Europa #435 G-RODO Build Journal - 2017 05
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|1||Forecast to be dry this morning but rain expected later so up early and start pulling stuff out of trailer to see what can be stored elsewhere and what can be lashed down in the trailer. Finish up with box 15 (temperfoam blocks) in trailer nose, then the windscreen, and a couple of rolls of carpet to act as buffers. Next, the engine box turned upside down to hold the tailplane and flap blue foam jigs. Find there is also room for the door transparencies, so wedge them in with a couple of bags of small pieces of foam. Next, lying thwartwise, the long box with polyethylene bubble wrap and sheet. The former box 9, with remaining blue foam bits, goes left of engine box. Tailplane holders go on top of the polyethylene sheet box and the trailer winch fittings box goes on the right. Lash down and forward with rope between side anchor points. Tailplanes go in garage behind prop; generator & chain block also go in garage. The big cable drum that the prop sat on goes into the carport roof space on top of the scaffold poles. The base of the engine box and the 3-tier trolley get lashed together to the side anchor points under the port wing, on the right side of the trailer. Pile carpets and cushions along sides.
Wheel the compressor round from the garage to the carport. Pull the trailer forward and out from the fence so I can get at both wheels. Inflate both tyres to 30 PSI from the compressor. Sweep up the pine cones and needles that have accumulated under the trailer, and pull out the ivy etc coming in through the fence. Push the trailer back by hand (much easier than expected), leaving it roughly centred ready to couple up, and put the compressor back in the garage. Fit towball to car & grease it.
Plan route to Nympsfield. Seems easiest to go down M5 & avoid Stroud. There will be the awkward corner at the top of Frocester Hill, but that is preferable to the many roundabouts in Stroud.
Make some measurements to re-check the lengths of the bolts required for mounting the oil cooler. The existing spacers measure from 79.84mm to 79.99 mm (I thought I had made them more closely similar than that!) and will need to be shortened by 20mm. The double flange of the duct measures 2.62mm (although I think it might compress slightly). The flange of the oil cooler measures 1.86mm at one side and 2.11mm at the other.
Thus, the grip length of the bolts must be no more than:
79.84 + 2.62 + 1.86 - 20 = 64.32mm = 2.5323". Thus, AN4-27 is the longest bolt that can be used, as the grip length of AN4-30 is 2.563".
The MS21042-4 stiffnut is 5.4mm thick, and the 2 threads beyond it required for safety would be 1.81mm. The overall length of the bolts must not be less than:
(79.99 + 2.62 + 2.11 - 20) + 5.4 +1.81 = 71.93mm = 2.8319". Thus AN4-27 is the shortest bolt that can be used, as the overall length of AN4-26 is 2.718".
The required new length of the spacers will be 59.9mm.
Set up the carbide insert parting tool and the tailstock live centre in the lathe. For each of the oil cooler spacers in turn, hold lightly in 3-jaw chuck with a strip of aluminium across the chuck face between the jaws as a backstop. Bring up the tailstock centre and tighten chuck. Check position of spacer end by bringing left-hand side of tool lightly up against it, then retract tool, wind along 20mm and part off. Deburr end, remove from chuck and check length. Shortened spacers come out at between 59.8mm & 59.9mm. Store them with the redundant AN4-35A bolts in box 20.
Put tools for removing ailerons and flaps in car, along with a tyre pump (as I had forgotten to check the pressure in the trailer spare tyre when I did the others). Pull the trailer forward until it is central in the carport, reverse car in and couple up. Drive out slowly and cautiously as this is the first test of the geometry of the drive since it was remodelled. All is fine, can get out without rubbing on any kerbs.
Drive to Roger Targett's workshop at Nympsfield and after removing the trolley & engine pallet get the port wing out. Discuss with Roger what needs to be done. Ask him if in addition to re-doing the wing repair and checking for correct bonding of the aft edge of the upper skins, he can then fill, profile and paint the wings. He quotes an approximate figure for all that plus filling & painting the fuselage. It seems a lot, but it will save me a lot of time and get the job done more satisfactorily, so I agree to go ahead. To save some cost, agree that I will fill the ailerons and flaps and return them to him for profiling and painting. Remove the ailerons and flaps and stow them in the car, then transfer the wing from the dollies to Roger's wing support trolley. Repeat for the starboard wing. Stow the dollies, pallet & trolley securely in the trailer again. Sign a work agreement with Roger and drive home again.
