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Thread: A flying wing pusher airplane design

  1. #21
    rwanttaja's Avatar
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    Quote Originally Posted by Dana View Post
    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.
    Years ago, a college student wrote a program to optimize the canard size. The final result was that the canard should be five times larger than the wing.....

    Ron "Think About It" Wanttaja

  2. #22

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    Quote Originally Posted by Dana View Post
    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.
    Any perceived advantage is offset by not one but several disadvantages. One designer seemed to have worked the pro/con formula out to perfection but I notice the industry didn't follow which they would have had there been any real advantage to a canard configuration. In fact, there would have be a very rapid shift to canard airplanes had there been a worthwhile improvement in efficiency.

  3. #23
    Jim Heffelfinger's Avatar
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    check this out............ http://www.marskeaircraft.com/

  4. #24
    Jim Heffelfinger's Avatar
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    Quote Originally Posted by FlyingRon View Post
    First off, you do not have a flying wing. A flying wing is a design without a prominent fuselage. You don't even appear to have a "tail-less" aircraft. Just a novel design to hang the tail off the wing tips.

    What I see of challenges here:

    As mentioned, the structure needed to support the yaw and pitch movements way out on the end of the wings like that (there's good reason that they normally attach elevators to the fuselage).

    The pitch control is going to be interesting. It appears you have the CG way ahead of the center of lift. This is going to mean you're going to have to generate a lot of downforce with your "elevator winglets" to keep the nose horizontal. This is going to decrease efficiency as well.

    Configuations like this often have some fun with aerodynamic things like flutter due to the flexibility of the components and the fact that you've got parts of them likely in the slipstream of the pusher.

    Ron - are you thinking of a blended wing ? http://www.marskeaircraft.com/

  5. #25
    FlyingRon's Avatar
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    He doesn't have that either.

  6. #26

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    Quote Originally Posted by Bill Berson View Post
    Takeoff can be tricky. Read the Sport Aviation archives for "Dean Delta". A fatal crash on first takeoff. The thrust on takeoff pushed the nose down. It wouldn't rotate with no prop blast over the tail. But when the pilot aborted at high speed, the lack of nose down thrust then caused a pitch up and it went out of control.
    Bill - I found one of the articles from 1963 but couldn't find anything else. Not to divert the thread but it is interesting given the level of effort put into designing and building the plane that he would have has such a misunderstanding of it's handling characteristics, doesn't it?

  7. #27

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    Well, test pilots can't think of everything. That's why they call them test pilots.
    I was a test pilot of my own design. It pitched up unexpectedly to 12 feet on a high speed test run. I had no intention of flight but it caught me unexpectedly. It was tail heavy and I was planning to add more nose weight the next day before the first flight.
    Last edited by Bill Berson; 07-18-2018 at 01:16 PM.

  8. #28

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    @Bill - hope i didn't imply anything derogatory about the designer/pilot by the way. But you're correct...unexpected events can happen to the best of us.

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