Europa #435 G-RODO Build Journal - 2018 10

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2 Get some more 150mm DA sander discs from Screwfix and Toolstation.
4 Discard the couple of 120 grit discs that have picked up so much and fit a fresh 120 grit disc on the DA sander. Work on the starboard tailplane underside with better success than last time; there is still a tiny amount of pickup but not enough to cause trouble and progress is good. Tidy up the tip and LE freehand with fine side of Perma-Grit short block and 120 grit disc on the hand pad. Clean up remaining blobs of filler from edges.

Set aside starboard tailplane and work on underside of port tailplane with DA sander. Tidy up tip, LE and edges.

Set aside tailplanes and start on starboard aileron TE underside with DA sander but soon switch to hand pad which is more controllable because so little needs to be removed. TE getting razor-sharp in places, so after doing upper side of TE rub it with the long Perma-Grit block to blunt and straighten it. Run folded 320 grit wet-and-dry sheet along the TE to further round it off a bit.

Repeat all above (but not using DA sander) on port aileron.

There are still some pinholes on the tailplanes but I think I will leave those to the painter to deal with. I think the tailplanes, tabs and ailerons are now ready to go for painting.
8 Start to weigh the parts in preparation to taking them for painting but realise that they're not ready yet as I haven't replaced the Flettner strips on the trim tabs after sanding them off.

Port tailplane: 4360g
Starboard tailplane: 4365g

Port aileron: 2670g
Starboard aileron: 2660g

Buy balsa TE sections at Cheltenham Model Centre. The preferred 1/2" x 3/16" is quite thick at the thin edge so it will need thinning down somehow. The 1" x 1/4" has a much sharper edge so buy some of that too; it might be easier to take off the thick edge of that than to plane down the smaller section.

9 Realise that the trim tabs are longer (26" / 660mm) than I remember, so I will need twice the amount of balsa TE section I bought since I can't get two Flettner strips out of each 36" length.
10 Buy more balsa TE sections at Cheltenham Model Centre. Get both 1/2" x 3/16" and 1" x 1/4" since I still haven't decided how best to get the final shape needed.
13 Set up bandsaw to trim the 1/4" x 1" balsa TE section down to 12mm. The thick edge runs against the fence, so a few trials are needed to get the required 12mm on the outside of the cut. Once set, trim all 4 36" lengths then remove hairy edges with a light rub against the fine Perma-Grit block. 2972.2
20 Cut the 4 pieces of the trimmed balsa TE stock to just over the length of the trim tabs.

Prepare 4 strips of polyethylene sheet about 100mm wide and a bit longer than the trim tabs, each with one good straight edge.

16.5C, 42% RH. Turn on fan heater at full power, thermostat 3.

Prepare 4 strips of peel-ply.

18.5C, 39% RH. Mix a peg-1 (30g) batch of Ampreg 21 and brush it in turn onto each side of starboard tab TE and a corresponding balsa strip. Press each strip into position and add peel-ply, with the straightest edge along the trailing edge of the balsa strip. When both strips positioned, place a polyethylene strip over the peel-ply each side and fit wooden clothes pegs to clamp balsa strips in place. Care needed to avoid balsa sliding off the tab TE under the clamping pressure, and also to ensure that the aft edges of the balsa strips are aligned well with the tab TE, or just very slightly proud of it.

Repeat the process for the port tab and balsa strips.

19.5C, 37% RH. Turn off the fan heater. Take the tabs and the sample cup in to the boiler cupboard where it is 28.5C, 25% RH, and leave them there to cure overnight.
22 28.2C, 20% RH in boiler cupboard. Sample cup well cured. Take the tabs out to the garage.

Remove the clothes pegs, polyethylene sheet and peel-ply. There are some patches where the epoxy has run onto the surface beyond the balsa strips and obviously the peel-ply has soaked up most of that. Rub off a few shiny areas (where epoxy fingerprints were not fully wiped off) with 400 grit disc on hand pad.
23 14.6C, 36% RH; turn on fan heater.

Trim off protruding ends of balsa strips with junior hacksaw and sand down flush to ends of tabs with short Perma-Grit block.