Not sure what is the easiest way to get the trailer the right way round for going back into the carport, but just drive straight forward and uncouple. Manhandle the trailer round in the road (with some assistance from the cleaners) and couple up again. Go forward a bit then try to reverse round the bend of the drive. After several false starts, manage to get it round the bend and reasonably lined up with the carport entrance. Reverse all the way in, uncouple and finally position the trailer by hand.
Realise that I hadn't mentioned the tailplanes to Roger so send an e-mail to confirm that I will also fill them and pass them on for profiling and painting.
|4||Ryan at Targett Aviation contacts me to suggest that I have the aeroplane painted in automotive 2-pack paint rather than gel-coat as it would be lighter, involve less labour so faster & cheaper, and would need less maintenance in the future. He also asks if I can send a deposit. The 2-pack seems the sensible choice, so reply agreeing to that; David Joyce hadn't mentioned the downsides of gel-coat when he recommended it!|
|5||AN525-10R7 & AN4-27A delivered from LAS Aerospace. Store them in box 20.
Responding to a request from Ryan, send him a copy of the wing repair scheme supplied by the Europa factory, plus my amended sketch & pointers to pictures of the whole thing on my website.
Will need more room in the garage for filling the control surfaces and tailplanes, so consider if now is the right time to install the tailwheel tracks and winch system in the trailer - it seems unlikely I would be able to get the fuselage (with the engine mounted) up the ramp into the trailer without the winch. Need to plan the sequence of events. Have a look at the pictures of Peter Davis' trailer interior to check how things should be arranged. I notice that he puts the inboard wheel of the wing dolly into the tailwheel track when loading/unloading. Both the wing dolly wheels and the tailwheel will fit comfortably in a 60mm slot.
Open the trailer and check the steel angle supplied for the tailwheel tracks. There is just enough length for the trailer floor, but none for the ramp (as seen on Peter's trailer). I now seem to recall that Roger Huttlestone said he'd found that tailwheel track on the ramp was not needed. In the garage, the aft tip of the rudder is about 1.6m above the floor at a spot about 400mm aft of the tailwheel axle. Get the tailwheel hook and the locating socket for it out of the trailer and offer up to the tailwheel. The notches for the tailwheel axle will need to be opened up slightly to get full engagement, but it looks as though that spot 400mm aft of the tailwheel axle should be about right for the first winch cable pulley. The socket doesn't sit flat on the floor when the hook is fully engaged - will need to modify the socket shape or mount it up on a small platform. Check trailer height in that area and it seems fine, there is more than 1.6m clearance to the frontmost arch (where the nose taper starts) and somewhat beyond. Get out the pulleys and blocks; one pulley is too wide and will need to be skimmed on the flanges to fit into any of the blocks.
|6||Check width of fuselage dolly guide rails in trailer. 988mm at inner end and 990mm at outer end. Mark the centres at each of those points; the outer one is pretty much in line with the pencil line on the floor, but the inner one is abut 10mm to the offside of the pencil line. Will need to mark a new true centre-line all the way in to the front of the parallel section of the trailer. Check the pencil line at that point; it is 897mm from nearside frame upright and 892mm from offside frame upright, so make a new mark 2mm to nearside of pencil line. Set up the laser line projector at the aft end and with several iterations line it up with the new marks at the extreme front and back of the floor. Go along the laser line and transfer it to the floor with a fine felt-tip pen mark at every subframe cross-member. Lay the tailwheel rail angles upside-down on the floor each side of the marks, to form a narrow channel. Along this run a thicker felt-tip pen, the full length of the rails.
Check what fasteners I have left in the box of trailer odds and ends. There are 16 off M6 x 80mm roofing bolts with stiffnuts, which is the number needed for attaching the tailwheel rails to the deep crosspieces. At 6 other places, shorter ones will be needed. There are 4 off M6 x 25mm & 16 off M6 x 40mm roofing bolts; not sure which length will be right for the angle cross-members - will need to check after drilling. From stock in garage find 6 off M6 x 30mm roofing bolts and stiffnuts.
Re-check height at forward end of trailer. with tailwheel rails set 15mm in from rear edge of ply floor (same as fuselage dolly rails) and tailwheel hook about 20mm in from the forward end of the rails, a spot 400mm forward of that is about 1625mm below the trailer roof (which is sloping down at that point). I'd feel happier with more than 25mm clearance, so the receptacle for the tailwheel hook could be butted up against the end of the rails. Before making any decisions, need to check that the spinner will be clear of the ramp when closed.
