4 ms·

Also interesting is that they settled on what would now be called a canard design with the pitch control surface on the front rather than the tail. This is act

Also interesting is that they settled on what would now be called a canard design with the pitch control surface on the front rather than the tail. This is actually a superior arrangement in most cases as both the wing and the stabliator are both generating positive lift. Most conventional aircraft have the center of gravity in front of the main wing, such that the system is dynamically stable (try throwing a dart backward and you'll see what I mean). To control pitch, they then have control surface in the rear pushing down to keep the nose up. In a canard, the CG is still forward of the wing (and the center of lift) but the control surface helps lift the nose up instead of pushing the tail down improving efficiency. This also has an important safety feature in that you can add a couple degrees to the canard's angle such that it will stall before the main wing. In effect, this means the pilot cannot fully stall the aircraft and put it into a spin, it'll simply mush about, descending in and out of canard stall until the control input is relaxed. Edit: an excellent example of a modern canard would be the Rutan LongEZ and it's accompanying, rather ridiculous, performance numbers: https://en.wikipedia.org/wiki/Rutan_Long-EZ https://en.wikipedia.org/wiki/Rutan_Long-EZ

WalterBright 8y ago
The canard design is unstable, which is why the first flight was of such short duration. Curtiss put canards on his racing airplanes, because he copied the Wrights. On one race, the pilot hit a fence and damaged the canard. He cut off the wreckage and rejoined the race. He then told Curtiss that the airplane flew better and faster without the canard. Curtiss immediately pulled them off of his other airplanes.
- AWildC182 8y ago
  It's only unstable if the aircraft is designed incorrectly. You can achieve the same situation with a far-aft CG in a traditional aircraft. It doesn't matter what the setup is, the aircraft will be unstable if the center of lift is near or in front of the center of gravity.
  - WalterBright 8y ago
    Modern canard designs also use active controls to compensate for the instability. You're right about the CG location relative to the center of pressure, but to make the canard effective it has to be big enough to also make it unstable.
    - AWildC182 8y ago
      Can you provide any sources on that? The only one I can think of would be military aircraft (ie. the Eurofighter) and they likely have relaxed stability (CoL ~= CG) as a design goal. All the GA examples (Long/VariEZ, the Velocity line, Cozy Mk*, etc.) have straight mechanical linkages and don't have any stability issues when operated correctly.
      - WalterBright 8y ago
        Here's a paper that mentions the instability of the Wright Flyer: https://www.researchgate.net/publication/315549654_A_STUDY_ABOUT_CANARD_TYPE_AIRPLANE_STABILITY https://www.researchgate.net/publication/315549654_A_STUDY_A... A bit about active controls for canards: https://en.wikipedia.org/wiki/Canard_(aeronautics)#Computer_control https://en.wikipedia.org/wiki/Canard_(aeronautics)#Computer_...
        AWildC182 8y ago
        I hate to do this but the relevant part of the linked section itself has [citation needed] :) I don't doubt that the Wright Flyer was unstable though. Canards are kinda picky about angle, airfoil, and aspect ratio so if you don't fully understand the system as was the case at the time, it can lead to some problems.
        WalterBright 8y ago
        https://authors.library.caltech.edu/21217/ https://authors.library.caltech.edu/21217/ "The paper shows that the 1903 Flyer was readily controllable about all axes but was intrinsically unstable in pitch and roll, and it could barely be stabilized by a skilled pilot."
- dTal 8y ago
  The canard design is most certainly not unstable. I have built model canards almost by accident, from scratch, from first principles. Nor can you simply remove the canard from a properly designed aircraft, any more than you can delete the tail from a Cessna. Take a wing shaped piece of card or balsa and attempt to fly it by itself. You will find that it rapidly pitches up and stalls, flips over on its back, and repeats the process as it flutters it the ground. You can prevent it from doing this by taping a pole sticking to the front - a pencil, perhaps - as a counterweight to the pitch-up moment. This arrangement flies, but is very difficult to trim and has a tendency to suddenly invert as soon as the angle of attack goes negative. To stabilise it, all you have to do is put a small horizontal surface on the end of the pole. You have made a canard glider. (If you actually try this, you will also need some vertical stabilisation.)
  - WalterBright 8y ago
    Taping a pole to a wing makes it an arrow. The bulk of the air surface is behind the CG. The wing becomes the "tail section".
    - dTal 8y ago
      Your argument is that anything with a center of lift behind the center of gravity is an arrow? In that case all aircraft are arrows.

