Announcement

Collapse
No announcement yet.

Svenson Prima, 3-Axis Trainer, from a Svenson kit...

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

    Svenson Prima, 3-Axis Trainer, from a Svenson kit...

    Oct 21, 2017

    For several reasons, I'm now looking for a new challenge, and have decided to learn flying with ailerons. I have a 3-axe 'plane (the Scorpio Basic 2000...), but would prefer something a little more staid for starters. The model club use the Svenson Prima for this, so I've acquired one in kit form for a winter build. It's a high-wing trainer, with a span of around 1m40, initially for glow, but I'll be building it as an electric. Here's the box lid, and the unfolded plan...





    I think I'll have to extend my building table; we'll see by how much when I've cleared the decks a little...

    Oct 25, 2017

    I've made a modest start on the Svenson Prima. The tailplane slots into the rear of the fuselage, so I decided that it would be best to have that part already assembled beforehand. The 'tail feathers' are about the easiest parts to work on, too, so a good starting point...
    Folded, the relevant part of the plan to work on just about fits onto my present building board; here's the outer frame of the tailplane 'dry-fitted' and pinned, awaiting glue...



    ... and the finished piece, with its stringers. Whilst waiting for the PVA glue to dry, I sanded up the elevator, and marked out the hinge positions...



    Hinges..! Now there's a subject..! How best to cut the slots required for this type (simple 'CA Nylon' thingies...), eh..? Here's the slots...



    ... and here's the method (read 'bodge'...) used ...



    With the mini-drill I made a series of holes, lined up to form a chain, then, with a pair of doubled-up, back-to-back n° 21 blades, plunged down to make the slot. Not the most elegant, and I've since ordered a set of blades to do a tidier job, as there are more hinges yet to be installed.
    Never mind, it seems I was lucky enough to get away with it, this time. On to the tail fin; this is the 'dry run'...



    ... and the glued-up part. Only one side of the triangular base reinforcement whilst it's flat on the board, and I use the waiting time to shape the rudder...



    Now for the second strengthener (is that port or starboard; I can never remember which is which..? :-\ )...




    Yes, I noticed the excess of squeezed-out glue, too, whilst editing the pics, so hurried back to wipe it clean (well, I say 'hurried'; it's all relative, you know..!).
    So, that's the state of the project as of this evening. Next step will be shaping and sanding of the fin, and preparing for fuselage assembly. I've read through the (rather sparse, and sometimes erroneous...) instruction sheets, and hope I've understood all the details, and the sequence of events. We'll see; back later. Maybe a bit of a rest now, I thi... ... Zzzzzzz ... Zzzzzzz

    Oct 26, 2017

    Here's the finished fin, ready, just about, for covering...



    What's next..? Oh yes, the fuselage. Oh dear. Still, one has to take the plunge sooner or later. First things first; rearrange the 'workshop'. Haul things around a bit, and bring up a spare panel of about the right size. Lay out the plan, and get down to business...
    The fuselage flanks are to be doubled with ply 'cheeks'; these need careful placing before glueing and allowing to dry under a light press. This is the result...



    The flanks are then cut away from their balsa sheets, like so ...




    I'll next pin the two together and sand the edges to match 'em up. There are also wing mounting fixtures to attach, and reinforcements around the perimeter to put into place; I'll start that tomorrow, probably. Back then...

    Oct 28, 2017

    Well, that's done, for better or worse. I wasn't too confident as to the best method for attacking this aspect; I hope I've not done anything too foolish. Firstly, now is the time to fix the wing fixtures, whilst we have easy access to the inside. These are supplied with 3mm bolts and Nylok nuts, but I didn't like the idea of having these bolts visible, so instead used 3mm dowelling and epoxy. The dowelling is flush with the outer skin, and will not be seen once covered. It must be strong enough; if there is a crash hard enough to break them, nuts and bolts would fare no better, I thought. Best not to crash, eh..?



    The flanks are to have their perimeter reinforced with triangular stock. The underbelly is curved, and I was a bit concerned that the bending could snap the piece. I did a dummy run, and it seemed to hold up; in the end I decided to use a 'belt & braces' approach, and sprayed the sticks with a mist of plain water, which I then pinned to the flanks. Once dried, the shape was largely kept, and there appeared to be less strain imposed, so I glued 'em and pinned 'em again. I jigged up a series of pincers to keep the flat surfaces firmly bonded, but it's not that simple when working with triangular stock..! Scrap wood was used to give the clamps something to grip, but it was a delicate operation...



    Here's the result of the first part ...



