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Free-flight 1935 Udet Flamingo, electrified for RC, built 200%...

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    #61
    The Deed is done ...



    A couple more cross-pieces this morning, a few delicate minutes with my X-Acto and the centre section becomes separate and autonomous..! A touch of sandpaper for tidying-up, this afternoon or evening, before getting the lower wings ready for attaching. Whatever I was thinking of doing had better work now..!

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      #62
      Here's the front locating peg on what I like to call the 'sled'...



      ... and the assembly being checked for alignment ...



      ... before installing a pair of rear locating pegs ...



      The rear pegs are only there to guide the wing to the right spot every time; in the event of a major mishap they'd probably snap off. I'd rather that than have the structure bust; they could be considered as having a sort of sacrificial 'fuse' role.
      I think I've got everything ready now for assembly of the lower wing elements. Probably this evening. Tomorrow I drive our daughter and the Littl'un to the station for their train back to Paris, and have a few things to pick up whilst I'm 'out', so won't have time for much. More Saturday then, I expect...

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        #63
        Now that the centre section has been freed, it's time to join the lower wings. No matter how many clamps one has, there's always a use for a medium-weight lump hammer...



        The clamps are still on, but the glue has set now ...



        ... and Bingo..! the lower wing is now whole..!...



        Will it now still fit snugly into the fuselage..? It would appear so ...





        There is still the fuselage to film; here the second flank is being fitted for a new costume ...



        Mustn't forget to glue in place the elevator servo before closing up the fuselage rear ...



        The glue has to set, so I'll start to prepare my pilot and copilot with an undercoat. I've an errand to run whilst all that is drying...



        Back in the workshop, the servo is now firmly glued in. I can continue and finish off the filming of the fuselage ...



        Meanwhile, the post has brought the Esaki paper ordered from Dave at Free Flight, stoutly rolled up in several thicknesses of newspaper. The weather is set for 'Fine' for the next few days; I should be able to profit from that and see how this new tissue fares when nitro-doped onto the film. If it's as successful as I hope, that'll be a serious step forward. First results tomorrow, probably, on the empennage, then the fun starts in earnest once I attack the wings and fuselage.
        To be continued...

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          #64
          No doping, today, and just as well, really, as the heat-gun arrived. I had stuff to do in the garden (repairing a chassis for the courgettes, and shifting the compost heap...), but after dinner climbed up to the lair and made a small test piece, loosely filmed. The gun tightened it up in no time flat, so I dared to have a go, 'live', on the wings. What a difference..! My Turnigy sealing iron dials up to 220°, and that's what I've been using to tension the film so far. I had been pleased with the result, but the gun really went to town on it all and showed what a difference another 50° or so can make. The air blows onto the film panels, creating shallow waves until the shrinkage kicks in, the panel tightens up and there are no more waves. By going gently from panel to panel, all around, everywhere was greatly improved on what looked, to me, to be already satisfactory. There were, it has to be said, a few spots where, by clumsy fitting or bad cutting, places where no amount of tightening was going to correct the flaws, but even those patches were better after passage of the heatwave. I applied the gun to both wings, the empennage and the fuselage; all are now tight as a drum (and I know about drums; I'm a drummer..! ). No photos, as the difference doesn't show up at all, but to the naked eye, whilst the magic is operating, it's grand..!
          One slight downside: I now have sore arms from holding the parts in the air whilst waving hot air at them for so long..! Well worth it, though, and a good omen for the application of the tissue. I'm glad I did this before doping. Tired now, then, but well pleased with what little has been achieved today. (I say 'little', the courgette cold frame was no mean feat, all thanks for the assistance of our two lads...).

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            #65
            A beautiful sunny day, very light breeze; great flying weather for learners such as I. I won't be taking advantage of it, though; not really well enough for such an outing, despite the ideal conditions. Never mind, it's also great doping weather, too, so I turn to that. All the Doculam covering is done (excepting one side of the tailfin, which will be finished when the rudder servo is installed there...). I've managed to overcome the stifling vapours, and, if I do short sessions at a time, can do it in some relative comfort in my 'den'. Here's a shot of the set-up...



