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Thread: Twin Jabiru!

  1. #1
    I intend to fly until my beard gets caught in the propeller. And since I don't plan on growing a beard, that may be a while. Ernest K. Gann, age 69


    Daily Diatribe - (Carl's Blog)

  2. #2
    They are going to have a few problems with this layout.

    The majority of the slip stream from the props appears to go below the wing this will reduce lift on the inboard section of the wing and create some very interesting stall problems. Power on stalls also may be violet or unpredictable as the inboard wing may have very uneven lift at hi AOA.

    Also may have some very strange roll tendencies with flap down.

    They may lose a lot of performance as the prop airflow arcs will impact the front of the fuselage asymmetrically and reducing the thrust and may have some interesting pitch and yaw tendencies with power changes.

    Also they may experience tail plan vibration or even elevator flutter due to the shape of the engine nacelles and their location in relation to the tail plane. ( this has been a problem on a lot of twins during first test flights and a lot of work had to be done to fix the problem )

    Rudder effectives may be reduced due to the prop slipstream being uneven over the fuselage sides this can also lead to air damming behind the props which can create unwanted vibration and noise. ( this is the problem with the islander the props are too close to the fuselage. They did this to reduce the VMCA but created a lot of other problems.)

    There is more but not as major as the items I see above.

    Hope I am wrong as aerodynamics is more of an art the science.

  3. #3
    It certainly seems that the design has its share of challenges built-in...

    Also, are those fixed-pitch props? Unless one can feather a dead engine, it'd be about as useful as Champion's Twin Lancer... useless as a trainer, possibly a cheap time-builder but mostly a novelty.

    Unless... they really got to work on cleaning up some of the built-in inefficiencies and turned it into a backcountry workhorse. Think Lockwood Air-Cam with a little less in the way of elemental exposure to the crew.

  4. #4
    I heard they are planning to develop a kit so owners of their singles can convert to twins.

    Not sure about that idea...

  5. #5
    the inboard wing may have very uneven lift at hi AOA.
    Last edited by Carl; April 24th, 2016 at 06:21.

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