Tail on ww2 planes

Discussion in 'Tips, Tutorials & Tools' started by paradox, Aug 8, 2006.

  1. paradox

    paradox New Member

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    Hey,
    I'm very new and trying to build my second ever plane, the de Havilland Vampire from trotskiy:
    http://trotskiy.moo.jp/71.html

    I thought it would be nice and easy and I could get a little more experience. Unfortunately I am having a lot of trouble trying to make the two spars with their tail planes. I've assembled them, but when I try them out on the wing, the tail is about 25 degrees away from vertical. I cant really bend them because the card starts to buckle. I also had problems getting a nice smooth transition from the vertical tail plane, to the rounded body.

    It seems that a lot of world war 2 era planes feature feature a nice smooth transition from the leading edge of the tail into a rounded body, and I was wondering if anybody had any hints for me.

    Here is a pic of the part that is giving me problems:
    [​IMG]

    Thanks!
    Paradox
  2. michik

    michik Member

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    As for the strange angle:
    To me this sounds like you simply tried to glue the tail booms to the wings. However, you have to cut slots into the front of the booms , and slide the booms over the wings. There are some black lines printed on the sides of the booms, that's where you have to place the slots.

    As for your other trouble:
    Well, Trotskiy models are always somewhat simplyfied, and in this case, the tail booms are designed for a rectangular cross section. Though it IS possible to build them with a rounded cross section, it is some kind of challenge, of course, in particular for a beginner. You might give it a try this way: Score the foldinglines on the backside (i.e. on the unprinted side) with a ball pen, and build the booms with the rectangular crossection (you have to leave them open at the front). When the glue is thoroughly dry and settled use something like a skewer to give the booms a more rounded shape.

    Bye!
    Michi
  3. paradox

    paradox New Member

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    Thanks!

    With the strange angle, nope, I did cut along the black lines. It seems like there is a twist in them caused by the way the tail merges into the rounded boom.

    The idea of scoring on the back and building them square, before using a skewer to round them is a good one! I just tried to round them before gluing and it obviously didn't work to well :) I'll try it out tonight.

    Paradox
  4. michik

    michik Member

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    I've had a second thought on your first problem. Thought 25 degrees seems a bit much to me I'd suggest to put together the wings, the tail, AND the fuselage, and THEN decide whether it looks right or not. It might well be that the problem solves itself.

    First:
    The Vampires's tail booms are actually looking upwards, as you can see in this drawing (->http://richard.ferriere.free.fr/3vues/dh100_vampire.jpg) and in this picture (->http://pictures.collector.free.fr/Aviation/Air Expo Muret 2005/pages/page_50.html), too . There are two simple reasons for that. One is to keep the horizontal stab clear from the jet stream. The other is to keep the tail away from the ground during take off and landing (the Vampire has a pretty short landing gear).

    Second:
    Trotskiy models are designed to really fly. Aerodynemics require a conventional plane (not a canard) to have a bigger angle of attack on the wing than on the horizontal stabilizer to fly stable. Obviously, a freeflying model need even more stability than a piloted one, and therefore it might well be that Trotskiy has increased the wing's angle of attack in comparison to the real Vampire.

    I hope this helps!
    Michi
  5. paradox

    paradox New Member

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    Hey,
    I put together a new set of booms, and sticking to a square cross section and scoring on the back with a pen worked a treat! They look a lot more crisp than my first attempt.

    I also figured out what the problem was with the angle being off. I used fairly thick card, and as you can see from the picture there is a large yellow tab on the top of the boom. Well, this meant that when I glued the model together, due to the thickness of the two pieces of layer card on top, I got a trapezoid instead of a straight rectangle. This meant that the slots to connect the boom onto the wing were at different heights, causing the angle.

    [​IMG]


    Anyway, I found that if I quickly test fitted the boom to the wing while the glue was still wet, it had a lot more give, and was able to fix the problem.

    Thanks for you help, I'll post pics when I am done!
  6. michik

    michik Member

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    Ahh,

    looks like I misunderstood you completely about the angle. But I'm glad to hear that you solved you problem anyway.

    Bye!
    Michi