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Thread: Flap extension

  1. #1

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    Default Flap extension

    I am working on a stretch project that will be licensed Exp Exibition. I am working on extending the flaps from 52 to 81 inch’s long, shortening the aileron a few inches and moving it to the end of wing after a squared wing tip mod. I am concerned about additional twist of the rear spar and would like to get drawings that would show reinforcement to account for this. Any guidance would be appreciated..
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  2. #2
    Stephen's Avatar
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    Default Re: Flap extension

    Not sure how you will end up with an 81 inch flap and shorter ailerons. My stretched which is per STC has a 90 inch flap. My aileron is 102 inches just like Super Cubs and is moved out to the wing tip attachment point. Which is squared off. Look at the pictures I just posted and you will see the rear spar reinforcement. The stretched wing also has more ribs, compression struts and drag wires than a Cub wing. Also the false spar area is boxed in with aluminum panel the whole flap length. And, the STC calls for two actuators linked together for each flap. I love having a 90 inch flap. I can make approaches in the 40's with good visibility.
    "You can only tie the record for flying low."

  3. #3
    Stephen's Avatar
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    Default Re: Flap extension

    If your plane is currently certified. Why not purchase the STC and get the plans?
    "You can only tie the record for flying low."

  4. #4

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    Default Re: Flap extension

    Quote Originally Posted by Stephen View Post
    Not sure how you will end up with an 81 inch flap and shorter ailerons. My stretched which is per STC has a 90 inch flap. My aileron is 102 inches just like Super Cubs and is moved out to the wing tip attachment point. Which is squared off. Look at the pictures I just posted and you will see the rear spar reinforcement. The stretched wing also has more ribs, compression struts and drag wires than a Cub wing. Also the false spar area is boxed in with aluminum panel the whole flap length. And, the STC calls for two actuators linked together for each flap. I love having a 90 inch flap. I can make approaches in the 40's with good visibility.
    I joined the inner left flap to the inner right flap for the left wing and kept the 33.5 hanger spacing. This allowed use of inner aileron position for outer flap hanger providing 81" flap. Not extending the wing just squaring. Not looking for a super stol, stol is enough and dont want to kill my cruize speed. As far as exp there are other mods I am planning such as turbo charging/normalizing, gear change to Supercub gear, matco brakes, etc.

  5. #5
    Stephen's Avatar
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    Default Re: Flap extension

    I did have to move several hinge brackets. My wing span is a bit over 37 feet. The cruise difference was around one mile per hour. Plus, it flies much better on the step at 2200 rpm. Good luck on your project. Post pictures.
    "You can only tie the record for flying low."

  6. #6

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    Default Re: Flap extension

    Longer wings don't always hurt speed. They will provide more lift with less AOA/drag.
    DENNY

  7. #7

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    Default Re: Flap extension

    Wow thats nice that you did not loss much cruise speed. I assumed since a Supercub is so much slower it was due to the wing span.

  8. #8
    Stephen's Avatar
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    Default Re: Flap extension

    Quote Originally Posted by nimdave View Post
    Wow thats nice that you did not loss much cruise speed. I assumed since a Supercub is so much slower it was due to the wing span.
    Super Cubs are slow because they have more angle of incidence. They get shorter take off distance but slower cruise.

    And, Denny is correct.
    "You can only tie the record for flying low."

  9. #9
    Administrator Steve Pierce's Avatar
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    Default Re: Flap extension

    I would not shorten a PA20/22 aileron from my experience. Moving it outboard to the tip of a squared wing does help give it adequate aileron response though.

  10. #10

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    Default Re: Flap extension

    Quote Originally Posted by nimdave View Post
    Wow thats nice that you did not loss much cruise speed. I assumed since a Supercub is so much slower it was due to the wing span.
    Cub gear is one of the big things that slow them down. PA 12s and Pacers will slow down quite a bit when you start adding Cub gear to them. If you put spring gear on a Cub you can increase cruse 10-15 mph. The angle of incidence is not that big of a factor, info from PA12 pilots that changed to cub incidence the tail will just fly different But now windscreen angle can effect speed. Covered gear and fairings can get you some speed. Every plane is different and one small change on any part of the plane can have effect on the entire plane. If it is only a few inches just push that last bay out to match the Aileron length. If you want to strengthen the rear spar area look at a full wrap around false spar like Javron does. " Just for clarification what do you mean by additional twist of the rear spar ".
    DENNY

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