Europa #435 G-RODO Build Journal - 2001 06

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1 Take off the lead weights and find the rudder is pleasingly straight on LE & TE. Put a small quantity of flox in a plastic box, like the q-cell, for easier dispensing. Mark out 2nd (port) side of rudder with lines at 30 degrees to LE. Cut 2 pieces of UNI and trim waste. Use finer pen for marking centre fibre which provides a line visually distinct from those on the foam. Start to mix resin for slurry, and the hardener valve is stuck again. Poke it with a clean stick and the next couple of pumps seem OK. Mix 8 strokes of resin with 4 doses of q-cell, which gives a fairly good consistency. Give it a good squeegee (think I was a bit light on that first time). There is enough spare to make some thicker (dry) micro for filling the dents and scratches etc. It seems to go in & fill quite well. Make flox mixture with 2 strokes; much more than needed. Make 8 strokes resin mix for first layup, which is just barely enough. Seems difficult to get the cloth straight both along and across, with many rumples; maybe it would be better to leave the waste triangles attached so it doesn't tend to go biassed. Some of the filled areas are showing bubbles; possibly the dry micro has been dragged out when painting on the neat resin. Mix 10 strokes resin to complete edges of first layer and do second. This was a bit hasty as I forgot I needed to scissor-trim before the 2nd layup. Paint most of resin on anyway to stop it going exothermic, then scissor-trim. Second layer quite hard work getting straight too. A larger radius roller would probably be helpful; time to dig out some of those tubes from the loft. Start to mix another 3 strokes to finish wetting out the edges, but the hardener pipe seems partly blocked as it's squirting sideways slightly. Poke it clear with a wire and it flows smoothly again. The pump is a great convenience when it is not being temperamental, but a mis-fire part-way through a layup is very irritating. This last mix is not all needed, but at least will provide a significant amount of sample for Martin. Squeegee, apply peel-ply and squeegee a bit more. Trim peel-ply, leaving enough to get hold of all round. Erect curing tent and quit for dinner about 20:00. 24.8
4 Lift the curing tent and have a quick look at the layup; seems to be a lot of bubbles in various places. The leftover resin has gone slightly into exotherm in places. Should have had a new float made for the hardener reservoir so I could paint it with spare resin.
5 With some effort, take rudder off jig block & scrape off the bits of foam where it was stuck. Must remember to use smaller blobs of epoxy next time. Peel back peel-ply in suspect areas. Seem to be bubbles along the TE and in some of the areas where I'd put dry micro. Worst is where the glass has lifted off the flox corner at the tip (seems hard to get things right there in the transition from wrap-around to flox corner). Take it to Martin Carolan and surprizingly he says the layup is generally good, and if all are to that standard, it will be fine! He suggests taking back the bad corner to the correct profile, and wrapping a couple of plies of cling-film-supported BID around it. He also reckons the flox mixture was not thick enough, and gives me a can of Cabosil to make it easier to work (later phones to say he'd taken it out of the wrong bag & it was actually micro-ballons he'd given me). He suggests I try T W Bayston on Tewkesbury Road in Cheltenham for anodizing the hinges, preferably in colour so any scratches can be seen. He thinks it is probably just as good to etch-prime as to anodise anyway. 25.2
9 Trim rudder trailing edge with small Perma-Grit wheel in Dremel. Sand back to straight edge. Start to cut out the recess in the leading edge, but when running the knife along the underside of the layup, it slices through it near the root end. It's in the area where the hinge reinforcement will be anyway so perhaps no extra plies will be needed to make good. Best to check with Martin, though. Peel the peel-ply off the back of the layup in the recess, with some difficulty as before in getting it started. Trying to sand the foam off the area beyond the peel-ply brings up sticky goo from the double-sided tape used to retain the peel-ply. Either the peel-ply didn't cover it completely in the first place, or else it got dragged off it during the straightening of the fibres. Quite difficult to get rid of the goo as there appears to be no solvent (including De-Solve-It) safe to use near the foam. A combination of scraping with a chisel, peeling off with sticky tape (clear cellulose seems to be better than duct tape), and sanding with rigid & flexible tools clears it fairly well (no tack to the touch) after much elbow-grease. Must find a better way to hold down peel-ply next time. Not quite sure how to treat root & tip ends of the recess; do they retain the radiused layup as a cantilever like the hinge edge, or does the recess go out to the end? Also, positioning of the hinge reinforcement plies is slightly problematic; as I've already rounded the LE root corner, hoping to get it about right for tailwheel rod clearance without additional rework, I don't have the original corner to measure from. I can project back to where it was along the existing edges, and measuring from that point in space seems to give a good appearance at the tip end, but I'd like to check it against someone else's rudder to be sure. Call Tim but just get answering machine. 28.9