Drop a laser line from the prop flange and measure from that spot to the tailwheel axle - 5325mm. The spinner is abut 375mm deep, so total length from tailwheel axle is 5700mm. With the tailwheel hook receptacle butted against the end of the rails, the distance from the hook centre to the aft end of the rails is almost exactly 6m, which gives plenty of clearance.
Looking at the pulley system, Roger Huttlestone supplied 8mm x 25mm clevis pins for the pulley pivots but they are just too short to get the split-pins into the holes. Maybe he had planned for thinner plate than the 6mm he used to make the pulley blocks. Will have to see if I can get 8mm x 30mm clevis pins. Tape up the bare ends of the wire rope with self-amalgamating tape.
I will need to think about a method of holding down the fuselage dolly to the floor, as advised by David Joyce.
Find a piece of wood 30mm wide and use it to mark the required spacing of the tailwheel rails from the centreline at each required fixing point. Lay one angle against the offside marks and position the aft end 15mm in from the edge of the floor (as for the fuselage dolly rails). Centre-pop about 35mm in from the edge of the floor, drill 3.5mm with cordless drill and open to 8mm with mains-powered drill to save changing bits. Then remember that the fixings for these rails are M6, not M8! Find a suitable M8 button-head screw and drop into hole to keep location. Align angle with next mark, centre-pop, drill 3.5mm & 6mm. Drill bit is not long enough to reach the bottom of the box-section until I move the angle out of the way and then it only just reaches. Don't have a long-series 6mm bit so will have to do the bottom holes later. Insert M6 x 80mm roofing bolt to hold the rail in place. For each remaining hole repeat the alignment, centre-pop, drill and insertion of screw process all the way to the forward end of the rail. Getting dark inside trailer so bring out inspection lamp. Repeat the whole process (except for the 8mm hole error!) for the 2nd rail on the nearside of the centreline.
Light rain starting, so put the wing dollies and control surfaces back in the trailer and close up.
|8||Lift out locating bolts and move tailwheel rails to one side. Drill through bottom of box section members in 16 places. Deburr holes in rails with snail countersink. Wipe rails clean of swarf with a thick pad of paper towel. Bring out vacuum cleaner and vacuum up swarf and much other fluff and rubbish from trailer floor. Reposition rails and insert all roofing bolts (using M6 x 40 where there is a single thickness of angle underneath, as 30mm is just too short).
Re-check how far aft of the tailwheel axle the rudder tip is, using the laser line level. I get different answers when projecting from each side of the rudder, so go back to old-fashioned plum bob and it strikes about midway between the laser-plotted lines, at 310mm aft of the tailwheel axle. From the floor at that point to the aft tip of the rudder is 1580mm. With tailwheel hook receptacle butted up against forward end of tailwheel rails,mark a point 310 mm forward of hook centres. Using the laser line projector, find a point vertically above that (the trailer floor is not far off horizontal). The distance between that spot on the roof and the mark on the floor is 1680mm. I feel reasonably comfortable with 100mm clearance of rudder from roof, so can go ahead with mounting receptacle and pulleys.
With round and half-round files, open up tailwheel hooks to fit stub axles, checking with engineers blue for best fit. Check how much receptacle has to be raised for a good fit of the hook - about 10 to 12mm. Find a suitable piece of 12mm birch plywood and cut to shape. Mark and drill holes 8mm. For a load-spreading doubler underneath the ply floor, find a piece of 0.25" aluminium plate and cut off a piece slightly larger than the receptacle base. Deburr edges and round corners. Clamp it to the receptacle and the plywood piece and drill through the holes 8mm. Insert M8 screws in 3 holes to maintain alignment & remove clamps. Line up against end of rails and drill 8mm holes in floor, moving screws into drilled holes in turn.
Place 1st pulley and block on floor to find suitable location. Draw line on floor tangent to pulley, towards 2nd pulley location. Bisect angle with a centre line and extend this centre line backwards to provide centreline for pulley block fixing hole. Lay pulley in place with rim tangent to rail centreline and line towards 2nd pulley. Mark pulley centre on angle-bisecting line. Lay block in place aligning pulley pivot hole with the mark just made, and mark on the back extension of the bisector the location of the block fixing hole. Drill there 8mm and insert screw to check length - M8 x 40mm is OK. For the receptacle will need M8 x 50mm. On nearside end of line projected from 1st pulley, position 2nd pulley block and mark holes. Drill through one hole 8mm then insert screw through block and drill through other hole.
