||Take BID tubes and samples down to Martin Carolan and he pronounces them sound. He suggests I might add a BID collar to the outboard end, extending further out on the tube, after laying up the outboard rib. Also says I should check alignment of tailplane halves when floxing in BID tubes. Send him a copy of the draft mod document by e-mail.
||Weather dry and bright so decide today's the day to re-park the trailer beside the house. Goes in OK with only minor corrections to first line-up. Lines made with angle-grinder on patio slabs are adequate, although can't be seen in wing mirrors. Reply received by e-mail from Martin Carolan on mod writeup; he is happy for it to go ahead as seen.
||Take peel-ply off BID tubes and measure diameter over bushes. It varies a bit, but max is about 43mm. Holes in TP2 cores are about 41mm (matching the original bush diameter). The part of the BID tubes extended beyond TP6 slides in nicely, but the rest won't go in without high risk of cracking open where the wire entry slot has been filled. Wrap one sheet of sandpaper around a foam rod from the torque tube hole and it just goes in. Add a second layer, and it cuts as it goes. After running it through from both ends, try BID tube and it's not quite ready to go through. Add a 3rd layer of sandpaper and run that through. BID tube now almost perfect fit in one core and slightly loose in the other. Set radial position of BID tube by getting TP5 flush with inboard face, then marking position of wire exit slot on BID. Extend that line back about 10mm. Get out the torque tube support jig again and set up torque tube in it after removing centre fittings. Attach BID tubes to TP4 with masking tape (a) to keep flox off TP4 and (b) to keep things in alignment. Check diagonally between LE and TE at inboard end. Difficult to measure but diagonals can be got almost equal. However, checking across the outboard rib faces gives an opposite error. Getting those surfaces parallel requires an adjustment full opposite of that required to get the inner diagonals equal. Check level of torque tube and core upper surfaces. TP4 is about -0.8 deg, surfaces are about -0.4 on the close-fitting one and -1.1 on the looser one. It can be adjusted to -1.2 degrees (or beyond) by moving the support blocks at the rear. Pause for thought, not sure what measurements to rely on for plan-view alignment.
||Take TP2s off torque tube again and lay them against each other; they are slightly different lengths on each corresponding face, which could explain why the diagonal measurements did not tally with those across the outer faces. Also, the joints between fore and aft halves of each core are different thicknesses and each have slight tapers in various directions. Most obvious is that top-to-bottom, which results in the airfoil surfaces not quite lining up when corresponding faces are offered up to each other. Do some more checks on rest of tailplane cores and conclude that probably keeping the outboard rib faces parallel is the best approach. Will have to ensure that when doing layups the cores are weighted down enough to solve the joint taper problem and make the airfoils symmetrical - don't feel like taking them apart and re-gluing at this stage! Mark BID tube with positions of outer faces. Remove TP2s and make trough between breathing holes in torque-tube hole, taking it around the towards the surface with the wire entry slot, which will be at the top during cure. Hot iron damages ends of torque-tube hole a bit, but not really beyond where the flox corner will go. Cut chamfer for flox corners at both ends now, as it's easy at this stage without bushes present. Rub down outsides of BID tubes with Perma-Grit sheet. Mix 3 strokes of epoxy with about 2 or 3 doses of flox, and paint it on to the bonding area of the BID tubes. Slide on TP2s and adjust to
previously determined alignment.
Weigh down, erect curing tent and leave it about 17:45. Switch off heat about 22:30
||Take down curing tent and put away torque tube jig. Make
supports for TP2
(during work on outboard rib), by boring hole in suitable sized block of mahogany & splitting to clamp tight on 32mm waste pipe (to match the one ready-made as a support for grinding insides of TP5/6) and mounting on a piece of ply. Mark out PLY0 for TP7 pieces and cut central hole with 45mm holesaw. Still not quite big enough to leave room for 2 layers of BID around TP6 and its enclosing BID tube, so enlarge with sandpaper wrapped around 40mm waste pipe. Quite hard work to being with, as it only just enters with 1 layer of sandpaper. Position on TP2 and mark edges for trimming. Cut to size with bandsaw. Round sides and start to chamfer ends. Decide to make a production line for chamfering all pieces at the same time, using power plane. Last one is disastrous as, on trying to run across again to correct minor misalignment of taper, plane digs in at inner end. Post request on Gloster Strut e-mail list for piece of suitable ply. Then thinking about it again, realize the chamfers I have made are too shallow anyway - they reach across to where the drive pins will be fitted on the inboard ribs, and it really should be full thickness of ply there. Check sketch in manual and it shows a 30 degree chamfer. Decide to order set of 4 replacement PLY0 from factory.
