Fit car roof bars and collect square steel tube from Roger Huttlestone. Clean up ends to avoid scratching wing skins. Send e-mail to Neville to confirm that the periphery of the skin is not to be included in the pre-bond process, only the intermediate ribs. He confirms that my understanding is correct.
||As advised by Neville, mark up and
trim away root end of aileron closeout
on starboard wing TE, leaving about 8mm flange all around. Clear accumulated stuff off table underneath wing. Start to collect hardware re-assembly of flap & aileron to wing. Find one of the OR5s (replaced under SB13) has a deep scratch right along it. Phone John at factory and agree to send it back for replacement. Try fitting a FL9 bush in the remaining OR5 and it seems very loose. Check with Roger at the factory to make sure that's allowable and he says yes - the the Loctite 638 will work even if it's not a tight fit, and in any case, it's got nowhere to go once assembled. Degrease OR5 & FL9, apply Loctite 638, wrap a piece of polyethylene sheet around and hold it in position with a toolmakers clamp while curing. Fetch starboard flap and aileron in from trailer and weight them in passing: flap 3.285kg, aileron 2.505kg. Quite surprising that the flap is heavier, considering the amount of lead in the aileron horns. Find FL1/W19 & FL2/W20 hardware bagged up from last assembly, but no sign of similar bag for the outboard hinge and outrigger mechanism. Check the photos of previous assembly to be sure of getting the correct arrangement without false starts (FL1 inboard of W19, nut inboard; W19 inboard of its W18, nuts outboard; FL2 outboard of W20, nut outboard; W20 inboard of its W18, nuts outboard). Assemble with nuts finger-tight the hinges and the outrigger mechanism using the old faulty OR5 for now. Can see why hardware for this wasn't bagged-up all together, but left in original bags with part-number labelling - too many similar sleeves, washers & springs etc. Although it's a bit boring having to get them out of their separate bags, it's much safer and avoids any errors of identification. Hold flap in retracted position with bungees to holes in ribs Find some vinyl offcuts in loft to use as spacers between flap / aileron and TE.
||Loctite 638 securing FL9 in OR5 seems to have gone off OK, although the excess on the polyethylene sheet is still only tacky. Tighten nuts on flap fittings. Fit the aileron using (as before)
spacers under screw heads
to prevent them going fully into stiffnuts. Bandsaw a piece of wood to make up the difference in thickness between the aileron and the tip moulding. Clamp aileron to tip & line up flap to it - only needs a slight shim pushed in at the bottom of the LE between it and the wing skin to get it correct. Check at root with flap alignment template & it looks OK there too. Cut strips of vinyl for spacers / release film at wing TE. Now need to figure out how to keep flap (and to a lesser extent aileron) up in correct position as there'll be nothing to attach the bungees to once the skin goes on. Consider making a wooden support, to keep flap hinges clear of table, tilt whole wing by about the 8 degrees needed to bring the bonding area roughly horizontal, and provide support under the bonding areas as well as the flap & aileron TEs, all the way to the tip. Largest obstruction is outboard flap hinge / outrigger bracket at 180mm below the wing lower surface. Note a few rough dimensions and draw up ideas in CADintosh. Could be quite a large and unwieldy construction.