Order some M8 x 30m clevis pins from Boneham & Turner.
|10||M8 x 30mm clevis pins delivered.
Invoice received from Targett Aviation for deposit payment; make online transfer for that.
Soak plywood spacer for tailwheel hook receptacle in wood preservative.
Put the oversize pulley in the reverse-jaw lathe chuck and skim a little less than 1mm off the face with a carbide-tipped tool. Reverse the pulley and similarly skim the other face. Now it fits the remaining pulley block nicely.
Grease each pulley bore and fit it to a block with an M8 x 30mm clevis pin, securing with a split-pin. Drop M8 x 40mm capscrews into 1st & 2nd pulley block fixing holes to keep them in position. Needed a large washer under the 1st block to compensate for the thickness of the clevis pin head.
Can't find suitable (M6 x 40mm) screws or bolts to fix the 3rd pulley block to the upper frame member, so order some from Screwfix.
|12||Take ply spacer out of preservative soak and leave to drain off. Collect bolts & nuts from Screwfix.|
|13||Fit (finger-tight) all nuts, washers and load spreader plate on underside of trailer. Get Chris from next door to hold heads of bolts and screws while I crawl underneath the trailer to tighten up the nuts.
Thread winch wire rope through 1st and 2nd pulleys then through 3rd pulley to set its location for best alignment. Mark location in pencil on upper frame member and clamp the pulley block to the frame. Drill first hole with tight fit drill kit. Drop in bolt to locate, shift clamp and drill 2nd hole. Remove pulley block and drill through bottom of box member (drill bit not long enough to reach with block in place). Fit pulley block with M6 x 40mm bolts. Re-fit winch handle right way round (was reversed when winch first fitted to avoid catching).
Move some of the stuff away from the nearside of trailer and see how the wire rope will run between the 3rd pulley and the winch drum. Thread the end of the wire rope through the holes in the side of the winch drum. When taut, the wire rope is just touching the outboard side of the spar clamp pillar and just above the upper bracket. It is also rather near the wiring where it passes the adjacent glass-fibre arch. Some fairleads or rubbing blocks will be needed, but the wire rope should be kept as straight as possible. Consider making a hole through the spar support pillar. Find a length of 1" SRBP round rod and cut off about 80mm of it. Chuck in lathe and face off then centre-drill. Then wonder if having the wire rope further away from the trailer side will cause it to foul the wing fairing. Check on photos and it certainly looks as though that would be a problem. Find some 25mm thick SRBF and it would be easy to attach that to the outboard face of the spar support pillar, but the wiring tie-wrapped to the upper frame member would obstruct fixings for a rubbing block there. Realise there is a loop in the wiring and it could be re-positioned. Cut off tie-wraps in the affected area and it should now be easy to attach a block of SRBF with bolts vertically through the upper member.
The block on the spar support could be about 40mm x 40mm. For the other one, the rope passes about 45mm inboard of the outer edge of the upper frame, so a piece of SRBF about 40mm x 55mm would be OK. Bandsaw 2 pieces of 25mm SRBF approximately to the above sizes. Mill the edges square and chamfer along one edge of the 40mm x 40mm piece to clear the weld line on the spar support pillar.
|15||Drill each piece of SRBF through 9mm for wire rope. Check the 40mm x 40mm piece against the spar support pillar and relieve the edges a bit more. Mark on inboard side of pillar where fixing holes should be. Centre-pop, drill 3mm to start than drill 6mm. Check lineup of drill bit in both planes before drilling through outboard side of pillar. Hold SRBF block in place and spot against it with the drill. Drill through on the spots 6mm with the bench drill. Open the inboard holes in the pillar to 16mm to clear a 10mm socket (easier & quicker with a holesaw than the step drill). Fit M6 x 40mm bolts through the pillar and SRBF block and secure with washers and stiffnuts. Remove wire rope from winch drum and pass through the block. Check height when taut, where it passes the location for the other block. Decide it would be best to lower the hole so to do that the block should be rebated. Bandsaw a rebate roughly half the thickness of the block and square it up on the mill. Drill 6mm in 2 places. Clamp in place on upper frame member and with tight fit drill kit drill 1/4" through the SRBF into the top of the tubular member. Insert bolt to locate, move clamp and similarly drill through other hole. Remove SRBF and start to drill through bottom of tubular member. Drill keeps snatching; switch to smaller bit to get through then up in steps but the 1/4" bit just keeps snatching. Rain starting so close up trailer. Get out the 1/4" hex angle drive adaptor and a 6mm bit to suit.|
|16||Try to drill through the lower face of the tubular frame member for the SRBF winch rope guide, using the 1/4" hex angle drive. Alas, it snatches and disables the adaptor! Give up with that approach and just put the hex-shaft 6mm bit in the cordless drill, then while pushing the drill body against the trailer side to get it square, drill through the bottom holes. Offer up SRBF guide to frame member and thread wire rope through. With the reduction in thickness from the rebate, the bolts I picked before are too long. Sorting through those in stock, find what I think are M6 x 50mm but turn out to be 1/4" BSF (26TPI) x 2". Haven't got a correct spanner for them but a 12mm AF socket seems to be close enough to get the first one tightened. The second one seems to have some problem with the threads and won't do up easily before I have to stop for another commitment.|
|18||Cut away the base of the glass-fibre arch for better access to 1/4" BSF nuts with adjustable spanner. Apply a little oil and tighten 2nd nut.
