REFLECTOR:Vortex Generators on XL

[John Dibble]

Jim Sower wrote:

>
><... 1/2" elevator trim to take off ...>
>With what kind of load in front seat?
>
170 lbs

>  Just you?  Or you and someone else?  What is
>your elevator position flat out at 8k ft?
>
At 160 k TAS, the elevator TE is about 1/4-3/8" higher than the canard TE.

>  Is it negative?  If so, how much?
>
>My best understanding of "stall proof" canard airplanes and "deep stall" is that (at
>the risk of over simplifying) canard airfoils have more chamber than main wing
>airfoils and therefore will stall at a lower AoA.  Negative (nose up, TE down)
>elevator increases effective camber and makes canard stall sooner still.  If the
>elevator deflection is negative (TE up) the effective camber decreases to the point
>that the main wing could stall first.  Soooo, assuming that all the incidences are
>correct, the danger of deep stall occurs when a) you are at high AoA, and b) you have
>TE up elevator.
>
It seems to me that to get a high AOA, the elevator TE needs to be 
down.  It also seems that once you are at a high AOA, you would need to 
put the elevator TE up in order to bring the nose down.  Are you saying 
that if I'm at a high AOA and I push the stick forward I increase the 
risk of a deep stall or am I confused?

John

>
>To the best of my knowledge, the neutral pitch stability that Scott alluded to does
>not really happen with positive (TE down) elevator in the steady state condition.
>
>Alex, please correct me if I'm wrong here .... Jim S.
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