WalterBright 8y ago

The canard design is unstable, which is why the first flight was of such short duration. Curtiss put canards on his racing airplanes, because he copied the Wrights. On one race, the pilot hit a fence and damaged the canard. He cut off the wreckage and rejoined the race. He then told Curtiss that the airplane flew better and faster without the canard. Curtiss immediately pulled them off of his other airplanes.

AWildC182 8y ago
It's only unstable if the aircraft is designed incorrectly. You can achieve the same situation with a far-aft CG in a traditional aircraft. It doesn't matter what the setup is, the aircraft will be unstable if the center of lift is near or in front of the center of gravity.
- WalterBright 8y ago
  Modern canard designs also use active controls to compensate for the instability. You're right about the CG location relative to the center of pressure, but to make the canard effective it has to be big enough to also make it unstable.
  - AWildC182 8y ago
    Can you provide any sources on that? The only one I can think of would be military aircraft (ie. the Eurofighter) and they likely have relaxed stability (CoL ~= CG) as a design goal. All the GA examples (Long/VariEZ, the Velocity line, Cozy Mk*, etc.) have straight mechanical linkages and don't have any stability issues when operated correctly.
    - WalterBright 8y ago
      Here's a paper that mentions the instability of the Wright Flyer: https://www.researchgate.net/publication/315549654_A_STUDY_ABOUT_CANARD_TYPE_AIRPLANE_STABILITY https://www.researchgate.net/publication/315549654_A_STUDY_A... A bit about active controls for canards: https://en.wikipedia.org/wiki/Canard_(aeronautics)#Computer_control https://en.wikipedia.org/wiki/Canard_(aeronautics)#Computer_...
      - AWildC182 8y ago
        I hate to do this but the relevant part of the linked section itself has [citation needed] :) I don't doubt that the Wright Flyer was unstable though. Canards are kinda picky about angle, airfoil, and aspect ratio so if you don't fully understand the system as was the case at the time, it can lead to some problems.
        WalterBright 8y ago
        https://authors.library.caltech.edu/21217/ https://authors.library.caltech.edu/21217/ "The paper shows that the 1903 Flyer was readily controllable about all axes but was intrinsically unstable in pitch and roll, and it could barely be stabilized by a skilled pilot."
dTal 8y ago
The canard design is most certainly not unstable. I have built model canards almost by accident, from scratch, from first principles. Nor can you simply remove the canard from a properly designed aircraft, any more than you can delete the tail from a Cessna. Take a wing shaped piece of card or balsa and attempt to fly it by itself. You will find that it rapidly pitches up and stalls, flips over on its back, and repeats the process as it flutters it the ground. You can prevent it from doing this by taping a pole sticking to the front - a pencil, perhaps - as a counterweight to the pitch-up moment. This arrangement flies, but is very difficult to trim and has a tendency to suddenly invert as soon as the angle of attack goes negative. To stabilise it, all you have to do is put a small horizontal surface on the end of the pole. You have made a canard glider. (If you actually try this, you will also need some vertical stabilisation.)
- WalterBright 8y ago
  Taping a pole to a wing makes it an arrow. The bulk of the air surface is behind the CG. The wing becomes the "tail section".
  - dTal 8y ago
    Your argument is that anything with a center of lift behind the center of gravity is an arrow? In that case all aircraft are arrows.