    For the next batch, I used a slightly less conventional method for pressing the glued elements. Useful tools, lump hammers...



    The smaller, more fiddly, pieces around the front next; careful cutting and matching up of 45° angles was required...



    It's getting a bit easier now; some straightforward reinforcing towards the rear...



    ... and the slot cut out for the tailplane, which is then adjusted. Here's the state of play this evening, then, with a dry fit of the tail feathers, just for the photo and the morale boost that that brings...




    The next stage will be mounting the formers between the flanks, to make the fuselage a one-piece structure. Maybe tomorrow, maybe Sunday; we'll see. I may take the work done so far to the model club (Saturday is workshop day...) and get it checked for conformity, before it's too late. I'll need some advice on servo mounting, too. Prudence...
    Last edited by Dad3353; 12-17-2017, 01:35 AM.

    #2
    Oct 29, 2017

    Not well enough for going out, so I plodded on stoutly on my own. Delicate stuff (but what isn't..? ), not helped by more-than-flimsy instructions. Much is worked out by deduction, coupled with dry runs, some Euclidean geometric principles, serendipity, uncouth muttering under my (short...) breath and many and often tea breaks. Here's the mock-up to see how it's all going to go...



    ... where we discover that the pieces for mounting the undercarriage need special preparation, and interpretation of the plan is something akin to the Hampton Court Maze. Still, that's what dry runs are for, so having outwitted the fiendish cunning of the folks that printed out the doc, I glued up the formers and bound it up with rubber bands, all the while rigorously checking the alignment...



    It'll be left until tomorrow, of course, when I'll do the undercarriage part that's left to do, and slim down the tail end for final gluing. Almost ready for top and bottom sheeting..! Once that's done, I'll put the fuselage to one side and prepare to start the wings. That's enough for today, then...

    Oct 29, 2017

    It doesn't look like much, but these little fiddly bits take up a disproportionately large chunk of one's time. The cross-bracing for the rear of the fuselage comprises small pieces of strip balsa, cut to 45° to match the triangular stuff inside, and adjusted to be flush with the top and underside, to support the future sheeting. It feels much like building Nelson's 'Victory' inside a rum bottle, using pins, tweezers, a tiny X-acto blade and minute droplets of PVA glue. It helps to not suffer from Parkinson's, too; at least that palsy has been spared me for now..! Much patience, then, and re-cutting of one or two, until all were done. Ooph..! More tea, then...



    Now then, at the other end, there's the nose (Nose..? Looks more like a snout to me..!) to be glued in. Once again, we'll have to juggle with the bending resistance of the balsa and ply and the binding force of a host of rubber bands. The first attempt came unstuck when I removed the elastic too soon... Boing..! The snout sprang apart as soon as my back was turned. Another glue session, to which I've added a reinforcing strip inside, hoping to get more adherence to the cheeks than is afforded by the narrow front bearer (just about visible here, inside, to the left, under the bands...)...



    Here's the view from the front; doesn't it look like a snout to you, too..?



    No more this evening, then, as the PVA needs to settle down fully. Here's hoping it does the job, and tomorrow the snout stays stuck..!
    Other news, I finally received the plans for the 'Lazy' 3-axis glider I'd ordered. I'll have to finish the present project first, of course, but that, too, will be an adventure, my first 'scratch' build solely from plans..! I'll put some photos up of the sheets received as soon as I can work out how to spread 'em out for that; they're very big sheets..!
    An evening TV then, for a change. Part Two of 'The Hobbit', and cottage pie, made yesterday.

    Mmm... Cottage pie..!

    Oct 30, 2017

    Here's the snout, relieved of its retaining bands; it's holding up, but I'm glad I put the extra pieces in place...



    Meanwhile, at the other end, more glueing, after having shaved down the tail end somewhat. Not as much as on the plan, as I may yet decide to have the elevator control rod come through here, rather than from the rear of the flank. Lousy photo, I know. (Note to self: add extra lighting sources for taking photos...)...



    Time passes...

    The PVA has set enough for the next step: sheeting. Here the rear lower sheet is being sized up...



    ... and here is my universal multifarious polymorphic press in action again. No workshop should be without a lump hammer or two...



    More time passes...

    Et voilà..! The first sheet is in place...




    I hope the extra lighting is appreciated..!
    Next step, the front underbelly sheeting. Meanwhile, I'll have to decide on the technology to adopt for the control rods, whilst the fuselage is still accessible enough for trials. Tried and tested balsa sticks..? Full metal rods..? Gold-n-rods..? Carbon straws..? Hmm... Some reflection needed still...