||Order set of replacement PLY0 and a couple of boxes of latex gloves from Europa factory. Phone around several places to see if I can find a 46mm Sandvik holesaw that will fit on my existing Sandvik arbour. Travis Perkins stock Sandvik, but not that particular size (would take a day or two to get). Buck & Hickman claim to have in stock a Roebuck one which might fit. Turns out to be Eclipse when seen, but it does fit the arbour, so take it. Check size on a ply offcut; seems about right and shouldn't need enlarging.
||PLY0 and gloves arrive from Europa factory.
||Find a couple of foam pieces to use as supports and set up both inboard tailplane cores TP2 to re-align joints between foam blocks and get sections more symmetrical. My set of cast lead weights is barely enough to load one sufficiently. Use water bottles for more weight. need to be careful that I don't burst open the hot-wire entry slots on one as they are in tension. Keep supports close together to minimise number of slots at risk. Mask off each side of slots and squeegee 5-min epoxy in. Lay polyethylene sheet over and weigh down. Mark up PLY0 for central hole and cut as a stack with 46mm holesaw. The recommended 2100 rpm for wood seems a bit fast as things get quite hot; possibly should be slower for ply. Maybe just needed to clear sawdust more frequently. Set up power plane inverted on bench stand. Check depth of cut at 30 degrees on waste pieces of ply, then chamfer ends of all new PLY0 pieces. Sand down on belt sander.
||Remove weights and peel masking tape off TP2 joint slots. Some epoxy still slightly proud, so run over it lightly with Dremel in router base. Set TP2s up on outboard rib layup stand and mark out edges of TP7 on PLY0 pieces. Trim to size on bandsaw. Ian McGugan arrives to have a look around. He seems eager to help; I suggest he could be most useful when large layups are being done. He says he will get a disposable boiler suit tomorrow! Round over edges of TP7s on belt sander. Mask off all TP2 surfaces except rib rebate with 50mm masking tape, old A4 paper ream wrappers, and 50mm parcel tape. Plug ends of BID tubes with foam and seal with parcel tape. Cut 8 pieces of polyethylene sheet for wetting and transporting BID (thinks: maybe I could have re-used one piece for all layups & saved some resin). Mark out 8 pieces of BID 700mm x 150mm at 45 degrees, and add marks with the weave for cross-cuts at TP6.
||The flox sample from securing the BID tubes is still in the mixing cup, so pop that out and leave for filing later. Notice slight tackiness at one point on bottom corner, but rest is beautifully hard. Cut out the BID pieces for the tailplane outboard ribs. Decide not to wet out on plastic sheet but to apply them dry so that it will be easier to get the cross-cut over the BID tube extending beyond TP6. Cut 2 pieces of peel-ply; full width will more than cover length of rib. About 15:10, mix 2 strokes epoxy with 10 doses of Q-cell for dry micro, which makes almost twice what was needed to fill all slots and dents on both TP2s. Mix 3 strokes epoxy with 3 doses of Q-cell for micro slurry - just about right quantity, with some to squeegee off. Mix 2 strokes epoxy with 3 doses of flox and one of cabosil for flox fillets around TP6. Mix 3 strokes epoxy and paint on. Lay on 1st layers of glass. Wet out with another 3 strokes. Adjust length and width to fit - only just wide enough in places. Scissor trimming quite difficult. Resting inner blade of scissors on rebate while cutting seems to be best way to get a straight line, but as I'm cutting right-handed that leaves length slightly short. Settle for that, as it's almost impossible to get it dead on. Waste needs to be lifted slightly ahead of scissors to avoid snagging, so whole process fairly tedious. Lay on second layer, wet out with another 2 strokes of epoxy and scissor trim. Mix 3 strokes epoxy with 2 doses of flox to coat ply pieces TP7. Needs fairly thick coat to prevent voids as ply is slightly curved along its length. Add small amount cabosil and small amount flox to thicken up remaining mix for edge fillets. Mix 5 strokes epoxy, add layer 3, wet out and scissor trim. Mix 6 strokes epoxy (to make sure there's enough for a sample), add layer 4, wet out & scissor trim. Cut peel-ply roughly to fit around BID tubes and apply in 2 pieces per rib, with slits at LE to conform. Wrap peel-ply offcuts around each BID tube. Erect curing tent, clean scissors & gloves, and leave garage about 20:45. When going to bed at around 23:30, top of layup is still slightly tacky, so leave heat on overnight.
||Take down curing tent. There are several bubbles in places where I'm sure there were none before.Take TP2s and epoxy samples to Martin Carolan, also chock. He says the bubbles could be injected with resin to fill them up, but it would be largely cosmetic as the surface inside the bubble would be glossy and the new resin would not adhere well to it. He signs off both the chock and the outboard rib. He can't do the rudder and other parts until they have the hardware attached. Send off inspection counterfoils for items 1, 2 & 4 to PFA*. After thinking more about bubbles, send e-mail to Martin asking for futher advice on several options for dealing with them.
