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  • Dad3353
    started a topic Svenson Prima, 3-Axis Trainer, from a Svenson kit...

    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.

  • Dad3353
    replied
    For those with long memories, I finally managed to align all the stars and planets required to get my Svenson Prima off the ground. Here's a (rather modest...) video of the Event. The 'plane looks like a speck in the sky, but it's a trick of the Sony Handycam lens; it's nothing like as far away as that, in reality. It's a 'first' for me, though, to have anything at all captured is a miracle, as there's no eyepiece, so it's 'point and shoot', with a hefty dose of luck. Today I was lucky.
    Another novelty, though, is the embedded 'parallel' video from the minute 'Go-Pro' knock-off, which a rubber-banded to the nose, as an experiment. It can be seen (glimpsed, really...) in the very opening frames; it's that black dot on the nose. Again, it captures what it captures; it'll be better next time..!
    Anyway, there it is. The 'plane flies, so I can have confidence in starting to fly her, knowing that, if it goes wrong, it's me, not the 'plane. -_-
    Here's the video...

    Leave a comment:


  • Dad3353
    replied
    S'been a long time, but my Prima has not been forgotten. I've been occupied with the Flamingo build, now finished, but the weather over the Spring was dreadful, and there has been no opportunity to get a maiden flight in. Today was the third time I took it to our club flying field, and the third time that the motor refused to behave itself. Tested at home, all is well. Arrive ready to fly... Motor stutters, goes into 'protect' mode, end of maiden attempt. Last week I thought I had it solved, as I'd found the cause of the stuttering: the ESC had switched to its 'default', new, mode, for 3S, heli mode. The Prima has a 4S, and the initialisation wit the default mode was the cause of the error 'beeps'. I had programmed (again...) the ESC for the correct mode, but, in the field this afternoon, we were treated to yet another display of capricious behaviour. It's now fixed, at home once more, as I've removed the YEP 30A ESC, replacing it with a Hobbyking 30A. I'll know at the next outing if it's going to do a better job; I'll be testing it on the bench at home every day, just to be sure that the parameters don't suddenly switch. Why does the YEP change its mode..? Goodness knows, and I'm not going to spend much time finding out. They're quite reputed (there are several at the club using 'em...), but I think I'll spend just a little more to get something in which I have confidence, and which is not going to spoil what should be a pleasant afternoon.
    On the Good side, the maiden won't be long coming, now, so nearly there...

    Leave a comment:


  • derfred
    replied
    No big deal, the washout is just a little twist on the wing like if the wing incidence was decreasing to the tip, the result is a more stable airplane with more control on the ailerons, this article explains it:
    http://www.boldmethod.com/learn-to-f...e-more-stable/

    When a wing needs much twist this has to be done right on the construction, flying wings can be like this, on a plane like the one you did you can just twist the wing after it´s been covered, this is not mandatory but the plane will fly better and more predictable.

    I usually ask someone to hold the wing, half wing on a table and raise the trailing edge then with the iron remove the wrinkles on the wing, on both sides, then put the twisted half wing on the table and see if the trailing edge has risen a bit, 1 to 2 cm is enough for a plane like the one you did. Repeat the process until the result it´s achieved and then do the same on the other half wing.

    The idea is to raise the trailing edge not just twist the wing or lower the leading edge, something that would not be easy to do.

    You can make an experiment, fly the plane as you have it, then try the washout, you´ll see the difference.

    Leave a comment:


  • Dad3353
    replied
    Originally posted by derfred View Post
    ...Have you added washout to the wing? I haven´t noticed that on your posts.
    Not really knowing what 'wash-out' is all about, I've just followed the plans as best as I could. Does it make a difference..? It's probably too late anyway..!
    This is a beginner's project; anything experts would do differently I'll maybe know how to do after I've done a few dozen myself. Whilst doing as best as I could, I'm not looking for optimum. To me, the most important criteria is reliability; performance comes much further down the list. If I can learn to fly '3-axe' with her she'll have done the job asked of her; any 'build' lessons are a bonus.
    Whilst waiting for a bit of dry weather, I've the Sky-Mite to attend to; will that benefit from 'wash-out' too..?

    Leave a comment:


  • derfred
    replied
    Congratulations for the build! I would just check the control surfaces travel and if they are all correctly configured and on a good day take it to the tarmac and taxi a bit just to see how it handles then fly it Get some altitude and trim it.

    Have you added washout to the wing? I haven´t noticed that on your posts.

    Leave a comment:


  • Dad3353
    replied
    Just a few minute details left now, such as ironing on the glazing...



    It looks grey in the photo, but it's silver, really. All the controls have been connected up and tested; they all work, which is a relief, but the real test will be in the air, of course. The C of G seems to be about right, although the latest test was only approximative. I'll probably add a few grammes of lead in the nose bay for the first flight, just to be sure. I can then remove until optimum is reached.
    Other than that, I'm only missing the wheel retainers I wish to use (ordered this evening...). there are star-washer-type clips in the kit, but they inspire me less than proper collars. Here, then, is the last photo for a while, until the weather perks up enough for getting out...



    I'm still not decided whether some glide testing in the fields out back would be useful; the club folks said not to bother 'Just take her up..!', but if we get a clear spell I may well do a trial or two, as it's just down the track, and costs nothing. More, then, when we get out...

    PS: I nearly forgot. I've ordered some transparent water-slide film, so as to be able to print my own aircraft registration lettering. Maybe a photo or two if that turns out well. Till then...

    (The screen goes blank, a low whistle is emitted, which quickly fades to silence. The house lights brighten slowly...)

    Leave a comment:


  • Dad3353
    replied
    The new Oracover has arrived, so I'll get back to covering the wing. Whilst that's happening, the epoxy can be setting for the hinges on the rudder and elevator...



    Transparent Orange was ordered, and Transparent Orange is what was delivered. Yes, it's much easier to apply, most especially when removing the backing film. Easy-peasy, unlike the orange/yellow roll. Never mind that now; here's the open structure covered. I've not tensioned it at all; that'll be done as a final stage when all is filmed...



    Now for a clever ruse. No, I can't claim to have invented it; it was a nice Australian bloke that described how he'd done it, so I used his method (thanks, Bernard...). I'd like a nice curve, you see, around the orange at the wing root. Rather than cut a whole piece of film to the desired shape, I cheat..! I create four 'patches', which will be applied first, just for the curve. I take a piece of white off-cut, and cut a square. With an X-acto fitted into a schoolboy's compass, I cut a circle from the middle of the square. This square is then cut in four, giving four 'patches'. Here's two of 'em applied on the underside...



    The discarded circle can be seen just in front of the wing, weighted down by the mitre box. The sharp-eyed among you will also notice another hot tip whispered to me (thanks, Dave...): Cover the fibre-glassed ribbon at the wing joint with masking tape, so that the film adheres better. That tip didn't fall into deaf ears, either.
    The centre section can now be filmed, in white...



    All goes pretty much according to plan. The rest of the sheeted wing is covered in white, and the result changes quite considerably the allure of the 'plane...





    We're now ready to fit the ailerons. Manipulating the wing is a bit cumbersome, although it feels much more resistant since applying the film. A bit slippery for these frail hands, so I wrack my brains for a sophisticated method of holding the wing steady whilst I do the gluing. Here's my technologically-challenged solution: a cardboard box with a couple of 'V's slashed at each end (I've not decided whether to patent it or not...)...



    ... and the ailerons are duly epoxied into place...



    The graceful lines of the cheat 'patches' can be admired..!
    'All very well', I hear you cry 'but what about the servo trays, eh..?' Fret not, they've been patiently waiting their turn, which now comes...



    There are many tips and tricks to be learned on the various forums; not all are heeded by numbskulls such as I. Yes, I know; don't forget to pass the servo wires before closing up the sheeting. Did I pass the wires..? Did I heck..! 'Roll a tube from paper to ease the passage of cables down the holes in the ribs'. Good advice. Did I heed it..? Nah; a bit of string with a fishing sinker and it'll be a doddle. Yeah; sure. A couple of hours later, spent 'fishing' with kitchen twine and lead shot and I finally manage to pass extension wires through. (I did, however, remember to check which connector end to pass through which hole..!)...



    The trays can now be presented to the wing, and the servos connected...



    Some slight trimming, for clearance, and the whole wing can be tested thoroughly, using a small battery pack and the 'plane's future Rx...



    I've programmed two channels, one for each side, to allow for eventual 'tweaks', if needed. Until then, I'm happy enough with the result so far.
    What's left..? The tailplane and fin are yet to be glued in place, and I'm still working on how best to attach the battery and Rx. That's all, I think. Oh, and fix the wheels on. Mustn't forget that. We'll need a spot of much finer weather than the dismal chilly damp we have presently for taking her out for even a test glide, but I can't do too much about that, unfortunately. Soon, however; soon...
    To be continued...

    Leave a comment:


  • Dad3353
    replied
    Whilst waiting for the new film to arrive, I can install the hinges on the control surfaces that are already covered. Once again, I prepare the space, and start with the rudder, then the elevator, and finally the ailerons. In order to pierce the film at the correct location, I line the piece up with its counterpart, tape 'em lightly together with a spot of masking tape, then put a couple of dots on the edge to be slit. That's one advantage of using translucent film; I can see where the slots are, and, as I've chosen to have one white, the other translucent for all the hinge lines, I can rely on not accidentally covering both sets of slots, leaving no easy way to find 'em again.
    When it came to the turn of the wing, I used the same method of alignment. As I removed the masking tape, after having marked the ailerons, to my astonishment, the orange (yes, I know; yellow..!) film came away with the tape..! It took no effort at all to peel away all the film from both wing panels I'd done yesterday..! So much for the glue, then. I'll consider myself lucky to have discovered this now, rather than in flight. The fuselage has also this yellow film on it, but as it's planked, and not open structure, maybe the film will stay on a bit better. I'll test a small part, but I'd rather not risk removing it all from there if it's not absolutely necessary.
    So now the wing is back to its natural wood, and will be covered entirely with the new Oracover (and the white I already have...).
    The hinges..? Yes, I did get them done, but no photos of the work in progress, as I'd left the camera by the PC, and had already mixed up the epoxy. Not too much time for doing all the parts; no rush, but no time to waste, either. I used a toothpick to get a little epoxy into the slot (not very easy...), then offer up the hinge, which has four little holes in each section. With the toothpick I fill those holes as best I can, then slide the hinge into position. Just before it reaches the full depth, I wipe away any excess from the hinge line, then achieve the positioning, making sure that it's lined up square and able to flex in both directions. Altogether, about two hours for the whole operation; the glue was just starting to stiffen up when I was finishing the last one. Here they all are, on display...



    I'll be able to fit them to their respective parts, but I'll wait until the wing is ready, then do them all at once, so as to not have to mix up this messy stuff more than I need to. I ended up holding the pieces with tissue paper so as not to leave glue marks on the film. I find it difficult to work with this stuff and keep my clumsy fingers completely free of it.
    This evening I may be inspired to finish off the servo trays, but it's far from certain, as I'm not feeling well. Tomorrow, maybe...

    Leave a comment:


  • Dad3353
    replied
    Part I of the covering...

    The reinforcing ribbon has gone off very nicely, so, after a final rub down, I'm ready to start covering with film. I've not done this for quite some time, so I prepare the workspace, and start off with the small elements which, in theory at least, will pose less problems. First up are the servo trays...



    The only slight trap here is that these are ply, not balsa, but they are a decent enough 'starter' for me. The elevator is next, and cooperates nicely...



    On, then to the other bits and pieces in white: the ailerons, motor hatch and tail-fin; I change colour for the tailplane and rudder...



    Now that I'm feeling a bit more confident, it's the turn of the fuselage. It's to be done in two colours: 'burnt orange' (it's really yellow, though...) for the front...



    ... and white for the rest. No great pitfalls; I'm glad that you can't see the slight wrinkles in places, though..!...



    Now up to full speed (although I'm slow, really; it's just an expression...), we start the underside wing panels. Orange (OK, yellow...) for the ribbed spaces; white for the sheeted parts. I enlist our eldest to help trim the edges, as I can't hold the wing and the knife at the same time...



    All goes off quite smoothly; I'll not tension these panels until the top is done, though. I turn the wing over and start to cover over the ribs again. Oh no..! Catastrophe..! I suddenly find the true cost of 'chinacote'. After tacking down the film, I start to go around the edges. A whole corner, at the wing centre section, has no glue..! It'll shrivel up well enough, but sticks to nothing..! Darn it..! Luckily, it's not so well stuck down that I can't strip it off, with the aid of the iron...



    I see no sense in trying another piece of film; the faulty piece was from the cut edge of the roll, so I would guess that the next part of the roll will also have no glue. How much more of the roll, indeed..? No, I'll leave the wing for now, and find another source of film. I doubt that I'll be buying much more of the cheaper stuff (hap'eth of tar, and all that...). That's all, then, until the postman brings a fresh batch of orange. It may even turn out to be really orange, and not yellow..!
    To be continued...

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  • Dad3353
    replied
    Now that the hinges have been measured up and prepared, the leading edge of the ailerons can be chamfered. They need to be held steady, and preferable at an angle, so I put one on top of the other, and pass pins through both into the building board. Not quite a 45°, but a decent head-start. I'm using a small block plane for this (some call 'em 'finger' planes, I believe...) and go steady, keeping the sole at a slight angle to get the final chamfer close to 45°. I've marked a centre line along the aileron, so as to see how far I've got. Here's the first shavings...



    ...and, a pile of shaving later, the result...



    A rub down with sandpaper to smooth 'em off, and they're done.
    One last task, then, before covering: the fibreglass ribbon for the wing. The epoxy was delivered this morning, so I got that done this evening. No photos of the process, as I was a bit busy sorting out stuff, and there's not too much time to waste. An example..? I 'borrowed' the digital kitchen scales so as to get the exact proportions by weight. A container on the scales, reset to zero, and I start to pour in the epoxy. The scales don't register. Zero grammes. I pour a bit more, and more yet; still no reading. The scales decide then to 'time out', and the screen goes blank. Darn it..! How much is in the pot..? Dunno. I quickly get another, identical, pot (a glass yoghurt jar...) and weigh it. The scales oblige, so I weigh the jar with the epoxy. 20 grammes..! Far too much for the task in hand, but at least I now have a reference weight for the hardener, needing a ratio of 1 to 0.6 by weight. OK, then, I have to add 12 grammes. I zero the scales, take the hardener, and pour it in carefully. The scales don't budge. I pour in a bit more. Still nothing. Again, thinking that the measuring is over, the scales shut down. I'm left finishing off the pouring to 'guestimate' a ratio of 1 to 0.7 by volume. How close did I get..? I'll know when (or if..?) the epoxy 'goes off'. Thirty minutes at 20°C, but it's much colder than that in my workroom, probably closer to 7 or 8.
    I'd already prepared the tape, marking and cutting slots for the dowel pegs, and striping each side of the area to be 'glassed' with a band of masking tape. I've given a small brush a severe trim, too, as I'll be more 'stippling' than painting with it. Not the easiest of jobs, but I think (I hope..!) I got away with it; here's the final result, after removing the masking tape...



    I'll know tomorrow if the epoxy has gone off correctly or not. Fingers and toes crossed until then...

    Leave a comment:


  • Dad3353
    replied
    It never fails...

    I mention in a couple of previous posts in this topic my order for magnets, placed in the first days of December. These were to hold down the hatch over the motor, but were long in arriving. I decided a few days ago to go without, and remodelled the hatch so as to no longer use these ordered magnets. Yes, you've guessed correctly; they arrived in the post this morning..! D'oh..! They'll be useful for future 'planes, of course, but still... I ordered tiny ones, but was still surprised when opening the envelope; they really are tiny..! Luckily I ordered a hundred, as only one would be almost invisible. I'll try them out later on, to see just how powerful they are. For the moment, despite their size (or lack of it...) I couldn't separate just one. I'll try later sliding 'em apart, but for now they're well and truly locked together. Still, that bodes well for their intended usage.

    Leave a comment:


  • Dad3353
    replied
    With the new hatch cover in place, I was not happy with the fit over the motor bay; the ply needed to bend more. Not wanting to make another hatch altogether, I decided rather to fill the gap, thus reducing the curve required. Using offcuts (I throw little away..!), I could lay them over the motor bay flanks, but needed to sand them down with a taper. How to ensure I don't sand too much..? A variant of a tip seen on other build logs: a couple of wood screws were taped to the nose, preventing the sanding block from rubbing further down at that end...



    The result..? A much better fit...



    ...which enables me to carry on sanding the fuselage, rounding off the corners and edges...



    The fuselage can now be put to one side, ready for covering. Now for another 'fun' task which I'm not looking forward to. Hinge slotting. Hands up those that revel in this activity..? No, I thought not; not many huh..? I'm not surprised. In a previous post, I described how I'd gone about slotting the hinges for the elevator. I 'invented' a tool for the job, but was not convinced that it was the best that could be done. Having seen positive revues on the subject, I invested in a Dubro slotting kit. 'At last..!' thought I, 'A tool which will make this much easier.' Well, not entirely wrong, but not entirely convinced, either. After a few trials on scrap pieces, I launch into the slotting for the rudder. I start by marking the hinge locations, after taping the pieces together to ensure a match...



    Then comes the gruelling part. Plunging the cutter into the delicate assemblies that I've been carefully protecting all this time..! Another mistake was revealed, too. It was not a Good Idea to profile the leading edges of the rudder. It makes finding the centre line with the parallelogram tool quite arbitrary..! Still, needs must, so I plunge away...



    Hmm... Not too bad, but not much easier than my makeshift tool. The centering gadget is worthwhile, though.
    On to the ailerons, then, where it's a very different story. If the ailerons themselves get slotted with reasonable accuracy and ease, not so the wings..! Behind the trailing edge is a balsa reinforcing block, placed there on the plan exactly for giving enough meat for the hinges. All well and good, but the balsa used is of a very different category; very hard and resistant. The poor slotting tool bent and twisted, and it started to feel more like butchery than model-making. Another approach was required...
    Dremel to the rescue. I improvise a jig, raising the wing on a couple of stock sheets (if ever one wonders why it's a Good Thing to buy those cheap bundles of balsa, here's one of their many uses...). The Dremel, in its holder became the right height to be able to chain-drill the slots, using a 1mm bit...



    I could slide the Dremel across the table and maintain the orientation quite easily. Once the drill bit had done most of the 'heavy lifting', it was much easier to finish off with the Dubro tools, and the final result was much cleaner. Lesson learned; next slotting session I'll go straight to the Dremel solution, I think.

    Once again, the time is ripe to put all this stuff together, to see how it will turn out. Here, then, is the progress so far...







    Still only naked wood, of course, but no longer a bunch of sticks and planks..!
    What's left to do..? I'll take delivery of laminating epoxy tomorrow or the next day, which will be for the glass fibre tape around the wing joint. I've just enough left from the Electra kit; I'll need some more for my next builds.
    Whilst mounted in this 'raw' fashion, I loaded her up with all the gubbins (a technical term...) to see if the C of G was somewhere close, and help with deciding battery location. At first, with the battery I'd intended to use, the 'plane wouldn't even stay on its nose-wheel..! Two batteries did the trick, and a rough test of CoG seemed to be perfect. I weighed the whole 'plane, too; she turns the scales, fully loaded but naked, at just under 1200 gr. I don't know if that's great or poor, but it's too late to change much, anyway..! I weighed the 3s Lipos at 110 gr each, then tried a 4s, much heftier, at 315 gr. Although it's rated for 4s if required, I think I prefer to start off with 3s, as I'm not looking for performance and acrobatics; rather a staid, stable flight for a beginner. I'll look, then, for a 3s weighing around 300gr.
    Phew..! A long post, eh..? Next up..? Probably the covering, after the taping of the wing joint. That's all until then, then...