    Nov 01, 2017

    On, then, to the next step, the front underbelly sheeting. Once again, some innovation is required for the battening down while the glue sets. This time there's a curve, so it's a combination of pins and suitable weights. In theory this could be done with rubber bands, but I've taken the option of glueing a whole sheet, to be cut to form afterwards. Doing this, a rubber band won't hold the sheet down flat. Never mind, I've got pins..!



    ... and the result..!



    Now is the time recommended to make prevision for the undercarriage, piecing a passage for the steerable nose landing gear (it's a tricycle, remember...). The bearing part is already installed on its bulkhead; I pass a drill down through that to transpierce the newly-applied sheeting. Whilst I'm at it, I'll sort out the rest of the undercarriage, drilling the holes for the supplied undercarriage legs. These are held firmly to a channel in a hardwood block by a pair of metal straps, bolted through. The legs are prevented from twisting by a 90° bend, up through more hardwood fixed to the flanks. Easier to see than to explain, so here's the pics, from the outside...



    ... and from the inside. We can see the tiller for the steering towards the front, below the nuts on the right....



    I've pulled one of the legs out to show the 90° bend to anchor the legs vertical...



    Result..! Ready for take-off..! (OK, not quite, but it's coming along nicely, I reckon...)



    Enough for this evening. Next will be working out how to do the battery hatch and 'windscreen'. There's no glow engine, so I'll be able to enclose the nose completely, unlike the plan version. Some imagination needed; I'll sleep on it...
    Last edited by Dad3353; 12-17-2017, 01:38 AM.

    Comment


      #3
      Nov 01, 2017

      Breaking news..! Our Eldest has a Sony flash, entirely compatible with my Sony A350, and, bonus, it has a wireless option..! Quite some experimentation to see how to set it up to be as fuss-free as possible, and an awkward moment before reading the doc to see how to get the two to communicate, but here's a pair of pics to show the difference it can make. The first, taken with simply the built-in flash, which I've been relying on up until now. The second, taken with exactly the same 'Auto' setting (in true 'Point'n'Shoot' style...) with the remote flash simply held at arm's length to my left...





      Is that better or what..?
      The pics are of my starting point for the nose hatches, of course. Here's hoping I can continue to get better photos each time, as there's still quite a lot left to do. More later, then...

      Nov 04, 2017

      Onward, then... The two rear parts of the hatch are to be glued together, hopefully at the correct angle to meet the fuselage shape. Sticky tape to hold the pieces in place temporarily, and my (patent pending...) press system 'entices' the parts to adopt the form needed...



      Some reinforcement is required; a scored square of scrap cardboard is requisitioned for the role, and a piece of scrap balsa put into place for a front locating dowel. This'll be drilled through from the front, to ensure alignment...



      Here's the hatch in place; the dowel can be seen protruding through the bulkhead...



      How to hold down the rear of the hatch..? One modern method is to use magnetic attraction, now that tiny, relatively light neo magnets can be easily and cheaply obtained. Here we go, then; my concession to modernity. The upper magnet, on the hatch, has been sunk slightly into the balsa and is held by a short nail (how modern can I get, eh..?). The clamp is holding in place the scrap balsa that will receive the lower magnet, but it'll need to dry overnight to not risk popping off under the attraction...



      The front hatch, over the motor, will have to wait for the arrival of the motor before any definitive attaching, to be sure it'll not interfere. This means suspension of proceedings until I receive either the motor (on back order, apparently...) or a set of push pins for starting on the wings. Yes, I have glass-headed dress-making pins, but they're too hard on my poor long-suffering fingertips to push into the worktop. OK for balsa-to-balsa, or even light ply, but I need a proper thumb-tack style pin for pinning the wing sheeting to the table. Shouldn't be long, though; my supplier is usually extremely prompt. Maybe tomorrow..?

      Nov 15, 2017

      The pins arrived, but not the motor parts yet. On, then, with the wings...

      Firstly, clear the decks, make some space, update the desk top and generally tidy up. OK, I know it doesn't last, but at least I start out that way..! The plan is laid out and ready to go...



      The timid trial of laying out the bottom sheets, before committing anything. There's still time to change my mind...



      OK, the plunge is taken. I star pinning and gluing. The aluminium mitre box is what I presently use as a square; the first rib is now in place...



      An evening is taken up by this part, getting all the ribs of this half-wing squarely in place. The parts fit together very well; I'm pleased so far with the quality of the wood and its cutting.



      Another evening's toil; a couple of ribs need some slight 'persuasion' to lie flat to the board whilst the glue sets. I'm feeling just a little more confident for now; I hope it lasts..!



