Europa #435 G-RODO Build Journal - 2002 08

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1 Check fit of mandrel and paxolin tube in drain side of tailplanes. It turns out that tailplane half must have got disturbed slightly before the first hole was taken right through TP4/TP6 as the holes align about half a millimetre before the tailplane is fully home. File out hole in surface a bit to allow easy fitting. Dig out recess in foam around top of hole. Roughen outside of tube and file a few grooves in them for grip. Decide I need a plug in the top of the tube to prevent epoxy getting down there, so turn down one end of a 10mm beechwood jointing dowel to 5/16". Degrease paxolin tubes with acetone. Wax mandrel and wooden plug. Clean hands and mix a couple of strokes epoxy with 2 small doses of flox, leaving it still quite runny; decant off about half and add another dose to make thick non-slump flox. Fill starboard drain recess & paint inside of hole with thick flox. Insert mandrel & plug in tube, coat outside of tube with thick flox and insert in hole, ensuring mandrel is through second side and well bottomed in the hole. Dribble thin flox into gap between tube and surface hole, and wiggle tube around a bit to encourage it to flow down. Leave to cure at about 20C, 69%RH without heat. 317.7
2 Remove wooden plug from paxolin tube; needs a touch around the interface with a file to break the hold because the dowel is ribbed. Turn tailplane over and tap out mandrel with a pin punch. Cut off protruding length of tube and file down excess flox. Some small voids appear as I get it flush. Check fit of pip-pin, still OK. Re-wax mandrel and wooden plug. Make another plug same as first, as I want to fill the holes around the starboard drain tube while doing the port one. Mix epoxy & flox as for first drain tube and fit port one same way. Find a thin piece of wire is good for encouraging thin flox to flow into small gaps. File the accumulated epoxy samples from begining of July. 319.4
3 Remove wooden plug and mandrel, trim off protruding drain tube and file flush. Check operation of pip-pins; all OK and make a very satisfying click when they go home. Bayonet tool not much use, though, as pins free to turn. Given a short length of 1/4" rod to push up with from underneath, I can do it by hand anyway as a finger will fit in upper hole to operate by push rather than pull. I may remove the spring pins and make a "crochet hook" tool later. We'll see how the pip-pins in the wings behave before writing off the bayonet tool approach. Alternatively, could a slightly different bayonet tool work? If the slot was horizontal (instead of ramped), at a depth which did not require spring compression, it would engage and work fine for removal, but could the top be pressed down far enough for insertion? Remove tabs from tailplanes. Store tailplanes on "outboard rib" stand. Check size of balsa TE section for Flettner strips. To get the 8-10mm overall thickness at the TE, needs about 1.5mm planed off it, which is just about the thickness of the thin edge anyway. Clean up TE joggles on tabs. 20C, 70%RH so turn on dehumidifer and set fan heater to 4. Mix 3 strokes epoxy with 10 doses of q-cell for dry micro (rather too much) and fill tab TE joggles. Prop tabs up so filled area is horizontal , to minimise effects of any possible slump. File yesterday's sampes, and also one from early July that had been hiding under the tailplane. Plane 1.5mm off balsa strips with power plane (after unsuccessful attempt with router). 323.3
15 File and sand down tab TE joggles flush to airfoil. Trim balsa TE strips to length. 324.0
19 22C, 69%RH. Heater on to 4, dehumidifier on. Mix 2 strokes epoxy & paint onto tab TEs and balsa strips. Stick in position and paint outer surface of balsa. Apply peel-ply tape (70mm tape split lengthwise) to each face and clamp balsa to TE with wooden clothes pegs. Adjust line of balsa strips to align with TE as necessary. Leave to cure, propped up on foam blocks to prevent pegs being dislodged. Down to 62% RH and 24C about 21:00 when heat switched off. Epoxy cured, sample in cup cracking off. 325.0