            Bang centre there are a few pieces drying (the nose cone, tailplane, rudder...), to the right of that on the wider table is the cutting area, with the fuselage being measured up on a new sheet of tissue. The smaller table to the left has the doping tray, which centralises the jars, brushes, paper hankies etc used during the process. One may note the wide-open window at the rear of the picture..!
            Which brings me to an observation: it has been stressed often enough that it is important to have adequate ventilation when doping with nitro. It has not, in my view, been stressed enough that this is anathema to light-weight tissue being delicately handled in a fragile state onto balsa models with any degree of precision. The slightest hint of a breeze and the tissue folds onto itself much more readily than onto the model..! I have tried the wetting process of dragging the tissue across a shallow dish of water, and even got it to work (well...) for quite small pieces, but was very lucky to avoid complete catastrophe when using the same technique for pieces as large as the tailplane. My first resolution, then, was to not even attempt covering wide areas in a single piece. I finished the tailplane by laying the tissue on dry, then very gently 'painting' it down with water, using a very soft camel-hair artist's brush. The following pieces were wetted with a fine garden mist spray bottle; I think that's what I'll adopt, as it seems to work best for me. Whatever method used, I still get tiny wrinkles after shrinkage, but the end result is satisfactory just the same. It'll improve, I hope, as I do more. Once very lightly wetted, I apply my '50/50' dope-thinners mixture with another, slightly stiffer, brush, quite rapidly, with broad strokes. I dope up to the edges, but no further; these will be doped down after trimming when this first coat has dried, along with the second coat which removes the 'blushing' milkiness of the first application. I trim using a stout pair of dress-maker's scissors, as I don't trust myself to be precise enough with the modelling knife when trying to hold things in the air at arm's length. Our Eldest is champion at trimming with a blade (he spent several years with a sign-writing company...), but is not always to hand. Here's the fuselage with its first application of tissue to the underside, doped, but not yet trimmed...



            I find that, for the moment, I can cut and dope one piece, trim and stick down a previous piece, then apply a second coat to a previously trimmed piece, in one session, then leave it all for a while, rinse and repeat. A couple of smaller pieces to be done (elevator, hatch...), the fuselage to complete, then I'll get stuck into the wings. I'm hoping that the experience gained with these 'easier' pieces will help me get a decent enough result on the wings, which have their own tricks and traps for me. Advancing, then, but slowly...

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              #66
              Things seem to be going along quite swimmingly (will it last ..? ). This is the last piece for the fuselage flank awaiting trim and a second coat. Just the top surfaces after that, then on to the wings...



              Meanwhile, indecision has crept in yet again. Despite the less-than-perfect finish, with numerous slight wrinkles and blemishes, I'm very pleased so far with the resulting aspect. It's certainly starting to take on the appearance of a vintage 'plane with somewhat traditional tissue covering. I'd envisaged, originally, a colour scheme, which would have been executed with the choice of tissue if the said tissue had come up to the mark, but I have no regrets in having finally used this Esaki stuff, except for the choice of (or lack of...) colour. The solution, I had thought, would be to paint the tissue, and, to this end, I've acquired a modest airbrush and the acrylic paints in the desired tints. "Ah, but are you then likely to ruin all this fine work with a lousy paint job..?" A good question; I'm glad you asked, and that is, indeed, my doubt. I tested the airbrush with a dummy run, spraying a trial quantity onto a sheet of paper pinned to the wall. Just to highlight my ineptitude, I chose to spray white onto an already white surface..! D'oh..!

              [

              Seeing (or rather, not seeing...) the result, I turned my attention to my ex-military-issue ammunition locker, where my Lipos are stored, and turned it from olive green to white...



              A few 'spatters', but not too bad for a first attempt, using a primitive mix of household paint to boot (I'd not yet got hold of the 'real deal' at that time...). So far so good, then, but applying the technique to tissue, using the correct tones..? One way to find out is more trials, of course. Here's a 'quick'n'dirty' frame I've filmed...



