REFLECTOR: Canard incidence

[Al Gietzen]

In a message dated 10/6/2006 9:59:50 A.M. Pacific Standard Time,
ALVentures at cox.net writes:

Clean stall (buffeting) is just below 70 kias, and 1 ½ - 2” trailing edge
down.

Al,

 

My STD-RG with the original canard w/cuffs & drooping tips stalls clean at
70kias with two up front, also showing 2" down deflection of the elevator.
On approach @ 90kt, I see 1" down deflection on the elevator. Your slow
speed #'s seem close.  If I remove the cuffs on the elevator, my stall will
be even less.  The 1 1/2" up at 175kias may or may not be out of whack.
With two up front @ cruise (158KIAS), my elevator is neutral.  Is that
175kias you mentioned in level flight?  If I point mine down hill to
175kias, I see about 1" up deflection on the elevator.  I know I have a
error in my airspeed, as I always true out at 174kt regardless of
altitude/temp.   

Yes, the 175 kias is level flight (that was about 195 ktas), and the plane
will go faster. Interesting; for roughly the same conditions, my elevators
are up about ½” further than yours.  With two of us, the trailing edge was
already up ½”+ at 155 kias.  Flying alone I would probably run out of
downtrim, and be pushing forward on the stick to stay level above about 160
kias.

 

Another thing just occurred to me. I have shimmed the right wing to lower
incidence to correct for a tendency to roll left – took the whole correction
on one side initially.  Now I am going to split the difference; IOW,
increase the incidence on both wings.  I presume that will result in
decreased canard incidence in flight. By how much – how sensitive is one to
the other?  Perhaps another flight is in order before messing up around the
canard.

 

The cuff/no-cuff controversy was going on when I was installing and
finishing my elevators.  I left about 60% of the cuff on.  In considering
removing the cuff to reduce landing speed, I decided it would make very
little difference at this point because at ½” down, there is very little gap
there anyway.

 

Al

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