10 Tim gets in touch and he will be at Kemble today, so take rudder over to compare hinge positions with some others. My inital marking-out from the point in space appears to be well aligned with all those in the Kemble hangar. Tim reminds me that the exact positioning is not that critical because the hinge positions on the fin are laid out from the rudder itself, and nothing else depends on the hinge positions.
11 Phone Martin Carolan about the cut in the LE flange & he says a scarf repair will be needed after the internal BID reinforcement has been done. I will need to mark the damaged area so it can be clearly identified. He is happy to do the grinding back for me, to let me see how it should be done.
15 Clean out the root & tip corners of rudder LE flange recess with small wire brushes on Dremel. Find they have left a few odd bristles behind, so check carefully and remove them all. Sand all exposed glass areas in the recess. Cut off a couple of chunks of foam and cut vees in them. Wedge the rudder TE into the vees and epoxy the blocks to the table. Cut layup pieces from BID; long ones with masking tape all around, but small hinge reinforcements without, as it seems quite hard to get the masking tape off the glass. Leaving it on would mean the pieces would need to be much larger to keep the masking tape clear of the working area. The small pieces are quite easy to handle with care. Put masking tape on both glass areas. The hardener valve on the pump needs unsticking again, and the outlet unclogging. Find that I get a good stiff dry micro mix with 4 strokes of the pump and 20 doses of micro, but this is more than twice what I need. Fill the dents in the foam and make a fillet at the bottom of the recess. The mixing stick seems about right to dress it when held at an angle. Make micro slurry with 4 strokes and 6 doses. Paint it on & remove both sets of masking tape. Make 6 strokes of resin and brush some on. Still quite easy to drag the micro fillet out of place, so apply resin mainly to glass areas and let it drip down into the corner. First main piece goes on fairly well, but care needed to ensure masking tape is kept clear of working areas. It goes into the root & tip corners better than I had expected. Only just enough width at root end. Scissor trim and try applying resin to first hinge reinforcement piece on polyethylene sheet before laying it up. That seems to work OK, but peeling the plastic sheet off tends to undo some of the neatness. Try next one just dry in the hand, and if anything, it goes even easier. Do the rest the same way. Lay on top full-length layer & trim. Peel-ply offcut I chose is just about the right width, but refold port peel-ply back over it to help hold down a few longish strands curling round the LE. Too tall for curing tent, so remove from support blocks and lay flat. Erect curing tent & turn on heat about 17:00. 34.1
18 Take rudder to Martin Carolan for him to grind back the damaged area of UNI on the hinge flange ready for me to repair. He says I should put in 1 layer of BID first, then 2 layers of UNI out to 30mm beyond the area he's taken down to the BID. He takes back the micro supplied in error & gives me a tin of Cabosil.
19 Trim the rudder hinge flange with Perma-Grit wheel on Dremel. Start to clean up some of the other excess resin areas. 34.9
21 File rudder hinge flange down to original edge. Still looks pretty straight, which is pleasing. Clean up most of the resin runs and drips around the root & tip ends. Reprofile the root & tip towards the TE, where the flox corner failed to be successful. Abrade surrounding area, and around hinge flange repair area. Cut BID, UNI & peel-ply for repairs. Unstick hardener valve. Get some bubbles in resin line on last stroke of 6, as resin level is going low, so discard that mix. Fill both hardener & resin reservoirs, purge lines and start again. Decant off some mix for dry micro to fill the small holes in one flox corner. Wet out both the root & tip repair patches on polyethylene sheet & find that works OK, although glass reluctant in places to stick to workpiece when trying to peel off polyethylene sheet. Second time re-use 1st sheet, and lay another on top for squeegeeing before applying it to workpiece, which gives more even coverage as excess resin forced out to edges already. Secure peel-ply with tape to hold curvature neatly. For flange repair, lay glass on dry & wet through with brush. Set on foam blocks & erect curing tent around 15:30. Switch off heat around 20:30; it has gone up to 35C, so back off the fan-heater thermostat from 4.5 to 4 for next time. 38.2
22 tick Dismantle curing tent. Check rudder repairs, seem OK. Check epoxy remains in mixing cups & all is well-cured with no tackiness anywhere. This is the first time I've used one of the Europa-supplied cups on a real layup, and can't get the resin sample out without destroying the cup. Tape up peel-ply ends to keep things clean & store rudder on top of not-yet-used foam parts.