              The doped tissue is drying as I type this, so it won't be long before I get to see if there's hope, or that 'nature' is maybe the best tint to go for.
              Meanwhile, and just to press home the proof of my capacity for messing things up, I had prepared four pieces of tissue for the elevator. The under surfaces went well enough, and were trimmed and given their second coat. Come the first of the upper surfaces; I'm content with the result, and look forward to finishing the job with the last piece. Oh dear..! I take the now-dried elevator, and find, to my great surprise, that there remain two surfaces to cover, not one..! What..? Closer inspection reveals the explanation. Some idiot (I wonder who..?) has doped the third piece over the already covered second part..! Two layers..! How dumb can one get without risking cutting one's fingers off with a blunt ruler..? Oh well, at least that part of the elevator will resist better than the rest..!
              One final note, concerning brushes. I've been rinsing the doping brush in a small quantity of acetone (which gets thrown away...), then rubbing a drop or two of washing-up liquid through the bristles before rinsing under the cold tap, then drying with kitchen roll. Is this a suitable method, or is there some way of avoiding the acetone stage..? It seems to be working so far, as I'm re-using the same brush each time; is there anything better..?
              Last edited by Dad3353; 05-21-2018, 05:39 PM.

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                #67
                Tissue done for all the pieces but the tailfin and wings; here's the first piece on the centre underside of the upper wing...



                Slightly more confident in the doping process, and using just the barest of sprays to simply give a hint of damp to the tissue. As soon as one thinks it's enough, it's already too much, I find. A rather delicate balance to be found each time, but it's beginning to work out reasonably well, if one accepts the wrinkles. I'll do the wings slowly, one piece at a time, and not be tempted to try to use large expanses of tissue.
                While that's happening, I've set up a spray department, for applying the acrylic paint. Here's my painting table...



                ... with the airbrush and its mini-compressor on the right, my test piece in the centre. To the left of that is one plastic bottle with the paint diluted from the tube (roughly one part paint, three parts water...), and another bottle with plain water, for cleaning. In the background is the poor fuselage, ignominiously hung out to dry after receiving a first mist of paint. It's still translucent, the colour is light Naples yellow (a light cream, really...); here's a closer view ...



                I've no real idea of what I'm doing, or whether it needs one, two or a dozen more coats; I'll find out now as I go along. There's no turning back, so I'd better get good at this new technique rather quickly..! It looks good for now, with no disgracious 'runs'. All the stuff I've seen on t'web and read up on insist that a few light dustings are better than one thick coat, so that's what I'm aiming for. The real test will come when I need to mask things off for applying another colour. Fun times, eh..?

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                  #68
                  Still benefiting from the great weather we're currently enjoying, I've finished all the tissue covering, and all the doping (except one last small piece for the tailfin, once I've fitted the servo inside...). I was able to squat down by the front step and do the second coats outside. This is the upper wing, after it's second coat...



                  I'll get no prizes for my brushwork, which is closer to Rolf Harris's 'Can you see what it is yet..?' than to Rembrandt's 'De Nachtwacht', but one has to work fast in this sun; it almost dries on the brush.
                  As an exercise, I thought I'd weigh the 'plane, now that all is ready bar a couple of licks of paint. Weighed in separate lots, the final total is close to 720 gr, more than double my original estimate..! There are reasons, of course, such as the wheels alone weighing 95 gr, and the pilots another 65. That's about 1 1/2 lbs in old money; we'll see if the 60 watt motor is up to the task, or if I have to think of slimming down somewhere, or boosting the power. Too early as yet, but I may need some margin for manoeuvre before she lifts off.
                  Airbrushing next, then, with a complete coat all over everything of the base colour, then, after letting it 'go off', the trim colour. Exciting..!