Fit tie-wraps to various places around the forward guide for the wire rope, to keep them all well clear of the rope.
Loosen wire rope where it passes through holes in side of winch drum and persuade the end slightly further into the last hole (where the rope exits). Mark holes each side of rope location for a wire rope clamp. Centre-pop and drill through 3.5mm then 5.5mm. Fit clamp from inside, enclosing both the end section and the exiting part of the wire rope. Fit nuts and tighten. Wind winch a few turns to get the rope nicely started on the drum.
Couple car to trailer and pull it straight out as far as possible, which just leaves enough room behind it to get the fuselage past.
Pull fuselage out of garage and wheel it past the trailer towards the carport, nose first. Extend the stabilisers to ensure trailer does not tip while loading (it's still coupled to the car, but better to take no chances). Move the ailerons & flaps from the trailer to the garage. Collect tools and materials etc and take them back to the garage. Move the other obstructions (generator, boxes, 3-tier trolley etc) out of the trailer. Lay the wing dollies flat in their stowed position. Consider that it might have been useful to have bungees or similar to hold the tops of the wing dollies upright against the trailer sides, but don't want to spend time on that now.
Unwind the wire rope almost fully from the winch drum, bringing the tailwheel hook to just beyond the edge of the ramp. Pull fuselage up towards the ramp and engage tailwheel hook. Crank the winch and wind the fuselage into the trailer. Check before dolly wheels reach the ramp that it is reasonably centred. Quite an effort getting the dolly up the ramp - besides the slope of the ramp, the trailer itself is on a slight uphill slope. Tailwheel hook goes home into the receptacle nicely with the fin and rudder comfortably clear of the trailer roof. Check that I can squeeze past the fuselage to the front of the trailer - no problem. Slide the big sheets of corrugated cardboard (from the wing boxes) into the offside of the trailer. Put some boxes back into the trailer between the cowl and the ramp and close up.
Take remaining stuff including 3-tier trolley into garage.
Reverse trailer back into its place. Uncouple and the nose lifts easily - there is almost no nose weight. I did wonder about having the engine weight at the back of the trailer, and now I fear I may have to add extra nose weight to make it safe to tow; I don't expect the wings to change the weight distribution much.
Pull out one of the 2 remaining scrap doors that have been stored on the big layup table. Mark and cut slots on one side to locate over the handles of the 3-tier trolley, to make a work surface.
Start the clock (2839.9). None of the work on the trailer has been timed.
Start to prepare port aileron for filling. To protect the underlying foam, will need to put flox into the clearance holes drilled for the hinge screws and rivets, but first enlarge the holes slightly to ensure full hinge movement. Check where more clearance needed by applying red paint marker to protruding parts and pressing hinge against surface. With coarse Perma-Grit flexible sheet, rub down epoxy runs, nibs and uneven layup transitions. Check weight: 2480g.
Similarly start to prepare starboard aileron by enlarging the holes for hinge screws and rivets.
|20||Rub down epoxy nibs, runs and uneven layup overlaps on starboard aileron. Weigh it: 2495g.
Can't find the thermo/hygrometer - thought it might have been left in the fuselage but a good rummage through fails to turn it up - so get the spare one out. After stabilising to the garage climate, it shows 19.4C, 31% RH.