20 Remove clothes pegs and peel-ply, with some difficulty on one tab as there was enough excess epoxy to stick the pegs down. The resulting rigidity of the peel-ply under the pegs means that small patches of balsa-wood are lifted up with the peel-ply at each peg location. Taper the flettner strips down to the airfoil shape at the root and tip ends. Sand the TEs square and flush with the glass. Cut peel-ply as before and also 2 narrow strips for TE face. Mix 2 strokes epoxy and paint over newly exposed wood, and thinly over rest of TEs. Apply peel-ply carefully on each side, just butting good edge up to TE. Set up tabs vertical, LE down, on foam wedges and paint TE faces with epoxy. Apply narrow peel-ply strips and leave to cure at 22C, 68% RH without any heat. 326.9
21 tick Re-fit tabs to tailplanes. Need to peel back peel-ply slightly on flettner strips to allow dressing to fit at outboard end. Get out rudder and check instructions for hinge fitting. 327.3
22 Peel off peel-ply on inside of rudder flange. Clean up repaired area near root. and bring edge in line with main length of flange. Mark out hinge rebate and hole positions. File rebates. Forget to protect inner rudder LE until last one, so a couple of small scratches appear, caused by the blunt end of the file. Find small offcut of stainless for a protector. Check what clamps required to clamp hinges to straight-edge. The 2" are ideal, but I only have 2 of them. Go to Toolite at Mitcheldean and get 4 more, and also 3.25" and 2.5" Morse holesaws (for aluminium panel) while I'm there. Clamp hinge leaves and sight along bore, but not happy with alignment. Decide there is a slight curve in the aluminium angle I'm using; other examples seem no better. Try the 50" clamp-guide instead and it seems perfect. I can clamp the hinges to the narrow face with the edge away from the knuckle parallel to the edge of the striaghtedge, which potentially gives better lineup than the using the knuckle edge. Bore-sighting looks fine from both ends. Offer up to rudder to check longitudinal position. Will need to support ends of straightedge before I can do that properly. Looks like about 52mm at tip and 90mm at root will be needed. 331.0
23 Bandsaw pieces of foam to support hinge jig. Chop out a hole in root end one for protruding part of clamp. Once alignment satisfactory, grease hinge wires with Duckhams Keenol, insert, and safety ends. Clean hands. Start to put parcel tape on both faces of first hinge, but realise that it's probably not wanted on underside. Leave that on temporarily to hold hinge straight while applying another piece to top, just covering hinge knuckle. Then remove tape from other side. Repeat for other hinges. Wooden wedges made for tab hinges don't work on rudder, as internal corner of flange is quite rounded, not so sharp as on tabs. Trim a bit off one wedge to allow it to go fully home, although it won't stay of its own accord. Set up bench backstop to push against and drill holes, using wooden wedge to hold hinge leaf up, and stainless sheet to protect rudder LE. Start with 3.2mm and open out to 3.3mm then hold with clecos, 2 per hinge. Dismantle and clear out swarf. Countersink holes with drill bit. Mix 1 stroke epoxy with one good dose of flox and butter onto underside of flange at hinge locations. Clear flox out of holes with a piece of copper wire. Offer up hinge jig. Clamp up lightly with 1 cleco per hinge, central. Dip each pop-rivet in Duralac and pull lightly until holding without looseness. Remove clecos and replace with rivets. Leave to cure with dehumidifier on; 22C, 66%RH. 334.4
24 Snap up rivets on rudder hinges. Unclamp straight-edge. Hinges a bit stiff. Remove parcel tape. Clean off excess Duralac from around rivets. Chip off some bits of flox from around hinge knuckles and apply some oil, which eases hinge movement a bit. 334.8