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                    #69
                    S'all very well having wheels, but they're of no use without an undercarriage, so I turn my attention to that. I'd already prepared the struts and spreader bar from the plan, and made a rudimentary mock-up. Time, now, to get serious...
                    I've doubled the spreader bar and cut a shallow groove down the length, into which the axle nestles. Once the 'sandwich' glue has set, that won't budge. I've then prepared a sheet, made from two butted cross-grained sheets, as there's a curve to the underbelly of the 'plane. A block is glued to the fore and aft fixation points for the struts, and, after having checked for alignment and fit of all the angles (I hope..!), the whole assembly is glued up and clamped...



                    It's on its back for drying, of course; the fore is in the foreground. Tomorrow, when it's set, I'll peg each strut to its block by drilling and inserting a 3mm dowel, parallel to the axle. My cunning plan for fitting this to the 'plane is to insert a 5mm dowel fore and aft of the lower wing. Once the lower wing has been located into the fuselage, the undercarriage will be slung beneath, and rubber bands hooked over the dowels will hold it tight to the underbelly, in similar fashion to standard 'old-timer' wing mounting. It should be a positive enough hold, unless something really rough occurs on landing (or take-off..?), when the elastic will 'give' before the structure gets too stressed. This is subject to evolution if tests prove it not to be as effective as I think, of course.
                    That's all for now; the finishing and decor are in full swing, and it won't be long now before the various elements are fitted together and rendered functional. Nearly there..!

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                      #70
                      Here's the fuselage receiving the airbrushed acrylic paint. Here's the poor thing, fully masked, waiting for the suffering to be over ...



                      A first light coat ...



                      ... then another ...



                      This is the result...



                      ... and with a bit more light ...



                      Very pleased; there's not a scrap of bleed. My original pencil line is still just about visible, but a brushed pin-stripe should do the job. I'll leave the fuselage to 'go off' whilst we try to get a similar result on the wings.
                      To be continued...

                      Comment


                        #71
                        For now, it's the turn of the wings to be 'strung up'. Fully masked, they're hung from my mic stand and sprayed with the Light Naples Yellow (the light cream, base coat colour...)...



                        This should ensure that, if there's to be any bleed, it'll be in the same colour as below, and will block the bleed passage for the next colour (Naples Yellow...). I'll let this dusting dry (about an hour or so...), then give a light coat of the final colour, maybe another coat before bedtime; if not, tomorrow. I'd like to get the final coat on before any of the masking has a chance to lift, though. It's been burnished down along the edges, but a lot can happen overnight. Firstly dinner, nevertheless, then we'll see...

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                          #72
                          OK, the Good News first it is, then. I applied the heat-gun for a couple of minutes to the tailplane, as suggested, then weighted it down with a metal tray and the usual lump hammer...



                          Yes, it's under there, somewhere..! It took a few goes, heating first the upper, then the lower, and the result is pretty convincing. There was a definite twist; now, while not absolutely perfect, it's as flat as it's going to get, I think...



                          Success, then, so thanks for the tip. The big advantage was in not damaging neither the skin, nor the finish, so doubly pleased. If it had not worked, the steaming was the next step, but I think we've dodged that one, this time...
                          Bad News..? Oh yes; I'd almost forgotten... Here's the second coat on the wings...



                          ... which has been left to go off before unveiling the result, seen here ...



                          My main worry was spray creeping under the masking, but I needn't have worried; there's none. Bad News..? Yes indeed. Three different types of masking tape were used, including special painter's film (clear sheet with one border pre-taped...), ornery buff-coloured tape and special, low-tack, sensitive surface yellow Frog tape. Each of these tapes, to a greater or lesser degree, managed to tear up bits of the underlying painted, doped tissue from the Doculam. Am I annoyed..? That would be an understatement, I fear. I'd read up about masking, with the risk of leaving the tape on for too long, making it impossible to remove. The Frog tape, especially, I'm disappointed with, as it's supposed to perform well in exactly these conditions. Before even taking off, then, there'll be some patching to do, both of the tissue itself and the paint job. Annoyed..? Yes, rather..! Tomorrow, probably, after I've cooled down a little.
                          Last edited by Dad3353; 06-07-2018, 10:26 PM.

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                            #73
                            The cabane needs to be done, which will make manipulation even more delicate, so I decided to fit the wiring loom in, first. I've soldered up all the connectors, and checked that it all works, ready for installation...



                            Then the fun begins. Checking the headroom with a dry-run mock-up ...



                            ... then comes the serious stuff, inverting the fuselage onto the cabane and checking for alignment in as many planes as I could think of ...



                            It looks to be square enough, so it gets glued up...



                            I had the able assistance of Our Eldest this evening, to help with measuring the distance between the wings, the fit of the cabane struts, the squareness of it all... Even then, four hands is sometimes not enough, but we manage to convince ourselves that it's as best as it's going to get, with our somewhat primitive means. The struts were Gorilla Glued into the cut-outs prepared in the fuselage, and PVA at the top end, where the struts marry blocks glued and pinned to the cabane 'roof'. Meanwhile, I've bolted hooks at various points on the wings and cabane for the rigging, which will hold the wings in place, much like the real 'plane. I'll be able to test rig when the cabane is stable, and add dowels for attaching the upper wing. More to be done, of course, but it's starting to look like a biplane..!
                            Back soon ...

                            Comment


                              #74
                              I need some method for keeping the upper wing firmly attached to the cabane roof. The original, free-flight rubber-powered model had this solved by gluing the wings, struts and fuselage all together. As I've gone for detachable wings, this won't be an option. I've adopted 'classic' elastic bands for the lower wing/undercarriage, so thought it reasonable to use the same technique for the upper wing. To this end, a pair of bamboo skewers, cut to length, have been glued underneath the cabane roof, protruding forward and aft enough to accept the bands...



                              The yellow tips are heat-shrink tubes shrunk over the protruding tips, with multiple roles. They will prevent the bamboo from splitting, and provide a knobble on the end to help keep an elastic from slipping off. I chose yellow to blend in a little with the colour scheme, so they have a slight deco aspect, too..!
                              The smaller clamps are holding a metal rule under the skewers, in the middle, to keep them flat to the ply sheet, for better glue contact ...



                              In theory, though, there should not be enormous force needed to hold the wing in place, as the biplane construction cumulates interlocking pieces, so once set up, there's not really one single 'weak point'. The 'plane itself is not constructed to withstand any aerobatics or high performance forces, either, and, I hope, will fly (if indeed she flies at all..! ) rather slowly. The hardest part will be landing, and I would prefer all the elastics to give way, rather than bust the structure. Much of this is conjecture on my part, of course; I may be building a flightless turkey, or an over-weight Flamingo..!
                              I'm now impatiently waiting on the delivery of a last element for the deco (shouldn't be long now, but the post from the UK to France can be stupidly long at times, for some unknown reason...). I'll need that to be able to finally add the hinges for the control surfaces and fit the tail feathers, now that the cabane has fixed the wing positions. Meanwhile I've a plan for getting some lettering for a fake, unauthentic, registration, so I'll get on with that.
                              To be continued...

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                                #75
                                I thought I was doing OK (I've installed the hinges, and tested the servo rods; all went reasonably well...), and turned my hand to one of the last delicate jobs before final assembly (yes, folks; we're very nearly there..! ). I've printed a set of decals for the 'registration' of the 'plane, so started to apply 'em. I tested the procedure on a piece I'd made for testing paint finishes, and found it to be reasonably easy. The first decal to go on the Flamingo, along the right flank, went swimmingly well, and inspired confidence. Treachery..! The other side refused to slide, and quickly became useless. Luckily I'd thought to print up a spare; no better, it rapidly disintegrated, unrecognisable through stretching and folding onto itself. Darn it..! I've bigger ones yet to apply to the wings, but hesitate now. I'll have another bash, maybe cutting them into smaller sections, rather than trying to slide the whole piece in one go, but this will, of course, have its own problems of alignment. If I can't get it done to my satisfaction, I'll simply finish the build for now, and probably enquire as to Callie Graphics or the like for a 'real' set of letters. I have the file, as a Pdf; I'll see how the next session goes when I've calmed down a little. Darn it...

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