Extract port tailplane foam block from storage & unpack. Find that the adhesive between the fore & aft sections of block has failed to take in several places, so will have to remake that joint when filling the hot-wire slots for the lightening holes. Put masking tape along all of the slots to be filled & mark out positions of epoxy dabs. Mix about 50mm of rapid epoxy & start to apply, but before I have done about 6 dabs, it starts to gel and exotherm. Quit & decide to use dry micro for the rest.

Plot tailplane tip shape in CADintosh & print out full size.
25 Prepare to use dry micro for securing tailplane lightening hole slots, but find that the resin pump is leaking slightly. The brass fitting securing the hardener swan-neck to the pump block is weeping slightly, with drips onto the baseplate, and obvious dried-up hardener around the outlet where it has retreated from the end. Dismantle & clean out, then re-assemble with Fernox joint sealer as originally used (don't know why I didn't use it again when re-assembling after the earlier problem). While that is curing, get out the other (starboard) tailplane half and mask off the slots on it, and mark the positions of the adhesive dabs. The fore and aft parts of this surface seem well attached. Although I'd started to take them out (well marked up to avoid confusion), decide to leave the waste pieces from the lightening holes in situ for this operation, as they will help to weigh things down onto the jig blocks. After purging the resin pump pipes, mix up 3 strokes of resin and add 15 measures of q-cell. Get about three-quarters way through the port surface (including re-sticking the inboard fore & aft halves together) when the pot goes off and gets warm. Notice that the ambient temp is now 31C, so no wonder it is going off smartly! Mix 2 strokes resin with 8 measures q-cell (slightly easier to squeegee into the cracks), and decant it into a tray-style container to reduce exotherm tendency. Just about manage to complete the job before it starts to stiffen up. Leave to cure without the tent. Send e-mail to Nigel Graham asking for the PFA* mod number of his TP5/TP6 mod.

* The Popular Flying Association (PFA) became the Light Aircraft Association (LAA) on 2008-01-01.
26 Peel masking tape off filled slots in tailplane surfaces. To make "breathing" holes between lightening holes, decide to use soldering iron with home-made extended bit instead of heating a rod with a gas torch. First attempt is with a piece of steel, turned down to fit in place of regular copper bit in Camping Gaz (electric) iron, and bent at end. Business end does not get very hot, and then start thinking about thermal conductivity of steel , which is pretty low. Don't have any copper, so first think about brass (twice as good as iron) and then remember a piece of 0.25" aluminium rod (only half as good as copper, but twice as good as brass) left over from making the log-periodic TV aerial. Turn that down to fit soldering iron & bend end. Works fine, and does not get so hot that many fumes are generated. Length of soldering iron plus aluminium bit gives enough reach to keep the breathing holes clear of all obstructions at the ends of the lightening holes. Move the bandsaw into the working area for foam cutting. Shorten all 4 jig blocks by 100mm which is quick & easy with bandsaw, although I have to take out part of the tall edge of the bottom jigs by hand. (Later find I seem to have shortened the starboard lower one twice!) Mark out the first tip for shaping using the template I printed out earlier. It butts up nicely against the masking tape, and marking is not too difficult using a fine felt-tip. It's a bit tricky to hold it flat on the bandsaw table while cutting. After first cut, a little outside the line to be on the safe side, find that the slight taper of the top & bottom surfaces means that if I hold it flat on the saw-table I can safely cut to the line, and if I do that for each surface, will get a truer & better finish than trying to sand down to the line. Push lightening hole cores in turn through from root end till they just fit, then mark flush with tip for cutting. Most go in again from tip end OK, some need a chamfer to encourage them. The chamfer is a good idea anyway as it will help to keep epoxy between the plug and the hole wall, rather than pushing it ahead of the plug. Mix up ordinary 5-minute clear epoxy to see if it will go off any more slowly than the Araldite 2012 (It's over 32C in the garage today). It goes off about as fast, but is also more runny, which is not helpful in this application. Mix small batches, about enough for 2 or 3 plugs at a time, and butter it on inside the mouth of the hole. Difficult to avoid drips, which I'm sure I will find hard to remove later. Do the same procedure on the port tailplane. Find I can use a broad felt-tip to mark the tip shape, using the paper template as a half-stencil. When cutting it seems harder to keep everything aligned, and a couple of wobbles leave notches that will likely need filling. Can't seem to do any better about keeping epoxy off the ends when fitting the tip plugs this time either, so not much learning happening today! Still 32C when I quit, after 22:00, but the dehumidifier seems to be keeping the RH down - worst was about 45% during the day. 53.3
28 Nigel Graham replied to say he hasn't got PFA* Engineering approval yet for his TP5/TP6 mod, and that he also has another mod in the pipeline for TP9/TP10 retention. Buy Dremel router adaptor & make rebates on outboard ends of inner tailplane sections with it. I forgot, for some unknown reason, to do the torque tube holes at the tips, so do that now. Mark up and bandsaw sections of lightening-hole plugs to fill the ends of the holes in the inboard section. Use cores from the root-end offcut at the root end, and the ones from TP2 at the outboard end. Seems no reason to make them as thick as for the tips, as there will be no shaping on these faces, so make them 25mm thick. Also as the faces are flat, I should be able to place them so that minimal sanding-down is required. Find I can just about get all the plugs on one face in with a single mix of 5-minute epoxy before it goes off. Use a piece of broken hacksaw blade in the slots to push out any plugs that go in too far.

* The Popular Flying Association (PFA) became the Light Aircraft Association (LAA) on 2008-01-01.
29 File and sand down tailplane tips. Slight problems with tears in foam around epoxy runs but there will be other areas that need filling with dry micro anyway. Accidentally crack open one of the slots, so mask up & add some epoxy to that again. 59.6
30 Send e-mail to Nigel Graham asking if he minds if I apply for PFA* approval of the TP5/TP6 mod, and to Martin Carolan asking for his opinion of the mod. Draft letter to PFA* Engineering about the mod.

* The Popular Flying Association (PFA) became the Light Aircraft Association (LAA) on 2008-01-01.

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