26 tick With great care to avoid scratching or nicking the hinges to cause stress risers, cut and chip away flox that has oozed around hinge knuckles. Eventually manage to get all 3 hinges operating reasonably smoothly. The safetying of the hinge wires makes them stiff in the flap not attached to the rudder, but not excessively so. Put rudder and tailplanes into trailer to make more room in garage. Note that I'll need a new number-plate for the trailer as it's still wearing L438WRT. Clear everything off layup table and brush it off; note that it's developing a slight twist - will need to be aware of that when doing any washout, etc, measurements. Mark out and cut the 2 flap hinge jigs from pieces of 13mm ply. Use router to get good square edges on critical faces. Get Loctite 638, FL1, FL2 FL3 & FL9 parts out and check diameters against bolts. Decide to use offcuts of 1/4" steel rod instead of bolts for lining up FL1 & FL2 with jigs. Drill jigs through with 1/4" Forstner bit. Peel back outer peel-ply on port flap to see closeout area better. Dig out false ribs from closeout area and remove peel-ply inside flanges (with usual struggle to get it started). Find port upper foam shells and support flap upside down on them. Cut back peel-ply to allow jigs to fit properly. Mark chordwise postions of hinge slots at root and tip. Mark mid hinge position with long straight-edge. 342.6
27 Mark flap hinge slot widths at root and tip. Use router bit in Dremel on router stand to mill out slots freehand. Bring them to size with Perma-Grit sheet. Find after some difficulty that the 5mm drill bit won't go down into the middle slot to rout it out - have to use 4.5 or 4mm. Get down to the top skin eventually with slow and careful progress by hand. Try lining up everything and it looks promising. File a small relief on the TE end of the jigs, as the TE joggle is proud of the flat underside of the flap and makes the jig sit up clear of the surface. Degrease the FL9 bushes and FL1, FL2, FL3 ends. Apply Loctite 638 and persuade the bearings into place with a hide mallet. Decide I should add a brace to the side of the jigs, to ensure they stay truly upright. Bandsaw a couple of small triangles out of oak, and screw them to the sides of the jigs. Mix some Holts Cataloy body filler and attach root jig with it, checking it's at right angles to flap bottom surface and to LE. By the time I've done this, the mix is going off, so mix a fresh batch for tip jig and align it likewise. Still not sure how to treat the hinges; inclined to treat them (as the hinges) with primer, but want to be sure Loctite has gone off before I start surface preparation for that. 347.0
28 Buy new trailer numberplate at Halfords. Would like to streamline the edges of FL1 / FL2 / FL3 instead of leaving them with square edges as supplied, but need to check that this s OK. Tech support at factory is limited to Andy and he's not in the office.
29 Fit new trailer numberplate. Buy reel of 0.75mm nylon monofilament line. Still can't get hold of Andy.
30 Finally reach Andy and he says it's fine to round off the edges, although he thinks John Tye is the only person he's seen to have done it. Find a bit of brass rod about .3" diameter. Taper turn to fit in FL1 / FL2 / FL3 hinge holes and drill through with number 68 drill (to fit 0.75mm nylon monofilament). Support end on centre and part off. Repeat to make a second the same. Find a piece of Perspex rod about 3/8" diameter and face off the end. After some false starts at too high a speed (drill melting the workpiece) manage to get a #68 hole centred in it. Turn diameter concentric. Scribe a 1/4" diameter circle on the face with the point of a tool. Part off and polish both sides. Check all parts assemble OK on nylon line. Find insert from chocolate-block connector to retain one end of line; first end will be knotted. Start to shape edges of FL1 with millenicut file, but hard to hold it. Restrain it with a bit of angle held in the vice, but not very satisfactory as I still need one hand to keep it from sliding sideways. After completing FL1, make up a clamp from a couple of pieces of aluminium angle. One hole tapped for 1/4" BSW screw through hinge hole; a second behind it to give more grip with a screw and nut. This is much better as I can use both hands on the file now, but the top piece of angle has to be filed away quite a bit to get the right sort of angle on the workpiece. Complete second FL1 and start on FL2. 349.7

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