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Canard design : Multiple perspectives .....

Discussion in 'Indian Air Force' started by ssatpathy, Jul 29, 2011.

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  1. ssatpathy

    ssatpathy FULL MEMBER

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    I started this thread since it appears there seems to be enough of an interest in the topic to demand its own thread.
     
  2. kish

    kish FULL MEMBER

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    Which country first used the canard . .
     
  3. @speaks

    @speaks Captain SENIOR MEMBER

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    Canard Advantages and Disadvantages

    Advantages:

    1. Possibility for very good stalling characteristics without elevator stops.
    2. Sometimes a desirable layout from the packaging standpoint: Main wing carry-through behind cabin, pusher engine installation simplified.
    3. Synergistic use of winglets for directional stability.
    4. In certain cases a simplified control linkage is possible.
    5. When wing flaps are not desired (for simplicity as in ultralights, or competition rules as with standard class sailplanes for example) the CLmax of a canard may exceed that of an aft-tail airplane.
    6. For unstable aircraft, canard designs may have a CLmax and/or drag advantage.
    7. Control authority is larger for unstable canard aircraft at high CL than for unstable aft-tail designs.

    Disadvantages:

    1. Fuel center of gravity lies farther behind aircraft c.g. than in conventional designs. This means that a large c.g. range is produced or that the fuel must be held elsewhere (e.g. strakes near the wing root.)
    2. CLmax problems with flaps or margin on the entire wing: Flaps produce a larger pitching moment about the c.g. on a canard aircraft. This results in the need for both large canard aerodynamic incidence change and high maximum canard lift coefficient. Note that since the value of a S is usually larger for canard designs, Cm0 has a greater impact on L than it does on aft-swept designs.
    3. Induced drag / CLmax incompatibility: Canard designs can achieve equal or better CLmax values than conventional designs, and similar values of span efficiency. However, the configurations with high CLmax values have terrible values of e and those with respectable e 's have low maximum lift coefficients.
    4. Directional stability: The distance from the aircraft c.g. to the most aft part of the airplane is usually smaller on canard aircraft. This poses a problem for locating a vertical stabilizer and may result in very large vertical surfaces. (Note, however, that winglets may be used to advantage in this case.)
    5. Wing twist distribution is strange and CL dependent: The wing additional load distribution is distorted by the canard wake.
    6. Power effects on canard - deep stall: Accidents have been associated with tractor canard configurations for which the propeller slipstream has prevented canard stall before wing stall. The result is a possible deep-stall problem.
    7. Finally, and perhaps most importantly, canard sizing is much more critical than aft tail sizing. By choosing a canard which is somewhat too big or too small the aircraft performance can be severely affected. It is easy to make a very bad canard design.
     
  4. Death.By.Chocolate

    Death.By.Chocolate 2nd Lieutant FULL MEMBER

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    USA, over 100 years ago.

    [​IMG]
     
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