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Thread: A flying wing pusher airplane design

  1. #11
    Quote Originally Posted by Bill Berson View Post
    I doubt these models have abandoned natural stability. They likely still have a normal positive stability margin.
    That's correct. They possess inherent stability. If you turn off the artificial stability, unlike a quadcopter, they will keep on flying (albeit requiring more pilot skill and attention).

    The most common digital stability augmentation system is the Spektrum AS3X (Automatic Stability 3-Axis), which has rate gyros and a heading hold gyro. It also has a separate function called SAFE (Sensor Assisted Flight Envelope) protection. This adds self-leveling and roll & pitch limiting.
    Last edited by David Lewis; 06-23-2018 at 09:39 AM.

  2. #12
    Quote Originally Posted by FlyingRon View Post
    It appears you have the CG way ahead of the center of lift.
    The dashed line on the wing depicts the mean aerodynamic chord. My intention is to have the CG a short distance ahead of the center of lift, and increase horizontal tail volume and electronic stability augmentation to compensate for the small static margin.

  3. #13

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    Dave i can feel for your interest for these tings, i do too, so many RC planes are flying wings.
    In the subject of safety and usability, why not use a canard like the Velocity or Berkuit, they are essentially flying wings with an elevator stablizer in the front.
    These are already developed and are very safe and useable. If you want to get more bang for your buck this is the way to go, It sometimes takes many years to develope
    a new model like this, you are risking your money and your life.
    jeff

  4. #14
    Thanks Jeff, Ron and Bill for valuable advice and suggestions. I never understood the advantage of canards over ordinary (tail-in-the-back) configurations. Can you enlighten me?

  5. #15

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    Very cool that you're thinking outside of the box - at the minimum you will learn what won't work, which is just as valuable as knowing what will.

    A question:

    The horizontal stabilizer provides the down force to counteract section pitching moment.
    I'm not exactly sure what you're driving at here, but you may have just answered your own question in regards to canards (other than canards up front are out of the way of prop blast streams of air and reduce drag, along with other things more educated folks will share).

    You could, if you wanted to make things simpler in one way and more complex in another, ditch it entirely. Have the ailerons do double duty, as it were.

    I think your sweep on the wings may be a tad aggressive. The overall shape of the design does not imply great speed.
    The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.

  6. #16

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    Dave here is a video on flying wings

    https://www.youtube.com/watch?v=dUCF...ature=youtu.be

    Horizontal stabilizer on the tail of an airplane produces negative loads to balance the airplane on the wings. It changes with flight speed.
    A canard has similar function but uses positive loads. The velocity is a well developed airplane, carrys 4 people at reasonble high speed, reasonably easy to build and very safe.
    My favorite airplane. It will be useable when you are done, you wont have to risk your life and money like . just my opinion
    Jeff

  7. #17
    Quote Originally Posted by Frank Giger View Post
    The overall shape of the design does not imply great speed.
    That's true, Frank, this is a maximum fun sport airplane. I went with a helicopter style canopy design. The cabin is roomy, which would make it too slow to serve as practical transportation. It's a high lift coefficient and low wing loading airplane. The ability to fly slowly is good for touring and sightseeing, and short field performance.
    Last edited by David Lewis; 06-25-2018 at 03:58 PM.

  8. #18
    Dana's Avatar
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    What you're showing is not a flying wing, it's a short coupled conventional design with very small (almost certainly too small) tail volume. Placing the pilot and passenger so far forward means a dramatic CG shift when flying solo or with a passenger... note that most successful designs have the payload (people, fuel, baggage) close to the CG. As drawn, the CG will be very far forward, probably well beyond the ability of the elevator to provide enough downforce for a landing flare.

    As others have pointed out, your basic configuration is much more suited to being a canard, then it would be a canard of more or less conventional proportions.

  9. #19

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    Quote Originally Posted by David Lewis View Post
    I never understood the advantage of canards over ordinary (tail-in-the-back) configurations. Can you enlighten me?
    There really are none because as you point out, the stabilizing surface does the same thing whether it's in front or in the back. A canard on your design will block out a large chunk of the visibility you are seeking. Now, three flying surfaces..........that has possibilities.

  10. #20
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    Quote Originally Posted by martymayes View Post
    There really are none because as you point out, the stabilizing surface does the same thing whether it's in front or in the back. A canard on your design will block out a large chunk of the visibility you are seeking. Now, three flying surfaces..........that has possibilities.
    In theory a canard can be more efficient because the forward stabilizing surface is lifting, decreasing the load the wing must carry, while an aft stabilizer exerts downforce, increasing the load the wing must carry. In practice, the forward stabilizer of a canard must be more highly loaded to insure manageable stall behavior, causing extra trim drag and negating much of the advantage.

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