      There, that's that part done..! The instructions ask now for the dihedral brace to be glued in place, but I'm going to leave that until the upper spar has been glued in, as I think it'll ensure a better fit that way. I've not yet cut the inboard ribs to accommodate this.
      On another note, I remembered, just in time, to make provision for the passage of servo wires (I'm going to 'mod' the design and install the servos in the wings, not one central aileron servo...). The holes can be seen at the root end, holes cut out with a home-made 'pastry cutter'-type tool, using a piece of plumbing for connecting a garden hose to a tap. I ground the edges to sharpen 'em a bit, and ended up giving the 'tool' a bash with the lump hammer to cut through in one foul swoop. I'd done a few trials with other methods, and this was the cleanest could come up with. Primitive..? Yup..!




      Next up is to establish the placing of these servos. So far I'm thinking of mounting them on a hatch, to be cut into the lower sheeting already existing two ribs out from the root. That's where the original aileron links are placed, but which I'll not be needing, and keeps them close enough to the fuselage to not need extensions to the wires. This could change, of course; any council, 'for' or 'against'..?

      Nov 19, 2017

      Time to get bold again and do a few necessary, but nerve-wracking, assemblies. Starting off 'cool', it's the upper spar, leading and trailing edges next. Again, with a well-cut kit, I've not had any adjusting to do; it all fits together nicely. Here they are, done; the rightmost leading edge is being held in place by my T-profile straight-edge...



      Each of the aileron hinges needs a small block behind the trailing edge, to accept the depth of the hinge. Here they've been glued and clamped; the dihedral brace has also been glued up for this half-wing...



      A close-up of the dihedral brace...



      ... and four of the aileron hinge blocks...



      For the curious, here's my 'build write-up' photo system; a remote flash which bounces light from the white door and wall of the water heater locale. The ceiling is pine; bouncing light from that gives an orange-yellow tint to everything, and direct flash is too powerful; it floods all the detail away. With my sophisticated boom arm attachment (OK, a wide rubber band...), I did quite a few experiments, and chose this as the best result. Could doubtless be improved further, but I'd rather spend the time building the 'plane..!



      I'm giving plenty of time to the dihedral glue; whilst that's setting I can advance the motor mount, as I've received that part of the order. This is a modification, of course, as the plans are for a glow engine. My mounting system involves slotting a mount bulkhead between the engine-room cheeks; I can remove the motor, by simply sliding it up, once the retaining screw is removed. Here, then, are the front guides being glued in place. Once set, the second pair (to be seen to the right of the motor...) will be glued, too. I've made the bulkhead from the aileron servo tray supplied in the kit; otherwise unused, as I'm building outboard aileron servos...



      Once again, the PVA glue needs time to gain its full strength, so that's all for this evening.

      Nov 19, 2017

      Following on, then, with the motor mount...

      One rear guide being fixed into position...



      All the guides are in place; here's the motor mount going into its slot...



      ... and now in position...



      I've yet to decide exactly how I'll attach the motor hatch, but there's plenty of time before it becomes urgent, and I like to cogitate awhile. Sometimes I even come up with a Good Idea..!

      Such as this one, maybe..? I've been scouting around, reading up on all sorts of suggestions for making holes in thin balsa ribs, for the passage of servo wires. I even tried a few out, with more or less conviction. I had a convex to execute on the motor mount (again, for allowing the wires to pass...) which I did using a conical grinding bit on the Dremel. Hmm... I wonder if this could pierce balsa..? A couple of trials on some scrap gave the answer: yes, it can, although it tends to burn its way through at too high a speed. I've six ribs to pierce, so I clamped 'em together with a piece of scrap behind and went for it. Hooray..! Here's the result...



      Nice neat holes, just the size for passing the connector, with no ragged edges or torn wood. OK, there's a pungent odour of charred wood, but I consider that a small price to pay..!

      Servo trays will be next, and I'm still awaiting receipt of the bits and pieces required for my push-rod experiments. Sleeved piano wire..? Balsa sticks..? I need to try a few things out before deciding, and it's the tubing that's yet to arrive. Patience...
      Last edited by Dad3353; 12-17-2017, 01:43 AM.

      Comment


        #4
        Dec 06, 2017

        Parts now received, I can continue with the build, having had (maybe...) enough time to mull over a few technicalities. Here we go, then, with another episode...

        Firstly, a bit of history for the younger readers... In days of yore, one would switch on the receiver in the 'plane, typically with a small slider switch. When landed, of course, one would naturally switch it off again. With the advent of electric flight, with modern ESC's with built-in BEC, it is less common to have separate Rx batteries, and the high current consumed by the electric motor precludes the use of a slider switch. It's quite normal, these days, to open the 'plane and plug/unplug the Lipo to turn it on and off. I'm 'old school', however, and so prefer to have a means of connecting from the outside. Here's my solution...

        A Deans socket is let into the fuselage, and the ESC positive battery wire is routed through this socket to the Lipo. A shorting plug, inserted into the side of the fuselage, completes the circuit to the ESC. To fly, the Tx is turned on, then the plug inserted, so powering the 'plane. Once landed, the plug is removed, cutting off all power. Not the most elegant, maybe, but it's how I prefer to handle the switching issue. Here's the basic elements, all prepared for installation...



        The ESC is not soldered to the socket; I use 'bullet' connectors so that the electronics may be removed without dismounting the Dean's socket. Here's a view from above, showing how it's all connected up ...



        ... and a view from outside, once the socket and plug are installed (no, the 'plane's not yet covered; that will come later. These are just 'dry run' installations...).



        Before going into the complexities of pushrods, I need to establish once and for all exactly where the main servos are to go. I make a tray to fit them...



        ... with a pair of fore and aft runners underneath, to keep the servos clear of the 'plane's floor...



        This is glued to the fuselage floor, just forward of the wing bolts. Is this the 'optimum' position..? Dunno, but I had to choose somewhere, so that's where..! ...



        Next instalment: Control rods, Part I.

        To be continued ...

        Dec 06, 2017

        Control rods, Part I...

        I've now got the first fixed points pretty well established: the servo for direction and the tricycle nose wheel. That seems to be as good a place to start as any. Of the various pieces received, there are 2mm steel push rods, with a metal clevis screwed onto one end. By the luckiest of chances, they are exactly the right length, too. The tiller arm for the nose wheel needed a hole opened up to receive the clevis pin, as did the servo arm for the adjustable 'domino' for the other end. Here's all the pieces...



        ... and here they are, installed...



        The 'domino' is a bit of a pig, with a less-than-tiny grub screw with a microscopic slot head. I can't think of much more fragile a piece; I'm not at all happy with the force needed to tighten it. To make things even better, the sub-miniature nut and washer holding it on to the servo arm were tightened only enough for the photo. They've since completely vanished; I hunted inside and outside the fuselage, and scoured the floor with a torch and magnet to no avail. Evaporation..? A mystery.

        Never mind; on to the next step: the rudder. I'm going to try 'snakes' for this and the elevator, so I'm even less sure of what I'm doing..! I've chosen a spot for the rod to exit the fuselage, leaving enough 'inner' to have the degree of movement required, but no more. I've some plastic covers for these exits which I'll try to fit, hoping to keep the lines of the 'plane clean. Here's how it looks for now...



        ... and here's the servo end. I've cut to length (with a bit to spare, I hope..!), but have not yet stripped back the 'outer', nor tried attaching to the servo arm yet...



        Here's a more global view...



        I'm not sure quite how to proceed next. I need to attach the rudder end of the 'outer' (epoxy to the fairing, then glued into side of fuselage..?) and decide how to fix the 'outer' at the servo end (glued/clamped to the fuselage side..? A cross-piece fixed to the adjacent fuselage former..? Dunno...). I've had a bit of a scout-around on t'web looking for inspiration, but have found nothing definitive as yet. It's become quite late; I'll sleep on it and see what I can dream up.

        To be continued...

        Dec 10, 2017

        I've taken another couple of steps (OK, baby steps, but steps just the same..! ) in dry-fitting the 'snakes' for the rudder and elevator. Just clamped for now, until the rear is milled to receive the exit fairings, and covering. I wanted to establish exactly where to fix the servo end. The test, using the Tx for 'realism', decided me to install a cross-member on a fuselage former (indicated by the big green arrow...). Much closer to the servos there's a fair bit of right/left movement due to the servo arm swing; fixing the 'snakes further back attenuates any binding, whilst still preventing the cable from bowing...



        Here's a close-up of the (temporary...) attachment to the servos...



        The 'dominoes' were supplied with M2 nuts and washers; I've chosen to use Nylok nuts instead, tightened just enough so that they may be free to pivot, yet not have the nut unscrew itself. It seemed better than the supplied method.

        That's all for now, until Our Eldest comes home, as he has a (home-made...) milling attachment for his Dremel. He uses it for inlaying mother-of-pearl into his guitar necks; milling out balsa for inlaying the 'snake' exit fairing should be a doddle..! Once that's done, I think I'll just iron on enough Solarfilm to allow me to glue the fairings and 'snakes' in place, then go on to sheeting the fuselage top and get back to where I was with the wings. Back soon...
        Last edited by Dad3353; 12-17-2017, 01:45 AM.

        Comment


          #5
          I've decided to go for the fairings just the same; my 'dry runs' and mock-ups give me enough confidence. If I find that, once completed, they cause issues, it won't be too difficult to remove 'em, back-fill and go the 'flush-cut' route. Meanwhile...
          Our Eldest obliged, not with his router, but 'old-school', using an n°11 blade and a home-made tiny chisel, fashioned from an electrical screwdriver. Not so easy to see in the photo, but here's one side...



          ...and again, with the fairing set in, flush with the flank...



          It's pretty darned chilly in my build room right now, so I'll put off gluing the 'snakes' to the fairings, then to the fuselage until I can clear enough space in a warmer room. Till then, back to the wings, and their servo trays...

          Comment


            #6
            Here we go, then with the aileron servo trays. After much reflection, these are the basic components conjured up by an over-heated and inexperienced intellect. Probably not optimum, but it'll be what it'll be. From right to left: the support tray, to be fixed inside the wing, above the sheeting, the servo tray itself, which will pass through a square cut-out in the lower sheeting, and the servo, to be screwed to the hardwood blocks glued to the tray...



            The gluing of the blocks to the tray, using the servo itself as a fitting guide. PVA glue alone, as with most of the previous construction...



            This servo assembly will go into the left-most sheeted bay. The holes for the cable passage have been cut into the ribs towards the root, in preparation...



            I try out the notion in situ, to see if it looks about right (not that I would know if it's not, really..!)...



            ...This is both trays being dry-fitted. It's normal for the nearest wing to not have the root-most ribs yet; they'll be fitted after the joining of the two wing halves....



            A change of workshop. The support trays need to be cut out where the servo will come up from below. Our Eldest has offered to oblige; here's the pieces ready to be worked on. Notice the detailed and extremely precise marking drawn onto the ply. What a mess of scribbles..!



            Getting started, with his jeweller's saw...



            Looking good, and faster than I would have thought...



            The servo tray now fits inside the cut-out...



            Back to the building board, to confirm the fit...



            ... and a close-up view...

            Last edited by Dad3353; 12-17-2017, 06:39 PM.

            Comment


              #7

              The time has come (the walrus said...) to start on the wing sheeting. The leading edge, upper sheeting is first, on the wing that has the dihedral plates in place. The other will have to wait until the wings are joined. I had planned to use a guide pinned to the underside of the leading edge, to have an edge for the sheeting to butt up to. I put a strip of blue masking tape along this guide, and pinned it in place. I did a dummy run, using spring clamps, and it seemed fine, so I applied a film of PVA glue along the LE, and the front of the ribs...



              Alas, it didn't work out so well when I started clamping, as the pins holding the guide in place came adrift. I had to abandon the guide, and align the forward edge of the sheeting by eye, then pin and clamp it. I just hope that there was enough glue to hold it down; I'll find out when I go to bend the sheet over the wing and glue it. Tomorrow, probably. Here's the sheet, glued, pinned and clamped...



              I must say that I'm less than enchanted with the quality of these pins. The concept is fine enough, but too many are either bending when pushed into soft balsa, or breaking off at the slightest opportunity. I'd have preferred a stouter metal shaft. They're sharp enough, but rather weak. A pity, as they're certainly more friendly on the fingers than my glass-headed dress-making pins. I may have to resort to those, though, if these blue ones keep busting the way they do. It's not as if I'm particularly heavy-handed.

              I drilled and fitted the captive claw nuts for the servo trays. I'm not happy with one of them (a hole too near the edge...); I may re-do that one. They're nearly ready to be set into the wings, which will be a major step towards lifting the wings from the board. I still have to find a way of cutting out the underside of the wing sheeting to match the servo tray, though. More thought needed...

              Comment


                #8
                Here's the result once all the pins and clamps come off. It needs cutting to width, so I mark each end and run a cutter along a straight-edge...



                ... and here's how I'm going to proceed. A fresh brush, the stopper from an aspirin tube and PVA glue. I'll 'paint' the rib tops and the spar top, then bend the sheet over and weight it down with magazines and stuff...



                ... like this..!



                Overkill..? Too much..? If that doesn't hold it down, I don't know what will..! The test will be tomorrow, when I remove that lot and see what has stuck to where. Suspense...

                Comment


                  #9
                  Here's the first sheet, with the weights removed...



                  ...and a view along the length, reassuring me that there's no 'ripple'; all seems straight...



                  The sheeting can't continue until the servo trays are installed. Again, after some agonising over method to adopt, I went for simplicity. I screwed the tray to its support 'backwards' (from the top...), then stuck a folded piece of masking tape to the underside of the tray. The support was put into place between the ribs, the screws removed and the support lifted away carefully. This left the tray stuck with the tape to the lower sheeting. I cut around this, and thus created the opening through which the tray will pass, from below. The support could then be glued into place; here's the first, glued and clamped...



                  ...now the pair...



                  To do this, the wings had to be unpinned and lifted from the board, so a major step has been taken..! Once the supports are firmly in place, I can finish off the sheeting of the first wing, then join them..! Soon...
                  Meanwhile, as the PVA takes its time to do its job, I need to advance my control 'snakes'. I've decided to epoxy the fairings to the outer tubes first, to be glued as assemblies into the fuselage once set. Here they are, glued and clamped...



                  Not much more to be done now until all the glues are dry, so it's a Merry Christmas to all until then.

                  Comment


                    #10
                    good job! I really like the notes on the fuselage side...has me thinking about covering all the outer surfaces on my next static model with similar and clear coating it. kind of a technical art form you have there
                    Last edited by my77gmc; 12-25-2017, 05:42 PM. Reason: clarification of my praise of this guys skills

                    Comment


                      #11
                      Things are about to get a bit disjointed now, as one part is glued and needs time to set, another detail is advanced. There is a sort of sequance to things, though, with more and more interdependance. One such was having to install the servo tray support before doing the root top sheet. Here, then, is the closing up of the root sheeting, invisible at first due to the library keeping the profile (hopefully..!)...



                      ... and the result when the covers come off...



                      Incidentally, I had read on a forum horror stories of having left pins inside, after having closed up the wing. Just as well, as I very nearly did exactly that..! I remembered to look at a very late stage, and bashfully removed a couple of stragglers.

                      As the half-wing is now free from the building board, I can turn to the lower front sheeting, which has been patiently waiting it's turn since the start of the build. Hmm... Not quite as easy as the top, as we no longer have the nice flat underside lending stability. I decided to clamp down the trailing edge to the board, to avoid the wing rocking when under load...



                      And what a load..! There's quite a steep curve, and not much to maintain pressure on the PVA. I tried a dummy run with pins, to no avail, and, with assistance from our eldest, came up with a variant on the 'library' theme, using a rake handle as a roller to squash the books onto the leading edge. A drum of cable, a loaded satchel and yet more books kept the sheet firmly in contact with both the ribs and the leading edge...



                      I tried, on a piece of scrap, wetting one side of the sheet, but it made such little difference I thought it not worthwhile. Inspection of each end gave me confidence that this would do the job...



                      And do the job it did..!...





                      Well, not quite to my entire satisfaction, just the same. the book holding down the centre was probably not quite as thick as the ends; there is a slight lifting there...



                      Out comes the glue brush again, to touch up under the lip, and the affected region is bound up with masking tape, giving a distinct 'walking wounded' impression..!



                      It's been put to one side, so we'll attack another aspect...

                      Comment


                        #12
                        I'll need to have the 'snakes' installed before sheeting the rear of the fuselage. Here's how they're to be fitted...



                        ... but first, that part of the fuselage will have to be covered. I don't want to cover the whole side yet, so I'll just do this local area, to allow the fairings to be glued in. This is the 'patient' on the operating table, the iron is heating, and I've prepared the two small pieces of white film, seen to the right, still tightly rolled...



                        That's the first one done and trimmed...



                        ... and a check that the fairing still fits...



                        The other side, for good measure...



                        Now for another delicate part. The fairings are to be epoxied, but it's rather chilly in my 'workshop'. I'm using 2-hour epoxy, but experience tells me that it'll take rather 2 days in these conditions. I'm not in any particular hurry, but if I can accelarate that somewhat...
                        I'll do the fairings one by one, so that gravity helps flow the semi-liquid into place. The rudder side is first; after mixing up what I judged to be a decent quantity (about 1 cm from each tube...) A toothpick carries the glue to the inside of the fairing, now held in place with the spring clamp. Four or fives 'dollops' (a technical term...) are carefully manipulated in the tight space and encouraged to flow around the 'snake', into the hollow of the fairing and onto the surrounding wood. Now for the ingenuity. In order to modestly accelerate the set, the 'plane takes a trip to the kitchen, and is cradled in the pan-lid holder such that the tail end is over the wood stove...



                        Not hot, at that distance, but warm enough to set the epoxy..! I had already done this when gluing the 'snakes to the fairings, so I think it'll work for this, too.
                        It's dinner time; I'll see what comes next a bit later on this evening...