* The Popular Flying Association (PFA) became the
Light Aircraft Association
(LAA) on 2008-01-01.
||Reply received from Martin Carolan. Seems there is no easy answer to bubbles.
||File samples from rib layups. Peel masking paper and tape off TP2s. Peel back peel-ply to allow room to work on rebate edges, which have a small ridge of resin and in places a few whiskers of glass extending over the masked-off foam. Grind ridges down with small Perma-Grit wheel in Dremel. Get out TP1s and try TP2s against them. Have to taper entry to torque tube hole slightly. File out housings for TP7s on faces of TP1s. Fit seems good and airfoil profiles appear to line up quite well, even though when the TP1s are placed root to root they exhibit the same asymmetry as the TP2s did before they were fixed. Looks like weighing them down in the jig blocks should get them all close enough at the outboard rib. Not quite enough room for both TP jigs under curing tent, so put starboard TP away again. Put masking tape on flange surface of rib. Attach a piece of polyethylene sheet to jig block at joint area. Mix 2 strokes of epoxy with 6 doses of Q-cell for non-slump micro. Paint on to face of port TP1 and join. Weigh down with usual lead weights, placed on plywood in case they get too locally hot for the foam. Add a couple of water containers to make sure LE area stays down. Erect curing tent and leave about 19:20. Leave on overnight as temperatures seem to be rather moderate - airflow must be quite different to previous setups.
||Power cut from 01:15 to about 04:00 so curing tent will have cooled down during that. Turn off heat about 09:30. Phone Ian McGugan to book him for 14:00 Thursday to help with layup. In afternoon take down curing tent. Everything looks fine. Remove masking tape from rib face and polyethylene from jig block. Put back inside casing. Bring out starboard tailplane and return port one to storage area. Photograph outboard rib face. Check alignment of starboard tailplanes parts; seems fine so mask off rib flange and tape some polyethylene sheet to joint area of jig block. Mix up 1 stroke of epoxy (as there was much too much yesterday with 2 stokes) with 2 doses of q-cell. Could almost have done with less q-cell than that as it finishes up quite stiff again, although usable. Just enough left for a sample this time. Join halves and weight down. Erect curing tent. Mark out 2 off 1500mm lengths of UNI and mark fibres 430mm in from each edge. File micro sample from yesterday.
||Take down curing tent. Remove masking tape. With file and Perma-Grit strip, clean up edge of joint where micro has gone beyond edge of foam. Stick root piece TP3 on with 5-minute epoxy. Mark out and cut off 50mm of LE edge of jig block (too tall for bandsaw so just use hacksaw blade which leaves a reasonably straight edge. Peel-ply TE, tab LE and root edge. Clear layup table and re-wax. Ian McGugan arrives as I am sticking the jig block and core down with 5-minute epoxy. Forgot to put masking tape patches on the core surface to avoid need for patching afterwards. Cut 2 pieces UNI to pre-marked length. Mix up 3 strokes epoxy with 7 doses Q-cell for dry micro and fill all dents, wire entry slots on surface and edges of lightening hole plugs at tip. When starting to fill the ragged edge of rib flange, realise I had forgotten to abrade rib flange for good adhesion, so do that while Ian carries on with applying dry micro to slots. Vacuum off dust and fill edge. Mix 2 strokes epoxy with 3 doses of flox and 1 of cabosil and lay flox fillet along face corner of rib. Mix 7 strokes resin and 5 doses Q-cell for micro slurry and spread on. Quantity about right after squeegeeing. Mix 8 strokes epoxy and brush on, in patches between the dry micro and flox areas. Drape 1st layer of UNI, and only need to reposition it once to get it covering all corners and leaving a triangle big enough to cut off and butt-up at the root corner. Mix 4 strokes epoxy and wet out. Mix 6 strokes epoxy and continue wetting out. Mix yet another 6 strokes epoxy and finaly get it all wetted out. LE corner is quite tricky to get smoothed down. Scissor trim. Drape 2nd layer without much trouble. Wet out with 8 strokes epoxy and and then another 4 strokes. Again LE corner tricky. Scissor trim. Cut off a length of peel-ply and get it on after several attempts. Trim it off and smooth down. Erect curing tent and leave about 18:55. Before going to bed around 23:30, some patches still slightly tacky.