Start work on port flap. There is a buildup of neat epoxy around the mid hinge, which seems to be a bit resistant to hand rubbing. Grind it off with the power file, but alas! did not use a light enough touch and have taken the top layer of UNI off in a few small places, over an area of about 50mm by 25mm. Will need to patch it to tie the flox corner on the hinge rib to the skin fully again. Abrade a good 50mm all around that area. Finish cleaning up the rest of the flap.
Turn on fan heater at thermostat 3, full power.
Degrease the abraded are with acetone-soaked tissue. From the BID offcuts, find a couple of suitable pieces and cut one 150mm x 75mm and another 100mm x 50mm. Mix a peg-1 (30g) batch of standard epoxy and paint the abraded area with it. Carefully lay on the larger piece of BID, butting it up against the hinge. Wet it out and similarly apply the smaller piece of BID. Apply peel-ply and leave to cure.
Mix a couple of doses of flox with the remaining epoxy. Push it into all the holes in the aileron leading edges with a thin mixing stick, then work it in further with a piece of wire. Apply more until all the holes are well filled flush to the surface. Fit a 3/8" button-head screw fully home in each of 16 anchor nuts; the length of screw thread protruding looks about right for the final fixing screws. Grease well the ends of the screws, the anchor nuts and their rivets. Press each hinge firmly against the LE to create recesses in the flox. Was wondering about clamping them but they all stay in place nicely without help. Leave to cure; 22.1C, 28% RH now.
Clean up starboard flap without any further problems.
Leave fan heater on; 21.6C, 28% RH.
At bedtime, epoxy in sample cup firm to the touch; 20.7C, 28% RH.
|21||20.2C, 28% RH. Epoxy-flox sample in mixing cup well cured - cracks off cup. Turn off fan heater.|
|22||Check some small plastic tubs (in the form of the frustum of a cone) which once held Gu mini-puds to see if they would be suitable to act as moulds for flap cross-tube guides in flap roots - they look just about perfect! In fact, since the bottom (small-end) diameter is slightly larger than the cross-tube, rather than using them as moulds, they could actually form the guides themselves, with flox and fibreglass reinforcement all around.
In turn for each of 4 aileron hinges, remove screws, pop hinge open, smooth off excess flox on LE. Relieve screw holes with small Perma-Grit cylindrical bit in cordless drill to remove mouldings of screw threads and allow anchor nuts to swing in. Replace screws and fettle holes again to allow screw tips to enter.
Remove peel-ply from port flap patch and rub down epoxy whiskers.
Weigh port flap - 3415g. Weigh starboard flap - 3495g.
Cover the temporary table with polyethylene sheet to avoid epoxy sticking to it. Lay port flap upside down on table and clamp edge of inboard closeout flange lightly to table with plywood softening piece. Closeout flange at outboard end is too short to clamp, so clamp a couple of pieces of aluminium angle to the table at that end to keep it in place. Abrade all over undersurface with coarse Perma-Grit flexible sheet, going about half way around LE. Wipe down with a rag soaked in acetone to degrease and remove dust. 25.5C, 28% RH with no heating. Mix a peg-10 (160g) batch of slow epoxy. Paint the entire undersurface of the flap with it. To the remainder, add 12 doses of Expancel. Spread over the flap underside with a filling knife. That works quite well, so decide not to bother trying to flatten it with the heated plate that I used for the rudder. It covers less than the half the area. Mix another peg-10 (160g) batch of slow epoxy. Add about 22 doses of Expancel to it. Spread that over rest of flap. Unclamp, change angle of flap to keep working surface more horizontal & re-clamp. Re-distribute filler from thicker areas to thinner ones until it looks about the same coverage all over. Just about enough to fully cover this side of the flap. 25.3C, 30% RH. Switch on fan heater at full power, thermostat 3 and leave to cure.
23C, 31% RH at bedtime; epoxy firming up but not yet hard in mixing cups.
|23||In the morning, 22C, 32% RH. After lunch, 22.9C, 35% RH. Sample in mixing cup still somewhat leathery. Some pin-holes visible in the filler in a few places. Leave fan heater running.
