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1935 Curtiss Condor, from static model plans, 200%, converted to electric RC ...

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    #16
    Here's the present state of the Condor... Gussets in place, a 'doubler' installed afore of the centre section, so as to, later, cut away the nose for access. A platform for equipment is prepared (not yet glued in...), resting on cross-pieces. To prepare for servo installation, I'll need the empennage, so I've started on the tail-plane/elevator, pinned to the plan. I had a go at laminating the curved sections, but the radius is too tight for the wood I have, so I traced the outline to sheet (respecting the grain direction as best as I could...), and cut them out, pinned together as pairs, with my new (to me...) jigsaw. I'll be 'cheating' a little; these parts will be flat, not profiled as aerofoils as per the plan. Sorry..!

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      #17
      Building continues slowly, with the extended glue drying times at these autumn temperatures, but steady as she goes...
      Here's the tail-plane all glued up...



      ... the platforms in there are to accept iron-on laminating film hinges. The structure is too delicate for much else, and I've previously done some experiments which lead me to believe they might work. Once un-pinned and shaped a little, that'll be the next step, so I'll soon know if there's hope or not.
      On another note, and maybe a bit prematurely, but I'm pondering whether to go for ailerons, or build in some dihedral. I'd much prefer to build 'flat', but there's not much scope for servos in the wings. Again, I may build a test piece, just to see what I can fit in there. Hmm... Another thing to cogitate when nodding off to sleep...

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        #18
        Still on the tail-plane, needed to know how to build the rear of the fuselage. It's all framed up; here's the joining of the elevators, using a suitable bent to shape 'trombone', pinned to each side and held in place with Gorilla Glue...



        Not the prettiest solution, but should be lightweight enough for the job.
        I had planned on using laminating film hinges, and did a small test piece. The film is light and transparent, and so does not photograph well, but here's a rig I cobbled up to join two strips, overlapped by 4mm with one inverted. The metal rulers are to help guide the sealing iron which will heat the join, welding the two strips together....



        The resulting strip is cut into 1cm-wide hinges. They worked enough, but even this one test piece was very fiddly (did I tell you I have clumsy, sausage fingers..? ...). I also did a trial using thin plastic squares (I think these are what some call 'CA' hinges, but I'm not sure...). My worry was that any slot cut into such a narrow tail-plane would weaken it too much, but my test showed that a slit using a N°11 blade was sufficient, and easy enough in the softish wood I'm using. On the other hand, gluing these 'squares' into the slit using CA proved to be useless. I've never liked the stuff anyway, so used another method. The hinges are slid into the slit, then a hole is drilled through the wood and hinge, into which I glue a toothpick, with PVA glue ...



        Once set, the excess length is clipped off with my flush-cut cutters. I've pinned the test piece open, to show the hinge movement...



        The hinge has a self-centre tendency, but that's maybe not a bad thing for an elevator..! I'll find out when I hinge together the elevators to the tail-plane.
        For that to happen (yes, all of these things anr inter-dependant..!), the empennage needs to be covered, using laminating film. The roll I've bought is now to be given its chance; the test pieces I did showed promise, but this is the first time on a real 'plane. It didn't take long, and was applied with ease. Another test, though, is to see if, by chance, the film can accept acrylic paint directly (unlike Doculam...), or will need tissue covering first. Here's how to find out... Suck it and see..!...



        First impressions are very encouraging. Using only a simple brush, my Vallejo paint is easy to apply, using only a couple of drops, and covers rather well. Once dry, I'll see if it's really bound into the film. If it rubs off, I'll have to apply tissue, but it it holds up, I'll paint directly, either with the brush or, maybe, my air-brush. I'll then be ready to install the hinges, and can carry on with the fuselage. More later, then...

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          #19
          The flank stringers are now in place...



          ...Glued firmly in the former notches, and pretty well lined up. I made a notching saw from a couple of hacksaw blades, in a saw handle that's supposed to use old broken blades, but which I'd lost a piece of. Nicely bodged, though, and it cuts just the right width for my stringers, which is handy.
          It may be noticed that the stringers don't go the whole length. That's because I'll be cutting off the nose (No, I'll call it the forward cabin; it's more elegant...), so I'll fit those stringers later.
          The 'plane has a rather 'pug' nose; here's my attempt to coax the longerons to take the bend. The fuselage is pinned to the board, and the outer side of the longerons has been imbibed with water, using a cotton bud. a pair of clamps will hold it in that position until the wood dries out, when the crosspieces will be glued in to (hopefully...) hold it secure...



          While that's happening (slowly...), it's time to prepare the next set of formers, for the upper and lower fuselage shape. Here, they're being traced through to the 3mm balsa sheet, using carbon paper...



          I found that a ball-point pen makes a better job, as it has less tendency to tear the plan, whilst allowing a fairly free run over the line being traced. These are plan copies, so I'm not worried about desecrating the plans..! The formers will be cut out with the jigsaw, and notched with my notching saw. They'll then be glued in place, but their stringers will have to wait until I've sorted out the servo placing. I'm not sure which servos to use; I had planned on using 5g metal geared ones, but I find that I only have one. I'll order more, but may use a nylon gear version instead. I'll see.
          I'll get back to my tracing once I've finished this cup of tea and my biscuit...

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            #20
            Well, not really a print of my feet, but rather the upper and lower fuselage formers, carbon-copied from the plan, and cut out on the jigsaw seen behind...



            In the foreground is the resulting pile of offcuts. The notches will be cut afterwards, when the formers are glued in place, to try to ensure straight stringer runs.
            I'll need access to the inside, so the forward cabin will be cut away to allow that. With unusual foresight, I've decided to install magnets at each corner of the future join, all lined up beforehand, the hope being that it all lines up again after the slicing away of the nose section. Here's the aft set of magnets glued and clamped...



            ... and the result...



            These are 6 x 1 magnets, for which a 6mm wood drill was used to make a 1mm deep recess in the triangles, turning the drill in reverse, by hand, slowly, so as not to tear the balsa. Gorilla Glue was 'spotted' into these depressions with the tip of a toothpick, and the magnet slid into place and clamped. Once set, the triangles were popped into position on the point of an X-acto knife, using Titebond. It feels at times much like building a ship in a bottle, having to access stuff where my Gulliver-sized hands can't possibly reach..!
            I'm marked these magnets with a black felt-tip on one side; the corresponding opposite magnets (even smaller..!) are marked with a green felt-tip, to ensure correct orientation. T'wouldn't do to have the front of the 'plane pop off on its own accord by magnetic repulsion, now would it..? Here they are, Gorilla Glued in their respective cross-pieces, which will then be presented and glued in place, facing the magnets already there...



            I'll then insert a couple of dowels, as locators, and sever the fuselage. This will allow me to fix the equipment floor inside; it's too wide to pass through the front right now. Later on this evening, maybe...

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              #21
              Today's progress (well, started last night, really...)... A bit more 'beef' will be needed to support the locating dowels, so extra cross-pieces are fitted...



              Whilst waiting for that to be ready, a few top formers are glued on. I can't do the T4 former before separating the front end, for fear of gluing the fore and rear formers to each other. Here's the first batch done, anyway...



              Having left all that to set overnight, I drilled the holes that will receive the dowels (seen in the foreground...) this morning. Not so easy, as my 5mm bit is too long to do it from inside, but too short to drill from the front..! I did a pilot hole instead, with a shorter, 3mm bit, not so much by 'hand' as by 'finger', twiddling the bit as best as I could. Luckily it's balsa; using ply I would have been sunk..! Never mind, the pilot holes were finally pierced. Then, taking a deep breath, I cut the corner stringers, thus freeing the front cabin section...



              The dowels are glued in, after checking for fit. A bit tight, but that'll ease up over time...



              It's delicate parting the two halves, of course, as they're still pretty delicate and fragile, but the two halves butt together nicely, held firmly enough by the magnets. I very much doubt that it'll come apart in flight..!
              Now I can fit the T4 formers, one to each side of the join. The magnets come in handy, holding the steel rules in place so as to clamp the former nicely vertical...



              The foremost T4 is clamped using my aluminium mitre box.
              Once that's all set, I'll fit the remaining top formers, and return to the installation of the equipment platform, waiting patiently to be inserted through the now-opened front. I'm to receive another lot of servos, too, and will decide which to use for the empennage. I'll clear the decks on another table for starting on the upper wing, too, but will need to prepare another batch of ribs for that. I'm beginning to think that the acquisition of the jigsaw was not a bad idea..!

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                #22
                All the wing ribs, both upper and lower, are exactly the same, excepting that most are 1.5mm balsa, but some are 1.5mm ply. Here's a 'set' of balsa ribs, traced from the ply templates made previously onto a stack of ten balsa strips pinned together, two ribs per strip...



                A quick blast of the jigsaw produces these two stacks, shaped, with notches prepared...



                I'll have to count up again (for the umpteenth time...) exactly how many will finally be needed of each, but I should have enough of both sorts to get started on the upper wing.
                I'm still not sure about dihedral. It would simplify a lot if I could build the upper wing as one, completely flat, unit (in the same way as my Aeromaster...), although the plans indicate the 'real' dihedral of 3/16" for the outer panels (which would equate to 1cm for my scaled-up version...). The plan is, however, for a static model, or, at best, a free-flight glider, so I don't really know how this translates into this RC 'plane. I'll be trying to build in ailerons on the upper wings; the plan calls for a similar dihedral on the lower wings, too. Any thoughts, recommendations, advice, warnings, experience available on this subject..? If it's really required, I can integrate this into the wings; will it really help the old bird to chug around the sky, or are ailerons enough..? Would it be wiser to incorporate the dihedral as per plan (or even more..?), and renounce the extra problems of functional ailerons..? Hmm... I've a few days left before deciding, but once I get cracking on the wings, the die will be cast.
                Last edited by Dad3353; 11-13-2018, 10:45 AM.

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                  #23
                  The engines on a Condor are outboard, on the lower wings, and so nacelles will be required. By a stroke of good fortune, I happen to notice that the form of a small plastic bottle of apple juice is just the right size, for the forward part at least, and will probably be better than anything I could have formed myself. Some 'sculpting' to be done, so out with the Forstner bit to remove the bottom of the bottle, where the motor will be...



                  S'not easy to take photographes of transparent objects..!
                  I'll be wanting reinforcement disks for the motor mount itself, and to keep the tubular shape; the jigsaw is again called into service, and six disks cut from light ply. This is not aircraft-quality birch ply, but rather rubbish stuff from the local hardware supplier, but will suffice, as it's not really all that structural. I tried to improvise a jig for cutting circles (can be seen skulking below the saw table...), but it didn't work as planned, so I cut 'free-hand'...



                  Another confusing photo, trying to show the first steps in mounting a motor mount...



                  The motor is already bolted to the foremost disk, then popped into the now-redundant neck of the bottle, to hold it steady. A series of spacers fix the height of the middle disk, with a drill bit keeping the disks concentric. Four stringers are glued in place, and the spacers removed. The assembly is held together by an elastic band; when set, the spacers will again serve for a rear disk, thus forming a cylindrical mount to be slid into the bottom half of the bottle. No, I know it's not very clear, written like that; wait a while and all will be revealed (I hope..!).
                  While the glue is setting, I can have another look at servos. I've chosen the push-rods, and fitted the clevises for the control surface ends, and placed the servos in the tray, still to be glued permanently in place...



                  I'm also toying with possible placings for the ESC; maybe diagonal, mid-wing, which will keep the wiring short (and thus save weight...). I've no idea just how much cooling these will need, so I may have to revise things later. Still, I'll experiment with any position that I think could have an advantage.
                  Another shot, from the rear...



                  The tailplane is simply perched for the moment; the orange colouring is the first trials with my acrylic paint applied with a brush directly over the film covering. It's holding up well, with no tendency to peel away or flake off. I've more trials to do with a different paint, using my airbrush, and may yet decide to dope tissue over the film. It's a bit chilly for painting or doping, though, so that'll wait.

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                    #24
                    Meanwhile, the first steps for building the upper wing have begun...



                    The trailing edge is notched, the lower spars in place and the ribs, after a dry fit each, are glued in place and held with the Lego blocks. It's cold, so I've had a radiator beneath the building table diffusing just enough heat to get the Titebond to set. I've switched it off now, but it'll be on again tomorrow when I fit the upper spars and leading edge. That'll do for the centre section; I'll start the outer panels once that's un-pinned. I'll leave the dihedral question until the moment arrives when the panels need joining (although, now I think about it, I may need some kind of reinforcing at that joint. Hmm... Something to think about; I'll sleep on it...).
                    More tomorrow.

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                      #25
                      The top spars and the leading edge go on...



                      I now discover that I've no stock of 6x6 for the leading edge, so a quick order is sent; that'll arrive before end of week, hopefully. Never mind, I'll start the outer panels just the same; the LE can go on at a later stage with no ill effects. Meanwhile, I'll need to cut out the 3mm sheet parts for the wing-tips. Here they are, at the tracing stage...



                      I've pinned two thicknesses together so as to cut a pair, with the jigsaw. I'll do that later this evening, probably, and maybe get a start on the starboard panel. Firstly, though, dinner...

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