                        Comment


                          #13
                          Originally posted by my77gmc View Post
                          good job! I really like the notes on the fuselage side...has me thinking about covering all the outer surfaces on my next static model with similar and clear coating it. kind of a technical art form you have there


                          Yes, it's a bit 'steam punk', I suppose, or a draughtsman's tattoo..! I don't understand why they printed that on there at all; if it's for the inside, it's immediately hidden by the ply flank doublers. That's why I made it that way. It'll not stay, unfortunately; the 'plane will receive a handsome coat of film at a later stage; watch this space.
                          (Well, I say 'handsome'; I'll do my best..! )

                          Comment


                            #14
                            Now is thr time for laying on the rib caps, cut from stock, glued in place and taped down. Pins won't help here; the ribs are too thin. Not the most fun part of building, and I've the joy of doing the second half-wing yet to come, but it doesn't take long...



                            As usual, the library is called upon to hold things down...



                            The result is satisfactory; a bit of sanding before covering will smooth out the inevitable minute disparities...



                            Talking of fun, here's another 'interesting' operation to be embarked upon. There's no sense in delaying it; it won't do itself. The wing-tips. There are many designs and methods for building them; this is not the simplest. They are to be fully sheeted, with a taper from outer top to bottom of last rib. This of course involves double curves to be cut and adjusted. Oh well; let's get started. Here's the pieces, and the unmolested outer end of the half-wing...



                            I first have to establish where, in fact, the trailing edge is to end, and for that, need to cut the ailerons to length and present them to the wing. I take a deep breath and start cutting...



                            I can imagine how an apprentice surgeon must feel when conducting his/her very first solo amputation. That nagging doubt ("Am I sure it's the right leg I'm cutting into..?") as I take the saw to the hitherto pristine assembly. It feels less like constructive modelling as savage butchery, but 'needs must', so I soldier on...



                            This is the upper rear sheet, supplied pre-formed, so glued and taped up...



                            ... and, of course, weighted down...



                            Here's what it looks like so far...



                            There's a bit more adjusting to do before gluing in place the lower sheet, but first, the triangular gussets have to set firmly. On to other stuff, then...
                            The 'snakes' are to be attached at the servo end. I decide to install a semi-bulkhead, pierced for passage of the outers, and glued into the fuselage. A dry run shows me that it would be best to have the passages 'staggered', to avoid any possibility of the inners rubbing against each other. It's a bit fiddly threading the outers through, with little leeway, but a bit of patience (and, yes, some light cussing under my breath...) gives the result desired...



                            The eagle-eyed reader of this build will certainly notice that one of the 'snake' outers is shorter than the other. The explanation is simple enough: I'm a fool. I thought of a wheeze to get the epoxy to better stick to the red plastic, by firstly sliding a heat-shrink tube, then shrinking it to 'grip' the outer, giving a better surface for the epoxy. Maybe so, but I'd not bargained on the red outer not appreciating the heating required for the shrink..! Too late; the damage was done, and the inner was now binding on the sad distorted outer. It had to be cut back. D'oh..! Why didn't I at least try it out on a piece of scrap, eh..? As it turned out, a trial of the whole 'snake', even with the shortened outer, gave no sign of buckling nor bending, as the white inner is stiff enough over the exposed distance. Still, it was a dumb idea.
                            Before closing down the session for tonight, I wanted to start programming the next step, which will be to join the wing halves. To this end, I did a rough trial run...



                            First impression are not too disappointing; I have to find the cause, and rectify, a gap of about 1mm , but I'll look into that, probably, tomorrow. Enough for now; time for a glass of milk and bed...


                            Comment


                              #15
                              I think (I hope..!) I've done all there is to do for the 'snakes', so the upper rear of he fuselage can be sheeted...



                              It's to be trimmed, obviously once the PVA has set. Yes, of course, the sheet gets lested down, as usual...



                              Now that that's been put to one side, the board is clear for another major step: the union of the wing halves. A final adjustment, following on from the trials last night, a pretty liberal application of glue to all relevant surfaces and we're off...



                              I think there's enough clamps in there..!



                              I'm still waiting for my tiny magnets to arrive, to be able to finish off the hatches. When the fuselage is ready I'll have to get them done, so as to sand it down and prepare for covering. Similarly, once the wing join is set, I can finish off the sheeting and wing-tips, and get the iron out for covering. Not much to be done in the meantime, so I'll get on with the washing-up and a few other household duties. Back later...

                              Comment

                              Working...
                              X