Set port flap aside and put starboard flap upside-down on temporary work table. Scuff-sand with coarse Perma-Grit flexible sheet and wipe off with acetone-soaked rag. Clamp lightly at root end so undersurface is roughly horizontal. Mix peg-10 (160g) batch of slow epoxy and paint it all over the flap underside. Add 12 doses Expancel to the remainder of the epoxy and spread onto flap, starting with the TE rebate. It covers just a small portion of the surface. 27C, 33% RH. Mix another peg-10 batch and add 15 generous doses of Expancel, which makes it slightly drier (although not evenly so - at the bottom of the cup it is still a bit wetter). Spread onto flap, leaving it slightly thicker than on the port flap. Still nearly half left to cover. Mix another peg-10 batch and add 16 biggish doses of Expancel. Spread it over remaining area of flap and top up any thin-looking areas. 27.8C, 32% RH. Leave to cure.
|24||28.3C, 32% RH. Sample in mixing cup well cured and cracks off cleanly. Set starboard flap aside.
Start to abrade port aileron then decide might be better to work on the flap cross-tube guides first.
Cut the bottom off one of the small Gu tubs and clean up the inside edge with the bearing scraper thus yielding a tapered guide. Try to measure flap pin diameter - can't quite get vernier caliper in there but it looks like 0.475". Try drilling a test hole 15/32" (0.4688") in a small offcut of hardwood. That is too small, the pin will not enter it. Drill through again 31/64" (0.4844") and now it slips snugly onto the pin. The pin is about 28mm long on the full diameter. To make a locating jig for bonding in the guide, find a piece of round nylon rod 2" diameter and cut off about 80mm. Chuck it in the lathe (barely fits above the saddle) and and start to turn down the diameter. It is hard work - the nylon prefers to melt off in a collar rather than forming swarf.
|25||Decide to give up on using the round nylon bar, but before removing it from the chuck, centre drill the end to make life easier if I ever want to chuck it again.
Find an offcut of round aluminium bar 1.625" diameter by 77mm long. The full diameter enters the guide to 23mm short of of the small end. Chuck in lathe and start to turn down the outer 52mm (ie 2mm + 28mm +1mm). Some chatter so centre-drill end and fit live centre which immediately cures the chatter on the next pass. Turn down to about 34.5mm then withdraw tailstock centre and check fit of guide on it. Won't quite go on. Take a skim off, test again & repeat until the guide just pushes on. Drill the end 7/64", 35mm deep.
|26||Drill end of former again 9/64" and 11/64".||2858.3|
|27||Drill end of former 13/64" & 15/64".
20.9C, 41% RH. Turn on fan heater.
Drill bits now too long to fit between tailstock chuck and workpiece so remove chuck from lathe and fit it to chuck holder. Bench drill table won't go down far enough so set chuck holder on various temporary spacers to continue drilling out in small increments. Lathe chuck doesn't have enough grip as drill size increases so hold workpiece in drilling vise with softening on jaws. Continue opening up to 15/32"; check on port flap pin - won't go on. Drill 31/64" and now it fits on the pin.
Fit the plastic guide on the former and it can be forced onto the pin with that in place, but it would be better to trim the guide a bit. Check on starboard flap and that is a slightly easier fit.
Fit the former in the lathe chuck other way round. Centre drill then drill through #27, #17, #7 & #5 (0.2055", 5.22mm). Tap 1/4" x 20 BSW for screw-eye. Fit screw-eye with locking nut.
Trim top (parallel-sided) flange off guide. Now the former with the guide in place slides onto the pin more easily and there is only a slight deflection of the guide against the upper flange of the flap root. In a piece of plastic from the base of an ice-cream tub, cut a hole to fit the small end of the former and trim it to fit within the flanges to form a barrier around the former, to prevent flox spreading beyond the end of the guide. Degrease the guide, abrade it all over the outer surface with a very coarse file and degrease again. Lightly grease the former all over and the inner surface of the guide at its big end. Slide guide onto former, taking great care not to get grease on the outer surface of the guide.
Scuff-sand and degrease bonding area on inside of upper root flange of port flap for a length of about 150mm. Position barrier sheet over pin. Will need about 240mm x 35mm BID to cover guide and extend 50mm each side onto flange. Cut 4 off 240mm x 35mm BID and lay on separate pieces of polyethylene sheet.
Mix a peg-3 (60g) batch of standard epoxy and wet out BID pieces, then paint bonding area with it. Add a couple of doses of flox to remaining epoxy to make it pretty stiff. Spread a little heap of the flox mixture on the centre of the bonding area where the guide will be. Slide former with guide onto flap pin. Pull barrier sheet up against small end of guide. Spread the rest of the flox around the sides of the guide to form a good fillet and corner each side. In turn trim each piece of polyethylene sheet along the edge of the BID so that it can be butted up to the barrier. Lay each layer of BID over the guide with equal lengths each side and back edge gently against the barrier, remove the polyethylene carrier and stipple down. The barrier does not stay in place as well as I had hoped and has to be re-positioned after each placement of BID, but as far as I can see it seems to be reasonably successful in keeping the flox at bay. Apply peel-ply and leave to cure. 24.9C, 32% RH.
Scuff-sand upper surface of starboard flap and blow off dust with air line. 25.4C, 31% RH. Mix a peg-10 (160g) batch of slow epoxy and paint the flap with it. Mix in about 12 doses of Expancel and spread on, starting with the TE joggle. Mix a peg-10 (160g) batch of slow epoxy, add about 19 doses of Expancel, spread it on. Mix a peg-10 (160g) batch of slow epoxy, add about 15 big doses of Expancel, spread it on to finish covering the flap.
25.4C, 31% RH; leave to cure overnight.
|28||23.2C, 30% RH. Flox & Expancel samples in mixing cups both cured. Turn off fan heater.|
|29||20.5C, 44% RH. Start fan heater.
Trim up a Gu tub for the cross-tube guide in the starboard flap.
Remove peel-ply from port flap cross-tube guide layup. The aluminium former is reluctant to come out but eventually persuade it to move after a few sharp taps on the end and some energetic levering with an old screwdriver through the screw-eye against a block of wood. There are a few small areas beyond the barrier where epoxy has adhered to it - maybe sliding on the guide removed the grease from the former in places. Scrape the epoxy off with a scalpel and polish up the former again with 400 grit wet and dry paper. Coat it with wax. Abrade outside of guide with coarse file and degrease. Carefully wipe wax on inside of guide while keeping outside clean. Slide guide onto former and re-wax exposed end of former, without contaminating guide.
With the bearing scraper, remove small ridge of epoxy that has crept into small end of guide. Cut off protruding edge of layup with padsaw and file back flush to flap flange with Perma-Grit block. The layup and flox have gone a bit past the barrier and formed a short cylindrical section beyond the small end of the guide. Using a half-round TC file at an angle, file that all back so it will not constrain the flap cross-tube. Set the port flap aside.
Make a plastic barrier as before to go around the former in the starboard flap root. Abrade the inner surface of the starboard flap upper root flange, about 80mm each side of the pin and degrease it. Push the barrier into place. Cut 4 off 240mm x 35mm BID and lay on polyethylene sheets. Mix a peg-3 (60g) batch of standard epoxy and wet out BID pieces, then paint bonding area with epoxy. Add a couple of doses of flox to remaining epoxy to make it really stiff. Spread a small heap of the flox mixture on the centre of the bonding area where the guide will be. Slide former with guide onto flap pin. Pull barrier sheet up against small end of guide. Spread the rest of the flox around the sides of the guide to form a large-radius fillet each side. In turn trim each piece of polyethylene sheet along the edge of the BID so that it can be butted up to the barrier. Lay each layer of BID over the guide with equal lengths each side and back edge gently against the barrier, remove the polyethylene carrier and stipple down with a split mixing stick. The barrier stays in place better this time. Apply several layers of peel-ply and leave to cure.
Scuff-sand upper surface of port flap and blow off dust with air line. 24.4C, 41% RH. Mix a peg-10 (160g) batch of slow epoxy and paint the flap with it. Mix in about 12 doses of Expancel and spread on, starting with the TE joggle. Mix a peg-10 (160g) batch of slow epoxy, add about 19 doses of Expancel, spread it on. This covers a larger area than last time. Mix a peg-5 (90g) batch of slow epoxy, add about 9 doses of Expancel, spread it on to finish covering the flap.
26.1C, 38% RH; leave to cure overnight.
22.5C, 34% RH. Turn off fan heater. Remove peel-ply from guide layup on starboard flap. Pull out the former - quite easy this time! Cut and file back the layup, flox and guide to match the profile of the flap root,making it a bit concave to allow for curve of fuselage. Load flaps into car, stop clock.
Drive to Nympsfield and deliver flaps to Ryan for profiling. He shows me how he's getting on with the wings in the spray shop - they are matt but look lovely, with the root cuffs faired in beautifully to the wings, and the joint between the top skins now invisible. He plans to do a little bit more filling & profiling before starting on the primer and paint. He's also got other work to do so next week will be OK for the ailerons. Ask about the door handles - he would prefer them left off for painting which is what I suspected.
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