Hi All,toggle quoted message Show quoted text
Some time ago, I did some airflow modeling on the tandem wing configuration of the Q-2 (LS1 canard and Eppler 1212 main wing). I have posted a diagram on Q-list group site that shows two models that I ran:
The model on the bottom of the diagram shows that the canard can fly at a high AOA (near stall angle) but because of the downwash from the canard, the main wing will be flying at a slightly higher(2-3 degrees) angle of attack than it does when the canard is flying at a low AOA (as shown in the top example in the diagram).
In this respect, the downwash does far more to prevent the main wing from stalling than does the angle of airplane as a whole. Because of this downwash effect on the main wing's AOA, mounting an AOA instrument on the main wing would be folly. The critical AOA is that of the canard, NOT the main wing so the canard is where the AOA instrument should be located (at least in the case of the Dynon-style pitot-based system).
By the way, if you fly the Q-2 inverted (negative G's), the downwash from the canard will be more pronounced on the main wing and will eliminate most or all of the lift from the main wing. And although the main wing is not technically "stalled", it will generate virtually no lift and the Q will enter a deep inverted stall. Positive G maneuvers won't do this, but negative G's will. This is why having the main wing mounted near the top of the fuselage and the canard mounted near the base of the fuselage is important to the stability of this design.
After I did this modeling, I realized that the main wing will never really stall, but it is capable of producing insufficient lift because of downwash from the canard. This may be an academic distinction, but it helps me think about how our unique design works.
Jay Scheevel -- Tri-Q, still building.
--- In Q-LIST@..., Mike Dwyer <q2pilot@...> wrote: