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

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    #31
    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...

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      #32
      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...)

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        #33
        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.

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          #34
          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..?

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            #35
            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.

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              #36
              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...

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                #37
                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...

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