Taper the ends of all the balsa strips, again using the short Perma-Grit block.

In several places at the forward edge of the balsa strips there is a slight ridge where the balsa does not come down flush to the glass surface. Work on those for quite some time with the edge of the soft pad and a 120 grit disc, tilted up so as not to touch the trailing edge at all.

To prevent runs onto the glass surface after painting the balsa with epoxy (thickened slightly with Expancel), I'd like to hang the tabs by their leading edges while curing. Spend some time thinking about how to design and construct a suitable support (that will also be easy to move to the boiler cupboard). Eventually settle on a piece of chipboard on a central supporting block, with machine screws near the corners onto which the hinges can be hooked. Mark out the pieces, drill and assemble them. Seems to do the job.
25 Mix a peg-1 (30g) batch of Ampreg 21 and brush it onto all the bare balsa areas of both tabs, hanging each tab on the stand when done. To the remainder of the epoxy add a dose of Expancel and a small amount of Cabosil. Brush this filler thinly onto the wetted balsa on each tab and wipe off some excess, hanging each one up again when done. When all the balsa is covered with filler, take the stand and tabs in to the boiler cupboard. It won't fit on the shelf because of lack of headroom, so put it on the floor where there is just enough room. Soon 26.5C, 25% RH. 2977.3
26 First thing in the morning the bulk of the sample is well cured but the fingers up the sides of the cup are still quite flexible rather than "glass-hard". The filler on the Flettner strips feels a bit leathery too, so no point in trying to sand it smooth just yet. Rather a lot of bubbles have appeared which is a bit disappointing.

By the evening the filler seems significantly harder, and the tops of the bubbles can be cracked off with a fingernail, rather than flexing.

27 26.9C, 20% RH in boiler cupboard. Take tabs out to garage.

Try sanding down filling on Flettner strips with fine side of small Perma-Grit block, but it's not very effective. Change to coarse side and that works better - the rather epoxy-rich filler was made up slightly runny so it could be brushed on, but that means it is harder to sand. Work first on the small craters left where bubbles have burst, then go over the whole of each Flettner strip surface with the coarse Perma-Grit. Smooth with 120 grit disc on hand pad then finish with 400 grit disc.

Weigh tabs.

Starboard: 635g

Port: 660g
29 tick Attach labels to ailerons pointing out the need for lightness. Load tailplanes, ailerons & trim tabs into car and take them to Targett Aviation. Toby says it will be a few weeks before he can fit them in to the spray shop but he will let me know when there is news. He asks if I had a paint code for the earlier work and as the only thing I know is automotive 2-pack he will check the previous dockets for info.

Start to work on moving the fuselage into the garage, but forget to start the clock until I've done about an hour.

Hitch trailer to car and pull it straight out onto the drive as far as possible. Open ramp and take out engine box full of blue foam and other impedimenta. Start to take the flaps out of the cockpit area, but not enough headroom to do that. Remove upper cowl to get at the socket for the safety bolt. Lower the dolly about as far as it will safely go and it's now much easier to get the flaps out. However, there are some scuff marks on the upper surfaces which will need to be polished out.

Start to winch out fuselage but find that the tailwheel keeps popping out of its track. Eventually realise it's because the dolly is so low. Pump it up a good bit higher and things go much more smoothly. Leave fuselage parked in carport and close ramp to allow room for getting fuselage past trailer.

Move a lot of stuff out of garage including trolley with door used as temporary work-table and the propeller on its stand. Vacuum up the now-clear space on the floor.

With some effort, haul the fuselage up the sloping drive from the carport and past the end of the trailer. Turn it around and roll it into the garage.

Open the trailer again and put down a large carpet offcut on the floor. Lay the flaps on it. Put the blue foam tailplane supports, the generator, trolley, door used as tabletop, propeller, engine dolly and engine box full of blue foam into the trailer. Close ramp and reverse trailer back into its parking spot.

Put all the miscellaneous stuff back into the garage, much of it in the space vacated by the propeller stand.

Bring a few spare Really Useful Boxes down from the loft to the garage, so they can be used to replace several cardboard storage boxes that are getting rather tired and emotional.

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