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  • Dad3353
    replied
    Short, but sweet...

    Now that the wing bolt supports are all in place, there's no point in putting it off any longer. The bolt holes are to be drilled in the fixed part of the trailing edge. How to align the holes with the threaded holders beneath, blind..? Thanks to a buddy for the tip: cheese-head bolts are screwed in, leaving the heads just flush with the underside of the wing when it's in its place. I start with the bolts slightly lower, then raise them a bit at a time until I feel that they touch the wing. Some blue marker is then applied to the heads and I offer up the wing again. Bingo..! There is enough of a round mark to be able to determine the centre of the future hole...



    The suspense is not yet over, however. The threaded holders are installed (as per the plan...) at an angle, so the bolt holes, too, have to respect that angle. I mark an approximation, by eye, on the trailing edge, then go for it..! A 3mm pilot hole, then a 6mm. The bolts are 6mm, so I pass a 6.5mm through, and here's the result...



    The two bolts slide through, with no 'play', and meet up with the threaded holder below. Pleased..? Yes, I'm pleased; I apprehended this stage, as it holds great scope for messing things up, and I really didn't want to have to patch up a bodged job. Thanks again, then, that hint worked a treat.
    I've not screwed the bolts fully down yet, as they're a bit tight, and will benefit from a touch of lubrication. Still, an important step has, again, been taken..!
    Next thing will be the marking out, cutting and dry fitting of the hinges for the control surfaces. Maybe later this evening; maybe tomorrow. Again, care is needed, so I'll go easy, and not rush it.
    To be continued...

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  • Dad3353
    replied
    There's one last piece for the fuselage: a cross-piece to support the trailing edge over the cabin, where the wing bolts will be holding the wing down. The plan calls for a simple piece of square; I've cut a slightly 'beefier' piece to marry exactly with the angle of the trailing edge, to ensure full support and stability, and glued it into place. Careful examination will reveal the 6mm bolts I'm going to use to find the exact spot for drilling the wing bolt holes. I'll edge them up, little by little, until they leave a mark on the underside of the wing; that'll be where to drill (I hope..!)...



    Once again, a method has to be found to hold the piece in place as the glue goes off; a steel rule is pliable enough, and, hopefully, will spring back to 'straight' afterwards..!

    A few details now need sorting. One such is a weakness at the nose, where the 'chin' sheet has a split. I thought that the best remedy would be a 1mm ply patch inside, glued flat after having 'wicked' PVA into the split. It's clamped down firmly...



    I know of no better way of making long-awaited parts arrive than to do without them..! With that in mind, I've decided to change the hatches over the motor and battery compartment, by uniting them into one, and changing the orientation so as to feed the new hatch from the front. To this end, I'll need to reverse the current peg for the battery hatch, taking it to the other side of the firewall, and attaching it to the underside of the new, longer, hatch. I can use the same piece, line it up with the dowel hole, then glue the hatch onto it. This should ensure alignment. This is the peg and its support; the blue masking tape is to ensure that the hatch doesn't stick to the firewall if there's any glue creep...



    Here are the constituent parts of the new hatch system. The two present hatches (to the right of the fuselage...) will be put in place on the nose, then a ply sheet (to the right of the two hatches...) laid over, to join them together...



    Here, the complete assembly has been presented over the nose, with the dowel peg in place. The new hatch has to be firmly held down to glue the peg support to the hatch, from underneath. Our trusty hammer does the trick, as usual...



    Slight complication: the nose has a top curve, so 'persuasion' is needed to hold the ply sheet flat to the motor hatch. The hammer of course, but not only...



    Whilst all that is drying, I can go over the whole wing, using balsa filler and sandpaper to get a decent finish in preparation for covering. 'Twon't be long now...



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